In situ recovery of shale oil

Claim 1

A method of recovering shale oil from an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation, which is to be fragmented by expansion toward such a columnar void, within said boundaries and extending away from a said free face; forming a plurality of blasting holes in said second portion extending substantially parallel to a said free face; loading explosive into said blasting holes; detonating said explosive for explosively expanding said second portion toward said columnar void; and retorting the fragmented formation containing oil shale in the in situ retort to recover shale oil and gaseous products therefrom.

Claim 2

A method of recovering shale oil from an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation, which is to be fragmented by expansion toward such a columnar void, within said boundaries and extending away from a said free face; forming a plurality of blasting holes in said second portion extending substantially parallel to a said free face; loading explosive into said blasting holes; detonating said explosive for explosively expanding said second portion toward said columnar void; and retorting the fragmented formation containing oil shale in the in situ retort to recover shale oil and gaseous products therefrom.

Claim 15

A method of recovering shale oil from a subterranean formation containing oil shale, comprising the steps of: excavating a first portion of said formation from a region in said formation to form a workroom having a floor plan approximately coextensive with the horizontal cross section of the region; excavating a second portion of said formation from said region to form at least one columnar void therein, the surface of the formation defining said columnar void providing at least one free face extending through said region, leaving a third portion of said formation, which is to be fragmented by expansion toward said columnar void, within said region extending away from a said free face; drilling, from the workroom, a plurality of blasting holes in said third portion substantially parallel to a said free face and extending for a principal portion of the length of the columnar void; loading the blasting holes with explosive, from the workroom; detonating the explosive to explosively expand said third portion toward said columnar void in a single round in a series comprising one or more layers parallel to a said free face to fragment said third portion and to fill with fragmented formation containing oil shale, said columnar void and the space in said region originally occupied by said third portion prior to the expansion; and retorting the fragmented oil shale-containing formation in said region to recover shale oil therefrom.

Claim 16

A method of recovering shale oil from a subterranean formation containing oil shale, comprising the steps of: excavating a first portion of said formation from a region in said formation to form a workroom having a floor plan approximately coextensive with the horizontal cross section of the region; excavating a second portion of said formation from said region to form at least one columnar void therein, the surface of the formation defining said columnar void providing at least one free face extending through said region, leaving a third portion of said formation, which is to be fragmented by expansion toward said columnar void, within said region extending away from a said free face; drilling, from the workroom, a plurality of blasting holes in said third portion substantially parallel to a said free face and extending for a principal portion of the length of the columnar void; loading the blasting holes with explosive, from the workroom; detonating the explosive to explosively expand said third portion toward said columnar void in a single round in a series comprising one or more layers parallel to a said free face to fragment said third portion and to fill with fragmented formation containing oil shale, said columnar void and the space in said region originally occupied by said third portion prior to the expansion; and retorting the fragmented oil shale-containing formation in said region to recover shale oil therefrom.

Claim 17

A method of recovering shale oil from an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation, which is to be fragmented by expansion toward such a columnar void, within said boundaries extending away from such a free face; forming a plurality of blasting holes in said second portion extending substantially parallel to such a free face; loading explosive into said blasting holes; detonating said explosive for explosively expanding said second portion toward said columnar void; and wherein the volume of such a columnar void, compared to the combined volume of such a columnar void and of the space occupied by the second portion prior to the expansion, is a. sufficiently small so that the expanded second portion fills such a columnar void and the space in the retort occupied by the second portion prior to the expansion, and b. sufficiently large so that the expanded second portion is fragmented; and retorting the fragmented formation containing oil shale in the in situ retort to recover shale oil and gaseous products therefrom.

Claim 18

A method of recovering shale oil from an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation, which is to be fragmented by expansion toward such a columnar void, within said boundaries extending away from such a free face; forming a plurality of blasting holes in said second portion extending substantially parallel to such a free face; loading explosive into said blasting holes; detonating said explosive for explosively expanding said second portion toward said columnar void; and wherein the volume of such a columnar void, compared to the combined volume of such a columnar void and of the space occupied by the second portion prior to the expansion, is a. sufficiently small so that the expanded second portion fills such a columnar void and the space in the retort occupied by the second portion prior to the expansion, and b. sufficiently large so that the expanded second portion is fragmented; and retorting the fragmented formation containing oil shale in the in situ retort to recover shale oil and gaseous products therefrom.

Claim 23

A method of recovering shale oil from an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one columnar void, the surface of the formation defining the columnar void providing at least one free face extending through the formation within said boundaries, and leaving a second portion of said formation, which is to be fragmented by expansion toward said columnar void, within said boundaries extending away from a said free face; explosively expanding said second portion toward said columnar void with a single round of explosions in one or more segments, including at least one layer of formation parallel to a said free face, to fragment said second portion and to fill with fragmented formation containing oil shale said columnar void and the space occupied by said second portion prior to the expansion; and wherein the volume of the columnar void is not greater than about 20% of the combined volume of said columnar void and of the space occupied by said second portion prior to the expansion; and retorting the fragmented formation containing oil shale in the in situ retort to recover shale oil and gaseous products therefrom.

Claim 24

A method of recovering shale oil from an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one columnar void, the surface of the formation defining the columnar void providing at least one free face extending through the formation within said boundaries, and leaving a second portion of said formation, which is to be fragmented by expansion toward said columnar void, within said boundaries extending away from a said free face; explosively expanding said second portion toward said columnar void with a single round of explosions in one or more segments, including at least one layer of formation parallel to a said free face, to fragment said second portion and to fill with fragmented formation containing oil shale said columnar void and the space occupied by said second portion prior to the expansion; and wherein the volume of the columnar void is not greater than about 20% of the combined volume of said columnar void and of the space occupied by said second portion prior to the expansion; and retorting the fragmented formation containing oil shale in the in situ retort to recover shale oil and gaseous products therefrom.

Claim 28

A method of recovering shale oil from in situ oil shale retorts in a subterranean formation containing oil shale, said retorts having top, bottom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating first portions of the subterranean formation to form an access and perimetric tunnel system leading to individual retort sites; excavating second portions of the subterranean formation at the individual retort sites to form a plurality of workrooms in communication with said tunnel system, arranged in rows and columns, the floor plan of such workrooms having dimensions approximating the dimensions of the retorts to be built using such workrooms; excavating a third portion of the formation from within the boundaries of the in situ oil shale retorts being formed to form at least one vertically extending columnar void in each such retort being formed, the surface of the formation defining the columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a fourth portion of said formation, which is to be fragmented by expansion towards said columnar void, within said boundaries and extending away from a said free face; explosively expanding said fourth portion toward said columnar void in a single round of explosions in one or more segments, including at least one layer of formation parallel to a said free face to fragment said fourth portion and to fill with fragmented formation containing oil shale said columnar void and the space occupied by said fourth portion prior to the expansion; retorting the fragmented formation containing oil shale in the retort by passing a retorting fluid therethrough; and removing the retorting products from the bottom of the respective retorts.

Claim 29

A method of recovering shale oil from in situ oil shale retorts in a subterranean formation containing oil shale, said retorts having top, bottom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating first portions of the subterranean formation to form an access and perimetric tunnel system leading to individual retort sites; excavating second portions of the subterranean formation at the individual retort sites to form a plurality of workrooms in communication with said tunnel system, arranged in rows and columns, the floor plan of such workrooms having dimensions approximating the dimensions of the retorts to be built using such workrooms; excavating a third portion of the formation from within the boundaries of the in situ oil shale retorts being formed to form at least one vertically extending columnar void in each such retort being formed, the surface of the formation defining the columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a fourth portion of said formation, which is to be fragmented by expansion towards said columnar void, within said boundaries and extending away from a said free face; explosively expanding said fourth portion toward said columnar void in a single round of explosions in one or more segments, including at least one layer of formation parallel to a said free face to fragment said fourth portion and to fill with fragmented formation containing oil shale said columnar void and the space occupied by said fourth portion prior to the expansion; retorting the fragmented formation containing oil shale in the retort by passing a retorting fluid therethrough; and removing the retorting products from the bottom of the respective retorts.

Claim 30

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation contained within the boundaries of the retort being formed to form at least one columnar void, the surface of the formation defining such void providing at least one free face extending vertically through the formation, in the retort being formed, leaving a second portion of said formation which is to be fragmented by expansion toward said columnar void, within said boundaries extending away from a said free face; and explosively expanding said second portion toward a said columnar void with a single round of sequential series of a plurality of explosions progressing outwardly from a said free face such that a series of segments comprising a plurality of vertically extending layers of formation parallel to said free face are expanded sequentially progressing away from a said free face, to fragment said second portion and to fill with fragmented formation containing oil shale said columnar void and the space occupied by said second portion prior to the expansion.

Claim 31

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation contained within the boundaries of the retort being formed to form at least one columnar void, the surface of the formation defining such void providing at least one free face extending vertically through the formation, in the retort being formed, leaving a second portion of said formation which is to be fragmented by expansion toward said columnar void, within said boundaries extending away from a said free face; and explosively expanding said second portion toward a said columnar void with a single round of sequential series of a plurality of explosions progressing outwardly from a said free face such that a series of segments comprising a plurality of vertically extending layers of formation parallel to said free face are expanded sequentially progressing away from a said free face, to fragment said second portion and to fill with fragmented formation containing oil shale said columnar void and the space occupied by said second portion prior to the expansion.

Claim 34

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having top, bottom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of said formation from within the boundaries of the retort to be formed to form a workroom intermediate the top and bottom boundaries, separating the formation in the retort being formed into an upper formation extending upwardly from the workroom and a lower formation extending downwardly from the workroom; excavating a second and a third portion of the said formation from said upper and lower formation, respectively, to form at least one vertically extending columnar void in each of said upper and lower formation, the surfaces of the formations defining such voids providing free faces extending vertically through said formations, leaving a fourth portion of the formation to be fragmented in said upper formation and a fifith portion of the formation to be fragmented in said lower formation which are to be fragmented by expansion toward said columnar voids, within said boundaries and extending away from said free faces; the volume of the columnar voids is from about 10% to about 20% of the combined volumes of said columnar voids and of the spaces occupied by said fourth and fifth portions of formation prior to the expansion; and explosively expanding each of the said fourth and fifth portions of the formation toward said columnar voids with a single round of sequential series of a plurality of explosions progressing outwardly from said free faces, such that a series of segments comprising a plurality of layers of formation parallel to said free faces are expanded sequentially progressing away from said free faces, to fragment said fourth and fifth portions and to fill with fragmented formation containing oil shale the columnar voids and the space in the in situ retort originally occupied by said fourth and said fifth portions prior to the expansion.

Claim 35

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having top, bottom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of said formation from within the boundaries of the retort to be formed to form a workroom intermediate the top and bottom boundaries, separating the formation in the retort being formed into an upper formation extending upwardly from the workroom and a lower formation extending downwardly from the workroom; excavating a second and a third portion of the said formation from said upper and lower formation, respectively, to form at least one vertically extending columnar void in each of said upper and lower formation, the surfaces of the formations defining such voids providing free faces extending vertically through said formations, leaving a fourth portion of the formation to be fragmented in said upper formation and a fifith portion of the formation to be fragmented in said lower formation which are to be fragmented by expansion toward said columnar voids, within said boundaries and extending away from said free faces; the volume of the columnar voids is from about 10% to about 20% of the combined volumes of said columnar voids and of the spaces occupied by said fourth and fifth portions of formation prior to the expansion; and explosively expanding each of the said fourth and fifth portions of the formation toward said columnar voids with a single round of sequential series of a plurality of explosions progressing outwardly from said free faces, such that a series of segments comprising a plurality of layers of formation parallel to said free faces are expanded sequentially progressing away from said free faces, to fragment said fourth and fifth portions and to fill with fragmented formation containing oil shale the columnar voids and the space in the in situ retort originally occupied by said fourth and said fifth portions prior to the expansion.

Claim 36

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having top, botom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of said formation from within the boundaries of the retort to be formed to form at least one workroom intermediate the top and bottom boundaries having a floor plan approximately coextensive with the cross-sectional dimensions of said retort, dividing the retort being formed into a plurality of sections of formation remaining within the retort; excavating a second portion of the said formation from at least one section to form at least one vertically extending columnar void in such section, the surface of the formation in the section defining such columnar void providing at least one free face extending vertically through said section, leaving a third portion in such section, which is to be fragmented by expansion towards said columnar void, within said boundaries and extending away from a said free face; the volume of the columnar void in said section being from about 10% to about 20% of the combined volume of said columnar void and of the space occupied by said third portion prior to the expansion; and explosively expanding said third portion toward said columnar void with a single round of sequential series of a plurality of explosions progressing outwardly from a said free face, such that a series of segments comprising a plurality of layers of formation parallel to a said free face are expanded sequentially progressing away from a said free face, to fragment said third portion and to fill with fragmented formation containing oil shale the columnar void and the space occupied by said third portion prior to the expansion.

Claim 37

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having top, botom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of said formation from within the boundaries of the retort to be formed to form at least one workroom intermediate the top and bottom boundaries having a floor plan approximately coextensive with the cross-sectional dimensions of said retort, dividing the retort being formed into a plurality of sections of formation remaining within the retort; excavating a second portion of the said formation from at least one section to form at least one vertically extending columnar void in such section, the surface of the formation in the section defining such columnar void providing at least one free face extending vertically through said section, leaving a third portion in such section, which is to be fragmented by expansion towards said columnar void, within said boundaries and extending away from a said free face; the volume of the columnar void in said section being from about 10% to about 20% of the combined volume of said columnar void and of the space occupied by said third portion prior to the expansion; and explosively expanding said third portion toward said columnar void with a single round of sequential series of a plurality of explosions progressing outwardly from a said free face, such that a series of segments comprising a plurality of layers of formation parallel to a said free face are expanded sequentially progressing away from a said free face, to fragment said third portion and to fill with fragmented formation containing oil shale the columnar void and the space occupied by said third portion prior to the expansion.

Claim 40

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having top, bottom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the said formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining the columnar void providing at least one free face extending vertically through the said formation in the retort being formed, leaving a second portion of said formation, which is to be fragmented by expansion toward said columnar void, within said boundaries extending away from a said free face; the horizontal cross-sectional area of the columnar void being from about 10% to about 20% of the horizontal cross-sectional area of the space occupied by said first and second portions prior to excavation; explosively expanding said second portion toward a said free face with a single round of sequential series of a plurality of groups of explosions progressing outwardly from said free face such that a series of segments comprising a plurality of layers of formation parallel to a said free face are expanded sequentially progressing away from a said free face, to fragment said second portion and to fill with fragmented formation containing oil shale the columnar void and the space occupied by said second portion prior to the expansion.

Claim 41

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having top, bottom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the said formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining the columnar void providing at least one free face extending vertically through the said formation in the retort being formed, leaving a second portion of said formation, which is to be fragmented by expansion toward said columnar void, within said boundaries extending away from a said free face; the horizontal cross-sectional area of the columnar void being from about 10% to about 20% of the horizontal cross-sectional area of the space occupied by said first and second portions prior to excavation; explosively expanding said second portion toward a said free face with a single round of sequential series of a plurality of groups of explosions progressing outwardly from said free face such that a series of segments comprising a plurality of layers of formation parallel to a said free face are expanded sequentially progressing away from a said free face, to fragment said second portion and to fill with fragmented formation containing oil shale the columnar void and the space occupied by said second portion prior to the expansion.

Claim 43

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having top, bottom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of said formation from within the boundaries of the retort to be formed to form a work room; excavating a second portion of said formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void therein, the surface of the formation defining the columnar void providing at least one free face extending vertically through the formation in the retort being formed, leaving a third portion of the formation which is to be fragmented by expansion toward said columnar void, within said boundaries extending away from a said free face; drilling, from the room, a plurality of blasting holes in said third portion substantially parallel to a said free face and extending for a principal portion of the length of said columnar void; loading the blasting holes from the room with explosive; and detonating the explosive to explosively expand said third portion toward said columnar void in a single round in one or more segments, at least one of which is a layer parallel to said free face to fragment said third portion and to fill with fragmented formation containing oil shale said columnar void and the space in the in situ retort originally occupied by said third portion prior to the expansion.

Claim 44

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having top, bottom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of said formation from within the boundaries of the retort to be formed to form a work room; excavating a second portion of said formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void therein, the surface of the formation defining the columnar void providing at least one free face extending vertically through the formation in the retort being formed, leaving a third portion of the formation which is to be fragmented by expansion toward said columnar void, within said boundaries extending away from a said free face; drilling, from the room, a plurality of blasting holes in said third portion substantially parallel to a said free face and extending for a principal portion of the length of said columnar void; loading the blasting holes from the room with explosive; and detonating the explosive to explosively expand said third portion toward said columnar void in a single round in one or more segments, at least one of which is a layer parallel to said free face to fragment said third portion and to fill with fragmented formation containing oil shale said columnar void and the space in the in situ retort originally occupied by said third portion prior to the expansion.

Claim 50

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having top, bottom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of said formation from within the boundaries of the in situ oil shale retort to be formed to form a work having a floor plan approximately coextensive with the horizontal cross-section of said retort; excavating a second portion of said formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void therein, the surface of the formation defining the columnar void providing at least one free face extending vertically through the formation in the retort being formed, leaving a third portion of the formation which is to be fragmented by expansion toward said columnar void, within said boundaries extending away from a said free face; drilling, from the room, a plurality of blasting holes in said third portion substantially parallel to a said free face and extending for a principal portion of the length of said columnar void; loading the blasting holes from the room with explosives; and detonating the explosive to explosively expand said third portion toward said columnar void in a single round in one or more segments, at least one of which is a layer parallel to said free face to fragment said third portion and to fill with fragmented formation containing oil shale said columnar void and the space in the situ retort originally occupied by said third portion prior to the expansion; wherein the horizontal cross-sectional area of the columnar void, relative to the horizontal cross-sectional area of the space occupied by said second and third portions prior to excavation of said second portion, is a. sufficiently small so that the expanded third portion fills the columnar void and the space in the retort occupied by the third portion prior to the expansion, and b. sufficiently large so that the expanded third portion is fragmented.

Claim 51

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having top, bottom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of said formation from within the boundaries of the in situ oil shale retort to be formed to form a work having a floor plan approximately coextensive with the horizontal cross-section of said retort; excavating a second portion of said formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void therein, the surface of the formation defining the columnar void providing at least one free face extending vertically through the formation in the retort being formed, leaving a third portion of the formation which is to be fragmented by expansion toward said columnar void, within said boundaries extending away from a said free face; drilling, from the room, a plurality of blasting holes in said third portion substantially parallel to a said free face and extending for a principal portion of the length of said columnar void; loading the blasting holes from the room with explosives; and detonating the explosive to explosively expand said third portion toward said columnar void in a single round in one or more segments, at least one of which is a layer parallel to said free face to fragment said third portion and to fill with fragmented formation containing oil shale said columnar void and the space in the situ retort originally occupied by said third portion prior to the expansion; wherein the horizontal cross-sectional area of the columnar void, relative to the horizontal cross-sectional area of the space occupied by said second and third portions prior to excavation of said second portion, is a. sufficiently small so that the expanded third portion fills the columnar void and the space in the retort occupied by the third portion prior to the expansion, and b. sufficiently large so that the expanded third portion is fragmented.

Claim 55

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having top, bottom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of said formation contained within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining the columnar void providing at least one free face extending vertically through said formation in the retort being formed, leaving a second portion of said formation, which is to be fragmented by expansion toward said columnar void, within said boundaries extending away from a said free face; explosively expanding said second portion toward a said free face with a single round of sequential series of a plurality of groups of explosions progressing outwardly from said free face such that a series of segments comprising a plurality of layers of formation parallel to a said free face are expanded sequentially progressing away from a said free face, to fragment said second portion and to fill with fragmented formation containing oil shale the columnar void andt space occupied by said second portion prior to the expansion; and wherein the time delay between consecutive series of explosions is sufficiently short so that the expansion of the formation in said second portion is completed before the first layer thereof that is expanded into said columnar void has had an opportunity to fall appreciably due to the pull of gravity.

Claim 56

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having top, bottom and side boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of said formation contained within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining the columnar void providing at least one free face extending vertically through said formation in the retort being formed, leaving a second portion of said formation, which is to be fragmented by expansion toward said columnar void, within said boundaries extending away from a said free face; explosively expanding said second portion toward a said free face with a single round of sequential series of a plurality of groups of explosions progressing outwardly from said free face such that a series of segments comprising a plurality of layers of formation parallel to a said free face are expanded sequentially progressing away from a said free face, to fragment said second portion and to fill with fragmented formation containing oil shale the columnar void andt space occupied by said second portion prior to the expansion; and wherein the time delay between consecutive series of explosions is sufficiently short so that the expansion of the formation in said second portion is completed before the first layer thereof that is expanded into said columnar void has had an opportunity to fall appreciably due to the pull of gravity.

Claim 65

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising steps of: excavating a first portion of said formation from within the boundaries of the retort to be formed to form a work room having a floor plan that is approximately coextensive with the horizontal cross section of the retort being formed; excavating in the formation means of access to a point underlying the work room; excavating a second portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining the columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a third portion of said formation, which is to be fragmented by expansion towards said columnar void, within said boundaries and extending away from a said free face, and wherein said columar void extends vertically from the means of access to a point spaced from the bottom of the work room, leaving a horizontal pillar of intact shale between the top of the columnar void and the bottom of the work room; drilling, from the work room, a plurality of blasting holes downwardly into said third portion and parallel to said free face, the blasting holes being distributed throughout said third portion; loading the blasting holes, from the work room, with explosive; and detonating the explosive to explosively expand and to fragment said third portion and to fill with fragmented formation containing oil shale said columnar void and the space occupied by said third portion prior to the expansion.

Claim 66

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising steps of: excavating a first portion of said formation from within the boundaries of the retort to be formed to form a work room having a floor plan that is approximately coextensive with the horizontal cross section of the retort being formed; excavating in the formation means of access to a point underlying the work room; excavating a second portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining the columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a third portion of said formation, which is to be fragmented by expansion towards said columnar void, within said boundaries and extending away from a said free face, and wherein said columar void extends vertically from the means of access to a point spaced from the bottom of the work room, leaving a horizontal pillar of intact shale between the top of the columnar void and the bottom of the work room; drilling, from the work room, a plurality of blasting holes downwardly into said third portion and parallel to said free face, the blasting holes being distributed throughout said third portion; loading the blasting holes, from the work room, with explosive; and detonating the explosive to explosively expand and to fragment said third portion and to fill with fragmented formation containing oil shale said columnar void and the space occupied by said third portion prior to the expansion.

Claim 70

A method for forming, in a subterranean formation containing oil shale, a plurality of in situ oil shale retorts having boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating first portions of the subterranean formation to form an access and perimetric tunnel system leading to individual retort sites; excavating second portions of the subterranean formation at the individual retort sites to form a plurality of work rooms in communication with said tunnel system, arranged in rows and columns, the floor plan of such work rooms having dimensions approximating the dimensions of the retorts to be built using such work rooms; excavating a third portion of the formation from within the boundaries of the in situ oil shale retorts being formed to form at least one vertically extending columnar void in each such retort being formed, the surface of the formation defining the columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a fourth portion of said formation, which is to be fragmented by expansion towards said columnar void, within said boundaries and extending away from a said free face; explosively expanding said fourth portion toward said columnar void with a single round of explosions in one or more segments, including at least one layer of formation parallel to a said free face, to fragment said fourth portion and to fill with fragmented formation containing oil shale said columnar void and the space occupied by said third portion prior to the expansion.

Claim 71

A method for forming, in a subterranean formation containing oil shale, a plurality of in situ oil shale retorts having boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating first portions of the subterranean formation to form an access and perimetric tunnel system leading to individual retort sites; excavating second portions of the subterranean formation at the individual retort sites to form a plurality of work rooms in communication with said tunnel system, arranged in rows and columns, the floor plan of such work rooms having dimensions approximating the dimensions of the retorts to be built using such work rooms; excavating a third portion of the formation from within the boundaries of the in situ oil shale retorts being formed to form at least one vertically extending columnar void in each such retort being formed, the surface of the formation defining the columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a fourth portion of said formation, which is to be fragmented by expansion towards said columnar void, within said boundaries and extending away from a said free face; explosively expanding said fourth portion toward said columnar void with a single round of explosions in one or more segments, including at least one layer of formation parallel to a said free face, to fragment said fourth portion and to fill with fragmented formation containing oil shale said columnar void and the space occupied by said third portion prior to the expansion.

Claim 79

A method of forming, in a subterranean formation containing oil shale, a plurality of in situ oil shale retorts having boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, said retorts being arranged in rows and columns comprising the steps of: excavating first portions of the subterranean formation to form an access and perimetrical tunnel system leading to individual retort sites comprising a. a plurality of work room access tunnels, each such work room access tunnel being located between a pair of rows of retort sites at the level at which said work rooms are to be excavated, and branch tunnels leading from said work room access tunnels to said work room area, b. a plurality of overlying access tunnels, overlying said retorts being formed, and connecting conduits leading from the overlying access tunnels to the top of the individual retorts and a perimetrical tunnel surrounding and interconnecting the overlying access tunnels, c. a plurality of underlying access tunnels, underlying said retorts being formed and lower connecting tunnels leading from the underlying access tunnels to the bottoms of the individual retorts being formed and a perimetrical tunnel surrounding and interconnecting the underlying access tunnels, excavating second portions of the subterranean formation to form a plurality of work rooms in communication with said branch tunnels, arranged in rows and columns, and located at a level intermediate the top and bottom of the retorts to be formed, the floor plan of such work rooms having dimensions approximating the dimensions of the retorts to be built using such work rooms, and a said work room dividing said formation within said boundaries of said retort to be formed into an upper section and a lower section; excavating a third portion of the formation from each of said upper and lower sections in a plurality of rooms to form in each section at least one vertically extending columnar void, the surface of the formation defining the columnar void providing at least one free face extending vertically through the formation of said section and leaving, in each section, a fourth portion of said formation, which is to be fragmented by expansion towards said columnar void, within said boundaries and extending away from a said free face; and explosively expanding said fourth portion toward said columnar void in each section in a single round of explosions in one or more segments, including at least one layer of formation parallel to a said free face, to fragment said fourth portion and to fill with fragmented formation containing oil shale said columnar void and the space occupied by said fourth portion prior to the expansion.

Claim 80

A method of forming, in a subterranean formation containing oil shale, a plurality of in situ oil shale retorts having boundaries of unfragmented formation and containing fragmented formation containing oil shale therein, said retorts being arranged in rows and columns comprising the steps of: excavating first portions of the subterranean formation to form an access and perimetrical tunnel system leading to individual retort sites comprising a. a plurality of work room access tunnels, each such work room access tunnel being located between a pair of rows of retort sites at the level at which said work rooms are to be excavated, and branch tunnels leading from said work room access tunnels to said work room area, b. a plurality of overlying access tunnels, overlying said retorts being formed, and connecting conduits leading from the overlying access tunnels to the top of the individual retorts and a perimetrical tunnel surrounding and interconnecting the overlying access tunnels, c. a plurality of underlying access tunnels, underlying said retorts being formed and lower connecting tunnels leading from the underlying access tunnels to the bottoms of the individual retorts being formed and a perimetrical tunnel surrounding and interconnecting the underlying access tunnels, excavating second portions of the subterranean formation to form a plurality of work rooms in communication with said branch tunnels, arranged in rows and columns, and located at a level intermediate the top and bottom of the retorts to be formed, the floor plan of such work rooms having dimensions approximating the dimensions of the retorts to be built using such work rooms, and a said work room dividing said formation within said boundaries of said retort to be formed into an upper section and a lower section; excavating a third portion of the formation from each of said upper and lower sections in a plurality of rooms to form in each section at least one vertically extending columnar void, the surface of the formation defining the columnar void providing at least one free face extending vertically through the formation of said section and leaving, in each section, a fourth portion of said formation, which is to be fragmented by expansion towards said columnar void, within said boundaries and extending away from a said free face; and explosively expanding said fourth portion toward said columnar void in each section in a single round of explosions in one or more segments, including at least one layer of formation parallel to a said free face, to fragment said fourth portion and to fill with fragmented formation containing oil shale said columnar void and the space occupied by said fourth portion prior to the expansion.

Claim 81

The method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having boundaries of unfragmented formation and containing fragmented oil shale therein, comprising the steps of: excavating a first portion of the formation contained within the boundaries of the retort being formed to leave at least one columnar void that has a first free face extending vertically through the oil shale in the retort being formed, the oil shale remaining within said boundaries including a second portion to be expanded adjacent said first free face; excavating a third portion of the formation contained within the boundaries of the retort being formed adjacent one end of the first free face to leave a room having a floor plan with a perimeter coinciding approximately with the perimeter of the horizontal cross-sectional area of the retort being formed and a second free face extending transverse to the first free face, the oil shale remaining within said boundaries including a fourth portion to be expanded adjacent said second free face; explosively expanding the second portion toward said first free face in a single round in one or more layers parallel to said first free face to fragment the second portion; and explosively expanding the fourth portion toward said second free face in a single round to fragment said fourth portion.

Claim 82

The method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having boundaries of unfragmented formation and containing fragmented oil shale therein, comprising the steps of: excavating a first portion of the formation contained within the boundaries of the retort being formed to leave at least one columnar void that has a first free face extending vertically through the oil shale in the retort being formed, the oil shale remaining within said boundaries including a second portion to be expanded adjacent said first free face; excavating a third portion of the formation contained within the boundaries of the retort being formed adjacent one end of the first free face to leave a room having a floor plan with a perimeter coinciding approximately with the perimeter of the horizontal cross-sectional area of the retort being formed and a second free face extending transverse to the first free face, the oil shale remaining within said boundaries including a fourth portion to be expanded adjacent said second free face; explosively expanding the second portion toward said first free face in a single round in one or more layers parallel to said first free face to fragment the second portion; and explosively expanding the fourth portion toward said second free face in a single round to fragment said fourth portion.

Claim 90

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a plurality of first portions of the formation from within the boundaries of the in situ oil shale retort being formed to form a plurality of vertically extending columnar voids, the surface of the formation defining each columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a plurality of second portions of said formation, which are to be fragmented by expansion toward the columnar voids, within said boundaries and extending away from such free faces; and forming a plurality of blasting holes in each of said second portions extending substantially parallel to such a free face; loading explosive into said blasting holes; and detonating said explosive for explosively expanding each of said second portions toward a columnar void to form a continuous mass of fragmented formation containing oil shale within said boundaries.

Claim 91

A method of forming, in a subterranean formation containing oil shale, an in situ oil shale retort having boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a plurality of first portions of the formation from within the boundaries of the in situ oil shale retort being formed to form a plurality of vertically extending columnar voids, the surface of the formation defining each columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a plurality of second portions of said formation, which are to be fragmented by expansion toward the columnar voids, within said boundaries and extending away from such free faces; and forming a plurality of blasting holes in each of said second portions extending substantially parallel to such a free face; loading explosive into said blasting holes; and detonating said explosive for explosively expanding each of said second portions toward a columnar void to form a continuous mass of fragmented formation containing oil shale within said boundaries.

Claim 103

A method of forming an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation which is to be fragmented by expansion toward such a columnar void within said boundaries and extending away from such a column void; forming a plurality of blasting holes in said second portion extending substantially parallel to such a free face; loading explosive in said blasting holes; and denoting said explosive for explosively expanding said second portion toward such a columnar void.

Claim 104

A method of forming an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation which is to be fragmented by expansion toward such a columnar void within said boundaries and extending away from such a column void; forming a plurality of blasting holes in said second portion extending substantially parallel to such a free face; loading explosive in said blasting holes; and denoting said explosive for explosively expanding said second portion toward such a columnar void.

Claim 114

A method of forming an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation which is to be fragmented by expansion toward such a columnar void within said boundaries and extending away from such a columnar void; forming a plurality of vertically extending blasting holes in said second portion; loading explosive in said blasting holes; and detonating said explosive for explosively expanding said second portion toward such a columnar void.

Claim 115

A method of forming an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation which is to be fragmented by expansion toward such a columnar void within said boundaries and extending away from such a columnar void; forming a plurality of vertically extending blasting holes in said second portion; loading explosive in said blasting holes; and detonating said explosive for explosively expanding said second portion toward such a columnar void.

Claim 120

A method of forming an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation which is to be fragmented by expansion toward such a columnar void within said boundaries and extending away from such a columnar void; forming a plurality of blasting holes in said second portion extending substantially parallel to such a free face; loading explosive in said blasting holes; and detonating said explosive in a single round of a sequential seris of detonations progressing outwardly from such a free face for explosively expanding said second portion toward such a columnar void.

Claim 121

A method of forming an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation which is to be fragmented by expansion toward such a columnar void within said boundaries and extending away from such a columnar void; forming a plurality of blasting holes in said second portion extending substantially parallel to such a free face; loading explosive in said blasting holes; and detonating said explosive in a single round of a sequential seris of detonations progressing outwardly from such a free face for explosively expanding said second portion toward such a columnar void.

Claim 122

A method of forming an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the insitu oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation which is to be fragmented by expansion toward such a columnar void within said boundaries and extending away from such a columnar void; forming a plurality of vertically extending blasting holes in said second portion; loading explosive in said blasting holes; and detonating said explosive in a single round of a sequential series of detonations progressing outwardly from such a free face for explosively expanding said second portion toward such a columnar void.

Claim 123

A method of forming an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the insitu oil shale retort being formed to form at least one vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation which is to be fragmented by expansion toward such a columnar void within said boundaries and extending away from such a columnar void; forming a plurality of vertically extending blasting holes in said second portion; loading explosive in said blasting holes; and detonating said explosive in a single round of a sequential series of detonations progressing outwardly from such a free face for explosively expanding said second portion toward such a columnar void.

Claim 124

A method of forming an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating the first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one substantially cylindrical vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation which is to be fragmented by expansion toward such a columnar void within said boundaries and extending away from such a columnar void; forming a plurality of vertically extending blasting holes in said second portion; loading explosive in said blasting holes; and detonating said explosive for explosively expanding said second portion toward such a columnar void.

Claim 125

A method of forming an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating the first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one substantially cylindrical vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving a second portion of said formation which is to be fragmented by expansion toward such a columnar void within said boundaries and extending away from such a columnar void; forming a plurality of vertically extending blasting holes in said second portion; loading explosive in said blasting holes; and detonating said explosive for explosively expanding said second portion toward such a columnar void.

Claim 128

A method of forming an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one substantially cylindrical vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation which is to be fragmented by expansion toward such a columnar void within said boundaries and extending away from such a columnar void; forming a plurality of vertically extending blasting holes arranged in a plurality of rings substantially parallel to such a free face and to form a rectangular border around the rings in said second portion; loading explosive in said blasting holes; and detonating in said explosive in a single round of a sequential series of a plurality of groups of detonations progressing outwardly from such a free face with time delays between the detonations of the groups progressing outwardly for explosively expanding said second portion toward such a columnar void.

Claim 129

A method of forming an in situ oil shale retort in a subterranean formation containing oil shale, said retort having top, bottom, and side boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one substantially cylindrical vertically extending columnar void, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation which is to be fragmented by expansion toward such a columnar void within said boundaries and extending away from such a columnar void; forming a plurality of vertically extending blasting holes arranged in a plurality of rings substantially parallel to such a free face and to form a rectangular border around the rings in said second portion; loading explosive in said blasting holes; and detonating in said explosive in a single round of a sequential series of a plurality of groups of detonations progressing outwardly from such a free face with time delays between the detonations of the groups progressing outwardly for explosively expanding said second portion toward such a columnar void.

Claim 130

A method of forming, in a subterranean formation containing oil shale, a plurality of in situ shale retorts having boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating first portions of the subterranean formation to form an access and perimetric tunnel system wherein access tunnels lead to individual retort sites; excavating second portions of the subterranean formation to form at least one work area at the site of each the in situ oil shale retorts being formed, such a work area being in communication with said tunnel system; excavating third portions of the formation from within the boundaries of each of the in situ oil shale retort being formed to form at least one vertically extending columnar void in each such retort being formed, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving in each such retort being formed a fourth portion of said formation extending away from such a free face which is to be fragmented by expansion toward such a columnar void; drilling, from such a work area, a plurality of blasting holes in said fourth portion extending substantially parallel to such a free face; loading explosive into the blasting holes from the work area; and detonating the explosive for explosively expanding said fourth portion toward such a columnar void.

Claim 131

A method of forming, in a subterranean formation containing oil shale, a plurality of in situ shale retorts having boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating first portions of the subterranean formation to form an access and perimetric tunnel system wherein access tunnels lead to individual retort sites; excavating second portions of the subterranean formation to form at least one work area at the site of each the in situ oil shale retorts being formed, such a work area being in communication with said tunnel system; excavating third portions of the formation from within the boundaries of each of the in situ oil shale retort being formed to form at least one vertically extending columnar void in each such retort being formed, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving in each such retort being formed a fourth portion of said formation extending away from such a free face which is to be fragmented by expansion toward such a columnar void; drilling, from such a work area, a plurality of blasting holes in said fourth portion extending substantially parallel to such a free face; loading explosive into the blasting holes from the work area; and detonating the explosive for explosively expanding said fourth portion toward such a columnar void.

Claim 135

A method of forming, in a subterranean formation containing oil shale, a plurality of in situ oil shale retorts having boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating first portions of the subterranean formation to form an access and perimetric tunnel system comprising; a. a plurality of upper access tunnels at a level in the formation above the retorts being formed and connecting conduits leading from the upper access tunnels to the tops of the individual retorts being formed and an upper perimetric tunnel surrounding and connecting the upper access tunnels, b. a plurality of lower access tunnels at a level below the retorts being formed and connecting tunnels leading from the lower access tunnels to the bottoms of the individual retorts being formed and a lower perimetric tunnel surrounding and connecting the lower access tunnels, c. a plurality of work area access tunnels and branch tunnels leading from said work area access tunnels to work areas to be formed and a work area perimetric tunnel surrounding and connecting the work area access tunnels; excavating second portions of the subterranean formation to form at least one work area, within the boudaries of each of the in situ oil shale retorts being formed, in communication with said tunnel system; excavating third portions of the formation from within the boundaries of the in situ oil shale retorts being formed to form at least one vertically extending columnar void in each such retort being formed, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving in each such retort being formed a fourth portion of said formation, extending away from such a free face, which is to be fragmented by expansion toward such a columnar void; drilling, from such a work area, a plurality of blasting holes in said fourth portion extending substantially parallel to such a free face; loading explosive into the blasting holes from the work area; and detonating the explosive for explosively expanding said fourth portion toward such a columnar void.

Claim 136

A method of forming, in a subterranean formation containing oil shale, a plurality of in situ oil shale retorts having boundaries of the formation and containing fragmented formation containing oil shale therein, comprising the steps of: excavating first portions of the subterranean formation to form an access and perimetric tunnel system comprising; a. a plurality of upper access tunnels at a level in the formation above the retorts being formed and connecting conduits leading from the upper access tunnels to the tops of the individual retorts being formed and an upper perimetric tunnel surrounding and connecting the upper access tunnels, b. a plurality of lower access tunnels at a level below the retorts being formed and connecting tunnels leading from the lower access tunnels to the bottoms of the individual retorts being formed and a lower perimetric tunnel surrounding and connecting the lower access tunnels, c. a plurality of work area access tunnels and branch tunnels leading from said work area access tunnels to work areas to be formed and a work area perimetric tunnel surrounding and connecting the work area access tunnels; excavating second portions of the subterranean formation to form at least one work area, within the boudaries of each of the in situ oil shale retorts being formed, in communication with said tunnel system; excavating third portions of the formation from within the boundaries of the in situ oil shale retorts being formed to form at least one vertically extending columnar void in each such retort being formed, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boundaries, and leaving in each such retort being formed a fourth portion of said formation, extending away from such a free face, which is to be fragmented by expansion toward such a columnar void; drilling, from such a work area, a plurality of blasting holes in said fourth portion extending substantially parallel to such a free face; loading explosive into the blasting holes from the work area; and detonating the explosive for explosively expanding said fourth portion toward such a columnar void.

Claim 137

A method of forming, in a subterranean formation containing oil shale, an in situ shale retort containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of said formation at the site of the in situ oil shale retort being formed to form a work area; excavating a second portion of said formation, to form a means of access to a point underlying the work area; excavating a third portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void having communication with the access means, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boudnaries, and leaving a fourth portion of said formation, which is to be fragmented by expansion toward such a columnar void, within said boundaries and extending away from such a free face, and wherein such a columnar void extends downwardly from a level spaced from the bottom of the work area, leaving a horizontal pillar of intact formation between the top of such a columnar void and the bottom of the work area, wherein the access means is utilized in excavating said third portion; drilling, from the work area, a plurality of blasting holes in said fourth portion extending substantially parallel to such a free face; loading explosive into the blasting holes from the work area; an detonating the explosive to explosively expand said fourth portion toward such a columnar void.

Claim 138

A method of forming, in a subterranean formation containing oil shale, an in situ shale retort containing fragmented formation containing oil shale therein, comprising the steps of: excavating a first portion of said formation at the site of the in situ oil shale retort being formed to form a work area; excavating a second portion of said formation, to form a means of access to a point underlying the work area; excavating a third portion of the formation from within the boundaries of the in situ oil shale retort being formed to form at least one vertically extending columnar void having communication with the access means, the surface of the formation defining such a columnar void providing at least one free face extending vertically through the formation within said boudnaries, and leaving a fourth portion of said formation, which is to be fragmented by expansion toward such a columnar void, within said boundaries and extending away from such a free face, and wherein such a columnar void extends downwardly from a level spaced from the bottom of the work area, leaving a horizontal pillar of intact formation between the top of such a columnar void and the bottom of the work area, wherein the access means is utilized in excavating said third portion; drilling, from the work area, a plurality of blasting holes in said fourth portion extending substantially parallel to such a free face; loading explosive into the blasting holes from the work area; an detonating the explosive to explosively expand said fourth portion toward such a columnar void.