Method and system for managing the injection of impure CO2

Abstract

A method comprising reducing the pressure of a carbon dioxide injection stream by a first pressure reducing device having a certain depth to generate a carbon dioxide stream with reduced pressure; reducing the pressure of the carbon dioxide stream with reduced pressure by a second pressure reducing device positioned at a depth lower than that of the first pressure reducing device to generate a further pressure-reduced carbon dioxide stream; and injecting the further pressure-reduced carbon dioxide stream into a storage section having a certain depth, wherein the pressure of the carbon dioxide stream at the depth of the first pressure reducing device is higher than the bubble point pressure of the carbon dioxide injection stream at the depth of the first pressure reducing device, and the pressure of the further pressure-reduced carbon dioxide stream at the depth of the storage section is lower than the minimum fracture pressure of the storage section at the depth of the storage section.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 353,039, filed on June 17, 2022.

Background Art

[0002] Existing industrial processes such as power generation need to recover carbon dioxide (CO2) in order to mitigate the effects of climate change. The recovered CO2 stream typically requires the removal of light components such as water and nitrogen before utilization or sequestration, but some components such as hydrogen cannot be easily removed. Hydrogen can worsen phase separation, resulting in the formation of a hydrogen - rich gas phase that can embrittle metals in pipelines or wells. Other impurities can also worsen the formation of the gas phase.

[0003] At the injection site, it is desirable to keep the CO2 stream in a single - phase to ensure smooth flow into the injection well, prevent hydrogen embrittlement, and prevent the formation of acidic substances. Single - phase flow can be ensured by maintaining the pressure above the bubble - point pressure, which is defined as the pressure at a given temperature at which the first vapor bubbles form within the liquid phase. For deeper strata, a sufficiently high injection pressure is required to keep the CO2 in a single - phase. However, shallower reservoirs require a lower injection pressure, which can result in a risk of phase separation. Additional constraints are applied by the reservoir itself having a minimum fracture pressure, above which the rock formation can be damaged up to the point where CO2 can leak out of the reservoir.

Summary of the Invention

[0004] A method and system for injecting a CO2 stream into a subterranean layer are disclosed herein. The CO2 stream can pass through a first pressure reducing device, such as a control valve on a surface, that can impart a first pressure drop to the CO2 stream and maintain the CO2 stream above its bubble point pressure. The CO2 stream can then enter a vertical wellbore that includes a second pressure, such as a control valve, an orifice plate, or a choke, that imparts a second pressure drop. The CO2 stream then enters the reservoir at a pressure below the minimum fracture pressure to avoid initiation and propagation of fracture of the reservoir rock. The pressure at the time of injection into the reservoir rock is measured in real time and can be fed to a surface controller that actuates the opening of the control valve to maintain a desired pressure. The operation of the controller can be designed to include both the first and second pressure drops to simultaneously eliminate hydrogen generation due to phase separation at the surface and relieve excess pressure at the bottom hole.

[0005] Also, chemical additives can be used in the CO2 stream to ensure that the bubble point pressure is lowered and the CO2 stream is maintained above the bubble point pressure and below the minimum fracture pressure. The chemical additives can also change the composition of the CO2 stream to the extent that the risks of phase separation and hydrogen generation are reduced.

Brief Description of the Drawings

[0006] These drawings illustrate some specific aspects of embodiments of the present disclosure and should not be used to limit or define the present disclosure.

[0007]

Figure 1

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Figure 4

[0011] The present disclosure is directed to methods and systems for injecting a CO2 stream into a subterranean formation. Further, the present disclosure includes methods and systems for using a pressure reducing device to meet the dual constraints of the bubble point pressure and the minimum fracture pressure in order to keep the CO2 stream in a single phase and maintain the integrity of the subterranean formation. The methods and systems disclosed herein can be utilized in processes such as subsea drilling and enhanced oil recovery. The CO2 stream can pass through a first pressure reducing device, such as a control valve on the surface, that can impart a first pressure drop to the CO2 stream and maintain the CO2 stream above its bubble point pressure. The CO2 stream can then enter a vertical wellbore that includes a second pressure, such as a control valve, an orifice plate, or a choke, that imparts a second pressure drop. The CO2 stream then enters the reservoir at a pressure below the minimum fracture pressure in order to avoid the initiation and propagation of fracture of the reservoir rock. The pressure at the time of injection into the reservoir rock can be measured in real time and fed to a surface controller that actuates the opening of the control valve to maintain the desired pressure. The operation of the controller can be designed to include both the first and second pressure drops in order to simultaneously minimize or eliminate hydrogen generation due to phase separation at the surface and reduce the bottom hole pressure.

[0012] In some embodiments, the CO2 stream can pass through a plurality of pressure reducing devices, the plurality of pressure reducing devices can be at least two, at least three, or at least four pressure reducing devices, and at least two, at least three, or at least four pressure drops can be imparted to the CO2 stream. Alternatively, the CO2 stream can pass through two or more pressure reducing devices, and the two or more pressure reducing devices can impart a higher pressure or pressure drop to the CO2 stream. In some embodiments, the operation of the controller can be designed to include two or more pressure drops to minimize or eliminate hydrogen generation due to phase separation at the surface and to reduce excessive bottom hole pressure.

[0013] Also, chemical additives can be used in the CO2 stream to ensure that the bubble point pressure is lowered and the CO2 stream is maintained above the bubble point pressure and below the minimum fracture pressure. The chemical additives can also change the composition of the CO2 stream to reduce the risk of phase separation and hydrogen generation.

[0014] Suitable chemical additives for use in the disclosed methods and systems include, but are not necessarily limited to, methane, cyclohexane, and dimethyl ether of polyethylene glycol. Suitable chemical additives for use in the disclosed methods and systems can be solvents effective for both CO2 and hydrogen. Suitable chemical additives for use in the disclosed methods and systems can react with hydrogen. The reaction of the chemical additive with hydrogen can be exothermic.

[0015] Figure 1 is a schematic diagram depicting a method for injecting a CO2 stream into a subsurface storage formation according to the present disclosure. The CO2 injection stream 102 can be delivered by a pipeline, or by other transport forms such as a tanker, a railroad car, a ship, or any suitable transport method. The CO2 injection stream 102 can contain impurities such as hydrogen, nitrogen, carbon monoxide, oxygen, hydrogen sulfide, and water. The pressure of the CO2 injection stream 102 can be reduced across a first pressure reducing device 110. In some embodiments, the first pressure reducing device 110 can be at the ground surface 120. In some embodiments, the first pressure reducing device 110 can be a dynamic pressure reducing device, which can be defined as a pressure reducing device such as a control valve whose flow coefficient can vary. The CO2 stream 112 with reduced pressure exits the first pressure reducing device 110 and the pressure can be further reduced across a second pressure reducing device 130 at a depth lower than the first pressure reducing device 110. In some embodiments, the second pressure reducing device 130 can be a static pressure reducing device defined as a pressure reducing device having a flow coefficient that is a function only of the stream characteristics and a geometric shape of the pressure reducing device such as an orifice plate or a choke. In some embodiments, the second pressure reducing device 130 can be a dynamic pressure reducing device. The further pressure-reduced CO2 stream 132 can then be injected into the storage formation 140. In some embodiments, the second pressure reducing device 130 can be located at a depth close to the first pressure reducing device 110 or the storage formation 140 or at the same depth as the storage formation 140, and this depth can be selected based on the flow characteristics and composition of the CO2 injection stream 102.

[0016] The CO2 injection stream 102 can be maintained above the bubble point pressure to keep the CO2 injection stream 102 in a single phase, and further, the CO2 stream 132 with reduced pressure can be maintained below the minimum fracture pressure of the reservoir 140. The formation of a vapor phase at the wellhead can result in corrosion due to acid gas dropout and hydrogen embrittlement, which may require expensive corrosion-resistant alloys when two-phase flow occurs. Operating within the range of both of these two constraints can be difficult because the static head of the CO2 column due to gravity increases the pressure at the bottom of the injection well 100. The use of the first pressure reducing device 110 and the second pressure reducing device 130, which can be static pressure reducing devices, weakens the pressure rise from the static head and enables both constraints to be met for a given flow rate of CO2 into the reservoir 140.

[0017] The second pressure reducing device 130 can also be used to reduce the temperature difference between the strata near the confinement interval and the CO2. The confinement interval can be defined as the strata that form the top of the reservoir 140 by preventing the vertical flow of CO2 and / or other fluids. When the second pressure reducing device 130 is located below the confinement interval, the pressure drop from the ground surface 120 to the reservoir 140 can shift from the first pressure reducing device 110 to the second pressure reducing device 130 for a given flow rate. The reduction in the pressure drop across the first pressure reducing device 110 can result in a smaller temperature drop, which can increase the temperature of the CO2 stream 112 with reduced pressure and reduce the expansion of the thermal expansion difference between the well casing, the concrete, and the strata, especially near the bottom of the confinement interval.

[0018] In some embodiments, the flow coefficient of the second pressure reducing device 130 can be changed, for example, in the case of a static pressure reducing device, by removing and replacing the second pressure reducing device 130 or by using a dynamic pressure reducing device as the second pressure reducing device 130. The flow coefficient of the second pressure reducing device 130 may need to be changed due to changes in the behavior of the storage unit 140, seasonal changes in the ground temperature, turn-down conditions requiring a low injection flow rate, a gradual increase in the pressure of the storage unit 140 over time when more CO2 is injected, and changes in the composition of the CO2 injection stream 102.

[0019] Changing the flow coefficient of the second pressure reducing device 130 can also be beneficial when considering a pipeline or a network of connected pipelines shared by multiple injection wells. The pipeline can operate at a pressure high enough to inject CO2 into the injection well 100 that requires the highest pressure due to factors including, but not limited to, a greater depth of the storage unit 140, a higher temperature of the CO2 (i.e., being closest to the CO2 compressor), lower injectivity, and a higher CO2 flow rate. Injectivity can be defined as the difference between the pressure of the storage unit 140 and the pressure at the bottom of the injection well 100 as a function of the CO2 flow rate in units of flow rate per unit pressure. In some embodiments, the injection well 100 may require a lower pressure for injection and may require a large pressure drop across the second pressure reducing device 130 to accommodate a greater temperature drop via Joule-Thomson cooling. As a result, the lower temperature of the CO2 can increase its density and further reduce the wellhead pressure.

[0020] The temperature of the CO2 injection stream 102 can also be controlled by raising or lowering the temperature exiting a compressor (not shown) that delivers the CO2 injection stream 102 to a pipeline (not shown). As a surprising result, the thermal mass of the CO2 injection stream 102 can be high enough to maintain a high temperature over a pipeline of several tens of kilometers without reaching ambient temperature. In that case, the elevated temperature can reduce the expansion differences between the well casing, the concrete, and the strata (not shown).

[0021] The injection well 100 can comprise a central conduit into which the pressure-reduced CO2 stream 112 is injected and that is surrounded by an annulus (not shown) separated at the top and bottom of the annulus. A heat transfer fluid, such as water, can circulate through the annulus to transfer geothermal heat along the length of the annulus to the well to reduce thermal stress. The heat transfer fluid can also be monitored to enable a pressure test and / or a radioactive tracer test. The heat transfer fluid can be circulated through a loop of tubing (not shown) inserted into the annulus. The loop of tubing can be attached to and / or clamped to the well.

[0022] In some embodiments, the first pressure reducing device 110 can be controlled by a controller 160 that can change the flow coefficient of the first pressure reducing device 110 in response to one or more sensors including a flow sensor F1 on the CO2 injection stream 102, a first pressure sensor P1 on the CO2 stream 112 with reduced pressure, and a second pressure sensor P2 located at or near the storage section 140. In this way, the flow coefficient of the first pressure reducing device 110 can be changed to keep the pressure of the further pressure-reduced CO2 stream 132 below the minimum rupture pressure of the storage section 140. Since the bubble point is also a function of temperature, the temperature of the pressure-reduced CO2 stream 112 and / or the temperature of the further pressure-reduced CO2 stream 132 can also be measured. Additionally, the temperature drop of the carbon dioxide in the injection well 100 can generate a positive feedback loop where the density of the carbon dioxide increases, increasing the pressure drop of the hydrostatic head between the storage section 140 and the ground surface 120, resulting in an increase in the Joule-Thomson cooling across the first pressure reducing device 110 and / or the second pressure reducing device 130, and further lowering the temperature of the pressure-reduced CO2 stream 112 and / or the temperature of the further pressure-reduced CO2 stream 132.

[0023] In some embodiments, controlling the pressure of the further pressure-reduced CO2 stream 132 using the first pressure-reducing device 110 may enable injection into a deeper reservoir 150. The deeper reservoir 150 may be another section of the same reservoir or a different formation than reservoir 140. Since the deeper reservoir 150 is under heavier weight rock, it may have a higher minimum fracture pressure than reservoir 140. In at least some embodiments, without changing the flow coefficient of the first pressure-reducing device 110, the further pressure-reduced CO2 stream 132 may exceed the minimum fracture pressure at the depth of reservoir 140, but may fall below the minimum fracture pressure at the depth of the deeper reservoir 150. By changing the flow coefficient of the first pressure-reducing device 110, injection of CO2 over a wide range of depths is enabled while maintaining a safe operation below the minimum fracture pressure. The control scheme may be designed to ensure that the second pressure-reducing device 130 causes the further pressure-reduced CO2 stream 132 to exceed the bubble point pressure over a wide injection depth, and that the flow coefficient of the first pressure-reducing device 110 is changed to control the pressure of the further pressure-reduced CO2 stream 132 to a level below the minimum fracture pressure of the current target injection depth.

[0024] In some embodiments, a plurality of injection wells 100 in fluid flow communication with the same CO2 source may also be controlled using the first pressure-reducing device 110 and the second pressure-reducing device 130 at a depth lower than the first pressure-reducing device 110 for each injection well 100. The second pressure-reducing device 130 for each injection well 100 may be at the same or different depths. This may enable independent control of each injection well 100 and maintenance of the CO2 pressure at the depths of each reservoir 140, 150 below the corresponding minimum fracture pressure. If the pressure of the wellhead with the highest pressure is close to the pipeline pressure, the second pressure-reducing device 130 of the wellhead with the highest pressure may be eliminated.

[0025] Due to geology, flow conditions, or carbon dioxide composition, conditions may exist where it is not possible to meet both the double constraints of bubble point pressure and minimum fracture pressure. In this case, one or more chemical additives 152 can be used to lower the bubble point pressure of the untreated CO2 stream 154 to produce a suitable CO2 injection stream 102 by injection into the reservoir 140. In some embodiments, one or more chemical additives 152 can be added to the untreated CO2 stream 154. In at least some embodiments, the untreated CO2 stream 154 can have a high bubble point pressure due to the presence of more than 0.1 mol%, more than 0.5 mol%, or more than 2 mol% hydrogen. Since there are additional capital and operating costs associated with removing hydrogen from CO2 at the time of recovery, it may be preferable to recover CO2 that can have a significant hydrogen concentration as described above. For example, when CO2 is recovered by an absorption system such as an amine absorber, reducing the hydrogen concentration in the recovered CO2 requires operation of a high-pressure flash and / or a reboiler with a higher heating duty. In some embodiments, the maximum concentration of hydrogen is the solubility limit of hydrogen in CO2 at the temperature and pressure of the untreated CO2 stream 154. The one or more chemical additives 152 can function by physical means that increase the critical point of the CO2 stream and / or increase the solubility of carbon dioxide with respect to the gas phase that can form impurities, in which case the desired properties of the one or more chemical additives 152 can include high solubility in both CO2 and hydrogen. The one or more chemical additives 152 can function by chemical or electrochemical means in which impurities are consumed by a chemical reaction of the one or more chemical additives 152 and / or with bulk CO2.

[0026] In some embodiments, one or more chemical additives 152 can be used during a cold start state or during a restart after a turndown where the pressure of the CO2 injection stream 102 can fall below the normal steady-state operating pressure.

[0027] Figure 2 is a schematic diagram depicting a modified form of Figure 1 in which a bypass stream is combined with one or more chemical additives. The untreated carbon dioxide stream 154 is divided into an untreated bypass stream 252 and a second untreated carbon dioxide stream 254. The untreated bypass stream 252 can be fed to an in-line reactor 270 where one or more chemical additives 152 can be combined with the untreated bypass stream 252. The in-line reactor 270 can comprise a catalyst in the form of a fixed bed or monolith. The in-line reactor 270 can comprise an electrochemical converter that can oxidize at least a portion of the hydrogen present in the untreated bypass stream 252 at the anode and reduce reactants such as carbon dioxide or oxygen in the atmosphere at the cathode. In the case of carbon dioxide reduction, the electrical power required to drive the reaction can be supplied by a renewable source. In the case of oxygen reduction, no electrical power is required since the electrochemical converter functions as a hydrogen fuel cell that can generate useful electrical power. In some embodiments, the hydrogen in the untreated bypass stream 252 can react with carbon dioxide and / or oxygen in the atmosphere without the addition of one or more chemical additives 152. The treated bypass stream 256 can then be recombined with the second untreated carbon dioxide stream 254 to form the carbon dioxide injection stream 102. In at least some embodiments, this configuration allows an operator to control the amount of chemical and / or electrochemical reactions by varying the fraction of the untreated carbon dioxide stream 154 that is divided to form the untreated bypass stream 252.

[0028] In at least some embodiments, the treated bypass stream 256 can have its pressure reduced across a second first pressure reducing device and can be recombined with the carbon dioxide stream 112 whose pressure has been reduced downstream of the first pressure reducing device 110 (not shown). In this case, the first pressure reducing device 110 can be fully closed and is the second first pressure reducing device used to control the pressure of the pressure-reduced CO2 stream 112 and the further pressure-reduced CO2 stream 132.

[0029] In some embodiments, the in-line reactor 270 can be used during a cold start state or during a restart after a turndown where the pressure of the CO2 injection stream 102 can fall below the normal steady-state operating pressure.

[0030] In some embodiments, one or more chemical additives 152 and / or the in-line reactor 270 can be used without the second pressure reducing device 130.

[0031] Figure 3 is a plot of the two-phase envelopes of two carbon dioxide streams having different compositions. The two-phase envelopes are graphed on a pressure-temperature plot, where the solid line is a mixture of 98 mol% CO2 and 2 mol% H2, and the dashed line is a mixture of 95 parts of a mixture of 98 mol% CO2 and 2 mol% H2 and 5 parts of methanol. The bubble point curve, i.e., the trace of the P-T points where the bubbles of vapor first form in the liquid phase, is the top part of the curve, and the dew point curve, i.e., the trace of the P-T points where the liquid droplets first form in the vapor phase, is the bottom part of the curve. The liquid phase and the vapor phase coexist between the top and bottom parts of the curve. In at least some embodiments, since both the pressure and temperature of the carbon dioxide stream increase with increasing depth, keeping the carbon dioxide stream at the depth of the first pressure reducing device 110 above the bubble point curve will result in maintaining a single-phase flow down the injection well 100. The addition of methanol lowers the bubble point curve for ambient temperatures below about 30 °C, and as a result, it can be seen that it enables the pressure to be made lower when the further pressure-reduced carbon dioxide stream 132 is injected into the reservoir 140.

[0032] One skilled in the art will recognize that the decline of the bubble point curve in Figure 3 is a relatively small amount. Physical solvents are more effective in lowering the bubble point curve for carbon dioxide streams containing very small amounts of light components such as hydrogen. Physical solvents such as methanol, which have good solubility with CO2, tend to have low solubility with H2, and the overall effectiveness decreases. In at least some embodiments, one or more chemical additives may be more effective when functioning by chemical means. When containing more than 0.5% H2, one or more chemical additives may include a copper-based catalyst that reacts hydrogen with carbon dioxide to form methanol, a compound with very high solubility in carbon dioxide. Industrially, most copper-based catalysts have low conversion for the methanol formation reaction, for example, 20 - 40%. However, in the present disclosure, the low conversion of hydrogen to form methanol may be sufficient to lower the bubble point pressure to meet the dual constraints of the bubble point pressure and the minimum rupture pressure. In at least some embodiments, one or more chemical additives may catalyze the reaction of hydrogen and carbon dioxide to form formate or formic acid. Whether one or more chemical additives are a single chemical additive that satisfies both methods, or two separate chemical additives where one functions via a physical method and one functions via a chemical / electrochemical method, they can function via both the physical method and the chemical / electrochemical method. The chemical / electrochemical method is H2 + CO2 => HCOOH or may include hydrogen-consuming reactions such as 3H2 + CO2 => CH3OH + H2O, etc., The reaction occurs in a packed catalyst bed or at the cathode of an electrochemical cell. The electrochemical method may include hydrogen oxide that can form 2H+ ions at the anode and then combine with reactants such as oxygen or carbon dioxide at the cathode. In the case of the electrochemical method combined with carbon dioxide, the relative amounts of formic acid and methanol formed may be a function of the overpotential voltage.

[0033] In at least some embodiments, the chemical reaction consuming hydrogen can be exothermic. The heat of reaction generated by the consumption of hydrogen can increase the temperature of the CO2 injection stream 102, reducing the risk of freezing when the ambient temperature is low, and / or having additional benefits of reducing the thermal expansion differences between the well casing, the concrete, and the strata.

[0034] Aspect 1: A method comprising delivering a carbon dioxide injection stream to a first wellhead, reducing the pressure of the carbon dioxide injection stream by a first pressure reducing device having a certain depth to generate a carbon dioxide stream with reduced pressure, and reducing the pressure of the carbon dioxide stream with reduced pressure by a second pressure reducing device, wherein the second pressure reducing device is positioned at a depth lower than the first pressure reducing device to further generate a carbon dioxide stream with further reduced pressure, and injecting the carbon dioxide stream with further reduced pressure into a reservoir having a certain depth, wherein the pressure of the carbon dioxide injection stream at the depth of the first pressure reducing device is higher than the bubble point pressure of the carbon dioxide stream at the depth of the first pressure reducing device, and the pressure of the carbon dioxide stream with further reduced pressure at the depth of the reservoir is lower than the minimum fracture pressure of the reservoir at the depth of the reservoir.

[0035] Aspect 2: The method according to aspect 1, wherein the carbon dioxide injection stream contains at least 0.1 mol% hydrogen.

[0036] Aspect 3: The method according to aspect 1 or aspect 2, wherein the confinement interval is located above the depth of the reservoir, and the second pressure reducing device is located at a depth lower than the confinement interval.

[0037] Aspect 4: The method according to any one of aspects 1 - 3, further comprising combining at least one chemical additive with an untreated carbon dioxide stream having a bubble point pressure to generate a carbon dioxide injection stream, wherein the bubble point pressure of the carbon dioxide injection stream is lower than the bubble point pressure of the untreated carbon dioxide stream.

[0038] Aspect 5: The method according to aspect 4, wherein the untreated carbon dioxide stream contains hydrogen and at least one chemical additive causes a chemical reaction that consumes at least a portion of the hydrogen in the untreated carbon dioxide stream.

[0039] Aspect 6: The method according to aspect 5, wherein the chemical reaction that consumes at least a portion of the hydrogen in the untreated carbon dioxide stream is exothermic.

[0040] Aspect 7: Further comprising reacting carbon dioxide with hydrogen in an untreated carbon dioxide stream having a bubble point pressure in the presence of a catalyst to produce a treated carbon dioxide stream, wherein the bubble point pressure of the treated carbon dioxide stream is lower than the bubble point pressure of the untreated carbon dioxide stream, and the carbon dioxide injection stream comprises the treated carbon dioxide stream, according to any one of aspects 1 to 6.

[0041] Aspect 8: Further comprising measuring the pressure of the further pressure-reduced carbon dioxide stream at the depth of the storage section and controlling the pressure of the further pressure-reduced carbon dioxide stream at the depth of the storage section by changing the flow coefficient of the first pressure-reducing device and / or the flow coefficient of the second pressure-reducing device, according to any one of aspects 1 to 7.

[0042] Aspect 9: Injecting the further pressure-reduced carbon dioxide stream into a deeper storage section having a certain depth, wherein the pressure of the further pressure-reduced carbon dioxide stream at the depth of the deeper storage section is lower than the minimum fracture pressure of the deeper storage section at the depth of the deeper storage section, according to any one of aspects 1 to 8.

[0043] Aspect 10: Further comprising controlling the temperature of the further pressure-reduced carbon dioxide stream by changing the flow coefficient of the first pressure-reducing device and / or the flow coefficient of the second pressure-reducing device, according to any one of aspects 1 to 9.

[0044] Aspect 11: Delivering a portion of the carbon dioxide injection stream to a second wellhead, reducing the pressure of a portion of the carbon dioxide injection stream by a third pressure reducing device having a certain depth to produce a carbon dioxide stream with a reduced second pressure, and reducing the pressure of the carbon dioxide stream with the reduced second pressure by a fourth pressure reducing device, wherein the fourth pressure reducing device is positioned at a depth lower than that of the third pressure reducing device to produce a carbon dioxide stream with a further reduced second pressure, reducing the pressure, injecting the carbon dioxide stream with the further reduced second pressure into a second reservoir having a certain depth, further comprising that the pressure of a portion of the carbon dioxide injection stream at the depth of the third pressure reducing device is higher than the bubble point pressure of a portion of the carbon dioxide stream at the depth of the third pressure reducing device, and the pressure of the carbon dioxide stream with the further reduced second pressure at the depth of the second reservoir is lower than the minimum fracture pressure of the second reservoir at the depth of the second reservoir, the method according to any one of Aspects 1 to 10.

[0045] Aspect 12: A method comprising delivering a carbon dioxide injection stream to a first wellhead, reducing the pressure of the carbon dioxide injection stream by a first pressure reducing device having a certain depth to produce a carbon dioxide stream with a reduced pressure, and reducing the pressure of the carbon dioxide stream with the reduced pressure by at least a second pressure reducing device, wherein the at least second pressure reducing device is positioned at a depth lower than that of the first pressure reducing device to produce a carbon dioxide stream with a further reduced pressure, reducing the pressure, and injecting the carbon dioxide stream with the further reduced pressure into at least one reservoir having a certain depth, further comprising that the pressure of the carbon dioxide injection stream at the depth of the first pressure reducing device is higher than the bubble point pressure of the carbon dioxide stream at the depth of the first pressure reducing device, and the pressure of the carbon dioxide stream with the further reduced pressure at the depth of the at least one reservoir is lower than the minimum fracture pressure of the at least one reservoir at the depth of the at least one reservoir.

[0046] Aspect 13: A system comprising a first pressure reducing device in fluid flow communication with a carbon dioxide injection stream, a second pressure reducing device in fluid flow communication with the first pressure reducing device and positioned at a depth lower than the first pressure reducing device, a storage section in fluid flow communication with the second pressure reducing device, and a controller configured to receive an electrical signal from at least one of a first pressure sensor downstream of the first pressure reducing device, a second pressure sensor downstream of the second pressure reducing device, and a flow rate sensor on the carbon dioxide stream and output an electrical signal for controlling the flow coefficient of the first pressure reducing device. Aspect 14: The system according to aspect 13, further comprising an injector in fluid flow communication with the first pressure reducing device and configured to combine at least one chemical additive with the untreated carbon dioxide stream.

[0047] Aspect 15: The system according to aspect 13 or 14, further comprising a reactor in fluid flow communication with the first pressure reducing device and configured to receive at least a portion of the untreated carbon dioxide stream and produce a treated carbon dioxide stream.

[0048] Aspect 16: The system according to any one of aspects 13 - 14, further comprising a reactor in fluid flow communication with the first pressure reducing device and configured to receive at least a portion of the untreated carbon dioxide stream and produce a treated carbon dioxide stream, the reactor including an electrochemical converter including an anode configured to oxidize hydrogen and a cathode configured to reduce at least one of carbon dioxide and oxygen.

[0049] Aspect 17: The system according to any one of aspects 13 - 16, further comprising a deeper storage section in fluid flow communication with the second pressure reducing device at a fourth level.

[0050] Aspect 18: The system according to aspect 13, further comprising at least a third pressure reducing device in fluid flow communication with the first pressure reducing device, the at least third pressure reducing device being positioned at a depth lower than the first pressure reducing device.

[0051] Aspect 19: The system according to aspect 13, wherein the controller is further configured to receive an electrical signal from at least a third pressure sensor downstream of at least a third pressure reducing device.

[0052] Aspect 20: The system according to aspect 13, further comprising at least a second reservoir in fluid flow communication with either the second pressure reducing device or at least the third pressure reducing device.

[0053] To facilitate a better understanding of the present disclosure, the following examples of some specific aspects of the method and system are provided. The following examples should in no way be read as limiting or defining the entire scope of the present disclosure.

Example

[0054] Three CO2 injection wells were modeled using proprietary thermodynamic data for a CO2 stream with 2% H2. Figure 4 is a plot of the pressure and temperature profiles as a function of the depth of the injection well under three conditions. The first case modeled a single well with a first pressure reducing device near the surface of the earth using a wellhead pressure of 1265 psig and 90°F. Figure 4 is a plot of the pressure and temperature profiles as a function of the depth of the injection well under three conditions. The corresponding bubble point is 1088 psig, which is below the wellhead pressure and thus is single phase. Since the pipeline pressure is 1300 psig, any Joule-Thomson cooling across the first pressure reducing device can be ignored. The second case considers adding a second well that requires a higher pressure to the same pipeline, resulting in the pipeline pressure rising to 2000 psig. The pressure drop across the first pressure reducing device for the first well becomes much higher, dropping the temperature at the wellhead from 90°F to 69°F and dropping the pressure at the wellhead from 1265 psig to 1000 psig. At this point, the pressure of the first well is below the bubble point, causing two-phase flow and potential hydrogen embrittlement from the hydrogen-rich vapor phase. The third case adds a second pressure reducing device to the first well at a depth of 2000 feet, shifting most of the pressure drop from the first pressure reducing device to the second pressure reducing device from 2000 psig to 1265 psig and keeping the wellhead above the bubble point.

[0055] While individual examples may be discussed herein, it should be understood that the disclosure encompasses all combinations of the disclosed examples, including but not limited to combinations of different components, combinations of method steps, and system properties.

[0056] Compositions and methods are described in terms of having, containing, or including various components or steps, and it should be understood that the compositions and methods may also consist essentially of or consist of various components and steps. Further, as used herein in the claims, the indefinite articles "a" or "an" are defined to mean one or more of the elements they introduce.

[0057] All numerical values within the detailed description and claims of this specification that are modified by "about" or "approximately" with respect to the values shown are intended to account for the experimental error and variations that would be expected by one of ordinary skill in the art.

[0058] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite ranges not explicitly recited, and ranges from any lower limit may be combined with any other lower limit to recite ranges not explicitly recited, and similarly, ranges from any upper limit may be combined with any other upper limit to recite ranges not explicitly recited. Additionally, whenever a numerical range having a lower and upper limit is disclosed, any numerical value and any included range within that range are specifically disclosed. In particular, any range of values (in the form of "about a to about b", or equivalently "approximately a to b", or equivalently "about a - b") disclosed herein is to be understood to recite any numerical values and ranges included within the broader range of values even if not explicitly recited. Thus, any point or individual value can serve as the lower or upper limit of itself in combination with any other point or individual value, or any other lower or upper limit, to recite ranges not explicitly recited.

Claims

Claim 1 A method comprising: delivering a carbon dioxide injection stream to a first wellhead; reducing the pressure of the carbon dioxide injection stream by a first pressure reducing device having a certain depth to produce a carbon dioxide stream with reduced pressure; reducing the pressure of the carbon dioxide stream with reduced pressure by a second pressure reducing device, wherein the second pressure reducing device is positioned at a depth lower than that of the first pressure reducing device to further produce a carbon dioxide stream with further reduced pressure; injecting the carbon dioxide stream with further reduced pressure into a reservoir having a certain depth; wherein the pressure of the carbon dioxide injection stream at the depth of the first pressure reducing device is higher than the bubble point pressure of the carbon dioxide stream at the depth of the first pressure reducing device; the pressure of the carbon dioxide stream with further reduced pressure at the depth of the reservoir is lower than the minimum fracture pressure of the reservoir at the depth of the reservoir. Claim 2 The method according to claim 1, wherein the carbon dioxide injection stream contains at least 0.1 mol% hydrogen. Claim 3 The method according to claim 1, wherein the confinement interval is located above the depth of the reservoir, and the second pressure reducing device is located at a depth lower than that of the confinement interval. Claim 4 The method further comprising combining at least one chemical additive with an untreated carbon dioxide stream having a bubble point pressure to produce the carbon dioxide injection stream; wherein the bubble point pressure of the carbon dioxide injection stream is lower than the bubble point pressure of the untreated carbon dioxide stream; the untreated carbon dioxide stream contains hydrogen; the at least one chemical additive causes a chemical reaction that consumes at least a portion of the hydrogen in the untreated carbon dioxide stream, and the chemical reaction is endothermic. Claim 5 The method further comprising reacting carbon dioxide with hydrogen in an untreated carbon dioxide stream having a bubble point pressure in the presence of a catalyst to produce a treated carbon dioxide stream; wherein the bubble point pressure of the treated carbon dioxide stream is lower than the bubble point pressure of the untreated carbon dioxide stream. The method according to claim 1, wherein the carbon dioxide injection stream comprises the treated carbon dioxide stream.

6. measuring the pressure of the further pressure-reduced carbon dioxide stream at the depth of the storage section; controlling the pressure of the further pressure-reduced carbon dioxide stream at the depth of the storage section by changing the flow coefficient of the first pressure-reducing device and / or the flow coefficient of the second pressure-reducing device, the method according to claim 1, further comprising.

7. further comprising injecting the further pressure-reduced carbon dioxide stream into a deeper storage section having a certain depth, wherein the pressure of the further pressure-reduced carbon dioxide stream at the depth of the deeper storage section is lower than the minimum fracture pressure of the deeper storage section at the depth of the deeper storage section, the method according to claim 1.

8. The method according to claim 1, further comprising controlling the temperature of the further pressure-reduced carbon dioxide stream by changing the flow coefficient of the first pressure-reducing device and / or the flow coefficient of the second pressure-reducing device.

9. delivering a portion of the carbon dioxide injection stream to a second wellhead; reducing the pressure of the portion of the carbon dioxide injection stream by a third pressure-reducing device having a certain depth to produce a second pressure-reduced carbon dioxide stream; reducing the pressure of the second pressure-reduced carbon dioxide stream by a fourth pressure-reducing device, wherein the fourth pressure-reducing device is positioned at a depth lower than the third pressure-reducing device to produce a second further pressure-reduced carbon dioxide stream; injecting the second further pressure-reduced carbon dioxide stream into a second storage section having a certain depth; further comprising, wherein the pressure of the portion of the carbon dioxide injection stream at the depth of the third pressure-reducing device is higher than the bubble point pressure of the portion of the carbon dioxide stream at the depth of the third pressure-reducing device; wherein the pressure of the second further pressure-reduced carbon dioxide stream at the depth of the second storage section is lower than the minimum fracture pressure of the second storage section at the depth of the second storage section, the method according to claim 1.

10. A method comprising: delivering a carbon dioxide injection stream to a first wellhead; Reducing the pressure of the carbon dioxide injection stream by a first pressure reducing device having a certain depth to produce a carbon dioxide stream with reduced pressure; Reducing the pressure of the carbon dioxide stream with reduced pressure by at least a second pressure reducing device, wherein the at least second pressure reducing device is positioned at a depth lower than that of the first pressure reducing device, and further reducing the pressure to produce a carbon dioxide stream with further reduced pressure; Injecting the carbon dioxide stream with further reduced pressure into at least one reservoir having a certain depth; comprising; the pressure of the carbon dioxide injection stream at the depth of the first pressure reducing device is higher than the bubble point pressure of the carbon dioxide stream at the depth of the first pressure reducing device; the pressure of the carbon dioxide stream with further reduced pressure at the depth of the at least one reservoir is lower than the minimum fracture pressure of the at least one reservoir at the depth of the at least one reservoir.

11. A system comprising: a first pressure reducing device in fluid flow communication with a carbon dioxide injection stream; a second pressure reducing device in fluid flow communication with the first pressure reducing device, the second pressure reducing device being positioned at a depth lower than that of the first pressure reducing device; a reservoir in fluid flow communication with the second pressure reducing device; a controller configured to receive an electrical signal from at least one of a first pressure sensor downstream of the first pressure reducing device, a second pressure sensor downstream of the second pressure reducing device, and a flow rate sensor on the carbon dioxide stream, and output an electrical signal for controlling the flow coefficient of the first pressure reducing device; A system comprising.

12. An injector in fluid flow communication with the first pressure reducing device, configured to combine at least one chemical additive with an untreated carbon dioxide stream; A reactor in fluid flow communication with the first pressure reducing device, configured to receive at least a portion of the untreated carbon dioxide stream and produce a treated carbon dioxide stream; The system according to claim 11, further comprising an electrochemical converter, wherein the reactor includes an anode configured to oxidize hydrogen and a cathode configured to reduce at least one of carbon dioxide and oxygen.

13. The system according to claim 11, further comprising a deeper reservoir in fluid flow communication with the second decompression device.

14. The system further comprises at least a third decompression device in fluid flow communication with the first decompression device, the at least third decompression device being positioned at a depth lower than the first decompression device, The system according to claim 11, wherein the controller is further configured to receive an electrical signal from at least a third pressure sensor downstream of the at least third decompression device.

15. The system according to claim 11, further comprising at least a second reservoir in fluid flow communication with either the second decompression device or the at least third decompression device.

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