Patent Description:
Carbon sequestration can be divided into two categories: the enhancement of the natural sinking rates of CO<NUM> and direct discharge of human generated CO<NUM>.

The sequestration options in the first category include terrestrial sequestration by vegetation, ocean sequestration by fertilization, and an enhancement of the rock weathering process. In the direct discharge options, the CO<NUM> produced from large point sources, such as thermal power stations, would be captured and separated, then transported and injected either into the ocean or underground.

Each option has advantages and disadvantages in terms of capacity, cost, the time scale of the sequestration, the stability of sequestered CO<NUM>, and additional environmental impacts, which depend on the location, time, and amount of sequestration. Reliable evaluations of the mitigation efficiency are desirable for each sequestration option upon implementation (Yamasaki, et al.

It has been stated that biological sequestration is a natural approach; however, despite this advantage it is known that significant disadvantages are associated with this approach. For example, while freshwater marshes have been shown to be strong sinks for carbon dioxide (CO<NUM>) on an annual basis relative to other wetland types, it is likely that these ecosystems are also strong emitters of methane (CH<NUM>), reducing their carbon (C) sequestration potential. Thus, the substantial CH<NUM> emissions from marshes need to be considered in national and global estimates of wetland greenhouse gas contribution to the global carbon cycle (Strachan et al, <NUM>).

Ocean sequestration is another approach that can be characterized as being natural. Although the oceans represent possibly the largest potential CO<NUM> sink, ocean sequestration involves problems including poorly understood physical and chemical processes, efficiency, cost, technical feasibility, and possibly the most worrying, long-term environmental impact. In addition, ocean circulation poses legal, political and international limitations to this technology. Carbon dioxide forms carbonic acid when dissolved in water, so ocean acidification is a significant consequence of elevated carbon dioxide levels, and limits the rate at which it can be absorbed into the ocean.

The sequestration of CO<NUM> by a sacrificial material that will then be used or disposed of represents a crossover between the two categories. For example, mineral CO<NUM> sequestration, i.e., carbonation of alkaline silicate Ca/Mg minerals, may be considered analogous to natural weathering processes. Mineral CO<NUM> sequestration may be considered for the reduction of carbon dioxide emissions to the atmosphere. However, the total volume of material required to make an impact on global CO<NUM> emissions would be cost prohibitive (Huijens, et al.

At this time, CO<NUM> sequestration in geological media appears to be an option for long-term sequestration of CO<NUM>. In such a system, it is proposed that CO<NUM> may be stored deep underground. At depth, hydrostatic pressure would act to keep the stored CO<NUM> in a liquid state (White, et al.

Sequestration in deep underground formations of large amounts of CO<NUM>, captured from large stationary sources, such as power plants, oil upgraders and refineries, is one method that is under consideration for reducing greenhouse gas emissions to the atmosphere in Canada and United States (Bennion and Bachu, <NUM>).

While in a typical well, the CO<NUM> would be sealed by capping the well with cement, degradation of the cement may prevent such wells from being a long-term solution. Exposure of well cements to CO<NUM> results in the formation of different CaCO<NUM> modifications, proving carbonation. Carbonation rates were relatively low, but most detrimental were the cracking of specimens as a result of massive CaCO<NUM> formation which comes along with expansion (Lesti et al. Although some of the reactions with cement can be beneficial, a loss of compressive strength of the cement is observed (Condor and Asghan, <NUM>).

<CIT> discloses proppants, and in particular reactive proppants capable of interacting with formation or activation fluids to be thereby activated to modify fracture flow paths in oil and gas reservoirs to, inter alia, enhance oil and gas production.

<CIT> discloses a method of fracturing a coalbed gas reservoir.

<CIT> discloses a method of using carbon dioxide in recovery formation deposits.

In summary, current CO<NUM> geologic sequestration technology suffers various problems and inadequacies. Failure of the geologic formation or reservoir to contain the CO<NUM> due to cement failure may result in catastrophic release of vast quantities of CO<NUM> at some undetermined point in the future.

Subject matter of this disclosure provides a method for sequestration in deep underground formations of large amounts of CO<NUM>, with improved risk of leakage such as, for example, long-term leakage.

According to the present invention, there is disclosed a method for storing 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, thereby forming fractures; removing hydrocarbons from in situ loci within the formation; injecting the carbon containing compounds into the formation; and injecting a solution into the formation, the solution capable of at least partially degrading the structural integrity of the proppant positioned within the formation, thereby resealing the fractures.

In an embodiment, a sequestration method may include storing CO<NUM> in an underground geologic formation by introducing the CO<NUM> into a well formed in the formation by hydraulic fracturing, and closing the fractures to seal the well with the CO<NUM> stored in the formation and prevent escape of the stored CO<NUM> through the well fractures. Such a sequestration method may include introducing the CO<NUM> into a well formed by hydraulic fracturing for the production of hydrocarbons such as, for example, shale gas, from a reservoir of the underground geologic formation. A sequestration method as disclosed may include degrading proppant in the fractures to cause resealing of the fractures, such as by geologic forces on the fractures. A large- scale sequestration method may include introducing a large volume of CO<NUM> into a plurality of wells formed by hydraulic fracturing for production of hydrocarbons from reservoirs of at least one underground geologic formation, and includes degrading proppant in the fractures so as to cause resealing of hydraulic fractures by geologic forces, which may prevent escape of stored CO<NUM> from the formation through the hydraulic fractures and well. It will be understood that suitable geologic formations may include shale formations. As used herein, "shale" includes shale(s), shale gas, shale reservoirs, shale source rocks, shale formations, shale wells, shale samples, shale (and tight oil) resources.

In an arrangement useful for understanding the invention, a sequestration system may include a well formed in the formation by hydraulic fracturing, CO<NUM> stored in the formation by introducing the CO<NUM> through the well, and a closed hydraulic fracture of the well sealing the stored CO<NUM> in the formation to prevent escape of the stored CO<NUM> through the fractures and well. In an embodiment, a sequestration system may include a well formed by hydraulic fracturing associated with production of hydrocarbons, such as shale gas, from a reservoir of the underground formation. A sequestration system as disclosed may include degraded proppant that provides for resealing of the fractures , such as by geologic forces on the fractures. In an eafoodiment, a large-scale sequestration system may include a plurality of wells formed by hydraulic fracturing associated with production of shale gas from reservoirs of at least one underground geologic formation, wherein the well includes sealed hydraulic fractures preventing escape of stored CO<NUM> from the formation through the hydraulic fractures.

In an arrangement useful for understanding the invention, the sequestration system for permanent storage of CO<NUM> may include a well formed in communication with a geologic formation with hydraulic fractures; CO<NUM> stored under pressure in the formation; and the hydraulic fractures sealed to prevent escape of stored CO<NUM> from the geologic formation through the hydraulic fractures into the wellbore. Such a sequestration system may include a well formed by hydraulic fracturing associated with production of hydrocarbons, such as shale gas, from a reservoir of the geologic formation. A sequestration system as disclosed may include degraded proppant, such that the hydraulic fractures are resealed by geologic forces.

It will be understood that shale gas represents the largest fraction of natural gas in the continental United States. With an estimated <NUM> trillion cubic feet (Tcf) (<NUM> trillion cubic metres) of hydrocarbon (Nicot and Scanlon, <NUM>), shale gas has the potential to be the primary energy source for power generation in the US for the coming decades. The ability to extract shale gas in an economic and timely manner has been achieved by the development and use of hydraulic fracturing and horizontal drilling techniques. Hydraulic fracturing (also known as "fracing" or "fracking") uses water, proppant, and various chemical additives, pumped at high pressures into the well bore, to induce fracturing of the shale source rock and thus create greater permeability so the gas can migrate into the well bore and to the surface. The facturing fluid chemistry is tailored on a case-by-case basis for each geographical area and sometimes even on a well-by-well basis.

Fracking is necessary to produce hydrocarbons from shale formations because shale has very low permeability (concrete is <NUM>-<NUM> times more permeable) and there has been little or no movement of fresh water (or waters of a different mineral content) since the rock was formed. Furthermore, shale is under-saturated to water and the level of salt in the connate water within the shale is often at salinity equal to the seawater the shale was deposited from. When shale is under-saturated, introducing fresh water or moderate salinity water in a frac, causes salts, some organics , and other minerals that were previously in equilibrium in the shale to becoming solubilized with the connate waters. It is important that shale reservoir has been "isolated" from external chemistry for several million years. In other words, until the shale reservoir is fracked, there is no route for hydrocarbons to escape, meaning,for example, that if natural gas could be exchanged for CO<NUM> and the reservoir returned to is pre-frack state the CO<NUM> would be contained by the same forces that contained the gas for millions of years. Given that shale gas in the U. is formed during the Jurassic period, this qives a proven stability of over <NUM> million years.

The present invention provides a method for the removal of natural gas/methane from in situ loci within wells to (i) provide fully de-carbonized surplus electricity, and (ii) power the re-injection of the resulting carbon formed (CO<NUM>) upon combustion in the electric generator along with large volumes of atmospheric CO<NUM>, culminating in a technically and commercially feasible, permanent (in terms of geologic time), and large scale removal of CO<NUM> from the Earth's surface/atmosphere.

For the methane molecules produced, this is a cradle-to-grave cycle wherein the same carbon atoms that are harvested and used for power generation are then returned to their original geologic resting place through the same fracture system, pipe and compression that delivered them into power generation service.

Once the shale reservoir and fracture systems are at or near full volumetric storage capacity with sequestered CO<NUM> (at or near discovery pressure) , the specialized proppant used in this invention is dissolved by injecting an acidic aqueous solution, thus allowing geologic forces, previously resisted by the proppant, to collapse and seal closed the fracture system, permanently trapping the CO<NUM> within the rock.

Concerning de-carbonization, the result of this process via this disclosed subject matter is the permanent, in terms of geologic time, storage of CO<NUM> that is not dependent upon wellbore sealing or the long term integrity thereof. A system, and method, as disclosed may provide de-carbonized, or fully de-carbonized, power generation that supports fully, or in part, the continued and economic use of intermittent supplies of electricity such as, for example, generation of electricity by wave, wind, and solar energy sources.

In an arrangement useful for understanding the invention, a sequestration system may include large cohorts of hydrocarbon productive shale wells that may be stimulated by hydraulic fracturing utilizing certain select reservoir fluids suffused with specialized proppant (the particles maintaining fracture patency during production and re-injection) which may be dissolved at the end of the CO<NUM> sequestration cycle with a small volume of an acidic aqueous solution. Embodiments may further include natural gas and carbon dioxide compatible surface facilities such as compression, dehydration, filter/separators, and measurement equipmens which may be functionally bi-directional.

Embodiments may optionally include, in certain circumstances, natural gas and/or carbon dioxide smaller scale temporary storage reservoirs or surface facilities which may facilitate the logistics of material movements and placement.

Embodiments may optionally include large (e.g. multi-hundred Megawatt F-class combined cycle turbines) and/or small (peaking gas fired generators) scale electric power generating and ancillary equipment.

Embodiments may optionally include pre-combustion (e.g. oxy-fuel systems which provide O<NUM> for combustion with the natural gas) and/or post-combustion carbon dioxide capture systems (e.g. electrolytic amine or Ca(OH)<NUM> systems).

Embodiments may optionally include freshwater surface handling facilities.

Sequestration of CO<NUM> underground is hampered by the paucity and adverse locational distribution of suitable reservoirs to serve as economically feasible containers of large volumes of CO<NUM>. Certainly depleted conventional reservoirs and deep aquifers could serve in this role. However, their relative limited capacity to meet the magnitude of the need and/or difficulties in overcoming discovery pressures are very challenging aspects to their utilization, irrespective of availability and location.

It may be vastly more efficient to store CO<NUM> in shales depleted of methane or CH<NUM>. Results have shown that CO<NUM> is approximately two to three times more adsorptive than CH<NUM> in both the pure mineral constituents and actual shale samples (R. Heller and Zoback, <NUM>). This does not include the volume attained by the proppant.

Given that natural gas is predominantly methane (CH<NUM>), its combustion during power generation would result in one molecule of CO<NUM> per molecule of CH<NUM> combusted. Combustion may be represented by the following equation: CH<NUM> + 2O<NUM> → CO<NUM> + <NUM><NUM>O. Based upon this, it can also be assumed that for every two to three molecules that can be adsorbed within a well, one of the CO<NUM> molecules was generated during power generation using the produced methane or CH<NUM>. Therefore, shale can be used for an over adsorption of one to two equivalents of CO<NUM> per each CH<NUM> produced from the original wells. This makes the entire process profoundly net reductive of atmospheric CO<NUM>. Disclosed subject matter makes possible the production of electricity from natural gas, using shale gas and current infrastructure, or new infrastructure as herein disclosed, with the significant benefit of net negative emissions of CO<NUM>.

While embodiments usable within the scope of the present disclosure can be powered using on-site reciprocating engines (e.g., diesel engines), coupled with turbine generators and/or similar power systems, in an embodiment, one or more system components can be configured for use with electrical power. For example, the pressure subsystem can include an electric-powered driver (e.g., an electric motor or similar source of force) in communication with and actuating the pump, while an electrical power source powers the electric-powered driver. In an embodiment, a turbine generator (e.g., a natural gas turbine or similar source) can be used to provide power to an electric motor, which in turn drives the pump. Alternatively, or additionally, a grid-based power source can be used to power the electric-powered driver. In an embodiment, an electric-powered driver can be configured for selective and/or simultaneous operation using a grid-based or an on-site power source. Where a grid-based power sourced is used, in an embodiment, one or more additional transformers can be used to convert power from the grid-based power source to a desired voltage. In use, a single pump can be actuated using a single electric-powered driver or multiple electric-powered drivers, and multiple pumps can be actuated using a single electric-powered driver or multiple electric-powered drivers. Similarly, a single power source can power one or multiple electric-powered drivers, or one or multiple electric-powered drivers can be powered by multiple power sources.

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:.

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.

Before describing selected embodintents 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, meansof operation, equipament structures and location, methodology, and use of mechanical equivalents may be made within the scope of the present invention as defined by the claims.

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.

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-limitind.

The present disclosure may provide to the oil/natural gas industry efficient systems and methods for storing CO<NUM> in shales depleted of CH<NUM>.

Energy Information Administration (EIA) estimates in the Annual Energy Outlook <NUM> that about <NUM> trillion cubic feet (<NUM> trillion cubic metres) of dry natural gas was produced directly from shale and tight oil resources in the United States in <NUM>. If we assume that <NUM> trillion cubic feet of CH<NUM> is produced, this is equivalent to <NUM> trillion Liters. At standard temperature and pressure, <NUM> Liters is equal to <NUM> mole of any gaseous material. Thus, <NUM> trillion Liters of CH<NUM> is equal to <NUM> trillion moles of CH<NUM> produced.

The molar mass of CO<NUM> is <NUM> grams/mol. If we assume a <NUM>-fold excess of C0<NUM> would be sequestered in addition to the C0<NUM> generated in CH<NUM> combustion. Then <NUM> trillion moles CO<NUM> would equal <NUM> trillion grams of CO<NUM>. <NUM> trillion grams of CO<NUM> is equal to <NUM> million (metric) tons of CO<NUM>. This would represent the amount of excess CO<NUM> sequestered into the shale reservoirs once the process reaches steady state per year assuming a twofold exchange. If the value is closer to three-fold than the amount of CO<NUM> sequestered in excess of that used in power generation would be <NUM>,<NUM> million tons of CO<NUM>.

On average the US emits <NUM>,<NUM> million ton of CO<NUM> 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<NUM> in the wells, then this process would result in a roughly <NUM>-<NUM>% reduction in CO<NUM> emissions in the US. The EU (European Union) has set a target of reducing greenhouse gas emissions by <NUM>% by <NUM>. 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 generationor chemical industry that are the major users of hydrocarbon combustion for electricity and energy (heat) generation.

<FIG> illustrates an exemplary components diagram of a system <NUM> for storing carbon compounds in an underground reservoir <NUM>.

System <NUM> includes components to inject a fluid under pressure into an underground reservoir via a well <NUM>. System <NUM> is used to stimulate the production (e.g., of hydrocarbons) by forming fractures in the well <NUM> through the provision of a pressurized proppant (that may be mixed with a fracturing fluid) through the well <NUM> and into the underground reservoir <NUM>, which may maintain and/or support the fractures while permitting the flow of hydrocarbons or other fluids from the formation into the well <NUM> and toward the surface. <FIG> may subdivide the depicted system <NUM> into a first subsystem: a fluid addition subsystem for providing fracturing fluid or a similar medium to the underground reservoir <NUM>, a second subsystem: a proppant addition subsystem for providing proppant or a similar medium into the fracturing fluid, a third subsystem: a solvent addition subsystem adapted to provide a solvent for dissolving the proppant to the underground reservoir <NUM>, a power subsystem/power generator <NUM> for providing power to one or more components of the system <NUM>, and a pressure subsystem for pressurizing fluid for injection into the underground reservoir <NUM>. It is noted that the fluid ionsubsystem, the proppant addition subsystern, the solvent addition subsystem, and the pressure subsystem may be represented be surface facilities <NUM>, The pressure system comprises a pump in connection 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 <NUM>. 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 <NUM>.

It should be understood that the number, type, and arrangement of componets shown in <FIG> 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 (fluid addition subsystem, proppant addition subsystem, solvent addition subsystem, power subsystem <NUM>, pressure subsystem) used in combination, it should be understood that in various embodiments, the fluid addition subsystem may be used in the absence of the other subsystems (proppant addition subsystem, solvent addition subsystem, power subsystem <NUM>, pressure subsystem) and/or in combination with conventional systems and/or components. Similarly, the proppant addition subsystem, the solvent addition subsystem, and the power and pressure subsystems <NUM> may be used independently or in combination with conventional systems and/or components.

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

System <NUM> may comprise a removal subsystem (not depicted1 to remove the natural gas from the underground reservoir <NUM>. The removal a subsystem may be incorporated within the pressure subsystem. In embodinants, the mechanism to pump fluids or other materials may be reversed in order to pump hydrocarbons out of the underground reservoir <NUM>,.

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 <NUM> and may be utilized to run components of system <NUM> to pump carbon compounds mack into the undergroind reservoir <NUM>, thus saving money on the cost of running system <NUM>. A power conversion unit (not depicted) may aid in this production of the electricity. The power conversion unit (not depicted) may break down the hydrocarbons pumped out of the well <NUM> (via combustion) and may produce electricity as well as byproducts, such as, but not limited to, carbon compounds including CO<NUM>, and H<NUM>O. The carbon compounds may be captured and subsequently pumped back into the underground reservoir <NUM> with the aid of the electricity (acting as a power source) produced by the power conversion unit. In embodiments, the power subsystem <NUM> may encompass the power conversion unit.

Once the underground reservoir <NUM> is at or near full volumetric capacity with sequestered CO<NUM> (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 <NUM>. The CO<NUM> thus may be trapped within the rock underground.

Referring to <FIG>, disclosed subject matter includes a sequestration system <NUM> for permanent storage of CO<NUM> in an underground geologic formation <NUM>. Such a system <NUM> may include introducing CO<NUM> under pressure from a CO<NUM> supply <NUM> the geologic formation <NUM> for storage therein. A system <NUM> as disclosed may include a well <NUM> having a wellbore that, during an introduction phase, is initially in fluid communication with open hydraulic fractures <NUM> formed in the geologic formation <NUM> for introducing the CO<NUM> under pressure into the geologic formation <NUM>. Such a system <NUM>, during a permanent storage phase, may include resealed hydraulic fractures formed by causing the open hydraulic fractures to be resealed, such as by geologic forces, to permanently prevent fluid communication between CO<NUM> stored in the formation and the fluid communication between CO<NUM> stored in the formation and the wellbore, and thus to permanently prevent CO<NUM> stored in the formation from escaping into the general atmosphere or environment above-ground via the wellbore. Such a sequestration system <NUM> may include the well <NUM> being formed by hydraulic fracturing for the production of hydrocarbons such as, for example, shale gas, from a reservoir of the underground geologic Formation <NUM>. A sequestration system <NUM> includes degradable proppant in the resealed hydraulic fractures <NUM>. In embodiments, degradable proppant may be degradable by exposure to a degradation agent for reducing integrity of the proppant. It will be understood that the resealed hydraulic fractures <NUM> may be resealed by geologic forces acting on the open hydraulic fractures in the presence of degraded proppant (not shown in <FIG>). It will be understood that, in a system <NUM>, proppant in open hydraulic fractures <NUM> may be degraded, for example, by exposing the proppant to a degrading agent such as, for example, a fluid degrading agent. It will be understood that a fluid degrading agent may be, for example, an acidic solution, an alkaline solution, or a fluid containing a degrading agent that is reactive with the proppant, or with at least a portion of the proppant, for dissolving, removing, reducing size, or reducing compressive strength of the proppant. Such a sequestration system <NUM> may include the well <NUM> formed in the geologic formation by hydraulic fracturing, CO<NUM> stored in the formation by introducing the CO<NUM> under pressure through the wellbore of well <NUM> , and a closed or resealed hydraulic fracture <NUM> sealing the stored CO<NUM> in the formation to prevent escape of the stored CO<NUM> into the wellbore of well <NUM>. Sequestration system <NUM> may include the well <NUM> formed by hydraulic fracturing associated with production of hydrocarbons, such as shale gas, from the underground formation <NUM>. A sequestration system <NUM> as disclosed may include degraded proppant that provides for resealing of the initially open hydraulic fractures, such as by geologic forces exerted on the fractures. A system may include proppants that are safe for human ingestion which satisfy other criteria in relation to density, buoyancy, distribution, strength, and particle size.

As shown in <FIG>, a sequestration system <NUM> may include reaction or combustion equipment <NUM> for combusting, reacting or converting hydrocarbons, such as shale gas, produced from the underground geologic formation <NUM> through well <NUM> to deplete the hydrocarbons from the geologic formation <NUM> and form reaction products including CO<NUM> <NUM>, for the reaction products including CO<NUM> to be introduced back into the hydrocarbon-depleted geologic formation <NUM> under pressure through the wellbore of well <NUM> during an initial introduction phase, before the open hydraulic fractures are caused to reseal to form resealed hydraulic fractures <NUM>. The resealed hydraulic fractures <NUM> during a permanent storage phase prevent fluid communication between CO<NUM> stored in the geologic formation <NUM> and the wellbore of well <NUM>, and thus prevent CO<NUM> stored in the geologic formation <NUM> from escaping through the wellbore of well <NUM> into with the general atmosphere in the above-ground region. It will be understood that the reaction or combustion equipment <NUM> may be associated with a generator <NUM> for producing electricity or power in another suitable form from combustion of hydrocarbons produced from the geologic formation <NUM> through well <NUM>. The generator <NUM> may produce electricity that is offset and fully de-carbonized, and that is sufficient to power both storing the immediate reaction products including CO<NUM> under pressure in the geologic formation <NUM> and also recovering and storing an additional amount of carbon-containing compounds such as CO<NUM> that is removed from Earth's surface region and atmosphere or otherwise provided from a supply of carbon-containing compounds such as CO<NUM> and that are to be permanently stored. It will be understood that system <NUM> may provide permanent storage of carbon-containing compounds such as CO<NUM> under pressure in deep geological formations, such as shale, wherein the carbon-containing compounds such as CO<NUM> under pressure are isolated from communication with the wellbore of well <NUM> by the resealed hydraulic fractures <NUM> being sealed by geologic forces and without incurring risk of gas being released into the general atmosphere due to failure of a cement or other mechanical seal in well <NUM>. It will be understood that such system <NUM> may provide for permanent storage of large volumes of atmospheric C0<NUM>, such as for large scale removal of CO<NUM> from the Earth's surface region and atmosphere.

<FIG> illustrates an exemplary production flowchart diagram <NUM> of the present disclosure. As shown, produced gas may be removed from the shale reservoir <NUM> via the well <NUM> using the pressure subsystem. Once removed, the gas may be transferred to the power subsystem <NUM>. It is at this point that the gas may be burned, which may produce CO<NUM> and H<NUM>O (<NUM> billion cubic feet (<NUM> million cubic metres) of CH<NUM> generates <NUM> million gallons (<NUM> thousand cubic metres) of pure fresh H<NUM>O), both of which may be captured and at least temporarily stored in appropriate storing chambers.

<FIG> illustrates an exemplary CH<NUM> recovery flowchart diagram <NUM> of the present disclosure. In some instances, it may be feasible/desirable to periodically re-inject CO<NUM> into the depleting shale reservoir <NUM> (via well <NUM>) which induces greater desorption of CH<NUM> and thus more natural gas production. This may be carried out using the pressure subsystem. The pressure subsystem may comprise a dual inlet/outlet and associated transferring equipment that may allow simultaneous extraction and transport of CH<NUM> and CO<NUM>, This is because shale reservoirs are often more adsorptive of CO<NUM> than CH<NUM>.

<FIG> illustrates an exemplary CO<NUM> top-off flowchart diagram <NUM> of the present disclosure. Upon completion of the cycle, according to an embodiment, a process may result in the sequestration of more CO<NUM> than is generated from electric power made with the produced CH<NUM> extracted from shale reservoir <NUM> via well <NUM>. In one aspect, a result may be low cost ubiquitously available electricity accompanied by profound net decreases in planetary CO<NUM>.

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

<FIG> illustrates an exemplary dissolved proppant flowchart diagram <NUM> of the present disclosure. In a final stage, the proppant may be dissolved (in embodiments, in a low pH H<NUM>O) 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<NUM> may be pumped into the shale reservoir <NUM> via the well <NUM> and 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.

<FIG> displays a method <NUM> for storing carbon compounds in an underground reservoir. Method <NUM> comprises injecting <NUM> proppant into an underground reservoir <NUM>. The proppant may be injected <NUM> using a proppant addition subsystem. Additionally, a fluid addition subsystem may provide fluid to the underground reservoir <NUM> in addition to the proppant. Once injected <NUM>, the proppant fractures <NUM> the underground reservoir <NUM>, allowing for accessibility of hydrocarbons. The hydrocarbons are removed <NUM> from in situ loci within the underground reservoir <NUM> e.g. using a pressure subsystem.

Once extracted, the hydrocarbons may be converted <NUM> into electricity via processing of the hydrocarbons. The conversion <NUM> may include, in embodiments, capturing a byproduct from the converting <NUM> 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 <NUM> into the underground reservoir <NUM>. This may be carried out using the pressure subsystem. In embodiments, the pressure subsystem 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 <NUM> into the underground reservoir <NUM>, the proppant transferred into the underground reservoir is dissolved <NUM>. This allows for the collapsing of the underground reservoir <NUM> and the trapping of the carbon compounds.

<FIG> illustrates an exemplary production flowchart diagram <NUM> of the present disclosure. The natural gas/methane Which has been extracted may be used for electric power generation. The CO<NUM> 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 <NUM> via the well <NUM> for permanent, sequestration. Large quantities of pure water (H<NUM>O) may also be formed when the natural gas CH<NUM> is burned with pure oxygen (O<NUM>) rather than air within combustion facility <NUM>. Generator <NUM> may convert the energy given off from the combustion of the natural gas into electrical energy, which may be supplied to residential and commercial establishments.

<FIG> illustrates an exemplary production flowchart diagram <NUM> of the present disclosure. Additional ambient CO<NUM> captured from the atmosphere may be added to the sequestration injection stream, given the shales may be many times more absorptive of CO<NUM> than the original methane. The CO<NUM> may be pumped back into the shale fractures <NUM> via well <NUM>. Large quantities of pure water (H<NUM>O) may also be formed when the natural gas (CH<NUM>) is burned with pure oxygen (O<NUM>) rather than air within combustion facility <NUM>. Generator <NUM> may convert the energy given off from the combustion of the natural gas into electrical energy, which may be supplied to residential and commercial establishments.

<FIG> illustrates an exemplary production flowchart diagram <NUM> of the present disclosure. Additional ambient CO captured from the atmosphere may be added to the sequestration injection stream, which may be shown being injected into the shales. The CO<NUM> may be pumped back into the shale fractures <NUM> via well <NUM>. Large quantities of pure water (H<NUM>O) may also be formed when the natural gas (CH<NUM>) is burned with pure oxygen (O<NUM>) (O<NUM>) rather than air within combustion facility <NUM>. Generator <NUM> may convert the energy given off from the combustion of the natural gas into electrical energy, wich may. be supplied to residential and commercial establishments.

<FIG> illustrates a method <NUM> for storing carbon containing compounds in a formation associated with a pre-existing fracturing well formed by hydraulic fracturing in accordance with embodiments. Method <NUM> comprises injecting <NUM> a solution into the formation. The solution is capable of at least partially degrading the structural integrity of proppant positioned within the formation. Method <NUM> further comprises injecting <NUM> the carbon containing compounds into the formation.

<FIG> illustrates a method <NUM> for storing carbon containing compounds in a formation associated with a fracturing well formed by hydraulic fracturing in accordance with embodiments. Method <NUM> comprises injecting <NUM> proppant into the formation. The formation is then fractured <NUM>. Hydrocarbons are then removed <NUM> from in situ loci within the formation.

Method <NUM> further comprises injecting <NUM> the carbon containing compounds into the formation. A solution is then injected <NUM> into the formation. The solution is capable of at least partially degrading the structural integrity of proppant positioned within the formation. In embodiments, a volume of the carbon containing compounds may be greater than a volume of the removed hydrocarbons.

<FIG> illustrates a method <NUM> for producing electricity by combustion of hydrocarbons without releasing carbon containing compounds into the atmosphere in accordance with embodiments. Method <NUM> may comprise injecting <NUM> proppant into the formation. The formation may then be fractured <NUM>. Hydrocarbons may then be removed <NUM> from in situ loci within the formation.

Method <NUM> may further comprise converting <NUM> the hydrocarbons into electricity. The converting <NUM> may produce the carbon containing compounds. The carbon containing compounds may then be injected <NUM> into the formation simultaneously with the converting. A solution may then be injected <NUM> into the formation. The solution may be capable of at least partially degrading the structural integrity of proppant positioned within the formation.

<FIG> is a simplified block diagram illustrating aspects of a system <NUM> for storing carbon containing compounds in a pre-existing fractured well in accordance with embodiments. System <NUM> may comprise a formation <NUM>. The formation <NUM> may comprise sealable fractures <NUM> including degraded proppant and a fractured well <NUM> formed by hydraulic fracturing. System <NUM> may further comprise a carbon containing compound supply <NUM>. In embodiments, at least a portion of the carbon containing compound supply <NUM> may be injected into the formation.

In embodiments, the proppant may be selected based on properties relative to degradation such as, for example, degradation of compressive strength, size, porosity, density, or molecular structure. In embodiments, the formation may be a shale.

<FIG> is a simplified block diagram illustrating a system <NUM> for storing carbon containing compounds in a fractured well. System <NUM> may comprise a formation <NUM>. The formation <NUM> may comprise sealable fractures <NUM> including degradable proppant and a fractured well <NUM> formed by hydraulic fracturing. System <NUM> may further comprise a carbon containing compound supply <NUM> and a combustion source <NUM>. The combustion source <NUM> may supply carbon containing compounds to the carbon containing compound supply <NUM>. In embodiments, the combustion source <NUM> may be capable of producing energy from the combustion of the carbon containing compounds. This energy may be converted via generator <NUM>. In embodinents, at least a portion of the carbon containing compound supply <NUM> may be injected into the formation <NUM>.

In embodiments, the proppant may be selected based on properties relative to degradation such as, for example degradation of compresive stregth, size, porosity, density, or molecular structure. In embodiments, the formation may be a shale.

In any embodiments of the aforementioned methods, the proppant may be selected based on properties relative to degradation such as, for example, degradation of compressive strength, size, porosity, density, or molecular structure.

In any embodiments of the aforementioned methods, the formation may be a shale.

In any embodiments of the aforementioned methods, the solution may be an alkaline solution.

In any embodiments of the aforementioned methods, the solution may be an acidic solution.

In any embodiments of the aforementioned methods, the at least partially degrading may comprise at least partially dissolving the structural integrity of the proppant.

Further, system <NUM> may provide back-up electrical power for the intermittent interruption in power generation provided by wind, wave, and solar devices.

In embodiments, underground reservoir <NUM> may be a shale reservoir.

In embodiments, hydrocarbons other than CH<NUM> may be extracted from one or more underground reservoirs <NUM> and subsequently processed.

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

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

In embodiments, the light weight alkanes may be recoverable.

In embodiments, pumps may be needed for the CO<NUM>.

The following references are relied upon:.

In embodiments, the proppant may be at least one of amorphous silica, mesoporous-amorphous silica, boron-laced or boro-amorphous silica, and boron-laced or boro-mesoporous-amorphous silica.

In embodiments, any of the mentioned proppants may be dissolvable via an acidic solution.

Claim 1:
A method for storing 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, thereby forming fractures;
removing hydrocarbons from in situ loci within the formation;
injecting the carbon containing compounds into the formation;
and
injecting a solution into the formation, the solution capable of at least partially degrading the structural integrity of the proppant positioned within the formation, thereby resealing the fractures.