Conductivity determination in a formation having a cased well

Claim 1

A method for use in determining conductivity of an underground formation adjacent to a cased well, comprising: using a cased well; providing electrode means for supplying current; positioning said electrode means in said cased well; supplying current to the cased well using said electrode means; obtaining a first determined magnitude relating to the conductance of the casing over a distance in said cased well; obtaining a second determined magnitude relating to voltages over said distance in said well; and using at least said first determined magnitude and said second determined magnitude to provide a value which is related to the conductivity of the underground formation adjacent to the cased well.

Claim 2

A method for use in determining conductivity of an underground formation adjacent to a cased well, comprising: using a cased well; providing electrode means for supplying current; positioning said electrode means in said cased well; supplying current to the cased well using said electrode means; obtaining a first determined magnitude relating to the conductance of the casing over a distance in said cased well; obtaining a second determined magnitude relating to voltages over said distance in said well; and using at least said first determined magnitude and said second determined magnitude to provide a value which is related to the conductivity of the underground formation adjacent to the cased well.

Claim 9

A method for use in determining conductivity of an underground formation adjacent to a cased well, comprising: using a cased well; providing electrode means for supplying current; locating said electrode means proximate to first and second sections of said cased well wherein voltages across said first and second sections substantially represent variations in casing conductance, and wherein voltage across said first and second section as substantially independent of formation conductivity; supplying current to the cased well using said electrode means; obtaining a determined magnitude by measuring a first voltage defined over said first section of the cased well, by measuring a second voltage defined over said second section of the cased well, and by defining a relationship between said first voltage and said second voltage; and using at least said determined magnitude to provide a value which is related to the conductivity of the underground formation adjacent to the cased well.

Claim 10

A method for use in determining conductivity of an underground formation adjacent to a cased well, comprising: using a cased well; providing electrode means for supplying current; locating said electrode means proximate to first and second sections of said cased well wherein voltages across said first and second sections substantially represent variations in casing conductance, and wherein voltage across said first and second section as substantially independent of formation conductivity; supplying current to the cased well using said electrode means; obtaining a determined magnitude by measuring a first voltage defined over said first section of the cased well, by measuring a second voltage defined over said second section of the cased well, and by defining a relationship between said first voltage and said second voltage; and using at least said determined magnitude to provide a value which is related to the conductivity of the underground formation adjacent to the cased well.

Claim 11

A method for use in determining conductivity of an underground formation adjacent to a cased well, comprising: using a cased well; providing at least a first electrode for supplying current; positioning said first electrode in said cased well; supplying current to said first current electrode within the cased well; permitting the current supplied to said first current electrode to flow a predetermined distance of at least ten times the radius of said cased well; obtaining a determined magnitude relating to at least two voltages each of said voltages being measured while said current is being supplied to said first current electrode and each of said voltages being relative to a distance in the cased well; and using at least said determined magnitude to provide a value which is related to the conductivity of the underground formation adjacent to the cased well.

Claim 12

A method for use in determining conductivity of an underground formation adjacent to a cased well, comprising: using a cased well; providing at least a first electrode for supplying current; positioning said first electrode in said cased well; supplying current to said first current electrode within the cased well; permitting the current supplied to said first current electrode to flow a predetermined distance of at least ten times the radius of said cased well; obtaining a determined magnitude relating to at least two voltages each of said voltages being measured while said current is being supplied to said first current electrode and each of said voltages being relative to a distance in the cased well; and using at least said determined magnitude to provide a value which is related to the conductivity of the underground formation adjacent to the cased well.

Claim 13

A method for use in determining conductivity of an underground formation adjacent to a cased well, comprising: providing first and second current electrodes; providing a source of electric current operably connected to said first and second current electrodes for causing a current to flow between said first and said second electrodes; positioning said first and second current electrodes in a first region within said well adjacent a section of well casing; positioning first and second pairs of receiver electrodes between said first and said second current electrodes wherein the casing between said first pair of receiver electrodes has a first conductance and wherein the casing between said second pair of receiver electrodes has a second conductance different from said first conductance; positioning a third current electrode at least a predetermined distance from said receiver electrodes; causing a current to flow between said first and said second current electrodes; measuring a first value of an electrical parameter related to voltage between said first pair of receiver electrodes; causing a current to flow between said first and said third current electrodes; measuring a third value of an electrical parameter related to voltage between said first pair of receiver electrodes; measuring a fourth value of an electrical parameter related to voltage between said second pair of receiver electrodes; using said first and second values to compensate for the difference between said first conductance and said second conductance; and using said third, fourth and fifth values to provide a value which is related to the conductivity of a first underground formation adjacent to the well.

Claim 14

A method for use in determining conductivity of an underground formation adjacent to a cased well, comprising: providing first and second current electrodes; providing a source of electric current operably connected to said first and second current electrodes for causing a current to flow between said first and said second electrodes; positioning said first and second current electrodes in a first region within said well adjacent a section of well casing; positioning first and second pairs of receiver electrodes between said first and said second current electrodes wherein the casing between said first pair of receiver electrodes has a first conductance and wherein the casing between said second pair of receiver electrodes has a second conductance different from said first conductance; positioning a third current electrode at least a predetermined distance from said receiver electrodes; causing a current to flow between said first and said second current electrodes; measuring a first value of an electrical parameter related to voltage between said first pair of receiver electrodes; causing a current to flow between said first and said third current electrodes; measuring a third value of an electrical parameter related to voltage between said first pair of receiver electrodes; measuring a fourth value of an electrical parameter related to voltage between said second pair of receiver electrodes; using said first and second values to compensate for the difference between said first conductance and said second conductance; and using said third, fourth and fifth values to provide a value which is related to the conductivity of a first underground formation adjacent to the well.

Claim 20

A method for use in determining conductivity of an underground formation adjacent to a well, comprising: providing a probe having a conductive body and bearing first and second pairs of receiver electrodes positioned between first and second current electrodes to define a first distance equal to the smallest of all the distances from each current electrode to each receiver electrode; positioning said probe in said well; positioning a third current electrode to define a second distance equal to the distance from the third electrode to the nearest point on the probe wherein said second distance is greater than said first distance; connecting a resistance element between said probe and said third current electrode; causing a current to flow between said first and said second current electrodes; measuring a first value of an electrical parameter related to voltage between said first pair of receiver electrodes; measuring a second value of an electrical parameter related to voltage between said second pair of receiver electrodes; causing a current to flow between said first and said third current electrodes; measuring a third value of an electrical parameter related to voltage between said first pair of receiver electrodes; measuring a fourth value of an electrical parameter related to voltage between said second pair of receiver electrodes; following said steps of measuring a first value and measuring a second value, using said first and second values to compensate for the difference of probe conductance between said first and second receiver electrodes from probe conductance between said second and third receiver electrodes; and following said step of measuring a third value and measuring a fourth value, using said first, second, third and fourth values to provide a value which is related to the conductivity of an underground formation adjacent to the well.

Claim 21

A method for use in determining conductivity of an underground formation adjacent to a well, comprising: providing a probe having a conductive body and bearing first and second pairs of receiver electrodes positioned between first and second current electrodes to define a first distance equal to the smallest of all the distances from each current electrode to each receiver electrode; positioning said probe in said well; positioning a third current electrode to define a second distance equal to the distance from the third electrode to the nearest point on the probe wherein said second distance is greater than said first distance; connecting a resistance element between said probe and said third current electrode; causing a current to flow between said first and said second current electrodes; measuring a first value of an electrical parameter related to voltage between said first pair of receiver electrodes; measuring a second value of an electrical parameter related to voltage between said second pair of receiver electrodes; causing a current to flow between said first and said third current electrodes; measuring a third value of an electrical parameter related to voltage between said first pair of receiver electrodes; measuring a fourth value of an electrical parameter related to voltage between said second pair of receiver electrodes; following said steps of measuring a first value and measuring a second value, using said first and second values to compensate for the difference of probe conductance between said first and second receiver electrodes from probe conductance between said second and third receiver electrodes; and following said step of measuring a third value and measuring a fourth value, using said first, second, third and fourth values to provide a value which is related to the conductivity of an underground formation adjacent to the well.

Claim 22

An apparatus for use in obtaining conductivity of an underground formation adjacent to a well, comprising: first, second and third current electrodes, at least one of said first, second and third electrodes being positioned in said well; means for supplying a first current between said first current electrode and said second current electrode; means for supplying a second current between said first current electrode and said third current electrode; receiver electrode means for receiving said first and second currents; and means responsive to said receiver electrode means for use in determining the conductivity of the underground formation using a first determined magnitude relating to voltage associated with said receiver electrode means responsive to said first current, and a second determined magnitude relating to voltage associated with said receiver means responsive to said second current.

Claim 23

An apparatus for use in obtaining conductivity of an underground formation adjacent to a well, comprising: first, second and third current electrodes, at least one of said first, second and third electrodes being positioned in said well; means for supplying a first current between said first current electrode and said second current electrode; means for supplying a second current between said first current electrode and said third current electrode; receiver electrode means for receiving said first and second currents; and means responsive to said receiver electrode means for use in determining the conductivity of the underground formation using a first determined magnitude relating to voltage associated with said receiver electrode means responsive to said first current, and a second determined magnitude relating to voltage associated with said receiver means responsive to said second current.

Claim 25

A method for use in determining conductivity of an underground formation adjacent to a well having a casing, comprising: measuring the value of at least a first electrical parameter in the well; using said measured value to obtain a first determined value relating to conductivity of the formation and conductance of the casing; and compensating said first determined value for variations in conductivity of the casing to provide a second determined value relating to conductivity of the formation.

Claim 26

A method for use in determining conductivity of an underground formation adjacent to a well having a casing, comprising: measuring the value of at least a first electrical parameter in the well; using said measured value to obtain a first determined value relating to conductivity of the formation and conductance of the casing; and compensating said first determined value for variations in conductivity of the casing to provide a second determined value relating to conductivity of the formation.

Claim 30

A method for use in determining conductivity of an underground formation adjacent to a well having a casing, comprising: providing at least three receiver electrodes; positioning said electrodes with at least one of said electrodes in the well to define first and second distances; obtaining a first determined value relating to conductivity of the formation and conductance of the casing using said receiver electrodes; and compensating said first determined value for differences between said first and second distances to provide a second determined value relating to conductivity of the formation.

Claim 31

A method for use in determining conductivity of an underground formation adjacent to a well having a casing, comprising: providing at least three receiver electrodes; positioning said electrodes with at least one of said electrodes in the well to define first and second distances; obtaining a first determined value relating to conductivity of the formation and conductance of the casing using said receiver electrodes; and compensating said first determined value for differences between said first and second distances to provide a second determined value relating to conductivity of the formation.

Claim 34

An apparatus for use in determining conductivity of at least a first underground formation adjacent to a well having a casing, comprising: means for measuring at least a first electrical parameter in the well; first means for obtaining a first determined value relating to conductivity of the formation and conductance of the casing using said means for measuring; and second means for compensating said first determined value for variations in conductance of the casing to provide a second determined value relating to conductivity of the first formation.

Claim 35

An apparatus for use in determining conductivity of at least a first underground formation adjacent to a well having a casing, comprising: means for measuring at least a first electrical parameter in the well; first means for obtaining a first determined value relating to conductivity of the formation and conductance of the casing using said means for measuring; and second means for compensating said first determined value for variations in conductance of the casing to provide a second determined value relating to conductivity of the first formation.

Claim 39

An apparatus for use in determining conductivity of at least a first underground formation adjacent to a cased well, comprising: at least three receiver electrodes, at least one of said three receiver electrodes being positioned in the well, said three receiver electrodes being positioned to define first and second distances; first means for obtaining a first determined value relating to conductivity of the formation and conductance of the casing, using said receiver electrodes; and second means for compensating said first determined value for the difference between said first and second distances to provide a second determined value relating to conductivity of the first formation.

Claim 40

An apparatus for use in determining conductivity of at least a first underground formation adjacent to a cased well, comprising: at least three receiver electrodes, at least one of said three receiver electrodes being positioned in the well, said three receiver electrodes being positioned to define first and second distances; first means for obtaining a first determined value relating to conductivity of the formation and conductance of the casing, using said receiver electrodes; and second means for compensating said first determined value for the difference between said first and second distances to provide a second determined value relating to conductivity of the first formation.

Claim 43

A method for use in determining conductivity of an underground formation adjacent to a well having a cased portion and an uncased portion, comprising: measuring the value of at least a first electrical parameter in the well; using said measured value to obtain a determined value relating to the conductivity of a portion of the formation adjacent the cased portion of the well; providing means for supplying current to the cased portion of the well; and compensating for the electrical effects of the uncased portion of the well.

Claim 44

A method for use in determining conductivity of an underground formation adjacent to a well having a cased portion and an uncased portion, comprising: measuring the value of at least a first electrical parameter in the well; using said measured value to obtain a determined value relating to the conductivity of a portion of the formation adjacent the cased portion of the well; providing means for supplying current to the cased portion of the well; and compensating for the electrical effects of the uncased portion of the well.

Claim 51

A method for use in determining conductivity of an underground formation adjacent to an uncased well, comprising: providing means for supplying current to said well; providing at least two current electrodes; providing at least three receiver electrodes; positioning at least one of said two current electrodes and three receiver electrodes in said well; obtaining a determined value relating to conductivity of the formation by measuring a value related to a voltage between at least two of said receiver electrodes while said means for supplying current is used to supply current to at least one of said current electrodes; and providing a means for simulating at least some electrical effects of a well casing.

Claim 52

A method for use in determining conductivity of an underground formation adjacent to an uncased well, comprising: providing means for supplying current to said well; providing at least two current electrodes; providing at least three receiver electrodes; positioning at least one of said two current electrodes and three receiver electrodes in said well; obtaining a determined value relating to conductivity of the formation by measuring a value related to a voltage between at least two of said receiver electrodes while said means for supplying current is used to supply current to at least one of said current electrodes; and providing a means for simulating at least some electrical effects of a well casing.

Claim 55

An apparatus for use in determining conductivity of an underground formation adjacent to an uncased well, comprising: means for supplying current to said well; at least two current electrodes and at least three receiver electrodes, at least one of said current electrodes and receiver electrodes being located in said well; means for obtaining a determined value relating to conductivity of the formation, by measuring one or more electrical parameters, said measured electrical parameters including the voltage across two of said receiver electrodes wherein said measuring occurs while said means for supplying current is used to supply current to at least one of said current electrodes; and means for simulating at least some electrical effects of a well casing.

Claim 56

An apparatus for use in determining conductivity of an underground formation adjacent to an uncased well, comprising: means for supplying current to said well; at least two current electrodes and at least three receiver electrodes, at least one of said current electrodes and receiver electrodes being located in said well; means for obtaining a determined value relating to conductivity of the formation, by measuring one or more electrical parameters, said measured electrical parameters including the voltage across two of said receiver electrodes wherein said measuring occurs while said means for supplying current is used to supply current to at least one of said current electrodes; and means for simulating at least some electrical effects of a well casing.

Claim 59

A method for use in determining conductivity of an underground formation adjacent to a well having a radius, comprising: placing spaced first, second and third receiver electrodes in said well; placing a first current electrode in said well wherein the distances from said first current electrode to each of said first, second and third receiver electrodes are each greater than about 10 times said radius; placing spaced second and third current electrodes in said well; using said first, second and third current electrodes to supply current to the well; measuring the value of at least a first electrical parameter in said well using said first, second and third receiver electrodes; and using said measured value to provide a determined value which is related to the conductivity of the underground formation adjacent to the cased well.

Claim 60

A method for use in determining conductivity of an underground formation adjacent to a well having a radius, comprising: placing spaced first, second and third receiver electrodes in said well; placing a first current electrode in said well wherein the distances from said first current electrode to each of said first, second and third receiver electrodes are each greater than about 10 times said radius; placing spaced second and third current electrodes in said well; using said first, second and third current electrodes to supply current to the well; measuring the value of at least a first electrical parameter in said well using said first, second and third receiver electrodes; and using said measured value to provide a determined value which is related to the conductivity of the underground formation adjacent to the cased well.

Claim 61

An apparatus for use in determining conductivity of an underground formation adjacent to a well having a radius, comprising: spaced first, second and third receiver electrodes positioned in said well; a first current electrode positioned in said well wherein each of the distances from said first current electrode to each of said first, second and third receiver electrodes is greater than about 10 times said radius; a second current electrode positioned in said well; means for supplying current to said well using said first and second current electrodes; means for measuring the value of at least a first electrical parameter in said well, using at least one of said first, second and third receiver electrodes; and means for providing a value which is related to the conductivity of the underground formation adjacent to the cased well using a value obtained by said means for measuring.

Claim 62

An apparatus for use in determining conductivity of an underground formation adjacent to a well having a radius, comprising: spaced first, second and third receiver electrodes positioned in said well; a first current electrode positioned in said well wherein each of the distances from said first current electrode to each of said first, second and third receiver electrodes is greater than about 10 times said radius; a second current electrode positioned in said well; means for supplying current to said well using said first and second current electrodes; means for measuring the value of at least a first electrical parameter in said well, using at least one of said first, second and third receiver electrodes; and means for providing a value which is related to the conductivity of the underground formation adjacent to the cased well using a value obtained by said means for measuring.

Claim 63

A method for use in determining conductivity of an underground formation adjacent to a well having a casing, comprising: measuring at least a first electrical parameter related to the formation conductivity wherein said first electrical parameter is affected by variations in the conductivity of the casing; and determining the conductivity of the formation while taking into account said variations in the conductivity of the casing.

Claim 64

A method for use in determining conductivity of an underground formation adjacent to a well having a casing, comprising: measuring at least a first electrical parameter related to the formation conductivity wherein said first electrical parameter is affected by variations in the conductivity of the casing; and determining the conductivity of the formation while taking into account said variations in the conductivity of the casing.

Claim 65

A method for determining the conductivity of an underground formation adjacent to a cased well, the steps of: defining a first distance and a second distance; measuring an electrical parameter related to the formation conductivity wherein said electrical parameter is affected by variation between said first distance and said second distance; and determining the conductivity of the formation while taking into account any variation between said first and second distances.

Claim 66

A method for determining the conductivity of an underground formation adjacent to a cased well, the steps of: defining a first distance and a second distance; measuring an electrical parameter related to the formation conductivity wherein said electrical parameter is affected by variation between said first distance and said second distance; and determining the conductivity of the formation while taking into account any variation between said first and second distances.

Claim 67

An apparatus for use in determining conductivity of an underground formation adjacent to a well having a casing, comprising: probe means for placement into the well; means for measuring an electrical parameter related to the formation conductivity using said probe means wherein said electrical parameter is affected by variations in the conductivity of the casing; and means for determining the conductivity of the formation while taking into account said variations in the conductivity of the casing.

Claim 68

An apparatus for use in determining conductivity of an underground formation adjacent to a well having a casing, comprising: probe means for placement into the well; means for measuring an electrical parameter related to the formation conductivity using said probe means wherein said electrical parameter is affected by variations in the conductivity of the casing; and means for determining the conductivity of the formation while taking into account said variations in the conductivity of the casing.

Claim 69

An apparatus for use in determining conductivity of an underground formation adjacent to a well having a casing, comprising: means from which a first distance and a second distance can be defined; means for measuring an electrical parameter related to the formation conductivity wherein said electrical parameter is affected by a difference between said first and second distance; and means for determining the conductivity of the formation while taking into account any difference between said first and second distances.

Claim 70

An apparatus for use in determining conductivity of an underground formation adjacent to a well having a casing, comprising: means from which a first distance and a second distance can be defined; means for measuring an electrical parameter related to the formation conductivity wherein said electrical parameter is affected by a difference between said first and second distance; and means for determining the conductivity of the formation while taking into account any difference between said first and second distances.