Method and system for sequestering carbon dioxide in a carbonate rock depleted reservoir

Abstract

The application discloses a method and system for storing carbon dioxide based on carbonate rock depleted reservoirs, the method selects a target injection well by collecting relevant data of depleted oil and gas fields, drills a monitoring well around the injection well, continuously injects a carbon dioxide saturated solution into the injection well to form a cavity under a first injection pressure, and realizes the storage of liquefied carbon dioxide under an injection pressure of 10-15 MPa after the solution in the bottom cavity is squeezed out by injecting carbon dioxide gas into the injection well under a second injection pressure, and continuously measures the monitoring. The application provides a new idea for carbon dioxide storage technology, can generate certain economic value, and improves the safety of storage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon dioxide geological storage, in particular to a method and system for storing carbon dioxide based on a carbonate rock depleted reservoir. BACKGROUND

[0002] With the deepening of the international community's scientific understanding of climate change, the conclusion that human activities, especially the emission of CO2 and other greenhouse gases, cause climate change has been generally accepted; improving efficiency, developing alternative energy and CO2 capture, utilization and storage have become effective means to reduce the greenhouse effect, among which burying CO2 in the ground for storage has become a hot research direction.

[0003] The oil and gas resources in the southwest region of China are relatively abundant, and many oil and gas field reservoirs are carbonate rocks, such as dolomite reservoirs of Qixia Formation and Anyue gas field. In the late development stage of such oil and gas fields, water injection is often used in the form of "horizontal well + volume fracturing" to extract oil and gas in the reservoir fractures and improve oil and gas production, but when the oil and gas is depleted, it is difficult to find secondary utilization value for the oil and gas field; since carbonate ions in carbonate rocks are soluble in water, when CO2 is injected into the reservoir, CO2 will dissolve in the water in the reservoir to form carbonic acid, which can react with carbonate ions in the reservoir under certain conditions to form bicarbonate, realizing long-term stable storage of CO2, therefore, carbonate rock depleted reservoirs have more advantages in CO2 underground storage.

[0004] However, there are few reports on the technology of using carbonate rock depleted reservoirs to store CO2, and there is an urgent need for a reliable method for storing CO2 using carbonate rock depleted reservoirs. SUMMARY

[0005] To solve the problems existing in the prior art and fill the current technical gap, the present application provides the following technical solutions:

[0006] The present application provides a method for storing carbon dioxide based on a carbonate rock depleted reservoir, which comprises the following steps:

[0007] S1, collecting carbonate rock reservoir distribution data in the depleted oil and gas field area, obtaining well depth data and bottom water data of each oil and gas well in the area, and selecting a target injection well.

[0008] Further, the well depth of the target injection well is not less than 700 meters.

[0009] S2, drilling at least one monitoring well around the target injection well, and connecting the bottom of the monitoring well and the bottom of the target injection well through a bottom water channel.

[0010] Further, the distance between the monitoring well and the injection well is in the range of 200-1000 meters

[0011] S3, continuously injecting the carbon dioxide saturated solution into the target injection well under a first injection pressure, the carbonates at the bottom of the well gradually dissolving to form a cavity, and the original liquid in the fracture and the bottom water of the oil and gas well being squeezed out through the monitoring well, outputting a bicarbonate aqueous solution and an oil and gas mixture; the first injection pressure is 5-8 MPa.

[0012] Further, the bicarbonate aqueous solution and the oil and gas mixture are subjected to pressure reduction treatment after being output through the monitoring well, so that the bicarbonate is precipitated from the solution and further decomposed into carbonates and carbon monoxide, and then subjected to gas, liquid and solid separation to obtain available oil and gas, and the separated carbon dioxide is continuously used in step S4 or step S5.

[0013] S4, injecting carbon dioxide gas into the target injection well under a second injection pressure, keeping the first pressure unchanged, and closing the output port of the monitoring well after the solution in the cavity at the bottom of the well is squeezed out; the second injection pressure is 4-7 MPa.

[0014] S5, injecting the liquefied carbon dioxide to be stored into the target injection well under an injection pressure of 10-15 MPa and continuously measuring the pressure value of the output port of the monitoring well, and stopping the injection when the pressure value exceeds 15 MPa.

[0015] S6, repeating step S5 when the wellhead pressure is lower than 10 MPa.

[0016] Further, a pumping well is drilled in the range of 100-200 meters from the monitoring well in the direction of the connection between the injection well and the monitoring well, the depth of the pumping well is 200-400 meters, and the pumping well is used to reduce the pressure value of the output port of the monitoring well to within 10 MPa when the pressure value of the output port of the monitoring well exceeds 15 MPa.

[0017] The application also provides a system for realizing carbon dioxide storage based on carbonate rock depleted oil and gas wells, which comprises a carbon dioxide absorption tower, a gas valve, a first booster pump, a liquid valve, a second booster pump, a liquefaction chamber, an injection chamber, a detection chamber, a pressure reduction precipitation chamber, and a separator.

[0018] Further, the carbon dioxide absorption tower is provided with a carbon dioxide gas inlet and an outlet, a water inlet and a saturated solution outlet, the carbon dioxide gas inlet is connected to the carbon dioxide exhaust gas from the factory and the separated carbon dioxide gas from the separator, the outlet is connected to the first booster pump and the liquefaction chamber respectively, the saturated solution outlet is connected to the second booster pump, and the front sections of the first booster pump and the second booster pump are respectively provided with a gas valve and a liquid valve.

[0019] Further, the injection chamber is arranged at a position above the wellhead of the injection well, and is provided with a pump for pressurizing the carbon dioxide delivered from the liquefaction chamber to a predetermined pressure and then sending the carbon dioxide into the injection well.

[0020] Further, the detection chamber is arranged at a position above the wellhead of the monitoring well, and is provided with a well pressure monitoring device for monitoring the wellhead pressure in real time, and is also used for discharging the aqueous solution of bicarbonate and the oil-gas mixture.

[0021] Further, the decompression precipitation chamber is connected with the detection chamber, and is used for decompressing the aqueous solution of bicarbonate and the oil-gas mixture, precipitating the bicarbonate from the aqueous solution of bicarbonate, and then delivering the remaining oil-gas and water mixture to the separator.

[0022] Further, the separator is used for further separating the oil-gas and water mixture, and is provided with a carbon dioxide discharge port and a water discharge port, which are connected with the carbon dioxide inlet of the carbon dioxide absorption tower and the water inlet respectively, so that the carbon dioxide can be recycled; and the separator is also used for separating the combustible oil-gas.

[0023] Further, the system further comprises a water pumping well arranged in the connecting direction of the injection well and the monitoring well and within a range of 100-200 meters from the monitoring well, and is used for controlling the downhole pressure value.

[0024] The present application has the following advantages and beneficial effects:

[0025] The present application uses the depleted carbonate rock oil-gas well and the monitoring well, forms a carbon dioxide storage cavity by continuously injecting the carbon dioxide saturated solution, and can collect the residual oil-gas mixture, so that certain economic value can be generated. In the storage process, the downhole pressure value is monitored in real time, and the water pumping well is arranged to adjust the downhole pressure, so that the carbon dioxide storage is safer. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The flow chart of the method for realizing carbon dioxide storage based on the depleted carbonate rock oil-gas well.

[0027] Figure 2 The schematic diagram of the relative positions of the injection well and the monitoring well.

[0028] Figure 3 The schematic diagram of the system composition for realizing carbon dioxide storage based on the depleted carbonate rock oil-gas well.

[0029] In the drawings, the reference signs are as follows:

[0030] 1-Injection chamber, 2-Detection chamber, 3-Carbon dioxide absorption tower, 4-Depressurization sedimentation chamber, 5-Separator, 6-Gas valve, 7-First booster pump, 8-Liquid valve, 9-Second booster pump, 10-Liquefaction chamber. Detailed Implementation

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] Example 1

[0033] like Figure 1 The diagram shows a flowchart of the method for achieving carbon dioxide sequestration based on depleted carbonate oil and gas wells according to the present invention. The method includes the following steps:

[0034] S1: Collect data on the distribution of carbonate reservoirs in depleted oil and gas fields, obtain well depth and bottom water data for each oil and gas well in the area, and select target injection wells.

[0035] It should be noted that the collected data on the distribution of carbonate reservoirs in depleted oil and gas fields includes information on reservoir thickness and density. CO2 exists as a gas at normal temperature and pressure, but it can also exist in three other states as temperature and pressure conditions change: solid, liquid, and supercritical. Carbon dioxide becomes supercritical when the temperature and pressure reach the critical point (31.06℃, 7.38MPa). This phase of carbon dioxide has unique physicochemical properties. Its volume decreases dramatically, its density is high (200~1000kg / m3) and close to that of a liquid, and its viscosity and diffusion coefficient are comparable to those of a gas. It has extremely strong flow properties. Therefore, before storage, it is necessary to investigate the physical information of the reservoir. Tight reservoirs can make storage safer.

[0036] The target injection well should theoretically be no less than 700 meters deep. Reservoirs with a depth of less than 700 meters do not have sufficient underground pressure to make carbon dioxide into a supercritical state, which is not conducive to the safe storage of carbon dioxide. As the injection depth increases, the density of CO2 does not change much.

[0037] S2, Drill at least one monitoring well around the target injection well, with the bottom of the monitoring well and the bottom of the target injection well connected by a bottom water channel.

[0038] It should be noted that the distance between the monitoring well and the injection well ranges from 200 to 1000 meters. Figure 2As shown in the figure, the relative position of the injection well and the monitoring well of the present application is shown, generally, in the later stage of oil and gas exploitation, the injection well often adopts the way of vertical well plus horizontal well, and water is injected into the reservoir to achieve the effect of fracturing and increasing production, during which period, the bottom water channel will be gradually formed, so when the monitoring well is set, the monitoring well should be set in the reservoir area connected with the bottom of the target injection well through the bottom water channel, and preferably in the reservoir area in the same direction as the horizontal well.

[0039] S3, under the first injection pressure, the carbon dioxide saturated solution is continuously injected into the target injection well, the carbonate rock at the bottom of the well is gradually dissolved to form a cavity, and at the same time, the original liquid in the downhole bottom water and the fracture is squeezed out through the monitoring well, and the bicarbonate aqueous solution and the oil and gas mixture are output; the first injection pressure is 5-8 MPa.

[0040] After the bicarbonate aqueous solution and the oil and gas mixture are output from the monitoring well, the bicarbonate is precipitated from the solution and further decomposed into carbonate and carbon monoxide through pressure reduction treatment, and then gas, liquid and solid separation is carried out, the available oil and gas is obtained, and the separated carbon dioxide is continuously used in step S4 or step S5.

[0041] It should be noted that the duration of step S3 is related to the required space design, one method of estimation is to estimate the volume of the expanded cavity in the underground reservoir by measuring the volume of the bicarbonate discharged from the sedimentation chamber, and when the cavity volume reaches the requirement, step S3 can be stopped.

[0042] S4, when the carbon dioxide gas is injected into the target injection well under the second injection pressure, the solution in the cavity at the bottom of the well is squeezed out, and the output port of the monitoring well is closed; the second injection pressure is 4-7 MPa.

[0043] S5, under the injection pressure of 10-15 MPa, the liquefied carbon dioxide to be stored is injected into the target injection well, and the pressure value of the output port of the monitoring well output well is continuously measured, and when the pressure value exceeds 15 MPa, the injection is stopped.

[0044] It should be noted that the injected carbon dioxide will react with water and other chemical components in the reservoir to generate new carbonate minerals and precipitate in the stratum. When carbon dioxide is injected into the aquifer, part of the carbon dioxide dissolves in water to form carbonic acid, and after hydrolysis, a large amount of H+ is generated, which causes some carbonate minerals, chlorite and feldspar minerals to dissolve, generating Na, Ca, Mg, Al, Fe ions.

[0045] When the ion concentration in the formation water is high, the continuously injected carbon dioxide will react with them to form new mineral precipitates, such as dawsonite, ankerite, etc., and the injected carbon dioxide will be finally fixed in the deep aquifer in the form of minerals, and the whole reaction process is a continuous state, and the reservoir pressure will gradually decrease as the reaction proceeds.

[0046] S6, when the wellhead pressure is lower than 10 MPa, repeating step S5.

[0047] It should be noted that, in order to control the pressure value of the whole reservoir, a pumping well can be drilled in the connecting direction of the injection well and the monitoring well, at a distance of 100-200 meters from the monitoring well, and the well depth of the pumping well is 200-400 meters. When the pressure value of the monitoring well outlet exceeds 15 MPa, the method of pumping water by the pumping well is used to reduce the pressure value of the monitoring well outlet to within 10 MPa.

[0048] Because the compression space of the rock pore is limited, in-situ extraction of fluid from the formation is an effective method to relieve pressure accumulation, and the setting of the pumping well not only can effectively regulate the formation pressure, but also can increase the migration distance of supercritical state carbon dioxide and the CO2 solubility in the formation water, and the smooth injection pressure can save costs.

[0049] Example 2

[0050] As shown in Figure 3 Fig. 1 is a schematic diagram of the system for realizing carbon dioxide storage based on the carbonate rock depleted oil and gas well according to the present application, which comprises a carbon dioxide absorption tower 3, a gas valve 6, a first booster pump 7, a liquid valve 8, a second booster pump 9, a liquefaction chamber 10, an injection chamber 1, a detection chamber 2, a decompression precipitation chamber 4, and a separator 5, and the system can be used to perform the method in Example 1.

[0051] The carbon dioxide absorption tower 3 is provided with a carbon dioxide gas inlet and outlet, a water inlet and a saturated solution outlet. The carbon dioxide gas inlet receives the carbon dioxide waste gas from the factory and the carbon dioxide gas separated by the separator, the gas outlet is connected with the first booster pump 7 and the liquefaction chamber 10 respectively, and the saturated solution outlet is connected with the second booster pump 9. The front sections of the first booster pump 7 and the second booster pump 9 are respectively provided with the gas valve 6 and the liquid valve 7.

[0052] The injection chamber 1 is arranged at a position above the wellhead of the injection well, and the injection chamber 1 is provided with a device for pressurizing the carbon dioxide delivered by the booster pump and the liquefaction chamber to a predetermined pressure and then sending it into the injection well.

[0053] The detection chamber 2 is arranged at a position above the wellhead of the monitoring well, and the detection chamber 2 is provided with a well pressure monitoring device for real-time monitoring of the wellhead pressure. The detection chamber 2 is also used to discharge the aqueous solution of bicarbonate and the oil and gas mixture.

[0054] The decompression precipitation chamber 4 is connected with the detection chamber 2, the decompression precipitation chamber 4 carries out decompression treatment to the aqueous solution of bicarbonate and the oil gas mixture, the bicarbonate is precipitated from the aqueous solution of bicarbonate, and then the remaining oil gas and water mixture is transmitted to the separator 5;

[0055] The separator 5 is used for further separating the oil gas and water mixture, the separator 5 is provided with a carbon dioxide discharge port and a water discharge port, the carbon dioxide discharge port and the water discharge port are respectively connected with a carbon dioxide inlet of a carbon dioxide absorption tower and a water inlet, so as to realize the recycling of carbon dioxide; the separator 5 is also used for separating the combustible oil gas.

[0056] The system is also provided with a pumping well, which is arranged in the connecting direction of the injection well and the monitoring well, and is arranged within the range of 100-200 meters from the monitoring well, and is used for controlling the downhole pressure value.

[0057] The above specific embodiments have further detailed the purposes, technical solutions and beneficial effects of the present application, and it should be understood that the above are only specific embodiments of the present application, and are not used to limit the protection scope of the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for sequestering carbon dioxide based on a carbonate rock depleted reservoir, characterized in that, The method comprises the following steps: S1, collecting data of carbonate reservoir distribution in the region of depleted oil and gas field, obtaining well depth data and bottom water data of each oil and gas well in the region, and selecting a target injection well; S2, drilling at least one monitoring well around the target injection well, and connecting the bottom of the monitoring well and the bottom of the target injection well through a bottom water channel; The well depth of the target injection well is not less than 700 meters, and the distance between the monitoring well and the injection well ranges from 200 to 1000 meters; S3, continuously injecting a saturated carbon dioxide solution into the target injection well at a first injection pressure, and gradually dissolving the carbonate rock at the bottom of the well to form a cavity, while extruding the original liquid in the bottom water and the fissures of the oil and gas well to discharge through the monitoring well, and outputting a bicarbonate aqueous solution and an oil and gas mixture; The bicarbonate aqueous solution and the oil and gas mixture are subjected to pressure reduction treatment after being output from the monitoring well, so that the bicarbonate is precipitated from the solution and further decomposed into carbonate and oxidized carbon, and then gas, liquid and solid are separated to obtain available oil and gas, and the separated carbon dioxide is continuously used in step S4 or step S5; S4, injecting carbon dioxide gas into the target injection well at a second injection pressure, keeping the first pressure unchanged, extruding the solution in the cavity at the bottom of the well, and then closing the output port of the monitoring well; The first injection pressure is 5-8 MPa, and the second injection pressure is 4-7 MPa; S5, injecting the liquefied carbon dioxide to be stored into the target injection well at an injection pressure of 10-15 MPa, and continuously measuring the pressure value of the output port of the monitoring well, and stopping the injection when the pressure value exceeds 15 MPa; S6, when the wellhead pressure is lower than 10 MPa, repeating step S5.

2. The method of claim 1, wherein, A pumping well is drilled in the range of 100-200 meters from the monitoring well in the direction of the connecting line of the injection well and the monitoring well, and the well depth of the pumping well is 200-400 meters, and when the pressure value of the output port of the monitoring well exceeds 15 MPa, the pumping well is used to reduce the pressure value of the output port of the monitoring well to within 10 MPa.

3. System for the sequestration of carbon dioxide based on carbonate depleted wells, characterized by, The system comprises a carbon dioxide absorption tower, a gas valve, a first booster pump, a liquid valve, a second booster pump, a liquefaction chamber, an injection chamber, a detection chamber, a pressure reduction and precipitation chamber, and a separator; The carbon dioxide absorption tower is provided with a carbon dioxide gas inlet and outlet, a water inlet and a saturated solution outlet, the carbon dioxide gas inlet receives carbon dioxide waste gas from a factory and carbon dioxide gas separated by the separator, the gas outlet is connected with the first booster pump and the liquefaction chamber respectively, the saturated solution outlet is connected with the second booster pump, and the front sections of the first booster pump and the second booster pump are respectively provided with a gas valve and a liquid valve; The injection chamber is arranged above the wellhead of the injection well, and the injection chamber is provided with a device for increasing the pressure of carbon dioxide delivered from the booster pump and the liquefaction chamber to a predetermined pressure and then sending the carbon dioxide into the injection well; The detection chamber is arranged above the wellhead of the monitoring well, and the detection chamber is provided with a well pressure monitoring device for monitoring the wellhead pressure in real time, and the detection chamber is also used for discharging the bicarbonate aqueous solution and the oil and gas mixture from the well. The reduced pressure precipitation chamber is connected with the detection chamber, and the reduced pressure precipitation chamber performs reduced pressure treatment on the aqueous solution of bicarbonate and the oil and gas mixture, separates the bicarbonate from the aqueous solution of bicarbonate, and then transmits the remaining mixture of oil and gas and water to the separator; The separator is used for further separating the mixture of oil and gas and water, and is provided with a carbon dioxide discharge port and a water discharge port, which are connected with the carbon dioxide inlet of the carbon dioxide absorption tower and the water inlet respectively, so that the carbon dioxide is recycled; the separator is also used for separating the combustible oil and gas.

4. The system for carbon dioxide sequestration in a carbonate rock depleted hydrocarbon well according to claim 3, wherein, The system further comprises a pumping well, which is arranged in the connecting direction of the injection well and the monitoring well and within the range of 100-200 meters from the monitoring well, and is used for controlling the downhole pressure value.

Images