SYSTEM AND METHOD FOR PERMANENT STORAGE OF CARBON DIOXIDE IN SHALE RESERVOIRS

Abstract

The present disclosure provides a system, method and apparatus for the removal of natural gas/methane from in situ loci within shale reservoirs to (i) provide fully de-carbonized surplus electricity, and (ii) power re-injection of the resulting carbon formed (CO.sub.2) upon combustion in an electric generator along with large volumes of atmospheric CO.sub.2, such as for large scale removal of CO.sub.2 from the Earth's surface/atmosphere.

Claims

1-6. (canceled)

7. A system for storing and extracting carbon compounds in an underground reservoir, said system comprising: a first supply subsystem adapted to provide a fluid to the underground reservoir; a second supply subsystem adapted to provide a proppant to the underground reservoir; a third supply subsystem adapted to provide a solvent for dissolving the proppant to the underground reservoir; and a pressure subsystem comprising a pump in communication with the fluid and the proppant for pressurizing at least one of the fluid and the proppant to a pressure sufficient to stimulate the underground reservoir, and for pressurizing the solvent sufficient to deliver the solvent to the underground reservoir.

8. The system of claim 7, the pump is in further communication with the solvent for pressurizing the solvent to a pressure sufficient to deliver the solvent to the underground reservoir.

9. The system of claim 7, further comprising a removal subsystem to remove hydrocarbons from the underground reservoir.

10. The system of claim 9, wherein the removed hydrocarbons being a fuel source for production of electricity.

11. The system of claim 9, further comprising a power conversion unit to produce electricity and byproducts from hydrocarbons.

12. The system of claim 11, wherein the byproduct produced includes the carbon compounds.

13. The system of claim 11, the electricity providing a power source for injection of the carbon compounds into the underground reservoir.

14. The system of claim 7, wherein the underground reservoir being a shale reservoir.

15. A method for storing carbon containing compounds in a formation associated with a pre-existing fracturing well formed by hydraulic fracturing, the method comprising: injecting a solution into the formation, the solution capable of at least partially degrading the structural integrity of proppant positioned within the formation; injecting the carbon containing compounds into the formation; and periodically reinjecting CO.sub.2 into the formation.

16. The method of claim 15, wherein the proppant being a conventional proppant.

17. The method of claim 15, wherein the formation being a shale.

18. The method of claim 15, wherein the solution being an alkaline solution.

19. The method of claim 15, wherein the solution being an acidic solution.

20. The method of claim 15, wherein the at least partially degrading comprising comprises at least partially dissolving the structural integrity of the proppant.

21. A method for storing and extracting carbon containing compounds in a formation associated with a fracturing well formed by hydraulic fracturing, the method comprising: injecting proppant into the formation; fracturing the formation; removing hydrocarbons from in situ loci within the formation; injecting the carbon containing compounds into the formation; injecting a solution into the formation, the solution capable of at least partially degrading the structural integrity of the proppant positioned within the formation; and periodically injecting CO.sub.2 into the formation; wherein a volume of the carbon containing compounds is greater than a volume of the removed hydrocarbons.

22. The method of claim 21, wherein the proppant being a conventional proppant.

23. The method of claim 21, wherein the formation being a shale reservoir.

24. The method of claim 21, wherein the solution being an alkaline solution.

25. The method of claim 21, wherein the solution being an acidic solution.

26. The method of claim 21, wherein the at least partially degrading comprises at least partially dissolving the structural integrity of the proppant.

27. A method for producing electricity by combustion of hydrocarbons without releasing carbon containing compounds into the atmosphere, the method comprising: injecting proppant into the formation; fracturing the formation; removing hydrocarbons from in situ loci within the formation; converting the hydrocarbons into electricity, wherein the converting produces the carbon containing compounds; powering components of the system of claim 7 with the electricity; utilizing the system to pump the carbon containing compounds into the formation subsequent to the converting; and injecting a solution into the formation, the solution capable of at least partially degrading the structural integrity of proppant positioned within the formation.

28. The method of claim 27, wherein a volume of the carbon containing compounds is greater than a volume of the removed hydrocarbons.

29. The method of claim 27, wherein the proppant being a conventional proppant.

30. The method of claim 27, wherein the formation being a shale.

31. The method of claim 27, wherein the solution being an alkaline solution.

32. The method of claim 27, wherein the solution being an acidic solution.

33. The method of claim 27, wherein the at least partially degrading comprising comprises at least partially dissolving the structural integrity of the proppant.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The novel features believed characteristic of the disclosed subject matter will be set forth in any claims that are filed. The disclosed subject matter itself, however, further objectives, and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:

[0034] FIG. 1 illustrates an exemplary components diagram of the present disclosure.

[0035] FIG. 2 illustrates an exemplary production flowchart diagram of the present disclosure.

[0036] FIG. 3 illustrates an exemplary CH.sub.4 recovery flowchart diagram of the present disclosure.

[0037] FIG. 4 illustrates an exemplary CO.sub.2 top-off flowchart diagram of the present disclosure.

[0038] FIG. 5 illustrates an exemplary dissolve proppant flowchart diagram of the present disclosure.

[0039] FIG. 6 displays a method for storing carbon compounds in an underground reservoir.

[0040] FIG. 7 illustrates an exemplary production flowchart diagram of the present disclosure.

[0041] FIG. 8 illustrates an exemplary production flowchart diagram of the present disclosure.

[0042] FIG. 9 illustrates an exemplary production flowchart diagram of the present disclosure.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0043] Reference now should be made to the drawings, in which the same reference numbers are used throughout the different figures to designate the same components.

[0044] Before describing selected embodiments of the present invention in detail, it is to be understood that the present invention is not limited to the particular embodiments described herein. The disclosure and description herein is illustrative and explanatory of one or more presently preferred embodiments of the invention and variations thereof, and it will be appreciated by those skilled in the art that various changes in the design, organization, order of operation, means of operation, equipment structures and location, methodology, and use of mechanical equivalents may be made without departing from the spirit of the invention.

[0045] As well, it should be understood the drawings are intended illustrate and plainly disclose presently preferred embodiments of the invention to one of skill in the art, but are not intended to be manufacturing level drawings or renditions of final products and may include simplified conceptual views as desired for easier and quicker understanding or explanation of the invention. As well, the relative size and arrangement of the components may differ from that shown and still operate within the spirit of the invention as described throughout the present application.

[0046] Moreover, it will be understood that various directions such as “upper”, “lower”, “bottom”, “top”, “left”, “right”, and so forth are made only with respect to explanation in conjunction with the drawings, and that the components may be oriented differently, for instance, during transportation and manufacturing as well as operation. Because many varying and different embodiments may be made within the scope of the inventive concept(s) herein taught, and because many modifications may be made in the embodiments described herein, it is to be understood that the details herein are to be interpreted as illustrative and non-limiting.

[0047] The present disclosure may provide to the oil/natural gas industry efficient systems and methods for storing CO.sub.2 in shales depleted of CH.sub.4.

[0048] The U.S. Energy Information Administration (EIA) estimates in the Annual Energy Outlook 2015 that about 11.34 trillion cubic feet of dry natural gas was produced directly from shale and tight oil resources in the United States in 2013. If we assume that 11 trillion cubic feet of CH.sub.4 is produced, this is equivalent to 311 trillion L. At standard temperature and pressure, 22.4 L is equal to 1 mole of any gaseous material. Thus, 311 trillion L of CH.sub.4 is equal to 13.884 trillion moles CH.sub.4 produced.

[0049] The molar mass of CO.sub.2 is 44 g/mol. If we assume a 1-fold excess of CO.sub.2 would be sequestered in addition to the CO.sub.2 generated in CH.sub.4 combustion. Then 13.884 trillion moles CO.sub.2 would equal 610 trillion g of CO.sub.2. 610 trillion g of CO.sub.2 is equal to 610 million (metric) ton of CO.sub.2. This would represent the amount of excess CO.sub.2 sequestered into the shale reservoirs once the process reaches steady state per year assuming a two-fold exchange. If the value is closer to three-fold then the amount of CO.sub.2 sequestered in excess of that used in power generation would be 1,220 million tons of CO.sub.2.

[0050] On average the US emits 5,000 million ton of CO.sub.2 per year from all sources. The main source is power generation. Assuming the ability of shale reservoirs to sequester two to three times the adsorptive capacity of CH.sub.4 in the wells, then this process would result in a roughly 12-24% reduction in CO.sub.2 emissions in the US. The EU has set a target of reducing greenhouse gas emissions by 40% by 2030. It was intended that this should be simply by generation changes. However, using this process almost half of this target could be achieved without alteration of the infrastructure needs of the power generation or chemical industry who are the major uses of hydrocarbon combustion for electricity and energy (heat) generation.

[0051] FIG. 1 illustrates an exemplary components diagram of a system 100 for storing carbon compounds in an underground reservoir 200 in accordance with embodiments. In embodiments, system 100 may include components to inject a fluid under pressure into an underground reservoir via a well 110. For example, system 100 may be used to stimulate the production (e.g., of hydrocarbons) by forming fractures in the well 110 through the provision of a pressurized proppant (that may be mixed with a fracturing fluid) through the well 110 and into the underground reservoir 200 to maintain and/or support the fractures while permitting the flow of hydrocarbons or other fluids from the formation into the well 110 and toward the surface. FIG. 1 may subdivide the depicted system into a first subsystem: a fluid addition subsystem 120 for providing fracturing fluid or a similar medium to the underground reservoir 200, a second subsystem: a proppant addition subsystem 130 for providing proppant or a similar medium into the fracturing fluid, a third subsystem: a solvent addition subsystem 140 adapted to provide a solvent for dissolving the proppant to the underground reservoir 200, a power subsystem 150 for providing power to one or more components of the system 100, and a pressure subsystem 160 for pressurizing fluid for injection into the underground reservoir 200. The pressure subsystem 160 may comprise a pump in communication with the fluid and the proppant in order to pressurize at least one of the fluid and the proppant to a pressure sufficient to stimulate the underground reservoir 200. In embodiments, the pump may be in further communication with the solvent for pressurizing the solvent to a pressure sufficient to deliver the solvent to the underground reservoir 200.

[0052] It should be understood that the number, type, and arrangement of components shown in FIG. 1 is only one exemplary embodiment, and that the depicted illustration is diagrammatic, intended to conceptually depict one embodiment of the present system. As such, it should be noted that any number, type, and arrangement of identical or similar components could be used without departing from the scope of the present disclosure. Further, while the depicted embodiment includes multiple subsystems (120, 130, 140, 150, 160) used in combination, it should be understood that in various embodiments, the fluid addition subsystem 120 could be used in the absence of the other subsystems (130, 140, 150, 160) and/or in combination with conventional systems and/or components. Similarly, the proppant addition subsystem 130, the solvent addition subsystem 140, and the power and pressure subsystems 150, 160 may be used independently or in combination with conventional systems and/or components without departing from the scope of the present disclosure.

[0053] In embodiments, the solvent addition subsystem 140 may comprise elements similar to that of the fluid addition subsystem 120 and the proppant addition subsystem 130. But due to the corrosive nature of the solvent, embodiments of the solvent addition subsystem 140 may comprise components including corrosive resistant interiors. This may reduce the frequency that components of the solvent addition subsystem 140 may need to be replaced.

[0054] In embodiments, system 100 may comprise a removal subsystem 170 to remove the natural gas from the underground reservoir 200. The removal subsystem 170 may be incorporated within the pressure subsystem 160. In embodiments, the mechanism to pump fluids or other materials may be reversed in order to pump hydrocarbons out of the underground reservoir 200.

[0055] It is noted that, in embodiments, the removed natural gas may act as a fuel source for the production of electricity. This electricity may be used as a power source by system 100 and may be utilized to run components of system 100 to pump carbon compounds back into the underground reservoir 200, thus saving money on the cost of running system 100. A power conversion unit 155 may aid in this production of the electricity. The power conversion unit 155 may break down the hydrocarbons pumped out of the well 110 (via combustion) and may produce electricity as well as byproducts, such as, but not limited to, carbon compounds including CO.sub.2 and H.sub.2O. The carbon compounds may be captured and subsequently pumped back into the underground reservoir 200 with the aid of the electricity (acting as a power source) produced by the power conversion unit 155. In embodiments, the power subsystem 150 may encompass the power conversion unit 155.

[0056] Once the underground reservoir 200 is at or near full volumetric capacity with sequestered CO.sub.2 (at or near discovery pressure), in embodiments, the proppant may be dissolved by injecting the aqueous solvent into the well, which may allow the geologic forces previously resisted by the proppant to collapse and seal closed the underground reservoir 200. The CO.sub.2 thus may be trapped within the rock underground.

[0057] FIG. 2 illustrates an exemplary production flowchart diagram 200 of the present disclosure. As shown, produced gas may be removed using pressure subsystem 160. Once removed, the gas may be transferred to the power subsystem 150. It is at this point that the gas may be burned, which may produce CO.sub.2 and H.sub.2O (1BCF of CH.sub.4 generates 11 MM gallons of pure fresh H.sub.2O), both of which may be captured and at least temporarily stored in appropriate storing chambers 210.

[0058] FIG. 3 illustrates an exemplary CH.sub.4 recovery flowchart diagram 300 of the present disclosure. In some instances, it may be feasible/desirable to periodically re-inject CO.sub.2 into the depleting shale reservoir which induces greater desorption of CH.sub.4 and thus more natural gas production. This may be carried out using pressure subsystem 160. The pressure subsystem 160 may comprise a dual inlet/outlet and associated transferring equipment that may allow simultaneous extraction and transport of CH.sub.4 and CO.sub.2. This is because shale reservoirs often more adsorptive of CO.sub.2 than CH.sub.4. See reference below.

[0059] FIG. 4 illustrates an exemplary CO.sub.2 top-off flowchart diagram 400 of the present disclosure. Upon completion of the cycle, according to an embodiment a process may result in the sequestration of more CO.sub.2 than is generated from electric power made with the produced CH.sub.4. In one aspect, a result may be low cost ubiquitously available electricity accompanied by profound net decreases in planetary CO.sub.2.

[0060] According to disclosed subject matter, produced/vacating gas provides a permanent container or containment for all of the CO.sub.2 this production creates upon combustion, and further may provide containment for even greater volumes of CO.sub.2 removed directly from the atmosphere by the system 100 when electric generation operations are not fully underway or idled. In embodiments, machinery that may extract additional CO.sub.2 from the atmosphere may be utilized in connection with other components of system 100.

[0061] FIG. 5 illustrates an exemplary dissolved proppant flowchart diagram 500 of the present disclosure. In a final stage, the proppant may be dissolved to allow permanent closure of the fractures by the enormous geologic pressure that has been temporarily resisted by the proppant particles. Once sealed, the CO.sub.2 may be stored in the rock throughout geologic time and may not be vulnerable to loss of the integrity of the well bores used to access the reservoir.

[0062] FIG. 6 displays a method 600 for storing carbon compounds in an underground reservoir. Method 600 may comprise injecting proppant into an underground reservoir 200. The proppant may be injected using a proppant addition subsystem 130. Additionally, a fluid addition subsystem 120 may provide fluid to the underground reservoir in addition to the proppant. Once injected, the proppant may fracture the underground reservoir 200, allowing for accessibility of hydrocarbons. The hydrocarbons may be removed from in situ loci within the underground reservoir 200 using a pressure subsystem 160.

[0063] Once extracted, the hydrocarbons may be converted into electricity via processing of the hydrocarbons. The conversion may include, in embodiments, capturing a byproduct from the converting of the hydrocarbons into electricity. In embodiments, the byproduct may include carbon compounds. Once the hydrocarbons are processed, carbon compounds created during the processing may be injected into the underground reservoir 200. This may be carried out using the pressure subsystem 160. In embodiments, the pressure subsystem 160 may comprise reversible components so that pumping out of the ground and into the ground may be accomplished. After the desired amount of carbon compounds have been injected into the underground reservoir 200, the proppant transferred into the underground reservoir may be dissolved. This may allow for the collapsing of the underground reservoir 200 and the trapping of the carbon compounds.

[0064] FIG. 7 illustrates an exemplary production flowchart diagram of the present disclosure. The natural gas/methane which has been extracted may be used for electric power generation. The CO.sub.2 that is formed upon combustion of the natural gas in the electric generator may be separated and captured to be re-injected into the shale fractures for permanent sequestration. Large quantities of pure water (H.sub.2O) may also be formed when the natural gas is burned with pure oxygen (O.sub.2) rather than air.

[0065] FIG. 8 illustrates an exemplary production flowchart diagram of the present disclosure. Additional ambient CO.sub.2 captured from the atmosphere may be added to the sequestration injection stream, given the shales may be many times more absorptive of CO.sub.2 than the original methane.

[0066] FIG. 9 illustrates an exemplary production flowchart diagram of the present disclosure. Additional ambient CO.sub.2 captured from the atmosphere may be added to the sequestration injection stream, which may be shown being injected into the shales.

[0067] Further, in an embodiment, system 100 may provide back-up electrical power for the intermittent interruption in power generation provided by wind, wave, and solar devices.

[0068] In embodiments, underground reservoir 200 may be a shale reservoir.

[0069] In embodiments, hydrocarbons other than CH.sub.4 may be extracted from one or more underground reservoirs 200 and subsequently processed.

[0070] In embodiments, the fracturing fluid may comprise light weight alkanes.

[0071] In embodiments, the specialized proppant may be dissolved by injecting a low pH fluid into a fracture system.

[0072] In embodiments, the light weight alkanes may be recoverable.

[0073] In embodiments, pumps may be needed for the CO.sub.2.

[0074] The following references are relied upon, and are hereby incorporated in their entirety:

[0075] Numerical Simulation and Modeling of Enhanced Gas Recovery and CO.sub.2 Sequestration in Shale Gas Reservoirs (Amirmasound K. Dahaghi, West Virginia University, Society of Petroleum Engineers 2010).

[0076] Carbon Dioxide Storage Capacity of Organic-Rich Shales (S. M. Kang, E. Fathi, R. J. Ambrose, I. Y. Akkutlu, and R. F. Sigal, The University of Oklahoma, Society of Petroleum Engineers 2011).

[0077] https://www.netl.doe.gov/publications/proceedings/01/c arbon_seq/7bl.pdf

[0078] http://mitei.mit.edu/news/new-way-capture-co2-emissions-lower-costs-easier-installation

[0079] https://www.globalccsinstitute.com/content/how-ccs-works-capture

[0080] http://www.ccsassociation.org/index.php/what-is-ccs/capture/post-combustion-capture/

[0081] http://www.ccsassociation.org/what-is-ccs/capture/oxy-fuel-combustion-systems/

[0082] In embodiments, the proppant may be boron laced meso-porous amorphous silica.

[0083] While various embodiments usable within the scope of the present disclosure have been described with emphasis, it should be understood that within the scope of the appended claims, the present invention can be practiced other than as specifically described herein.