CA2002595C - Methane production from carbonaceous subterranean formations - Google Patents
Methane production from carbonaceous subterranean formationsInfo
- Publication number
- CA2002595C CA2002595C CA 2002595 CA2002595A CA2002595C CA 2002595 C CA2002595 C CA 2002595C CA 2002595 CA2002595 CA 2002595 CA 2002595 A CA2002595 A CA 2002595A CA 2002595 C CA2002595 C CA 2002595C
- Authority
- CA
- Canada
- Prior art keywords
- gas
- methane
- inert gas
- well
- solid carbonaceous
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Abstract
ABSTRACT
A method of producing methane by injecting inert gas, such as nitrogen, through an injection well into a solid carbonaceous subterranean formation (e.g., coal) and recovering methane from a production well(s). Methane desorption is achieved by reduction in methane partial pressure rather than by reduction in total pressure alone.
A method of producing methane by injecting inert gas, such as nitrogen, through an injection well into a solid carbonaceous subterranean formation (e.g., coal) and recovering methane from a production well(s). Methane desorption is achieved by reduction in methane partial pressure rather than by reduction in total pressure alone.
Description
PATENT
2~59~ 90950l Puri/Stein METHANE PRODUCTION FROM CARBONACEOUS
SUBTERRANEAN FORMATIONS
RELATED APPLICATIONS
This application is related to Canadian Application No. 605,297.
FIELD OF THE INVENTION
The present invention is a method of producing methane from a solid carbonaceous subterranean formation.
More specifically, the invention is a method of producing methane from a solid carbonaceous subterranean formation by injecting an inert gas through an injection well into the solid carbonaceous subterranean formation to strip methane from the carbonaceous materials in the formation and sweep the produced gases into a production well.
BACKGROUND OF THE INVENTIOM
During the conversion of peat to coal, methane gas is produced as a result of thermal and biogenic proc-esses. Because of the mutual attraction between the coal surface and the methane molecules, a large amount of meth-~ f '1 '-.' .'. '.": ,, ,' ' ' ," ' '' ', "i ` ~ ' "' ~
`` , ` '~; ~ ' . '- . ~, ,'. ' . .:- `
': . ' ' ' ' ' ; ~ ' ,' :" '.' . , ~' , , ,' ` ; ' . :
~` 2~25~
ane can remain trapped in-situ as gas adhered to the organic matter (i.e., carbonaceous materials) in the for-mation. The reserves of such ~methane~ in the United States and around the world are huge. Most of the 5 reserves are found in coal, but significant reserves are -la-. :
.
:
~ 2~
found in gas shales and other solid carbonaceous subterra-nean formations.
Conventional methane recovery methods are based on reservoir pressure depletion strategy; that is, methane 5 is desorbed from the carbonaceous surfac~s by reducing the reservoir pressure. While this method of methane pro-duction is simple, it is not efficient. Loss of reservoir pressure deprives the pressure depletion process of the driving orce necessary to flow methane gas to the well-10 bores. Consequently, the gas production rate from a wellis adversely affected by the reduction in reservoir pres-sure.
Another method of recovering methane is by injecting into the solid carbonaceous subterranean forma-15 tion a gas, such as CO2, having a higher affinity for coalor other carbonaceous material than the adsorbed methane, thereby establishing a competitive adsorption/desorption process. In this process, the CO2 displaces methane from the surface of coal, thereby freeing the methane so that 20 ît can flow to a wellbore and be recovered. This method is disclosed in the reference by A. A. Reznik, P. K. Singh, and W. L. Foley, "An Analysis of the Effect f C2 Injection on the Recovery of In-Situ Methane from Bituminous Coal: An Experimental Simulation," Society of 25 Petroleum Engineers Journal, October lg84. The problem with this method is the larse volume of CO2 that must be injected into the solid carbonaceous subterranean forma-tion in order to exchange sites with methane. In most instances, such an amount would be uneconomical. This .: ; .. , . .; . -., .... .. . . . ... ..
i;9S~
reference reports that mixing even small amounts of nitro-gen gas with CO2 significantly reduces the effectiveness of displacement desorption of methane by CO2.
There is a need for a method of producing meth-5 ane from coal and other solid carbonaceous subterraneanformations that accelerates the production rate and improves recoverable gas reserves economically.
SUMMARY OF TEIE INVENTION
The present invention overcomes the foregoing 10 deficiencies and meets the above-described needs. The present invention is a method for producing methane from a solid carbonaceous subterranean formation penetrated by at least one producing well. The method comprises injecting an inert gas through the injection well and into the solid 15 carbonaceous subterranean formation, and producing the inert gas and the methane from the production well.
Coalbed methane recovery is accelerated and substantial improvement is made in the net recoverable reserves.
BRIEF DESCRIPTION OF DRAWINGS
FIGURE 1 is a graphical representation of a sorption isotherm illustrating the relationship between the reservoir pressure of a coal seam and the gas content of the coal. ~he sorption isotherm is a representation of the maximum methane holding capacity of coal as a function 25 of pressure at a fixed temperature.
FIGURE 2 is a graphical representation of a sorption isotherm of a coal sample in the presence of an inert gas.
FIGURE 3 is a top view of a four-spot repeating well patt~rn described in the Example.
FIGURE 4 is a graphical representation of the methane production rate versus time for the four spot 5 repeating well pattern.
FIGURE 5 is a graphical representation of the original gas in place recovered versus time for the four spot repeating well pattern.
FI&URE 6 is a graphical representation of the 10 mole percent of gas produced versus time for the four spot repeating well pattern.
DETAILED DESCRIPTION OF THE INVENTION
The desorption of methane from the carbonaceous surface of the formation is controlled by the partial 15 pressure of methane gas rather ~han the total system pres-sure. Therefore, methane is desorbed as a result of reduction in methane partial pressure. The methane recov-ery from a solid carbonaceous subterranean formation can be accelerated and enhanced by the continuous injection of 20 an inert gas into the solid carbonaceous subterranean for-mation. While the total reservoir pressure is maintained, if not increased, the partial pressure of methane is reduced. The term "inert gas" defines a gas that (i) does not react with the coal or other carbonaceous material in 25 the formation under conditions of use (i.e., the standard meaning for "inert") and (ii~ that does not significantly adsorb to the coal. Carbon dioxide and gaseous mixtures, such as flue gas, that contain carbon dioxide as a signif-icant constituent do not meet the later criteria. It is -- 2~2~9~
known that coal has a higher affinity for carbon dioxlde than for adsorbed methane. It is also known th~t coal has a lower affinity for the inert gases used herein than for adsorbed methane. See, for example, the French paper 5 "Etude de la liaison gaz-charbon" by J. Gunther, Rev. Ind~
Min. 47, 693-708 (October, 1965) and also the disclosure in USP 4,043,395, Every (for CO2). Examples of inert gases include nitrogen, helium, argon, air and the like.
Nitrogen is preferred based on current commercial avail-10 ability and price. FIGURE 2 shows the equilibrium sorp-tion isotherm of a coal sample in the presence of an inert gas. As illustrated, 35% of the gas in place can be recovered from coal by either reducing the total pressure from 465 psi to 200 psi or by diluting the free methane 15 gas concentration in coal with an inert gas so as to reach an equilibrium value of 43% methane and 57% inert gas without any change in the total pressure.
The use of inert gas to desorb methane is eco-nomically and technically feasible primarily because of 20 the low effective porosity of the carbonaceous formation.
For example, the permeability of coal is in the order of 1%. Injection of a relatively small amount of inert gas into the solid carbonaceous portion of the formation causes a large reduction in the partial pressure of free 25 methane gas in the treated carbonaceous portion of the formation, such as the cleat system of a coalbed. Conse-quently, methane is desorbed from the carbonaceous ~ ;
: ::
, : : ~:
- .. . ~ :: : . ~ ~
2~2~9~
materials in the formation until a new equilibrium is reached, as per the sorption isotherm. Th~ mixture of methane and -5a-. ,:.
~2~5 inert gas flows across and through the solid carbonaceous subterranean formation along with water until it is recov-ered at the surface by means of producing wells~ The pro-duced gas is separated from water and recovered using 5 known separation methods. Methane is separated from the inert gas also using known separation methods. The meth-ane is then marketed, the inert gas can be recycled. Eco-nomics of the methods are enhanced by recycling the inert gas.
The novel inert gas stripping method of the pre-sent invention can be further improved by heating the inert gas before it is injected into the solid carbona-ceous subterranean formation.
The injection pressure of the inert gas should 15 preferably-he lower than the fracture parting pressure of the solid carbonaceous subterranean formation but should be higher than the initial reservoir pressure. Mainte-nance of a constant injection pressure is also desirable, although not necessary.
The present invention requires at least one injection well and at least one production well. The number and location of the injection and production wells can be varied and will usually be determined after reser-voir engineering and economics of a specific field project 25 have been evaluated.
During the present process, the solid carbona-ceous subterranean formation is dewatered, but reservoir pressure is not lost. This is an important advantage because maintenance of reservoir pressure in a methane - ` - - . , . , . - . .
,, : : ,~
25~;
field also helps reduce water migration from the surround-ing aquifers. This is particularly advantageous in solid carbonaceous subterranean formations with high permeabil-ity and effective cleat porosity. Over the life of the 5 degas project, the amount of water that is recovered from and disposed of can be reduced because of the reduced water migration in the field.
Inert gas injection can al50 be conducted in existing fields that have been on pressure depletion for a 10 period of time prior to such injection. In this method, methane is produced through at least a first and second well. Then such production is ceased in the first well and inert gas in injected through the first well into the solid carbonaceous subterranean formation. The inert gas 15 and methane is then produced from the second well.
EXAMPLE
Four wells are drilled in a 320 acre square in a repeating well pattern (as shown in Figure 3) and produced at total gas rates of approximately 1200 thousand standard 20 cubic feet per day for a period of five years (base case) using a reservoir pressure depletion technique. At that time, one of the wells (No. 1) is converted into an injection well and nitrogen is injected through this well and into the solid carbonaceous subterranean formation for 25 the next twenty years.
FIGURE 4 shows the gas production rates for the four producing wells of the base case and for the three producing wells during N2 injection. As shown, methane recovery from the field increases substantially when N2 9s injection is initiated. FIGURE 5 shows the percent of original gas in place recovered for the base case and for the three producing wells during N2 injection. As illus-trated, the injection of inert gas in the field increases 5 the net recoverable reserves of methane gas by more than a factor of 2. The composition of the produced gas is shown as a function of time in FIGURE 6.
This example shows that inert gas injection in coal is of considerable value in accelerating and enhanc-10 ing methane recovery from coal.
The present invention h~s been described in par-ticular relationship to the attached drawings. However, it should be understood that further modifications, apart from those shown or suggested herein, can be made within 15 the scope and spirit of the present invention.
., ., ;,, , , " ,, r : ' :~ ' ' ' ' ' ' '
SUBTERRANEAN FORMATIONS
RELATED APPLICATIONS
This application is related to Canadian Application No. 605,297.
FIELD OF THE INVENTION
The present invention is a method of producing methane from a solid carbonaceous subterranean formation.
More specifically, the invention is a method of producing methane from a solid carbonaceous subterranean formation by injecting an inert gas through an injection well into the solid carbonaceous subterranean formation to strip methane from the carbonaceous materials in the formation and sweep the produced gases into a production well.
BACKGROUND OF THE INVENTIOM
During the conversion of peat to coal, methane gas is produced as a result of thermal and biogenic proc-esses. Because of the mutual attraction between the coal surface and the methane molecules, a large amount of meth-~ f '1 '-.' .'. '.": ,, ,' ' ' ," ' '' ', "i ` ~ ' "' ~
`` , ` '~; ~ ' . '- . ~, ,'. ' . .:- `
': . ' ' ' ' ' ; ~ ' ,' :" '.' . , ~' , , ,' ` ; ' . :
~` 2~25~
ane can remain trapped in-situ as gas adhered to the organic matter (i.e., carbonaceous materials) in the for-mation. The reserves of such ~methane~ in the United States and around the world are huge. Most of the 5 reserves are found in coal, but significant reserves are -la-. :
.
:
~ 2~
found in gas shales and other solid carbonaceous subterra-nean formations.
Conventional methane recovery methods are based on reservoir pressure depletion strategy; that is, methane 5 is desorbed from the carbonaceous surfac~s by reducing the reservoir pressure. While this method of methane pro-duction is simple, it is not efficient. Loss of reservoir pressure deprives the pressure depletion process of the driving orce necessary to flow methane gas to the well-10 bores. Consequently, the gas production rate from a wellis adversely affected by the reduction in reservoir pres-sure.
Another method of recovering methane is by injecting into the solid carbonaceous subterranean forma-15 tion a gas, such as CO2, having a higher affinity for coalor other carbonaceous material than the adsorbed methane, thereby establishing a competitive adsorption/desorption process. In this process, the CO2 displaces methane from the surface of coal, thereby freeing the methane so that 20 ît can flow to a wellbore and be recovered. This method is disclosed in the reference by A. A. Reznik, P. K. Singh, and W. L. Foley, "An Analysis of the Effect f C2 Injection on the Recovery of In-Situ Methane from Bituminous Coal: An Experimental Simulation," Society of 25 Petroleum Engineers Journal, October lg84. The problem with this method is the larse volume of CO2 that must be injected into the solid carbonaceous subterranean forma-tion in order to exchange sites with methane. In most instances, such an amount would be uneconomical. This .: ; .. , . .; . -., .... .. . . . ... ..
i;9S~
reference reports that mixing even small amounts of nitro-gen gas with CO2 significantly reduces the effectiveness of displacement desorption of methane by CO2.
There is a need for a method of producing meth-5 ane from coal and other solid carbonaceous subterraneanformations that accelerates the production rate and improves recoverable gas reserves economically.
SUMMARY OF TEIE INVENTION
The present invention overcomes the foregoing 10 deficiencies and meets the above-described needs. The present invention is a method for producing methane from a solid carbonaceous subterranean formation penetrated by at least one producing well. The method comprises injecting an inert gas through the injection well and into the solid 15 carbonaceous subterranean formation, and producing the inert gas and the methane from the production well.
Coalbed methane recovery is accelerated and substantial improvement is made in the net recoverable reserves.
BRIEF DESCRIPTION OF DRAWINGS
FIGURE 1 is a graphical representation of a sorption isotherm illustrating the relationship between the reservoir pressure of a coal seam and the gas content of the coal. ~he sorption isotherm is a representation of the maximum methane holding capacity of coal as a function 25 of pressure at a fixed temperature.
FIGURE 2 is a graphical representation of a sorption isotherm of a coal sample in the presence of an inert gas.
FIGURE 3 is a top view of a four-spot repeating well patt~rn described in the Example.
FIGURE 4 is a graphical representation of the methane production rate versus time for the four spot 5 repeating well pattern.
FIGURE 5 is a graphical representation of the original gas in place recovered versus time for the four spot repeating well pattern.
FI&URE 6 is a graphical representation of the 10 mole percent of gas produced versus time for the four spot repeating well pattern.
DETAILED DESCRIPTION OF THE INVENTION
The desorption of methane from the carbonaceous surface of the formation is controlled by the partial 15 pressure of methane gas rather ~han the total system pres-sure. Therefore, methane is desorbed as a result of reduction in methane partial pressure. The methane recov-ery from a solid carbonaceous subterranean formation can be accelerated and enhanced by the continuous injection of 20 an inert gas into the solid carbonaceous subterranean for-mation. While the total reservoir pressure is maintained, if not increased, the partial pressure of methane is reduced. The term "inert gas" defines a gas that (i) does not react with the coal or other carbonaceous material in 25 the formation under conditions of use (i.e., the standard meaning for "inert") and (ii~ that does not significantly adsorb to the coal. Carbon dioxide and gaseous mixtures, such as flue gas, that contain carbon dioxide as a signif-icant constituent do not meet the later criteria. It is -- 2~2~9~
known that coal has a higher affinity for carbon dioxlde than for adsorbed methane. It is also known th~t coal has a lower affinity for the inert gases used herein than for adsorbed methane. See, for example, the French paper 5 "Etude de la liaison gaz-charbon" by J. Gunther, Rev. Ind~
Min. 47, 693-708 (October, 1965) and also the disclosure in USP 4,043,395, Every (for CO2). Examples of inert gases include nitrogen, helium, argon, air and the like.
Nitrogen is preferred based on current commercial avail-10 ability and price. FIGURE 2 shows the equilibrium sorp-tion isotherm of a coal sample in the presence of an inert gas. As illustrated, 35% of the gas in place can be recovered from coal by either reducing the total pressure from 465 psi to 200 psi or by diluting the free methane 15 gas concentration in coal with an inert gas so as to reach an equilibrium value of 43% methane and 57% inert gas without any change in the total pressure.
The use of inert gas to desorb methane is eco-nomically and technically feasible primarily because of 20 the low effective porosity of the carbonaceous formation.
For example, the permeability of coal is in the order of 1%. Injection of a relatively small amount of inert gas into the solid carbonaceous portion of the formation causes a large reduction in the partial pressure of free 25 methane gas in the treated carbonaceous portion of the formation, such as the cleat system of a coalbed. Conse-quently, methane is desorbed from the carbonaceous ~ ;
: ::
, : : ~:
- .. . ~ :: : . ~ ~
2~2~9~
materials in the formation until a new equilibrium is reached, as per the sorption isotherm. Th~ mixture of methane and -5a-. ,:.
~2~5 inert gas flows across and through the solid carbonaceous subterranean formation along with water until it is recov-ered at the surface by means of producing wells~ The pro-duced gas is separated from water and recovered using 5 known separation methods. Methane is separated from the inert gas also using known separation methods. The meth-ane is then marketed, the inert gas can be recycled. Eco-nomics of the methods are enhanced by recycling the inert gas.
The novel inert gas stripping method of the pre-sent invention can be further improved by heating the inert gas before it is injected into the solid carbona-ceous subterranean formation.
The injection pressure of the inert gas should 15 preferably-he lower than the fracture parting pressure of the solid carbonaceous subterranean formation but should be higher than the initial reservoir pressure. Mainte-nance of a constant injection pressure is also desirable, although not necessary.
The present invention requires at least one injection well and at least one production well. The number and location of the injection and production wells can be varied and will usually be determined after reser-voir engineering and economics of a specific field project 25 have been evaluated.
During the present process, the solid carbona-ceous subterranean formation is dewatered, but reservoir pressure is not lost. This is an important advantage because maintenance of reservoir pressure in a methane - ` - - . , . , . - . .
,, : : ,~
25~;
field also helps reduce water migration from the surround-ing aquifers. This is particularly advantageous in solid carbonaceous subterranean formations with high permeabil-ity and effective cleat porosity. Over the life of the 5 degas project, the amount of water that is recovered from and disposed of can be reduced because of the reduced water migration in the field.
Inert gas injection can al50 be conducted in existing fields that have been on pressure depletion for a 10 period of time prior to such injection. In this method, methane is produced through at least a first and second well. Then such production is ceased in the first well and inert gas in injected through the first well into the solid carbonaceous subterranean formation. The inert gas 15 and methane is then produced from the second well.
EXAMPLE
Four wells are drilled in a 320 acre square in a repeating well pattern (as shown in Figure 3) and produced at total gas rates of approximately 1200 thousand standard 20 cubic feet per day for a period of five years (base case) using a reservoir pressure depletion technique. At that time, one of the wells (No. 1) is converted into an injection well and nitrogen is injected through this well and into the solid carbonaceous subterranean formation for 25 the next twenty years.
FIGURE 4 shows the gas production rates for the four producing wells of the base case and for the three producing wells during N2 injection. As shown, methane recovery from the field increases substantially when N2 9s injection is initiated. FIGURE 5 shows the percent of original gas in place recovered for the base case and for the three producing wells during N2 injection. As illus-trated, the injection of inert gas in the field increases 5 the net recoverable reserves of methane gas by more than a factor of 2. The composition of the produced gas is shown as a function of time in FIGURE 6.
This example shows that inert gas injection in coal is of considerable value in accelerating and enhanc-10 ing methane recovery from coal.
The present invention h~s been described in par-ticular relationship to the attached drawings. However, it should be understood that further modifications, apart from those shown or suggested herein, can be made within 15 the scope and spirit of the present invention.
., ., ;,, , , " ,, r : ' :~ ' ' ' ' ' ' '
Claims (33)
1. A method for producing methane from a solid carbonaceous subterranean formation penetrated by at least one injection well and at least one production well, the method of production comprising the steps of:
(a) injecting a gas, consisting essentially of an inert gas, through the injection well and into the solid carbonaceous subterranean formation, the inert gas being a gas that (i) does not react with solid carbonaceous material in the solid carbonaceous formation under conditions of use and (ii) does not significantly adsorb to the solid carbonaceous mate-rial; and (b) producing a composition comprising inert gas and methane from the production well.
(a) injecting a gas, consisting essentially of an inert gas, through the injection well and into the solid carbonaceous subterranean formation, the inert gas being a gas that (i) does not react with solid carbonaceous material in the solid carbonaceous formation under conditions of use and (ii) does not significantly adsorb to the solid carbonaceous mate-rial; and (b) producing a composition comprising inert gas and methane from the production well.
2. A method of Claim 1 wherein the inert gas is is selected from the group consisting of nitrogen, helium, argon and air.
3. A method of Claim 1 wherein the inert gas is nitrogen.
4. A method of Claim 1 wherein the injection pressure is maintained substantially constant.
5. A method of Claim 1 including injecting the gas into the solid carbonaceous subterranean formation by continuous injection.
6. A method of Claim 1 wherein the gas is injected at a pressure less than reservoir parting pres-sure but greater than reservoir pressure at the injection well prior to initiation of gas injection.
7. A method of Claim 6 including maintaining or increasing reservoir pressure at the production well as compared to the reservoir pressure at the production well prior to initiation of gas injection.
8. A method of Claim 1 wherein water is pro-duced in step (b) and separated from the inert gas and the methane.
9. A method of Claim 1 including the steps of separating the inert gas from the composition, and recycl-ing the separated inert gas by reinjecting the separated inert gas into the solid carbonaceous subterranean forma-tion.
10. A method of Claim 1 wherein the solid car-bonaceous material within the solid carbonaceous subterra-nean formation comprises coal.
11. A method for producing methane from a solid carbonaceous subterranean formation penetrated by at least a first well and a second well, the method of production comprising the steps of:
(a) producing methane from the solid carbo-naceous subterranean formation from the first well and second well;
(b) ceasing the production of methane from the first well and injecting a gas, consisting essen-tially of an inert gas, through the first well into the solid carbonaceous subterranean formation, the inert gas being a gas that (i) does not react with solid carbonaceous material in the solid carbonaceous formation under conditions of use and (ii) does not significantly adsorb to the solid carbonaceous mate-rial; and (c) producing a composition comprising inert gas and methane from the second well.
(a) producing methane from the solid carbo-naceous subterranean formation from the first well and second well;
(b) ceasing the production of methane from the first well and injecting a gas, consisting essen-tially of an inert gas, through the first well into the solid carbonaceous subterranean formation, the inert gas being a gas that (i) does not react with solid carbonaceous material in the solid carbonaceous formation under conditions of use and (ii) does not significantly adsorb to the solid carbonaceous mate-rial; and (c) producing a composition comprising inert gas and methane from the second well.
12. A method of Claim 11 wherein the inert gas is selected from the group consisting of nitrogen, helium, argon and air.
13. A method of Claim 11 wherein the inert gas is nitrogen.
14. A method of Claim 11 wherein the injection pressure is maintained substantially constant.
15. A method of Claim 11 including injecting the gas into the solid carbonaceous subterranean formation by continuous injection.
16. A method of Claim 11 wherein the gas is injected at a pressure less than reservoir parting pres-sure but greater than reservoir pressure at the first well prior to initiation of gas injection.
17. A method of Claim 16 including maintaining or increasing the reservoir pressure at the second well as compared to the reservoir pressure at the second well prior to initiation of gas injection.
18. A method of claim 11 wherein the inert gas produced in step (b) is separated from the methane.
19. A method of Claim 11 wherein water is pro-duced in steps (a) and (c) and separated from produced 5 gases.
20. A method of Claim 11 wherein the solid car-bonaceous material within the solid carbonaceous subterra-nean formation comprises coal.
21. A method of recovering methane from a solid carbonaceous subterranean formation penetrated by an injection well and a production well, the method compris-ing:
(a) injecting inert gas through the injection well into the solid carbonaceous subterra-nean formation at a pressure higher than reservoir pressure at the injection well prior to the initi-ation of inert gas injection, the inert gas being a gas that (i) does not react with solid carbonaceous material in the solid carbonaceous formation under conditions of use and (ii) does not significantly adsorb to the solid carbonaceous material; and (b) recovering inert gas and methane through the production well;
(c) separating recovered inert gas from recovered methane; and (d) recycling the separated inert gas by reinjecting the separated inert gas into the solid carbonaceous subterranean formation.
(a) injecting inert gas through the injection well into the solid carbonaceous subterra-nean formation at a pressure higher than reservoir pressure at the injection well prior to the initi-ation of inert gas injection, the inert gas being a gas that (i) does not react with solid carbonaceous material in the solid carbonaceous formation under conditions of use and (ii) does not significantly adsorb to the solid carbonaceous material; and (b) recovering inert gas and methane through the production well;
(c) separating recovered inert gas from recovered methane; and (d) recycling the separated inert gas by reinjecting the separated inert gas into the solid carbonaceous subterranean formation.
22. A method of Claim 21 wherein the solid car-bonaceous material within the solid carbonaceous subterra-nean formation comprises coal.
23. A method of Claim 21 including maintaining or increasing reservoir pressure at the production well as compared to reservoir pressure at the production well prior to initiation of inert gas injection.
24. A method of Claim 21 wherein the inert gas consists essentially of nitrogen.
25. A method of Claim 21 further comprising the steps of heating the inert gas above an initial temper-ature of the subterranean formation prior to the inert gas being injected into the injection well.
26. A method of Claim 21 including injecting the inert gas through the injection well at a pressure lower than reservoir parting pressure.
27. A method of recovering methane from a solid carbonaceous subterranean formation, penetrated by an injection well and a production well, the method compris-ing:
(a) injecting gas that desorbs methane from solid carbonaceous material into the subterranean formation through the injection well at a pressure higher than reservoir pressure at the injection well prior to the initiation of gas injection and lower than reservoir parting pressure; and (b) recovering the gas that desorbs methane and methane through the production well while main-taining or increasing reservoir pressure at the pro-duction well as compared to reservoir pressure at the production well prior to the initiation of injection of the gas that desorbs methane.
(a) injecting gas that desorbs methane from solid carbonaceous material into the subterranean formation through the injection well at a pressure higher than reservoir pressure at the injection well prior to the initiation of gas injection and lower than reservoir parting pressure; and (b) recovering the gas that desorbs methane and methane through the production well while main-taining or increasing reservoir pressure at the pro-duction well as compared to reservoir pressure at the production well prior to the initiation of injection of the gas that desorbs methane.
28. A method of Claim 27 wherein the gas that desorbs methane injected in step (a) comprises at least one gas selected from the group consisting of nitrogen helium, argon and air.
29. A method of Claim 27 wherein the gas that desorbs methane consists essentially of nitrogen.
30. A method of Claim 27 wherein carbonaceous material within the solid carbonaceous subterranean forma-tion comprises coal.
31. A method of Claim 27 wherein the gas that desorbs methane comprises a gas that does not react with carbonaceous material in the solid carbonaceous subterra-nean formation under conditions of use.
32. A method of Claim 27 wherein the gas that desorbs methane comprises a gas that does not signif-icantly adsorb to carbonaceous material in the solid car-bonaceous subterranean formation.
33. A method of Claim 27 wherein the gas that desorbs methane comprises a gas that (a) does not react with carbonaceous material in the solid carbonaceous sub-terranean formation under conditions of use, and (b) does not significantly adsorb to carbonaceous material in the solid carbonaceous subterranean formation.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US391,212 | 1989-08-08 | ||
| US07/391,212 US5014785A (en) | 1988-09-27 | 1989-08-08 | Methane production from carbonaceous subterranean formations |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2002595A1 CA2002595A1 (en) | 1991-02-08 |
| CA2002595C true CA2002595C (en) | 1993-10-05 |
Family
ID=23545734
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2002595 Expired - Lifetime CA2002595C (en) | 1989-08-08 | 1989-11-09 | Methane production from carbonaceous subterranean formations |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2002595C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8256282B2 (en) | 2007-07-19 | 2012-09-04 | Schlumberger Technology Corporation | In situ determination of critical desorption pressures |
-
1989
- 1989-11-09 CA CA 2002595 patent/CA2002595C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2002595A1 (en) | 1991-02-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5014785A (en) | Methane production from carbonaceous subterranean formations | |
| US5566756A (en) | Method for recovering methane from a solid carbonaceous subterranean formation | |
| Gunter et al. | Deep coalbed methane in Alberta, Canada: a fuel resource with the potential of zero greenhouse gas emissions | |
| US4756367A (en) | Method for producing natural gas from a coal seam | |
| US5388642A (en) | Coalbed methane recovery using membrane separation of oxygen from air | |
| US5402847A (en) | Coal bed methane recovery | |
| US5388643A (en) | Coalbed methane recovery using pressure swing adsorption separation | |
| US5388641A (en) | Method for reducing the inert gas fraction in methane-containing gaseous mixtures obtained from underground formations | |
| AU669517B2 (en) | Recovery of natural gases from underground coal formations | |
| US5099921A (en) | Recovery of methane from solid carbonaceous subterranean formations | |
| US5388640A (en) | Method for producing methane-containing gaseous mixtures | |
| CA2425930C (en) | Process for recovering methane and/or sequestering fluids in coal beds | |
| US20070144747A1 (en) | Coal bed pretreatment for enhanced carbon dioxide sequestration | |
| CA2216059A1 (en) | Gravity concentrated carbon dioxide eor process | |
| US5267615A (en) | Sequential fluid injection process for oil recovery from a gas cap | |
| CA2199863A1 (en) | Slurrified reservoir hydrocarbon recovery process | |
| US5944104A (en) | Chemically induced stimulation of subterranean carbonaceous formations with gaseous oxidants | |
| CA2002595C (en) | Methane production from carbonaceous subterranean formations | |
| CA2176588C (en) | Method for disposing carbon dioxide in a coalbed and simultaneously recovering methane from the coalbed | |
| US3964545A (en) | Processes for secondarily recovering oil | |
| MacLean | Design of a field-wide hydrocarbon miscible flood for the Kaybob Beaverhill Lake" A" Pool | |
| Cornelius et al. | CO2 Removal from Hydrocarbon Gas in Water Bearing Underground Reservoir | |
| Samaniego V et al. | On the waterflooding exploitation of carbonate naturally fractured reservoirs | |
| Copen | Sheldon |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |