Method and system for geothermal development of saline aquifers and carbon dioxide sequestration

Abstract

The application provides a method and system for exploiting a saline aquifer and storing carbon dioxide. The system comprises a geothermal exploitation well, a geothermal water reinjection well, an auxiliary injection well and a carbon dioxide injection and dissolving device; the geothermal exploitation well, the geothermal water reinjection well and the auxiliary injection well are respectively used for extracting saline water of a saline aquifer to be exploited, injecting reinjection water into the saline aquifer to be exploited and injecting an auxiliary agent into the saline aquifer to be exploited; the auxiliary injection well is arranged between the geothermal exploitation well and the geothermal water reinjection well; the carbon dioxide injection and dissolving device is used for dissolving carbon dioxide into the saline water to be reinjected to form the reinjection water; the carbon dioxide injection and dissolving device is provided with a carbon dioxide inlet, a saline water inlet and a reinjection water outlet; the saline water inlet of the carbon dioxide injection and dissolving device is used for introducing the saline water to be reinjected after being used by a saline water geothermal energy utilization device into the carbon dioxide injection and dissolving device; and the reinjection water outlet of the carbon dioxide injection and dissolving device is connected with the geothermal water reinjection well.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of geothermal development and carbon dioxide storage, and particularly relates to a method and system for geothermal development of a saline aquifer and carbon dioxide storage. BACKGROUND

[0002] Geothermal development and carbon dioxide storage are widely valued. Geothermal energy is mainly derived from deep saline water with a temperature of 25-150 DEG C and dry hot rock above 150 DEG C. The deep saline water in the formation, as one of the main sources of geothermal energy, can be used for heating, power generation and functional industry production. In the process of geothermal development of the saline aquifer, the saline water cannot be discharged at will due to high salinity and large extraction amount. At present, the saline water after extraction of geothermal energy needs to be injected back into the formation. The geothermal water injection as the end link of geothermal development will increase the economic cost of geothermal development, and the economic and environmental value has not been effectively tapped.

[0003] At present, the mainstream way of carbon dioxide storage is to inject carbon dioxide directly into abandoned oil and gas reservoirs or deep saline aquifers. In this storage mode, carbon dioxide is in dense gaseous or supercritical state. There are many problems in the application of the above storage mode for carbon dioxide storage: (1) high requirement for the geological conditions of the reservoir, resulting in few available reservoirs; (2) high injection pressure, resulting in high difficulty and risk in construction; (3) poor safety and durability of storage, and there is a risk of leakage and induced earthquake; (4) not suitable for carbon dioxide storage in small amount of discharge. For the case of small amount of carbon dioxide discharge, a special carbon dioxide collection system needs to be established, which increases the economic cost of carbon dioxide storage.

[0004] At present, no technical scheme can simultaneously consider geothermal development and carbon dioxide storage has been researched. SUMMARY

[0005] The purpose of the present application is to provide a method and system that can simultaneously consider geothermal development and carbon dioxide storage, and effectively realize the effective cooperation of geothermal development and carbon dioxide storage.

[0006] In order to achieve the above purpose, the present application provides the following two technical schemes.

[0007] In the first aspect, the present application provides a system for geothermal development of a saline aquifer and carbon dioxide storage, wherein the system comprises:

[0008] a geothermal development well, a geothermal water injection well, an auxiliary injection well and a carbon dioxide injection and dissolution device;

[0009] The geothermal development well is used to extract the brine of the brine layer to be developed to supply the brine with geothermal energy to the brine geothermal energy utilization equipment; the geothermal water injection well is used to inject the injection water into the brine layer to be developed; the auxiliary injection well is arranged between the geothermal development well and the geothermal water injection well, and is used to inject the auxiliary agent into the brine layer to be developed; the carbon dioxide injection and dissolution device is used to dissolve the carbon dioxide into the brine to be injected to form the injection water, and is provided with a carbon dioxide inlet, a brine inlet and an injection water outlet; the brine inlet of the carbon dioxide injection and dissolution device is used to introduce the brine to be injected after being utilized by the brine geothermal energy utilization equipment into the carbon dioxide injection and dissolution device; and the injection water outlet of the carbon dioxide injection and dissolution device is connected with the geothermal water injection well.

[0010] When the brine layer geothermal development and carbon dioxide storage system is used to develop the brine layer and store the carbon dioxide, the brine of the brine layer to be developed is extracted by the geothermal development well, the extracted brine is introduced into the brine geothermal energy utilization equipment to utilize the geothermal energy, the brine to be injected after the utilization of the geothermal energy is introduced into the carbon dioxide injection and dissolution device, the carbon dioxide to be stored is dissolved into the brine to be injected to form the injection water in the carbon dioxide injection and dissolution device; the injection water is injected into the brine layer to be developed by the geothermal water injection well to be stored; the auxiliary agent is injected into the brine layer to be developed by the auxiliary injection well, the injection water reacts with the auxiliary agent injected by the auxiliary injection well to form the carbonate precipitation, the carbon dioxide participating in the reaction is better stored, the carbonate precipitation formed by the reaction cuts off the water flow channel between the geothermal water injection well and the geothermal development well to reduce the possibility that the injection water with the dissolved carbon dioxide injected by the geothermal water injection well is extracted by the geothermal development well, the carbon dioxide is better stored in the form of dissolution in the underground brine layer, and the stability and storage amount of the carbon dioxide stored in the brine layer are enhanced.

[0011] According to the preferred embodiment of the first aspect, the auxiliary injection well is arranged around the geothermal water injection well;

[0012] Further, 3-6 auxiliary injection wells are arranged around the geothermal water injection well; the auxiliary injection wells are arranged around the geothermal water injection well, which helps to better enclose the injection water with the dissolved carbon dioxide in a certain range, reduces the possibility of secondary release of the carbon dioxide, and further enhances the stability of the carbon dioxide stored in the brine layer.

[0013] Further, the geothermal development well is drilled to the top-to-bottom 1 / 2-3 / 4 layer of the brine layer to be developed, the geothermal water reinjection well is drilled to the top-to-bottom 1 / 4-1 / 2 layer of the brine layer to be developed, and one of the auxiliary injection wells circumferentially arranged around the geothermal water reinjection well is drilled to the top-to-bottom 1 / 8-1 / 4 layer of the brine layer to be developed, one of the auxiliary injection wells is drilled to the top-to-bottom 3 / 4-7 / 8 layer of the brine layer to be developed, and the rest of the auxiliary injection wells are drilled to the top-to-bottom 1 / 2-3 / 4 layer of the brine layer to be developed.

[0014] According to the preferred implementation of the first aspect, the distance between the geothermal water reinjection well and the geothermal development well is not less than 1 / 2 (i.e. 2 / 5) of the length of the brine layer to be developed in the direction of the line connecting the geothermal water reinjection well and the geothermal development well.

[0015] According to the preferred implementation of the first aspect, the distance between the geothermal water reinjection well and the auxiliary injection well is 2 / 5-3 / 5 (i.e. 2 / 5 to 3 / 5) of the distance between the geothermal water reinjection well and the geothermal development well.

[0016] According to the preferred implementation of the first aspect, the bottom of the auxiliary injection well is provided with a downhole carbon dioxide concentration sensor for monitoring the carbon dioxide content in the formation fluid.

[0017] Further, the sensitivity of the carbon dioxide concentration sensor is not less than 1% of the solubility of carbon dioxide in brine.

[0018] According to the preferred implementation of the first aspect, the carbon dioxide injection and dissolution device is provided with a carbon dioxide dissolution tank, a brine storage tank, and a carbon dioxide concentration monitoring sensor.

[0019] The brine storage tank is connected to the carbon dioxide dissolution tank to supply the carbon dioxide dissolution tank with the brine to be reinjected after being used by the brine geothermal energy utilization device; the capacity of the brine storage tank is not less than 0.5 times the volume of the brine extracted by the geothermal development well per day, and the capacity of the carbon dioxide dissolution tank is not less than 0.5 times the volume of the brine extracted by the geothermal development well per day.

[0020] The carbon dioxide concentration monitoring sensor is installed at the bottom of the carbon dioxide dissolution tank to monitor the carbon dioxide concentration in the brine in the carbon dioxide dissolution tank.

[0021] Further, the carbon dioxide injection and dissolution device is further provided with a temperature sensor installed in the carbon dioxide dissolution tank to monitor the temperature of the brine in the carbon dioxide dissolution tank.

[0022] Further, the brine storage tank is closed and does not communicate with the atmosphere.

[0023] Further, the carbon dioxide dissolution tank is closed and does not communicate with the atmosphere.

[0024] Furthermore, the sensitivity of the carbon dioxide concentration monitoring sensor is no less than 1% of the carbon dioxide solubility in saline water;

[0025] Furthermore, the carbon dioxide dissolution tank and carbon dioxide concentration monitoring sensor are resistant to carbon dioxide corrosion.

[0026] According to a preferred embodiment of the first aspect, the system further includes a saline geothermal energy utilization device, which includes a heat exchanger, a heat energy transmission pipeline, and at least two temperature sensors. The heat exchanger is used to extract heat energy from the saline water, and the temperature of the extracted saline water should not exceed 30°C. One end of the heat energy transmission pipeline is connected to a geothermal development well, and the other end is connected to the heat exchanger, for transporting high-temperature saline water to the heat exchanger. The temperature sensors are respectively installed at the outlet and inlet of the heat exchanger to monitor the temperature of the saline water flowing into and out of the saline geothermal energy utilization device. The upper limit of the detection range of the temperature sensors is not lower than the highest temperature of the saline water layer to be developed, and the error is preferably not more than 0.1°C. The extracted heat energy can be used for, but is not limited to, heating and power generation.

[0027] According to the preferred embodiment of the first aspect, the depth of the saline aquifer to be developed is 1000-3000 meters underground, the thickness is not less than 30m, and the temperature is not less than 80℃.

[0028] According to a preferred embodiment of the first aspect, a carbon dioxide concentration detection sensor is installed in the geothermal development well to monitor the carbon dioxide content in the saline water extracted from the geothermal development well.

[0029] According to a preferred embodiment of the first aspect, a temperature sensor is installed at the wellhead of the geothermal development well to monitor the temperature of the saline water extracted from the geothermal development well.

[0030] According to a preferred embodiment of the first aspect, a packer is installed in the geothermal development well at a position 10-20m above the saline aquifer to be developed.

[0031] According to the preferred embodiment of the first aspect, a production tubing is installed in the wellbore of the geothermal development well. The production tubing is made of salt-resistant heat-insulating material. A carbon dioxide concentration detection sensor is installed at the bottom of the production tubing. A flow thermometer is installed at the wellhead of the geothermal development well. A packer is installed 10-20m above the saline layer to be developed in the geothermal development well. An electric submersible pump is installed in the wellbore in the middle of the saline layer to be developed in the geothermal development well.

[0032] According to a preferred embodiment of the first aspect, the system further includes a high-pressure pump connected to the geothermal reinjection well for providing power for the reinjection of the reinjection water.

[0033] According to a preferred embodiment of the first aspect, the system further includes an automatic control device;

[0034] Further, the automatic control device comprises an instruction receiver, a data processor and an instruction transmitter; the instruction receiver is used to acquire the data monitored by the sensor, the instruction receiver is connected with the sensor through a data line or wireless transmission, the instruction receiver is connected with the data processor and the instruction transmitter, the data processor and the instruction transmitter are used to form a control instruction based on the data acquired by the instruction receiver and transmit the formed control instruction to the component to be controlled;

[0035] Further, the carbon dioxide injection and dissolution device is provided with a reinjection water outflow speed detection sensor at the reinjection water outlet, and the carbon dioxide injection and dissolution device is provided with a carbon dioxide delivery speed control equipment; the automatic control device is used to control the carbon dioxide delivery speed control equipment to control the carbon dioxide delivery speed according to the reinjection water outflow speed detected by the reinjection water outflow speed detection sensor; wherein the carbon dioxide delivery speed satisfies the following relationship:

[0036] Q1=Q w ×min(D1,D2)

[0037] In the formula, Q1 is the carbon dioxide delivery speed, m 3 / h; Q w is the reinjection water outflow speed, m 3 / h; D1 is the carbon dioxide dissolution rate under the surface condition, m 3 / m 3 ; D2 is the carbon dioxide dissolution rate under the formation condition, m 3 / m 3 ;

[0038] Further, the automatic control device is used to control the auxiliary agent injection speed based on the data monitored by the downhole carbon dioxide concentration sensor of the auxiliary injection well; wherein the auxiliary agent injection speed satisfies the following relationship:

[0039]

[0040] In the formula, Q2 is the auxiliary agent delivery speed, m 3 / h; Qr is the carbon dioxide content reduction speed in the formation, mol / h; D3 is the auxiliary agent concentration, mol / m 3 ; Vz is the water body range of the carbon dioxide distribution, m 3 ;

[0041] In a specific embodiment, the instruction receiver is used to receive data monitored by a carbon dioxide concentration detection sensor and a temperature sensor in a geothermal development well, data monitored by a temperature sensor in a saline geothermal energy utilization device, data monitored by a carbon dioxide concentration monitoring sensor and a re-injection water flow rate detection sensor in a carbon dioxide injection dissolving device, and data monitored by a downhole carbon dioxide concentration sensor in an auxiliary injection well, and the instruction receiver is connected to each sensor through a data line or wireless transmission; the data processing and instruction transmitter is used to form a control instruction based on the data obtained by the instruction receiver and transmit the formed control instruction to the control system of the component to be controlled to control the operation of the component; specifically, the data processing and instruction transmitter forms a carbon dioxide delivery rate control instruction based on the re-injection water flow rate and transmits the instruction to a carbon dioxide delivery rate control device to control the carbon dioxide delivery rate; specifically, the data processing and instruction transmitter forms an auxiliary agent injection control instruction based on the data monitored by the downhole carbon dioxide concentration sensor in the auxiliary injection well and transmits the instruction to a control device to control the injection of the auxiliary agent, wherein the injection of the auxiliary agent is controlled when the downhole carbon dioxide concentration sensor in the auxiliary injection well monitors that the content of carbon dioxide in the formation fluid is 80%-90% of the solubility, and the injection of the auxiliary agent is stopped when the downhole carbon dioxide concentration sensor in the auxiliary injection well monitors that the content of carbon dioxide in the formation fluid is reduced to 50%-70% of the solubility; specifically, the data processing and instruction transmitter forms an auxiliary agent injection rate control instruction based on the data monitored by the downhole carbon dioxide concentration sensor in the auxiliary injection well and transmits the instruction to a control device to control the injection rate of the auxiliary agent.

[0042] To achieve the above-mentioned purpose, the present application provides a saline aquifer geothermal development and carbon dioxide storage method, wherein the method comprises:

[0043] A well pattern arrangement step: setting a geothermal development well, a geothermal water re-injection well, and an auxiliary injection well; wherein the auxiliary injection well is arranged between the geothermal development well and the geothermal water re-injection well; the geothermal development well is used for extracting saline water from a saline aquifer to be developed; the geothermal water re-injection well is used for injecting re-injection water into the saline aquifer to be developed; and the auxiliary injection well is used for injecting an auxiliary agent into the saline aquifer to be developed;

[0044] A geothermal development step: extracting saline water from the saline aquifer to be developed by using the geothermal development well, and delivering the extracted saline water to a saline geothermal energy utilization device for geothermal energy utilization;

[0045] A re-injection water preparation step: dissolving carbon dioxide in the saline water to be re-injected after being utilized by the saline geothermal energy utilization device to obtain re-injection water;

[0046] A geothermal water re-injection step: injecting the re-injection water into the saline aquifer to be developed by using the geothermal water re-injection well;

[0047] The auxiliary agent injection step is injecting an auxiliary agent into the brine layer to be developed by using the auxiliary injection well; wherein the auxiliary agent is selected from an auxiliary agent capable of reacting with carbon dioxide to form carbonate precipitate.

[0048] In the brine layer geothermal development and carbon dioxide storage method provided by the present application, the brine in the brine layer to be developed is extracted by using the geothermal development well, the extracted brine enters the brine geothermal energy utilization equipment for geothermal energy utilization, and the carbon dioxide to be stored is dissolved in the brine to be injected after the geothermal energy utilization; the injection water is injected into the brine layer to be developed for storage by using the geothermal water injection well; and the auxiliary agent is injected into the brine layer to be developed by using the auxiliary injection well, and the injection water reacts with the auxiliary agent injected by the auxiliary injection well to form carbonate precipitate, which realizes better storage of the carbon dioxide participating in the reaction, and the carbonate precipitate formed by the reaction cuts off the water flow channel between the geothermal water injection well and the geothermal development well, reduces the possibility of the injection water dissolved with carbon dioxide injected by the geothermal water injection well being extracted by the geothermal development well, better stores the carbon dioxide in the form of dissolution in the underground brine layer, and enhances the stability and storage amount of the carbon dioxide stored in the brine layer.

[0049] According to the preferred embodiment of the second aspect, the auxiliary agent is selected from an aqueous solution containing a soluble compound capable of reacting with carbon dioxide to form carbonate precipitate; in a specific embodiment, the auxiliary agent is selected from a calcium hydroxide solution.

[0050] According to the preferred embodiment of the second aspect, in the auxiliary agent injection step, when the content of carbon dioxide in the formation fluid in the formation at the bottom position of the auxiliary injection well reaches a first threshold value, the auxiliary agent is injected into the brine layer to be developed by using the auxiliary injection well; preferably, the first threshold value is 80%-90% of the carbon dioxide solubility in the formation fluid.

[0051] Further, in the auxiliary agent injection step, the auxiliary agent is injected into the brine layer to be developed by using the auxiliary injection well until the content of carbon dioxide in the formation fluid in the formation at the bottom position of the auxiliary injection well drops to a second threshold value, and then the auxiliary agent injection is stopped; preferably, the second threshold value is 50%-70% of the carbon dioxide solubility in the formation fluid.

[0052] According to the preferred embodiment of the second aspect, in the auxiliary agent injection step, the auxiliary agent injection speed satisfies the following relationship:

[0053]

[0054] In the formula, Q2 is the auxiliary agent delivery speed, m 3 / h; Qr is the carbon dioxide content reduction speed in the formation, mol / h; D3 is the auxiliary agent concentration, mol / m 3 ; Vz is the water body range of carbon dioxide distribution, m3 .

[0055] According to the preferred embodiment of the second aspect, the geothermal water reinjection well is surrounded by auxiliary injection wells.

[0056] Further, 3-6 auxiliary injection wells are arranged around the geothermal water reinjection well. The auxiliary injection wells arranged around the geothermal water reinjection well help to better confine the reinjection water dissolving carbon dioxide within a certain range, reduce the possibility of secondary release of carbon dioxide, and further enhance the stability of carbon dioxide storage in the saline aquifer.

[0057] Still further, the geothermal development well is drilled to a position of 1 / 2-3 / 4 of the top-to-bottom interval of the saline aquifer to be developed, the geothermal water reinjection well is drilled to a position of 1 / 4-1 / 2 of the top-to-bottom interval of the saline aquifer to be developed, one of the auxiliary injection wells arranged around the geothermal water reinjection well is drilled to a position of 1 / 8-1 / 4 of the top-to-bottom interval of the saline aquifer to be developed, one of the auxiliary injection wells is drilled to a position of 3 / 4-7 / 8 of the top-to-bottom interval of the saline aquifer to be developed, and the remaining auxiliary injection wells are drilled to a position of 1 / 2-3 / 4 of the top-to-bottom interval of the saline aquifer to be developed.

[0058] According to the preferred embodiment of the second aspect, the distance between the geothermal water reinjection well and the geothermal development well is not less than 1 / 2 (i.e., 2 / 5) of the length of the saline aquifer to be developed in the direction of the line connecting the geothermal water reinjection well and the geothermal development well.

[0059] According to the preferred embodiment of the second aspect, the distance between the geothermal water reinjection well and the auxiliary injection well is 2 / 5-3 / 5 (i.e., 2 / 5 to 3 / 5) of the distance between the geothermal water reinjection well and the geothermal development well.

[0060] According to the preferred embodiment of the second aspect, in the step of preparing reinjection water, the carbon dioxide delivery rate in the process of dissolving carbon dioxide into the saline water to be reinjected after being used by the saline geothermal energy utilization device to obtain the reinjection water satisfies the following relationship:

[0061] Q1 = Q w × min(D1, D2)

[0062] In the formula, Q1 is the carbon dioxide delivery rate, m 3 / h; Q w is the flow rate of the reinjection water, m 3 / h; D1 is the carbon dioxide solubility under surface conditions, m 3 / m 3 ; D2 is the carbon dioxide solubility under formation conditions, m 3 / m 3 .

[0063] According to the preferred embodiment of the second aspect, the depth of the brine layer to be developed is 1000-3000 meters underground, the thickness is not less than 30m, and the temperature is not less than 80℃.

[0064] According to the preferred embodiment of the second aspect, the method is performed using the brine layer geothermal development and carbon dioxide storage system provided in the first aspect of the application.

[0065] The technical solution provided by the application can simultaneously consider geothermal development and carbon dioxide storage, effectively realizing the effective cooperation of geothermal development and carbon dioxide storage. Compared with the prior art, the technical solution provided by the application has the following beneficial effects:

[0066] (1) The operating pressure is relatively low, and there is no risk of high pressure accumulation.

[0067] (2) The carbon dioxide is transported and stored in the stratum in a dissolved state, and the leakage risk is low.

[0068] (3) The carbon dioxide becomes acidic after being dissolved in the brine, which can increase the permeability of the brine layer to a certain extent, and reduce the backfilling pressure and difficulty of the geothermal water;

[0069] (4) The storage of carbon dioxide is more reliable with the cooperation of the auxiliary agent, and the possibility of secondary release of carbon dioxide is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0070] Figure 1 A structure diagram of a brine layer geothermal development and carbon dioxide storage system is provided for the embodiment 1 of the application.

[0071] Figure 2 A flowchart of a brine layer geothermal development and carbon dioxide storage method is provided for the embodiment 2 of the application. DETAILED DESCRIPTION

[0072] To make the purpose, technical solution and advantages of the embodiments of the application more clear, the technical solution in the embodiments of the application will be described in detail below with reference to the drawings of the embodiments of the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0073] Embodiment 1

[0074] This embodiment provides a brine layer geothermal development and carbon dioxide storage system, as shown in the figure, the system comprises: Figure 1

[0075] ​The geothermal development well 100, the geothermal water reinjection well 403, the auxiliary injection well 603, the carbon dioxide injection and dissolving device 300, and the saline water geothermal energy utilization equipment 200;

[0076] The geothermal development well 100 is used to realize the extraction of saline water in the saline water layer to be developed, and supply the saline water geothermal energy utilization equipment 200 with saline water having geothermal energy;

[0077] The geothermal water reinjection well 403 is used to realize the injection of reinjection water into the saline water layer to be developed;

[0078] The auxiliary injection well 603 is arranged between the geothermal development well 100 and the geothermal water reinjection well 403, and is used to realize the injection of an auxiliary agent into the saline water layer to be developed;

[0079] The carbon dioxide injection and dissolving device 300 is used to dissolve carbon dioxide into the saline water to be reinjected to form reinjection water. The carbon dioxide injection and dissolving device 300 is provided with a carbon dioxide inlet, a saline water inlet, and a reinjection water outlet. The saline water inlet of the carbon dioxide injection and dissolving device 300 is used to introduce the saline water to be reinjected after being utilized by the saline water geothermal energy utilization equipment 200 into the carbon dioxide injection and dissolving device 300. The reinjection water outlet of the carbon dioxide injection and dissolving device 300 is connected with the geothermal water reinjection well 403.

[0080] Further, the auxiliary injection well 603 is arranged around the geothermal water reinjection well 100. The geothermal water reinjection well 100 is circumferentially and uniformly provided with 3-6 auxiliary injection wells. Further, the geothermal development well 100 is drilled to the top 3 / 4 of the saline water layer to be developed. The geothermal water reinjection well 403 is drilled to the top 1 / 4 of the saline water layer to be developed. Among the auxiliary injection wells 603 circumferentially arranged around the geothermal water reinjection well 403, one is drilled to the top 1 / 4 of the saline water layer to be developed, one is drilled to the top 3 / 4 of the saline water layer to be developed, and the rest are drilled to the top 1 / 2-3 / 4 of the saline water layer to be developed.

[0081] Further, the distance between the geothermal water reinjection well and the geothermal development well is not less than 1 / 2 of the length of the saline water layer to be developed in the direction of the line connecting the geothermal water reinjection well and the geothermal development well.

[0082] Further, the distance between the geothermal water reinjection well 403 and the auxiliary injection well 603 is 2 / 5 of the distance between the geothermal water reinjection well 403 and the geothermal development well 100.

[0083] Further, the bottom of the auxiliary injection well 603 is provided with an underground carbon dioxide concentration sensor for monitoring the content of carbon dioxide in the formation fluid. The sensitivity of the carbon dioxide concentration sensor is not less than 1% of the solubility of carbon dioxide in the saline water of the saline water layer to be developed.

[0084] Further, the carbon dioxide injection and dissolving device 300 is provided with a carbon dioxide conveying pipeline 301, a salt water injection pipeline 302, a salt water storage pool 303, a communication valve 304, a carbon dioxide dissolving pool 305, a salt water outflow channel 306, a valve 307 and a carbon dioxide concentration monitoring sensor 308; wherein the outlet of the salt water injection pipeline 302 is connected with the salt water geothermal energy utilization equipment 200, the inlet is connected with the salt water storage pool 303, the salt water storage pool 303 is communicated with the carbon dioxide dissolving pool 305 through the communication valve 304, the outlet of the salt water outflow channel 306 is connected with the carbon dioxide dissolving pool 305, the inlet is connected with the geothermal water reinjection well 403, the carbon dioxide conveying pipeline 301 is connected with the carbon dioxide dissolving pool 305, the carbon dioxide concentration monitoring sensor 308 is installed at the bottom of the carbon dioxide dissolving pool 305, and the valve 307 is arranged at the outlet of the carbon dioxide dissolving pool 305; the outlet of the salt water outflow channel 306 is the reinjection water outlet of the carbon dioxide injection and dissolving device 300, the inlet of the salt water injection pipeline 302 is the salt water inlet of the carbon dioxide injection and dissolving device 300, and the inlet of the salt water outflow channel 306 is the carbon dioxide inlet of the carbon dioxide injection and dissolving device 300;

[0085] The capacity of the salt water storage pool is not less than 0.5 times of the volume of the salt water extracted by the geothermal development well per day, and the capacity of the carbon dioxide dissolving pool is not less than 0.5 times of the volume of the salt water extracted by the geothermal development well per day.

[0086] The temperature sensor is further arranged in the carbon dioxide dissolving pool 305 to monitor the temperature of the salt water in the carbon dioxide dissolving pool 305.

[0087] The salt water storage pool 303 is closed and not communicated with the atmosphere.

[0088] The carbon dioxide dissolving pool 305 is closed and not communicated with the atmosphere.

[0089] The sensitivity of the carbon dioxide concentration monitoring sensor 308 is not less than 1% of the carbon dioxide solubility of the salt water in the carbon dioxide dissolving pool 305.

[0090] The communication valve 304, the carbon dioxide dissolving pool 305, the salt water outflow channel 306, the valve 307, the carbon dioxide concentration monitoring sensor 308 and the temperature sensor in the carbon dioxide dissolving pool 305 have the anti-carbon dioxide corrosion ability.

[0091] Further, the saltwater geothermal energy utilization device 200 comprises a heat exchanger 201, a heat energy conveying pipeline 202, and two temperature sensors 203; the heat exchanger 201 is used to extract heat energy from the saltwater, and the temperature of the extracted saltwater should not be higher than 30℃; the inlet of the heat energy conveying pipeline 202 is connected with the geothermal development well 100, and the outlet is connected with the heat exchanger 201, and the two temperature sensors 203 are respectively installed at the outlet and the inlet of the heat exchanger 201.

[0092] The upper limit of the detection of the temperature sensor 203 is not lower than the highest temperature of the saltwater layer to be developed, and the error is not more than 0.1℃.

[0093] The extracted heat energy can be used for, but not limited to, heating and power generation, etc.

[0094] Further, the geothermal development well 100 is provided with a production string 101 in the wellbore, a carbon dioxide concentration detection sensor 102 is arranged at the bottom of the well, a temperature sensor 103 is arranged at the wellhead, a packer 104 is arranged at a position 10-20m above the saltwater layer to be developed, and an electric submersible pump 105 is arranged in the middle of the wellbore in the saltwater layer to be developed.

[0095] The production string 101, the carbon dioxide concentration detection sensor 102, the temperature sensor 103, the packer 104, and the electric submersible pump 105 are made of salt-resistant and heat-insulating materials.

[0096] Further, the outlet of the carbon dioxide injection and dissolution device 300 is connected with the geothermal water reinjection well 403 through the ground conveying pipeline 402; the high-pressure pump 401 is arranged on the ground conveying pipeline 402.

[0097] Further, the system is provided with an auxiliary agent conveying pipeline 602 and a high-pressure pump 601; the outlet of the auxiliary agent conveying pipeline 602 is connected with the auxiliary injection well 603, and the high-pressure pump 601 is arranged on the auxiliary agent conveying pipeline 602.

[0098] Further, the system further comprises an automatic control device 500, which comprises an instruction receiver 501 and a data processing and instruction transmitter 502; the instruction receiver 501 is used to acquire the data monitored by the sensor, and is connected with the sensor through a data line or a wireless transmission mode; the instruction receiver 501 is connected with the data processing and instruction transmitter 502; the data processing and instruction transmitter 502 is used to form a control instruction based on the data acquired by the instruction receiver 501 and transmit the formed control instruction to the component to be controlled.

[0099] Further, the carbon dioxide injection dissolving device 300 is provided with a reinjection water outlet flow rate detection sensor at the reinjection water outlet of the carbon dioxide injection dissolving device 300, and the carbon dioxide injection dissolving device 300 is provided with a carbon dioxide delivery rate control device; the automatic control device 500 is used to control the carbon dioxide delivery rate control device to control the carbon dioxide delivery rate according to the reinjection water outlet flow rate detected by the reinjection water outlet flow rate detection sensor; wherein the carbon dioxide delivery rate satisfies the following relationship:

[0100] Q1=Q w ×min(D1,D2)

[0101] In the formula, Q1 is the carbon dioxide delivery rate, m 3 / h; Q w is the reinjection water outlet flow rate, m 3 / h; D1 is the carbon dioxide solubility under surface conditions, m 3 / m 3 ; D2 is the carbon dioxide solubility under formation conditions, m 3 / m 3 ;

[0102] Further, the automatic control device 500 is used to control the auxiliary agent injection rate based on the data monitored by the downhole carbon dioxide concentration sensor of the auxiliary injection well 603; wherein the auxiliary agent injection rate satisfies the following relationship:

[0103]

[0104] In the formula, Q2 is the auxiliary agent delivery rate, m 3 / h; Qr is the carbon dioxide content decrease rate in the formation, mol / h; D3 is the auxiliary agent concentration, mol / m 3 ; Vz is the water range of carbon dioxide distribution, m 3 ;

[0105] Further, the instruction receiver 501 is configured to receive data monitored by the carbon dioxide concentration detection sensor 102 and the temperature sensor 103 in the geothermal development well 100, data monitored by the temperature sensor 203 of the saline geothermal energy utilization device 200, data monitored by the carbon dioxide concentration monitoring sensor 308 and the reinjection water flow rate detection sensor in the carbon dioxide injection and dissolution device 300, and data monitored by the downhole carbon dioxide concentration sensor of the auxiliary injection well 603, and the instruction receiver 501 is connected with each sensor through a data line or wireless transmission; the data processing and instruction transmitter 502 is configured to form a control instruction based on the data obtained by the instruction receiver 501 and transmit the formed control instruction to the operation of the component control system to be controlled; specifically, the data processing and instruction transmitter 502 forms a carbon dioxide delivery rate control instruction based on the reinjection water flow rate and transmits the carbon dioxide delivery rate control instruction to the carbon dioxide delivery rate control device to control the carbon dioxide delivery rate; specifically, the data processing and instruction transmitter 502 forms an auxiliary agent injection control instruction based on the data monitored by the downhole carbon dioxide concentration sensor of the auxiliary injection well 603 and transmits the auxiliary agent injection control instruction to the control device for controlling the injection of the auxiliary agent to control the injection of the auxiliary agent, wherein the injection of the auxiliary agent is controlled to be performed when the downhole carbon dioxide concentration sensor of the auxiliary injection well 603 monitors that the content of carbon dioxide in the formation fluid is 80% of the solubility, and the injection of the auxiliary agent is controlled to be stopped when the downhole carbon dioxide concentration sensor of the auxiliary injection well 603 monitors that the content of carbon dioxide in the formation fluid is reduced to 50% of the solubility; specifically, the data processing and instruction transmitter 502 forms an auxiliary agent injection rate control instruction based on the data monitored by the downhole carbon dioxide concentration sensor of the auxiliary injection well 603 and transmits the auxiliary agent injection rate control instruction to the control device for controlling the injection rate of the auxiliary agent to control the injection rate of the auxiliary agent.

[0106] Further, the depth of the saline layer to be developed is 1000-3000 meters underground, the thickness is not less than 30m, and the temperature is not less than 80℃.

[0107] Embodiment 2

[0108] The embodiment provides a saline layer geothermal development and carbon dioxide storage method. The method is performed by using the saline layer geothermal development and carbon dioxide storage system provided in the embodiment 1.

[0109] As shown in the method, the method comprises the following steps. Figure 2

[0110] Step S1: performing a well pattern step; specifically,

[0111] ​The geothermal development well, the geothermal water reinjection well and the auxiliary injection well are arranged; the auxiliary injection well is arranged between the geothermal development well and the geothermal water reinjection well; the geothermal development well is used for extracting brine of the brine layer to be developed; the geothermal water reinjection well is used for injecting reinjection water into the brine layer to be developed; and the auxiliary injection well is used for injecting auxiliary agent into the brine layer to be developed.

[0112] Step S2: geothermal development; specifically:

[0113] The brine of the brine layer to be developed is extracted by the geothermal development well, and the extracted brine is transported to the brine geothermal energy utilization equipment for geothermal energy utilization.

[0114] Step S3: preparation of reinjection water; specifically:

[0115] Carbon dioxide is dissolved in the brine to be reinjected after being utilized by the brine geothermal energy utilization equipment to obtain reinjection water.

[0116] Step S4: geothermal water reinjection; specifically:

[0117] The reinjection water is injected into the brine layer to be developed by the geothermal water reinjection well.

[0118] Step S5: auxiliary agent injection; specifically:

[0119] The auxiliary agent is injected into the brine layer to be developed by the auxiliary injection well; wherein the auxiliary agent is selected from auxiliary agents that can react with carbon dioxide to form carbonate precipitate.

[0120] Further, the auxiliary agent is selected from aqueous solutions containing soluble compounds that can react with carbon dioxide to form carbonate precipitate, such as calcium hydroxide solution.

[0121] Further, during the auxiliary agent injection process, when the content of carbon dioxide in the formation fluid in the formation at the bottom position of the auxiliary injection well reaches the first threshold value, the auxiliary agent is injected into the brine layer to be developed by the auxiliary injection well; wherein the first threshold value is 80% of the solubility of carbon dioxide in the formation fluid.

[0122] Further, during the auxiliary agent injection process, the auxiliary agent is injected into the brine layer to be developed by the auxiliary injection well until the content of carbon dioxide in the formation fluid in the formation at the bottom position of the auxiliary injection well drops to the second threshold value, and then the auxiliary agent injection is stopped; wherein the second threshold value is 50% of the solubility of carbon dioxide in the formation fluid.

[0123] Further, during the auxiliary agent injection process, the auxiliary agent injection speed satisfies the following relationship:

[0124]

[0125] In the formula, Q2 is the auxiliary agent delivery speed, m 3 / h; Qr is the carbon dioxide content reduction speed in the formation, mol / h; D3 is the auxiliary agent concentration, mol / m 3 ; Vz is the water body range of carbon dioxide distribution, m 3 .

[0126] Further, in the process of preparing the reinjection water by dissolving carbon dioxide in the brine after being used by the brine geothermal energy utilization equipment, the carbon dioxide delivery speed satisfies the following relationship:

[0127] Q1 = Q w × min (D1, D2)

[0128] In the formula, Q1 is the carbon dioxide delivery speed, m 3 / h; Q w is the reinjection water outflow speed, m 3 / h; D1 is the carbon dioxide solubility under the surface condition, m 3 / m 3 ; D2 is the carbon dioxide solubility under the formation condition, m 3 / m 3 .

[0129] Further, the depth of the brine layer to be developed is 1000-3000 meters underground, the thickness is not less than 30m, and the temperature is not less than 80℃.

[0130] The above examples show that, by applying the present application, the amount of free hydrocarbon and adsorbed hydrocarbon in shale can be accurately evaluated, compared with the traditional method, the generation and evolution of shale oil and the flow performance of crude oil can be better understood from the deep level, so that the shale oil sweet spot section optimization and the geological recoverable reserve evaluation can be quickly and accurately completed.

Claims

1. A saline aquifer geothermal development and carbon dioxide sequestration system wherein, The system comprises: a geothermal development well, a geothermal water reinjection well, an auxiliary injection well, a carbon dioxide injection and dissolving device, and an automatic control device; The geothermal development well is used to extract brine from a brine layer to be developed, and supply the brine with geothermal energy to a brine geothermal energy utilization device; the geothermal water reinjection well is used to inject reinjection water into the brine layer to be developed; the auxiliary injection well is arranged between the geothermal development well and the geothermal water reinjection well, and is used to inject an auxiliary agent into the brine layer to be developed; the carbon dioxide injection and dissolving device is used to dissolve carbon dioxide into the brine to be reinjected to form reinjection water, and is provided with a carbon dioxide inlet, a brine inlet, and a reinjection water outlet; the brine inlet of the carbon dioxide injection and dissolving device is used to introduce the brine to be reinjected after being utilized by the brine geothermal energy utilization device into the carbon dioxide injection and dissolving device; and the reinjection water outlet of the carbon dioxide injection and dissolving device is connected with the geothermal water reinjection well. The auxiliary injection well is provided with a downhole carbon dioxide concentration sensor at the bottom of the well, which is used to monitor the content of carbon dioxide in the formation fluid. The automatic control device comprises an instruction receiver, a data processing and instruction transmitter; The instruction receiver is used to acquire the data monitored by the sensors, and is connected with the sensors through a data line or wireless transmission; the instruction receiver is connected with the data processing and instruction transmitter; the data processing and instruction transmitter is used to form a control instruction based on the data acquired by the instruction receiver, and transmit the formed control instruction to the components to be controlled; The instruction receiver is used to receive the data monitored by the carbon dioxide concentration detection sensor and the temperature sensor in the geothermal development well, the data monitored by the temperature sensor of the brine geothermal energy utilization device, the data monitored by the carbon dioxide concentration monitoring sensor and the reinjection water outflow speed detection sensor in the carbon dioxide injection and dissolving device, and the data monitored by the downhole carbon dioxide concentration sensor of the auxiliary injection well; the instruction receiver is connected with each sensor through a data line or wireless transmission; the data processing and instruction transmitter is used to form a control instruction based on the data acquired by the instruction receiver, and transmit the formed control instruction to the components to be controlled to control the operation of the system; The data processing and instruction transmitter forms an auxiliary agent injection control instruction based on the data monitored by the downhole carbon dioxide concentration sensor of the auxiliary injection well, and transmits the control instruction to a control device for controlling the injection of the auxiliary agent to control the injection of the auxiliary agent; when the downhole carbon dioxide concentration sensor of the auxiliary injection well monitors that the content of carbon dioxide in the formation fluid reaches a first threshold value, the injection of the auxiliary agent is controlled; when the downhole carbon dioxide concentration sensor of the auxiliary injection well monitors that the content of carbon dioxide in the formation fluid decreases to a second threshold value, the injection of the auxiliary agent is stopped.

2. The system of claim 1, wherein, The geothermal water reinjection well is surrounded by auxiliary injection wells.

3. The system of claim 2, wherein, The geothermal water reinjection well is circumferentially provided with 3-6 auxiliary injection wells.

4. The system of claim 3, wherein, The geothermal development well is drilled to the top to bottom 1 / 2-3 / 4 layer position of the brine layer to be developed, the geothermal water reinjection well is drilled to the top to bottom 1 / 4-1 / 2 layer position of the brine layer to be developed, one of the auxiliary injection wells circumferentially arranged in the geothermal water reinjection well is drilled to the top to bottom 1 / 8-1 / 4 layer position of the brine layer to be developed, one of the auxiliary injection wells is drilled to the top to bottom 3 / 4-7 / 8 layer position of the brine layer to be developed, and the rest of the auxiliary injection wells are drilled to the top to bottom 1 / 2-3 / 4 layer position of the brine layer to be developed.

5. The system of any one of claims 1-4, wherein, The distance between the geothermal water reinjection well and the geothermal development well is not less than 1 / 2 of the length of the brine layer to be developed in the direction of the line connecting the geothermal water reinjection well and the geothermal development well.

6. The system of any one of claims 1-4, wherein, The distance between the geothermal water reinjection well and the auxiliary injection well is 2 / 5-3 / 5 of the distance between the geothermal water reinjection well and the geothermal development well.

7. The system of claim 1, wherein, The carbon dioxide injection and dissolution device is provided with a carbon dioxide dissolution tank, a brine storage tank and a carbon dioxide concentration monitoring sensor. The brine storage tank is connected with the carbon dioxide dissolution tank and supplies the carbon dioxide dissolution tank with the brine to be reinjected after being used by the brine geothermal energy utilization equipment; the capacity of the brine storage tank is not less than 0.5 times the volume of the brine extracted by the geothermal development well per day, and the capacity of the carbon dioxide dissolution tank is not less than 0.5 times the volume of the brine extracted by the geothermal development well per day. The carbon dioxide concentration monitoring sensor is installed at the bottom of the carbon dioxide dissolution tank and is used to monitor the carbon dioxide concentration in the brine in the carbon dioxide dissolution tank.

8. The system of claim 1, wherein, The reinjection water outlet of the carbon dioxide injection and dissolution device is provided with a reinjection water outflow speed detection sensor, and the carbon dioxide injection and dissolution device is provided with a carbon dioxide delivery speed control equipment; the automatic control device is used to control the carbon dioxide delivery speed of the carbon dioxide delivery speed control equipment according to the reinjection water outflow speed detected by the reinjection water outflow speed detection sensor; wherein the carbon dioxide delivery speed satisfies the following relationship: wherein Q1 is the carbon dioxide transport velocity, m 3 / h; Q w is the injection water flow rate, m 3 / h; D1 is the carbon dioxide solubility under surface conditions, m 3 / m 3 ; D2 is the carbon dioxide solubility under formation conditions, m 3 / m 3 .

9. The system of claim 1, wherein, The automatic control device is used to control the auxiliary agent injection speed based on the data monitored by the downhole carbon dioxide concentration sensor of the auxiliary injection well; wherein the auxiliary agent injection speed satisfies the following relationship: In the formula, Q2 is the auxiliary agent delivery speed, m 3 / h; Qr is the carbon dioxide content reduction speed in the formation, mol / h; D3 is the auxiliary agent concentration, mol / m 3 ; V z is the water body range of carbon dioxide distribution, m 3 .

10. A method of saline aquifer geothermal development and carbon dioxide sequestration, wherein, The method comprises: The well pattern arrangement step: setting a geothermal development well, a geothermal water reinjection well and an auxiliary injection well; wherein the auxiliary injection well is arranged between the geothermal development well and the geothermal water reinjection well; the geothermal development well is used for extracting brine from the brine layer to be developed; the geothermal water reinjection well is used for injecting reinjection water into the brine layer to be developed; and the auxiliary injection well is used for injecting an auxiliary agent into the brine layer to be developed; The geothermal development step: extracting brine from the brine layer to be developed by using the geothermal development well, and delivering the extracted brine to a brine geothermal energy utilization equipment for geothermal energy utilization; The reinjection water preparation step: dissolving carbon dioxide in the brine to be reinjected after being used by the brine geothermal energy utilization equipment to obtain reinjection water; The geothermal water reinjection step: injecting the reinjection water into the brine layer to be developed by using the geothermal water reinjection well; The auxiliary agent injection step: injecting an auxiliary agent into the brine layer to be developed by using the auxiliary injection well; wherein the auxiliary agent is selected from an auxiliary agent capable of reacting with carbon dioxide to form carbonate precipitate. Specifically, when the carbon dioxide content in the formation fluid at the bottom of the auxiliary injection well reaches a first threshold, an auxiliary agent is injected into the saline water layer to be developed using the auxiliary injection well. In the auxiliary agent injection step, the auxiliary agent is injected into the saline water layer to be developed using the auxiliary injection well until the carbon dioxide content in the formation fluid at the bottom of the auxiliary injection well decreases to a second threshold, after which the auxiliary agent injection is stopped.

11. The method of claim 10, wherein, The auxiliary agent is an aqueous solution containing a soluble compound that can react with carbon dioxide to form a carbonate precipitate.

12. The method of claim 11, wherein, The auxiliary agent is a calcium hydroxide solution.

13. The method of claim 10, wherein, The first threshold is 80%-90% of the carbon dioxide solubility in formation fluids.

14. The method of claim 10, wherein, The second threshold is 50%-70% of the carbon dioxide solubility in formation fluids.

15. The method of any one of claims 10, 13, 14, wherein, During the adjuvant injection step, the injection rate of the adjuvant satisfies the following relationship: In the formula, Q2 is the auxiliary agent delivery speed, m 3 / h; Qr is the carbon dioxide content reduction speed in the formation, mol / h; D3 is the auxiliary agent concentration, mol / m 3 ; V z is the water body range of carbon dioxide distribution, m 3 .

16. The method of claim 10, wherein, Auxiliary injection wells are set up around the geothermal water reinjection well.

17. The method of claim 16, wherein, Three to six auxiliary injection wells are installed around the geothermal water reinjection well.

18. The method of claim 17, wherein, Geothermal development wells are drilled to the 1 / 2-3 / 4 layer from the top to the bottom of the saline layer to be developed. Geothermal water reinjection wells are drilled to the 1 / 4-1 / 2 layer from the top to the bottom of the saline layer to be developed. Among the auxiliary injection wells set around the geothermal water reinjection wells, one auxiliary injection well is drilled to the 1 / 8-1 / 4 layer from the top to the bottom of the saline layer to be developed, another auxiliary injection well is drilled to the 3 / 4-7 / 8 layer from the top to the bottom of the saline layer to be developed, and the remaining auxiliary injection wells are drilled to the 1 / 2-3 / 4 layer from the top to the bottom of the saline layer to be developed.

19. The method of claim 10 or 16, wherein, The distance between the geothermal reinjection well and the geothermal development well shall not be less than half the length of the saline aquifer to be developed in the direction of the line connecting the geothermal reinjection well and the geothermal development well.

20. The method of claim 10 or 16, wherein, The distance between the geothermal reinjection well and the auxiliary injection well is 2 / 5 to 3 / 5 of the distance between the geothermal reinjection well and the geothermal development well.

21. The method of claim 10, wherein, In the reinjection water preparation step, during the process of dissolving carbon dioxide into the saline water to be reinjected after it has been utilized by the saline geothermal energy utilization equipment, the carbon dioxide transport rate satisfies the following relationship: wherein Q1 is the carbon dioxide transport velocity, m 3 / h; Q w is the produced water flow rate, m 3 / h; D1 is the carbon dioxide solubility under surface conditions, m 3 / m 3 ; D2 is the carbon dioxide solubility under formation conditions, m 3 / m 3 .

22. The method of claim 10, wherein, The saline aquifer to be developed is located at a depth of 1000-3000 meters underground, with a thickness of no less than 30 meters and a temperature of no less than 80℃.

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