In situ oil shale retorts with gas barriers for maximizing product recovery

Claim 1

A method of recovering liquid and gaseous products from a plurality of in situ oil shale retorts in a subterranean formation containing oil shale, wherein each retort contains a fragmented permeable mass of formation particles containing oil shale, the method comprising the steps of: excavating at least one void in each of a plurality of in situ oil shale retort sites, leaving a remaining portion of unfragmented formation within each retort site adjacent such a void; explosively expanding such a remaining portion of unfragmented formation within each retort site toward such a void for forming a fragmented permeable mass of formation particles containing oil shale in each of a plurality of in situ oil shale retorts; leaving a gas barrier between the fragmented masses in an adjacent pair of such retorts in the form of a vertically extending partition of substantially unfragmented formation sufficiently thick to inhibit substantial gas flow between the fragmented masses in such adjacent retorts and sufficiently thin that the partition independently supports substantially the same proportionate amount of the load from overburden above the elevation of the retorts as is supported by the fragmented masses in such adjacent retorts for permitting substantially uniform subsidence of overburden above the gas barrier and above the fragmented masses; establishing a combustion zone in at least one of such fragmented masses; introducing an oxygen-supplying gas to such fragmented mass for sustaining the combustion zone and for advancing the combustion zone through such fragmented mass, and for retorting oil shale to produce liquid and gaseous products in a retorting zone on the advancing side of the combustion zone; and withdrawing such liquid and gaseous products from such a fragmented mass on the advancing side of the retorting zone.

Claim 2

A method of recovering liquid and gaseous products from a plurality of in situ oil shale retorts in a subterranean formation containing oil shale, wherein each retort contains a fragmented permeable mass of formation particles containing oil shale, the method comprising the steps of: excavating at least one void in each of a plurality of in situ oil shale retort sites, leaving a remaining portion of unfragmented formation within each retort site adjacent such a void; explosively expanding such a remaining portion of unfragmented formation within each retort site toward such a void for forming a fragmented permeable mass of formation particles containing oil shale in each of a plurality of in situ oil shale retorts; leaving a gas barrier between the fragmented masses in an adjacent pair of such retorts in the form of a vertically extending partition of substantially unfragmented formation sufficiently thick to inhibit substantial gas flow between the fragmented masses in such adjacent retorts and sufficiently thin that the partition independently supports substantially the same proportionate amount of the load from overburden above the elevation of the retorts as is supported by the fragmented masses in such adjacent retorts for permitting substantially uniform subsidence of overburden above the gas barrier and above the fragmented masses; establishing a combustion zone in at least one of such fragmented masses; introducing an oxygen-supplying gas to such fragmented mass for sustaining the combustion zone and for advancing the combustion zone through such fragmented mass, and for retorting oil shale to produce liquid and gaseous products in a retorting zone on the advancing side of the combustion zone; and withdrawing such liquid and gaseous products from such a fragmented mass on the advancing side of the retorting zone.

Claim 12

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each in situ oil shale retort containing a fragemented permeable mass of formation particles containing oil shale, and a gas barrier between an adjacent pair of such fragmented masses, the gas barrier comprising a vertically extending partition of substantially unfragmented formation that is sufficiently thick to inhibit substantial gas flow between the adjacent fragmented masses and sufficiently thin that the partition independently supports substantially the same proportionate amount of load from the overburden at elevations above the retorts as is supported by the fragmented masses in the adjacent retorts for permitting substantially uniform subsidence of overburden above the gas barrier and above the fragmented masses.

Claim 13

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each in situ oil shale retort containing a fragemented permeable mass of formation particles containing oil shale, and a gas barrier between an adjacent pair of such fragmented masses, the gas barrier comprising a vertically extending partition of substantially unfragmented formation that is sufficiently thick to inhibit substantial gas flow between the adjacent fragmented masses and sufficiently thin that the partition independently supports substantially the same proportionate amount of load from the overburden at elevations above the retorts as is supported by the fragmented masses in the adjacent retorts for permitting substantially uniform subsidence of overburden above the gas barrier and above the fragmented masses.

Claim 17

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale, and a gas barrier between an adjacent pair of such fragmented masses, the gas barrier comprising a vertically extending partition of substantially unfragmented formation that is sufficiently thick to inhibit substantial gas flow between the adjacent fragmented masses and sufficiently thin that the partition yields structurally under load from the overburden at elevations above the retorts, without substantial fragmenting of the partition for permitting substantially uniform subsidence of overburden above the gas barrier and above the fragmented masses.

Claim 18

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale, and a gas barrier between an adjacent pair of such fragmented masses, the gas barrier comprising a vertically extending partition of substantially unfragmented formation that is sufficiently thick to inhibit substantial gas flow between the adjacent fragmented masses and sufficiently thin that the partition yields structurally under load from the overburden at elevations above the retorts, without substantial fragmenting of the partition for permitting substantially uniform subsidence of overburden above the gas barrier and above the fragmented masses.

Claim 21

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each of such in situ oil shale retorts being filled with a fragmented permeable mass of formation particles and separated from at least one adjacent in situ oil shale retort by a gas barrier in the form of a vertically extending partition of substantially unfragmented formation that is sufficiently thick to inhibit substantial gas flow between the adjacent retorts, and sufficiently thin that the partition supports only a portion of the load of overburden at elevations above the retorts with approximately the same proportionate amount of load being supported by such partition as by the fragmented masses in adjacent retorts for permitting uniform subsidence of overburden above the gas barrier and above such a fragmented mass.

Claim 22

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each of such in situ oil shale retorts being filled with a fragmented permeable mass of formation particles and separated from at least one adjacent in situ oil shale retort by a gas barrier in the form of a vertically extending partition of substantially unfragmented formation that is sufficiently thick to inhibit substantial gas flow between the adjacent retorts, and sufficiently thin that the partition supports only a portion of the load of overburden at elevations above the retorts with approximately the same proportionate amount of load being supported by such partition as by the fragmented masses in adjacent retorts for permitting uniform subsidence of overburden above the gas barrier and above such a fragmented mass.

Claim 24

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each of such in situ oil shale retorts being filled with a fragmented permeable mass of formation particles and separated from at least one adjacent in situ oil shale retort by a gas barrier in the form of a vertically extending partition of substantially unfragmented formation that is sufficiently thick to inhibit substantial gas flow between the adjacent retorts, such a gas barrier being sufficiently thin that the partition yields structurally under load from the overburden at elevations above the retorts without fragmenting the partition form permitting substantially uniform subsidence of overburden above the gas barrier and above the fragmented masses.

Claim 25

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each of such in situ oil shale retorts being filled with a fragmented permeable mass of formation particles and separated from at least one adjacent in situ oil shale retort by a gas barrier in the form of a vertically extending partition of substantially unfragmented formation that is sufficiently thick to inhibit substantial gas flow between the adjacent retorts, such a gas barrier being sufficiently thin that the partition yields structurally under load from the overburden at elevations above the retorts without fragmenting the partition form permitting substantially uniform subsidence of overburden above the gas barrier and above the fragmented masses.

Claim 27

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each of such in situ oil shale retorts being filled with a fragmented permeable mass of formation particles and separated from at least one adjacent in situ oil shale retort by a gas barrier in the form of a vertically extending partition of substantially unfragmented formation that is sufficiently thick to inhibit substantial gas flow between the adjacent retorts and sufficiently thin that subsidence of an upper portion of the partition is substantially the same as subsidence of fragmented masses in adjacent retorts from permitting substantially uniform subsidence of overburden above the gas barrier and above the fragmented masses.

Claim 28

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each of such in situ oil shale retorts being filled with a fragmented permeable mass of formation particles and separated from at least one adjacent in situ oil shale retort by a gas barrier in the form of a vertically extending partition of substantially unfragmented formation that is sufficiently thick to inhibit substantial gas flow between the adjacent retorts and sufficiently thin that subsidence of an upper portion of the partition is substantially the same as subsidence of fragmented masses in adjacent retorts from permitting substantially uniform subsidence of overburden above the gas barrier and above the fragmented masses.

Claim 29

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each of such in situ oil shale retorts being filled with a fragmented permeable mass of formation particles and separated from at least one adjacent in situ oil shale retort by a gas barrier in the form of a vertically extending partition of substantially unfragmented formation that has a thickness at least about 50% greater than a selected distance wherein at least about 3/4 of the naturally occurring cleavage planes in the formation are spaced apart less than the selected distance, such a gas barrier being sufficiently thin that the partition yields structurally under load from the overburden at elevations above the retorts without fragmenting the partition.

Claim 30

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each of such in situ oil shale retorts being filled with a fragmented permeable mass of formation particles and separated from at least one adjacent in situ oil shale retort by a gas barrier in the form of a vertically extending partition of substantially unfragmented formation that has a thickness at least about 50% greater than a selected distance wherein at least about 3/4 of the naturally occurring cleavage planes in the formation are spaced apart less than the selected distance, such a gas barrier being sufficiently thin that the partition yields structurally under load from the overburden at elevations above the retorts without fragmenting the partition.

Claim 31

A system of in situ oil shale retorts in a suberranean formation containing oil shale, each of such in situ oil shale retorts being filled with a fragmented permeable mass of formation particles and separated from at least one adjacent in situ oil shale retort by a gas barrier in the form of a vertically extending partition of substantially unfragmented formation having a thickness at least about 50% greater than the maximum spacing of about 3/4 of the naturally occurring cleavage planes in the formation and sufficiently thin that subsidence of an upper portion of the partition is substantially the same as subsidence of fragmented masses in adjacent retorts.

Claim 32

A system of in situ oil shale retorts in a suberranean formation containing oil shale, each of such in situ oil shale retorts being filled with a fragmented permeable mass of formation particles and separated from at least one adjacent in situ oil shale retort by a gas barrier in the form of a vertically extending partition of substantially unfragmented formation having a thickness at least about 50% greater than the maximum spacing of about 3/4 of the naturally occurring cleavage planes in the formation and sufficiently thin that subsidence of an upper portion of the partition is substantially the same as subsidence of fragmented masses in adjacent retorts.

Claim 33

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each of such in situ oil shale retorts being filled with a fragmented permeable mass of formation particles and separated from at least one adjacent in situ oil shale retort by a gas barrier in the form of a vertically extending partition of unfragmented formation having a thickness greater than the spacing between most of the naturally occurring cleavage planes in the formation, such a partition being sufficiently thin that subsidence of an upper portion of the partition is substantially the same as subsidence of fragmented masses in adjacent retorts.

Claim 34

A system of in situ oil shale retorts in a subterranean formation containing oil shale, each of such in situ oil shale retorts being filled with a fragmented permeable mass of formation particles and separated from at least one adjacent in situ oil shale retort by a gas barrier in the form of a vertically extending partition of unfragmented formation having a thickness greater than the spacing between most of the naturally occurring cleavage planes in the formation, such a partition being sufficiently thin that subsidence of an upper portion of the partition is substantially the same as subsidence of fragmented masses in adjacent retorts.

Claim 49

A method for forming a plurality of in situ oil shale retorts in a subterranean formation containing oil shale wherein each retort contains a fragmented permeable mass of formation particles containing oil shale, the method comprising the steps of: excavating at least one void in each of a plurality of in situ oil shale retort sites leaving a remaining portion of unfragmented formation within each retort site adjacent such a void; drilling a plurality of mutually spaced apart blasting holes in such remaining portion of unfragmented formation within such a retort site; loading explosive into such blasting holes; and detonating such explosive for explosively expanding such remaining portion of formation towards such a void for forming a fragmented permeable mass of particles within such a retort and leaving a gas barrier in the form of a vertically extending partition of substantially unfragmented formation between such fragmented permeable mass and an adjacent retort site, the gas barrier having a thickness in the range of from about one to 1.5 times the burden distance of explosive in blasting holes located closest to the gas barrier.

Claim 50

A method for forming a plurality of in situ oil shale retorts in a subterranean formation containing oil shale wherein each retort contains a fragmented permeable mass of formation particles containing oil shale, the method comprising the steps of: excavating at least one void in each of a plurality of in situ oil shale retort sites leaving a remaining portion of unfragmented formation within each retort site adjacent such a void; drilling a plurality of mutually spaced apart blasting holes in such remaining portion of unfragmented formation within such a retort site; loading explosive into such blasting holes; and detonating such explosive for explosively expanding such remaining portion of formation towards such a void for forming a fragmented permeable mass of particles within such a retort and leaving a gas barrier in the form of a vertically extending partition of substantially unfragmented formation between such fragmented permeable mass and an adjacent retort site, the gas barrier having a thickness in the range of from about one to 1.5 times the burden distance of explosive in blasting holes located closest to the gas barrier.

Claim 55

A method for forming a plurality of in situ oil shale retorts in a subterranean formation containing oil shale while each retort contains a fragmented permeable mass of formation particles containing oil shale, the method comprising the steps of: excavating at least one void in each of a plurality of in situ oil shale retort sites, leaving a remaining portion of unfragmented formation within each retort site adjacent such a void; drilling a plurality of mutually spaced apart blasting holes in such remaining portion of unfragmented formation within such a retort site; loading explosive into such blasting holes; and detonating such explosive for explosively expanding such remaining portion of formation towards such a void for forming a fragmented permeable mass of particles within such a retort and leaving a gas barrier in the form of a vertically extending partition of substantially unfragmented formation between such fragmented permeable mass and an adjacent retort site, the gas barrier having a thickness in the range of from about one to 1.5 times the spacing distance of explosive in blasting holes located closest to the gas barrier.

Claim 56

A method for forming a plurality of in situ oil shale retorts in a subterranean formation containing oil shale while each retort contains a fragmented permeable mass of formation particles containing oil shale, the method comprising the steps of: excavating at least one void in each of a plurality of in situ oil shale retort sites, leaving a remaining portion of unfragmented formation within each retort site adjacent such a void; drilling a plurality of mutually spaced apart blasting holes in such remaining portion of unfragmented formation within such a retort site; loading explosive into such blasting holes; and detonating such explosive for explosively expanding such remaining portion of formation towards such a void for forming a fragmented permeable mass of particles within such a retort and leaving a gas barrier in the form of a vertically extending partition of substantially unfragmented formation between such fragmented permeable mass and an adjacent retort site, the gas barrier having a thickness in the range of from about one to 1.5 times the spacing distance of explosive in blasting holes located closest to the gas barrier.

Claim 62

A method for forming a plurality of in situ oil shale retorts in a subterranean formation containing oil shale, wherein each of a pair of adjacent first and second retorts contains a fragmented permeable mass of formation particles containing oil shale, and wherein such adjacent retorts are separated by a gas barrier in the form of a vertically extending partition of substantially unfragmented formation, the method comprising the steps of: excavating at least one void within the retort site of a first one of such adjacent in situ retorts, and leaving a remaining portion of unfragmented formation within the first retort site adjacent the void; placing explosive in a plurality of mutually spaced apart blasting holes in the remaining portion of unfragmented formation within the first retort site; and detonating such explosive to explosively expand the remaining portion of unfragmented formation toward such a void for forming a fragmented permeable mass of formation particles containing oil shale in such first in situ oil shale retort, and leaving a gas barrier in the form of a vertically extending partition of substantially unfragmented formation between the fragmented mass in the first in situ retort and a fragmented permeable mass of formation particles containing oil shale in an adjacent second in situ oil shale retort, the gas barrier being sufficiently thick to inhibit substantial gas flow between the adjacent fragmented masses, the gas barrier also being sufficiently thin that it supports proportionately about the same amount of load from the overburden at elevations above the retorts as is supported by the adjacent fragmented masses for permitting substantially uniform subsidence of overburden above the gas barrier and above the fragmented masses.

Claim 63

A method for forming a plurality of in situ oil shale retorts in a subterranean formation containing oil shale, wherein each of a pair of adjacent first and second retorts contains a fragmented permeable mass of formation particles containing oil shale, and wherein such adjacent retorts are separated by a gas barrier in the form of a vertically extending partition of substantially unfragmented formation, the method comprising the steps of: excavating at least one void within the retort site of a first one of such adjacent in situ retorts, and leaving a remaining portion of unfragmented formation within the first retort site adjacent the void; placing explosive in a plurality of mutually spaced apart blasting holes in the remaining portion of unfragmented formation within the first retort site; and detonating such explosive to explosively expand the remaining portion of unfragmented formation toward such a void for forming a fragmented permeable mass of formation particles containing oil shale in such first in situ oil shale retort, and leaving a gas barrier in the form of a vertically extending partition of substantially unfragmented formation between the fragmented mass in the first in situ retort and a fragmented permeable mass of formation particles containing oil shale in an adjacent second in situ oil shale retort, the gas barrier being sufficiently thick to inhibit substantial gas flow between the adjacent fragmented masses, the gas barrier also being sufficiently thin that it supports proportionately about the same amount of load from the overburden at elevations above the retorts as is supported by the adjacent fragmented masses for permitting substantially uniform subsidence of overburden above the gas barrier and above the fragmented masses.