METHODS AND SYSTEMS FOR CO2 SEQUESTRATION
A method of sequestering carbon dioxide is provided, the method comprising injecting carbon dioxide into a saline formation below an oil reservoir. The carbon dioxide may be sequestered at a pressure above about 10 MPa. The carbon dioxide may be sequestered at a pressure below about 30 MPa. The carbon dioxide may be sequestered at a temperature above about 25° C. The carbon dioxide may be sequestered at a temperature below about 60° C. The saline formation and the oil reservoir may contact each other, thereby forming an oil-water contact (OWC) layer. The carbon dioxide to be sequestered may be injected greater than about 10 m below the OWC layer. The carbon dioxide may be a gas, a liquid, a supercritical fluid, or a mixture thereof, when the carbon dioxide is injected into the saline formation.
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This patent application claims priority to U.S. Provisional Patent Application No. 61/347,297 filed May 21, 2010, the content of which is incorporated herein by reference in its entirety.
INTRODUCTIONMuch scientific evidence suggests that the global temperature has increased over the last 100 years. A significant proportion of these changes may be attributed to the emission of anthropogenic CO2 into the atmosphere. Based on this premise, it has been suggested that it is necessary to reduce current CO2 emissions (about 7.1 billion tonnes per year of carbon) to curb the increase of global temperature. To achieve this goal, many countries have ratified the Kyoto Protocol, a multinational agreement to reduce greenhouse gas emissions, drafted by the United Nations Framework Convention on Climate Change in 1997. After considering the economical and technological aspects of multiple technologies, as well as improved efficiency, it is anticipated that geologic CO2 sequestration may be the most beneficial and effective short-term approach to curbing global warming.
SUMMARYA method of sequestering carbon dioxide is provided, the method comprising injecting carbon dioxide into a saline formation below an oil reservoir. The carbon dioxide may be sequestered at a pressure above about 10 MPa, such as at a pressure above about 15 MPa. The carbon dioxide also may be sequestered at a pressure below about 30 MPa, such as at a pressure below about 25 MPa. For example, the carbon dioxide may be sequestered at a pressure between about 10 MPa and about 30 MPa, such as at a pressure between about 15 and about 30 MPa, between about 10 MPa and about 25 MPa, or between about 15 MPa and about 25 MPa. The carbon dioxide may be sequestered at a temperature above about 25° C., such as at a temperature above about 35° C. The carbon dioxide also may be sequestered at a temperature below about 60° C., such as at a temperature below about 50° C. For example, the carbon dioxide may be sequestered at a temperature between about 25 and about 60° C., such as at a temperature between about 35 and about 60° C., between about 25 and about 50° C. or between about 35 and about 50° C. The saline formation and the oil reservoir may contact each other, thereby forming an oil-water contact (OWC) layer. The carbon dioxide to be sequestered may be injected greater than about 10 m below the OWC layer, such as greater than about 100 m below, or even greater than about 500 m below OWC layer. The carbon dioxide may be a gas, a liquid, a supercritical fluid, or a mixture thereof, when the carbon dioxide is injected into the saline formation.
A system for sequestering carbon dioxide also is provided, the system comprising a well coupled to a saline formation that is beneath an oil reservoir, and a pump operatively connected to the well and configured to inject carbon dioxide through the well and into the saline formation. The pump may be operatively connected to a pipeline containing CO2. Alternatively or additionally, the pump may be operatively connected to one or more tanks of CO2, such as a tank of compressed CO2. For example, the pump may be removably attachable to one or more tanks of CO2. In some embodiments, the system for sequestering carbon dioxide may be a system for sequestering carbon dioxide under a seafloor, comprising a well coupled to a saline formation beneath an oil reservoir beneath a seafloor, and a pump operatively connected to the well and configured to inject carbon dioxide into the saline formation.
The system(s) for sequestering carbon dioxide may include a monitoring system configured to monitor the amount of CO2 in a portion of the saline formation, a portion of the oil reservoir, or both. The monitoring system may include a monitoring station, and one or more sensors coupled to the monitoring station, where each sensor may be in contact with the oil reservoir and/or the saline formation, and may be configured to take measurements that correlate to the amount of CO2 in the environment surrounding the sensor. For example, each sensor may be configured to measure at least one of the temperature, salinity, pH, pressure, and/or CO2 concentration of fluids in contact with the sensor. The monitoring system also may include one or more monitoring wells, where each monitoring well is coupled to either the saline formation and/or the oil reservoir, and each sensor is coupled to the monitoring system by a coupling element that extends through one of the monitoring wells. For example, a particular sensor may be physically coupled to the monitoring station by a cable coupling element, such as may be wrapped around a winch so that the sensor can be raised and lowered within the monitoring well to desired depths, and can be removed from the well for maintenance. Alternatively or additionally, a particular sensor may be electrically coupled to the monitoring station by an electrical wire coupling element that permits one- and two-way wired communication between the sensor and the monitoring station, although a sensor also may be in wireless communication with the monitoring station. Some monitoring systems may include at least a first sensor in contact with the oil reservoir and a second sensor in contact with the saline formation. The first and second sensors each may be coupled to the monitoring station by coupling elements that extend through the same or different mentoring wells.
The monitoring system may be configured to produce an alert when the amount of CO2 in the portion of the saline formation or the portion of the oil reservoir exceeds a predetermined amount. For example, the monitoring system may be configured to produce an alert when the amount of CO2 in fluids surrounding a particular sensor exceeds a value of about 0.001% CO2, about 0.0025% CO2, about 0.005% CO2, about 0.0075% CO2, and/or about 0.01% CO2, among other suitable values. Likewise, the monitoring system may be configured to produce an alert when the amount of CO2 in fluids surrounding a particular sensor exceeds a value of about 300 ppm CO2, about 400 ppm CO2, about 500 ppm CO2, about 600 ppm CO2, and/or about 700 ppm CO2, among other suitable values. Alternatively or additionally, the monitoring station may be configured to produce an alert when the amount of CO2 in the portion of the saline formation or the portion of the oil reservoir changes from some baseline amount (such as a preselected concentration, an amount equal to an average observed amount based on measurements of CO2 over a selected period of time, or any other desired baseline amount) by some predetermined amount, or by some integer or non-integer factor of the baseline amount. For example, the monitoring station may be configured to produce an alert when the baseline amount changes by any desired factor, including but not limited to a factor of 2, 2.5, 5, 10, 15.5, 25.5, 50.25, 100.73, or any other desired factor.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
The present disclosure provides methods and systems for sequestering carbon dioxide by injecting carbon dioxide into a saline (brine) formation below an oil reservoir (aka, CO2 Storage Beneath Oil Reserves, or CSBOR). These methods and systems may provide at least one advantage over storage in a saline formation alone, including, but not limited to:
1) Enhanced CO2 solubility: CO2 solubility in crude oil is about 30 times greater than that in pure water. Further, CO2 is less soluble in salt water (brine) than in pure water. Thus, at least 30 times more CO2 can be solubilized (i.e. solubility-trapped) in oil reservoirs that in brine formations.
2) Reduced buoyancy-driven flow of CO2: CO2 is less buoyant and migrates less in oil reservoirs than in brine due to the smaller difference in density between CO2 and crude oil as contrasted to the larger difference in density between CO2 and brine.
3) Reduced mobility of CO2: Oil contained in reserves is more viscous than water. This difference in viscosity causes CO2 to be less mobile in oil than in water. Further, CO2 mobility is reduced when three phases (CO2+residual brine+oil) coexist compared to two phases (CO2+brine).
4) Enhanced component partitioning: In saline formations, CO2 is the only component that partitions between gas and liquid phases. In oil reservoirs, several different gas components can concurrently partition between the oil and gas phases. Additionally, studies suggest that CO2 mobility in multiple component-partitioning simulation is smaller than that in single component-partitioning simulation.
5) Availability of caprock: While CO2 is unlikely to migrate through the oil reservoir, most oil reservoirs are always covered by a caprock, whose seal integrity is already proven by the presence of oil over geologic time. Therefore, it is likely that CO2 in oil reservoirs will not escape easily through caprock.
6) Availability of existing infrastructure: Above oil reservoirs, infrastructure such as roads, pipelines and wells (e.g., for monitoring) are already in place, and injection sites are easily accessible.
To obtain advantages in terms of CO2 storage capacity, and to minimize buoyancy-driven migration, CO2 may be injected below the OWC layer in oil reservoirs and into deep saline formations below oil reservoirs, i.e., a “CSBOR” method. In many oil reservoirs, a significant amount of formation volume exists below the OWC layer. Because the oil-portion of these reservoirs is so effective for trapping CO2 and minimizing buoyancy-driven migration, CO2 will be injected as deep as possible below the OWC layer to maximize storage capacity. Additionally, existing production wells can be utilized to monitor for CO2 movement into the active (productive) area(s) of the reservoir.
In general, CO2 migration and trapping after injection below the OWC layer in an oil reservoir can be discussed in three stages. The stages are shown schematically in
In Stage II (
In Stage III (
Possibly, some CO2 is not trapped and keeps migrating, as mobile CO2, upwardly through the oil reservoir. Although this mobile CO2 moves vertically through the oil reservoir, it may be trapped at the bottom of the caprock.
Generally, after CO2 is injected into a target storage formation, it will be trapped by different trapping mechanisms such as hydrodynamic, residual, solubility, and mineral trapping, depending on ambient reservoir conditions such as pressure, temperature, salinity, and composition. Solubility trapping, specifically, is defined as trapping CO2 by dissolution in ambient reservoir fluids such as brine and oil. The amount of CO2 stored by solubility trapping can be estimated with calibrated solubility algorithms.
Buoyancy-driven migration is governed by contrasts of fluid densities. CO2 will migrate vertically more quickly through a fluid having a greater density contrast than through a fluid having a lesser density contrast. To compare buoyancy-driven CO2 migration in brine formations and oil reservoirs, the fluid densities of CO2, brine, and crude oil were compared (
CO2 is a highly compressible fluid compared to both water and crude oil and its density radically increases from about 300 to about 800 kg/m3 at pressure ranging from about 10 to about 25 MPa (
A brine density with about 159,000 ppm concentration corresponds to a density of about 1100 kg/m3. Therefore, the approximate density contrast between CO2 and brine is about 450 kg/m3 at 15 MPa. This comparison suggests that the density contrast between CO2 and surrounding fluids is about 2.25-4.5 times greater in brine formations than in oil reservoirs. Correspondingly, buoyancy-driven CO2 migration tends to be 2.25-4.5 times greater in brine formations.
Density of CO2−dissolved brine becomes greater as more CO2 dissolves. Other researchers suggest that the density of CO2−dissolved brine can be as much as 2-3% greater than surrounding brine. Consequently, CO2−dissolved brine will sink and create density instability resulting in convective transport mixing after several hundred years. In oil reservoirs, dissolution of CO2 in oil increases the density of CO2−dissolved oil, which causes such gravitation segregation.
Because gravitational segregation occurs due to the density contrast between CO2−dissolved fluids and surrounding fluids, the incremental density contrast as CO2 dissolves may be evaluated. To evaluate this aspect, densities of both CO2−dissolved brine and oil were compared (
Several correlation algorithms are available for the density of CO2−dissolved brine. Among these algorithms, an equation-of-state was adapted to calculate the density of CO2−dissolved brine (
To investigate temperature effects on the density of CO2−dissolved brine, temperature was increased from 18.33° C. to 35° C. (rectangle vs. diamond symbols in
Greater contrasts of density between CO2 and ambient reservoir fluids enhance buoyancy-driven CO2 migration. However, greater contrasts of viscosity between CO2 and reservoir fluids possibly prohibit vertical CO2 migration and may induce viscous fingering at CO2 displacement fronts. In
A plot of viscosities for different fluids suggests that viscosity variation of crude oil is significantly dependent on both API gravity (density) and temperature (
The overall range of pure water viscosity is from about 0.7-1 mPa s. With greater salinity (0.2 NaCl mole fraction), its viscosity increases to about 2-3 mPa s, suggesting that the effects of both salinity and temperature on water viscosity is relatively minor. The overall range of CO2 viscosity is shown to be about 0.1 mPa s, indicating that CO2 is the most mobile fluid and its viscosity variation with temperature is the smallest among these reservoir fluids.
In general, this comparison indicates that the contrasts of viscosities between CO2 and crude oil are significantly greater than that between CO2 and brine. Therefore, viscosity effects on buoyancy-driven CO2 migration will be greater in oil reservoirs than those effects in brine formations. In addition, displacement fronts of CO2 plumes will likely exhibit significant viscosity fingering in CO2−crude oil systems.
Additionally, the viscosity of crude oil is significantly reduced as CO2 dissolves in oil (
The viscosity of 0.02 molality NaCl brine without dissolved CO2 at 30° C. (circle symbol) is about 0.82 mPa s and does not vary with pressure (
This comparison suggests that viscosity contrasts between CO2−dissolved oil and straight (no CO2) crude oil vary more than hundreds of mPa s (
The tendency of buoyancy-driven CO2 migration can be quantified with the gravity number (N), which is the ratio of gravity forces to viscous forces. Typically, the influence of gravity forces will cause a CO2 plume to reach quickly below a low permeability caprock and consequently decrease the sweep efficiency of oil during CO2 enhanced oil recovery. In CO2 sequestration, greater gravity forces accelerate vertical CO2 migration and, hence, increase the probability that vertically mobile CO2 may come into contact with faults or other leakage pathways, especially as it contacts caprock.
In this study, N of CO2 was compared in brine formations and oil reservoirs to quantify the degree of gravity-driven CO2 migration. N is determined from
where f represents either brine or oil, kx is the horizontal permeability, ρCO2 is the density of CO2, g is gravity, kxKrCO2 is the relative permeability of CO2, μCO2 is the viscosity of CO2, and v is the velocity of CO2. For solely investigating the effect of thermodynamic properties, it was assumed that kxkrCO2/v is equal to 1 in this calculation.
Both plots show that an increase in pressure causes a decrease in N, which indicates that density contrasts between CO2 and fluids (i.e., brine and oil) decrease as pressure increases. In addition, these plots also indicate that N increases as temperature increases. This analysis suggests that CO2 injection into targeted formations and reservoirs with high pressure and low temperature conditions will help minimize buoyancy-driven CO2 migration, and suggests that CO2 injection into high temperature systems will possibly cause significant buoyancy-driven migration.
Finally, examination of this data reveals that a near-perfect seal condition exists in oil reservoirs where the CO2 plume is not buoyant because the CO2 density is greater than the density of surrounding oils. In
Because
It may be advantageous to sequester CO2 as a supercritical fluid. CO2 exists as a supercritical fluid when it is at or above its critical temperature (about 31.1° C.) and pressure (about 7.39 MPa). Supercritical CO2 has somewhat uncommon properties that are midway between those of a gas and a liquid. More specifically, it expands to fill a space like a gas, but has a density like that of a liquid. As shown and discussed above, supercritical carbon dioxide may be ideally suited for CSBOR. When CO2 is injected into a saline formation as a supercritical fluid, lighter oil reservoirs may provide an opportunity to effectively serve as a seal that prevents buoyancy-driven CO2 migration, much like a caprock would. As such, the methods disclosed herein may include sequestering CO2 at pressures above about 10 MPa, such as at pressures above about 15 MPa. In view of conditions that may be observed in the field, the CO2 may be sequestered at pressures below about 30 MPa, such as at pressures below about 25 MPa. For example, the carbon dioxide may be sequestered at pressures between about 10 MPa and about 30 MPa, such as at pressures between about 15 and about 30 MPa, between about 10 MPa and about 25 MPa, or between about 15 MPa and about 25 MPa. The methods disclosed herein also may include sequestering CO2 at temperatures above about 25° C., such as at temperatures above about 35° C. The carbon dioxide also may be sequestered at temperatures below about 60° C., such as at a temperature below about 50° C. For example, the carbon dioxide may be sequestered at temperatures between about 25 and about 60° C., such as at temperatures between about 35 and about 60° C., between about 25 and about 50° C. or between about 35 and about 50° C.
The tendency of buoyancy-driven CO2 migration can be quantified with N. In a similar manner, the tendency of CO2 mobility, where fluids compete with each other, can be estimated with viscosity ratio (M), which is determined from
Here, f represents either brine or oil, kr is relative permeability, and μ is the viscosity of fluid. For solely investigating the effect of thermodynamic properties, it was assumed that krCO2/krf is equal to 1.
For CO2 injection in brine formations,
Systems for sequestering carbon dioxide beneath the OWC layer are also disclosed. In some embodiments, the system may allow for the sequestration of carbon dioxide under land, and thus may include one or more well heads that are onshore. In some embodiments, the system may allow for the sequestration of carbon dioxide under the seafloor, and thus may include a well head that is underwater, such as at the bottom of the ocean. Systems may comprise a well extending from the well head to a saline formation beneath an oil reservoir, and a pump, operatively connected to the well and capable of injecting carbon dioxide into the saline formation beneath the oil reservoir. The pump may be operatively connected to a pipeline containing CO2. Alternatively or additionally, the pump may be operatively connected to one or more tanks of CO2, such as a tank of compressed CO2. For example, the pump may be removably attachable to one or more tanks of CO2. The CO2 may be a gas, a liquid, a supercritical fluid, or a mixture thereof, when the carbon dioxide is injected into the saline formation.
Pumps, wells, pipes, wellheads, and compression stations suitable for use in the presently disclosed systems are known to those of skill in the art of enhanced oil recovery. However, the presently disclosed system for sequestering CO2 differs from those used for enhanced oil recovery in that the CO2 is injected at a depth below the oil-water contact layer, such as at least about 10 m, and more typically at least about 100 m, and more typically at least about 500 m below the OWC layer. Moreover, the CO2 is injected as a supercritical fluid, such as at a pressure between about 10 and about 30 MPa, and more typically between about 15 and about 25 MPa, and at a temperature between about 25 and about 60° C. and more preferably between about 35 and about 50° C.
Additionally, because the CO2 is intended to be stored for geologically-meaningful time periods, it may be necessary to monitor the oil layer, the saline layer, and the area surrounding the injection site for system changes due to the sequestered CO2. For example, it would be desirable to know whether a large amount of CO2 were to cross the oil-water contact layer, or escape the caprock. As such, the presently disclosed systems for sequestering CO2 also may include a monitoring system configured to monitor the amount of CO2 in a portion of the saline formation, a portion of the oil reservoir, or both. The monitoring system may include a monitoring station, and one or more sensors coupled to the monitoring station, where each sensor may be in contact with the oil reservoir and/or the saline formation, and may be configured to take measurements that correlate to the amount of CO2 in the environment surrounding the sensor. For example, each sensor may be configured to measure at least one of the temperature, salinity, pH, pressure, and/or CO2 concentration of fluids in contact with the sensor. The monitoring system also may include one or more monitoring wells, where each monitoring well is coupled to either the saline formation and/or the oil reservoir, and each sensor is coupled to the monitoring system by a coupling element that extends through one of the monitoring wells. For example, a particular sensor may be physically coupled to the monitoring station by a cable coupling element, such as may be wrapped around a winch so that the sensor can be raised and lowered within the monitoring well to desired depths, and can be removed from the well for maintenance. Alternatively or additionally, a particular sensor may be electrically coupled to the monitoring station by an electrical wire coupling element that permits one- and two-way wired communication between the sensor and the monitoring station, although a sensor also may be in wireless communication with the monitoring station. Some monitoring systems may include at least a first sensor in contact with the oil reservoir and a second sensor in contact with the saline formation. The first and second sensors each may be coupled to the monitoring station by coupling elements that extend through the same or different mentoring wells.
The monitoring system may be configured to produce an alert when the amount of CO2 in the portion of the saline formation or the portion of the oil reservoir exceeds a predetermined amount. For example, the monitoring system may be configured to produce an alert when the amount of CO2 in fluids surrounding a particular sensor exceeds a value of about 0.001% CO2, about 0.0025% CO2, about 0.005% CO2, about 0.0075% CO2, and/or about 0.01% CO2, among other suitable values. Likewise, the monitoring system may be configured to produce an alert when the amount of CO2 in fluids surrounding a particular sensor exceeds a value of about 300 ppm CO2, about 400 ppm CO2, about 500 ppm CO2, about 600 ppm CO2, and/or about 700 ppm CO2, among other suitable values. Alternatively or additionally, the monitoring station may be configured to produce an alert when the amount of CO2 in the portion of the saline formation or the portion of the oil reservoir changes from some baseline amount (such as a preselected concentration, an amount equal to an average observed amount based on measurements of CO2 over a selected period of time, or any other desired baseline amount) by some predetermined amount, or by some integer or non-integer factor of the baseline amount. For example, the monitoring station may be configured to produce an alert when the baseline amount changes by any desired factor, including but not limited to a factor of 2, 2.5, 5, 10, 15.5, 25.5, 50.25, 100.73, or any other desired factor.
It is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the present description. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also it is to be understood that the phraseology and terminology used herein is for the purpose of description only, and should not be regarded as limiting. Ordinal indicators, such as first, second, and third, as used in the description and the claims to refer to various structures, are not meant to be construed to indicate any specific structures, or any particular order or configuration to such structures. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification, and no structures shown in the drawings, should be construed as indicating that any non-claimed element is essential to the practice of the invention.
Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. For example, if a concentration range is stated as 1% to 50%, it is intended that values such as 2% to 40%, 10% to 30%, or 1% to 3%, etc., are expressly enumerated in this specification. These are only examples of what is specifically intended, and all possible combinations of numerical values between and including the lowest value and the highest value enumerated are to be considered to be expressly stated in this application.
Further, no admission is made that any reference, including any non-patent or patent document cited in this specification, constitutes prior art. In particular, it will be understood that, unless otherwise stated, reference to any document herein does not constitute an admission that any of these documents forms part of the common general knowledge in the art in the United States or in any other country. Any discussion of the references states what their authors assert, and the applicant reserves the right to challenge the accuracy and pertinency of any of the documents cited herein.
EXAMPLES Example 1 Comparison of Simulated CO2 Sequestration in a Saline Formation And Simulated CO2 Sequestration in an Oil Reserve Below a Saline FormationThe model shown in
The simulation is built to investigate buoyancy-driven migration of injected CO2 several decades after CO2 injection has ceased. At this time, the effect of injection-induced pressure will disappear and the main cause of CO2 vertical migration will be due to the density contrast between CO2 and surrounding fluids. To investigate buoyancy-driven CO2 migration only, 99% of initial CO2 saturation is placed at the bottom of the model (See
The comparisons shown in
Oil-bearing formations comprising a saline aquifer beneath an oil reservoir, similar to the formation shown in
In order to verify that the CO2 is being delivered to the aquifer, and in order to monitor whether the CO2 is staying sequestered, the system for sequestering CO2 may include a monitoring system configured to monitor the amount of CO2 in a portion of the saline formation, a portion of the oil reservoir, or both, such as is illustrated in
The monitoring system may be configured to produce an alert when the amount of CO2 in the portion of the saline formation or the portion of the oil reservoir exceeds a predetermined amount. For example, the monitoring system may be configured to produce an alert when the amount of CO2 in fluids surrounding a particular sensor exceeds a value of about 0.001% CO2, about 0.0025% CO2, about 0.005% CO2, about 0.0075% CO2, and/or about 0.01% CO2, among other suitable values. Likewise, the monitoring system may be configured to produce an alert when the amount of CO2 in fluids surrounding a particular sensor exceeds a value of about 300 ppm CO2, about 400 ppm CO2, about 500 ppm CO2, about 600 ppm CO2, and/or about 700 ppm CO2, among other suitable values. Alternatively or additionally, the monitoring station may be configured to produce an alert when the amount of CO2 in the portion of the saline formation or the portion of the oil reservoir changes from some baseline amount (such as a preselected concentration, an amount equal to an average observed amount based on measurements of CO2 over a selected period of time, or any other desired baseline amount) by some predetermined amount, or by some integer or non-integer factor of the baseline amount. For example, the monitoring station may be configured to produce an alert when the baseline amount changes by any desired factor, including but not limited to a factor of about 2, about 2.5, about 5 about 10, about 15.5, about 25.5, about 50.25, about 100.73, or any other desired factor.
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Claims
1. A method of sequestering carbon dioxide comprising injecting carbon dioxide into a saline formation below an oil reservoir.
2. The method of claim 1, wherein the carbon dioxide is injected into the saline formation at a pressure between about 5 and about 30 MPa.
3. The method of claim 2, wherein the carbon dioxide is injected into the saline formation at a pressure between about 15 and about 25 MPa.
4. The method of claim 1, wherein the carbon dioxide is injected into the saline formation at a temperature of about 25 to about 90° C.
5. The method of claim 4, wherein the carbon dioxide is injected into the saline formation at a temperature of about 35 to about 50° C.
6. The method of claim 1, wherein the saline formation and the oil reservoir contact to form an oil-water contact (OWC) layer, and the carbon dioxide is injected into the saline formation at a depth greater than about 10 m below the OWC layer.
7. The method of claim 6, wherein the carbon dioxide is injected into the saline formation at a depth greater than about 100 m below the OWC layer.
8. The method of claim 6, wherein the carbon dioxide is injected into the saline formation at a depth greater than about 500 m below the OWC layer.
9. The method of claim 1, wherein the carbon dioxide is a gas, a liquid, a supercritical fluid, or a mixture thereof, when the carbon dioxide is injected into the saline formation.
10. The method of claim 9, wherein the carbon dioxide is a supercritical fluid when the carbon dioxide is injected into the saline formation.
11. A system for sequestering carbon dioxide, the system comprising:
- a well in fluid communication with a saline formation beneath an oil reservoir; and
- a pump operatively connected to the well and configured to inject carbon dioxide through the well and into the saline formation beneath the oil reservoir.
12. The system of claim 11, further comprising a pipeline containing the CO2, wherein the pump is in fluid communication with the pipeline to draw the CO2 from the pipeline.
13. The system of claim 11, further comprising a tank containing CO2, wherein the pump is in fluid communication with the tank to draw the CO2 from the tank
14. The system of claim 11, further comprising a monitoring system configured to monitor the amount of CO2 in a portion of the saline formation, a portion of the oil reservoir, or both.
15. The system of claim 14, wherein the monitoring system is configured to produce an alert when the amount of CO2 in the portion of the saline formation or the portion of the oil reservoir exceeds a predetermined amount.
16. The system of claim 14, wherein the monitoring system includes a monitoring station and a sensor in communication with the monitoring station and positioned in the saline formation or the oil reservoir, wherein the sensor is configured to take measurements that correlate to the amount of CO2 in the environment surrounding the sensor.
17. The system of claim 16, wherein the sensor is configured to measure at least one of the temperature, salinity, pH, pressure, and CO2 concentration of fluids in contact with the sensor.
18. The system of claim 16, further comprising a monitoring well in fluid communication with either the saline formation or the oil reservoir, and a coupling element that extends through the monitoring well and is coupled to the sensor.
19. The system of claim 16, wherein the sensor is a first sensor in contact with the oil reservoir, and wherein the system further includes a second sensor in communication with the monitoring station and in contact with the saline formation, wherein the second sensor is configured to take measurements that correlate to the amount of CO2 in the environment surrounding the second sensor.
20. The system of claim 19, further comprising a second monitoring well in fluid communication with the saline formation, and a second coupling element that extends through the second monitoring well and is coupled to the second sensor.
Type: Application
Filed: Jul 12, 2010
Publication Date: Mar 14, 2013
Applicant: UNIVERISTY OF UTAH RESEARCH FOUNDATION (Salt Lake City, UT)
Inventors: Weon Shik Han (Salt Lake City, UT), Brian J. McPherson (Salt Lake City, UT)
Application Number: 13/699,044
International Classification: E21B 33/10 (20060101);