Device and method for testing CO2 injection recovery rate of edge-bottom water gas reservoir

Abstract

The invention discloses a device and a method for testing the CO2 injection recovery rate of an edge-bottom water gas reservoir. The device comprises a core holder, a first container, a second container, a third container, a fourth container, a first pressure sensor and data processing equipment, wherein the first container and the second container are respectively connected with the input end of the core holder; the third container is connected with a plurality of CO2 injection points arranged on the core holder; the fourth container is connected with the output end of the core holder; the number and the positions of CO2 injection points arranged on the core holder are set according to experiment requirements; the first container and the second container are respectively used for containing different substances for simulating the edge-bottom water gas reservoir so as to simulate the edge-bottom water gas reservoir; the third container is used for containing CO2 gas so as to inject CO2 into the simulated edge-bottom water gas reservoir to develop the gas reservoir; the fourth container is used for collecting products of CO2 injection gas reservoir development of the simulated edge-bottom water gas reservoir and removing CO2 gas in the products; and the first pressure sensor is used for collecting the pressure of the gas in the fourth container and transmitting the pressure to the data processing equipment so as to calculate the recovery rate of CO2 injection development of the edge-bottom water gas reservoir.

Description

Technical Field

[0001] This article relates to the field of core testing technology for oil and gas field development, and in particular to a device and method for testing CO2 recovery rate in edge and bottom water gas reservoirs. Background Technology

[0002] For edge-bottom water gas reservoirs, gas reservoir development generally faces the problem of low recovery rate caused by water intrusion.

[0003] In some technologies, CO2-driven natural gas experimental studies use core holders to investigate the recovery rate of natural gas in tight gas reservoirs by CO2 injection at a constant pressure difference. The methane flow rate at the displacement outlet is measured by a flow meter and a chromatograph. However, since the chromatograph and flow meter are easily damaged by water, the experiment is not accurate enough.

[0004] Therefore, developing an apparatus and method for testing CO2 recovery rates in edge-bottom water-gas reservoirs to improve recovery rates is an urgent problem to be solved. Summary of the Invention

[0005] This application provides an apparatus and method for testing the CO2 recovery rate of edge-bottom water-gas reservoirs. Through this experimental apparatus, edge-bottom water-gas reservoirs can be simulated, and CO2 injection at different injection locations can be tested to accurately calculate the CO2 recovery rate.

[0006] In a first aspect, this application provides an apparatus for testing the CO2 recovery rate of a bottom-water gas reservoir. The apparatus includes: a core holder, a first container and a second container respectively connected to the input end of the core holder, a third container connected to multiple CO2 injection points set on the core holder, a fourth container connected to the output end of the core holder, a first pressure sensor, and a data processing device. The number and location of the CO2 injection points set on the core holder are set according to experimental requirements. The first and second containers are used to hold different simulated bottom-water gas reservoir materials to simulate the bottom-water gas reservoir. The third container is used to hold CO2 gas to inject CO2 into the simulated bottom-water gas reservoir for gas reservoir development. The fourth container is used to collect the products from the CO2 injection into the simulated bottom-water gas reservoir and remove the CO2 gas from the products. The first pressure sensor is used to collect the pressure of the gas in the fourth container and transmit it to the data processing device to calculate the CO2 recovery rate of the bottom-water gas reservoir.

[0007] Secondly, embodiments of the present invention also provide a method for testing the CO2 recovery rate of a simulated edge-bottom water-gas reservoir, using the apparatus for testing the CO2 recovery rate of a simulated edge-bottom water-gas reservoir as described in any of the above embodiments; the method includes:

[0008] Different simulated edge-bottom water-gas reservoir materials are injected into the core held by the core holder through the first and second containers to simulate the edge-bottom water-gas reservoir.

[0009] CO2 gas is injected into a selected injection point among multiple CO2 injection points set on the core holder through a third container to simulate CO2 injection development of a side-bottom water-gas reservoir.

[0010] During the simulated CO2 injection development of the edge-bottom water-gas reservoir, relevant pressure data were collected, and the recovery rate of CO2 injection in the edge-bottom water-gas reservoir was calculated using data processing equipment.

[0011] Compared with related technologies, this application provides an apparatus for testing the CO2 recovery rate of a bottom-water gas reservoir. The apparatus includes: a core holder, a first container and a second container respectively connected to the input end of the core holder, a third container connected to multiple CO2 injection points set on the core holder, a fourth container connected to the output end of the core holder, a first pressure sensor, and a data processing device. The number and location of the CO2 injection points set on the core holder are set according to experimental requirements. The first and second containers are used to hold different simulated bottom-water gas reservoir materials to simulate the bottom-water gas reservoir. The third container is used to hold CO2 gas to inject CO2 into the simulated bottom-water gas reservoir for gas reservoir development. The fourth container is used to collect the products from the CO2 injection into the simulated bottom-water gas reservoir and remove the CO2 gas from the products. The first pressure sensor is used to collect the pressure of the gas in the fourth container and transmit it to the data processing device to calculate the CO2 recovery rate of the bottom-water gas reservoir. This application utilizes the device and method to effectively simulate the process of CO2 injection to enhance the recovery rate of edge and bottom water gas reservoirs, determine the CO2 injection recovery rate of edge and bottom water gas reservoirs, provide direct basis for the scientific formulation of CO2 injection enhancement schemes for edge and bottom water gas reservoirs, and play an important supporting role in enhancing the recovery rate of edge and bottom water gas reservoirs.

[0012] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the solutions described in the description and the accompanying drawings. Attached Figure Description

[0013] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0014] Figure 1 This is a schematic diagram of an apparatus for testing CO2 recovery rate in a side-floor water-gas reservoir according to an embodiment of this application.

[0015] Figure 2 This is a flowchart illustrating the method for testing CO2 recovery rate in edge-bottom water-gas reservoirs according to an embodiment of this application.

[0016] Figure 3 This is a schematic diagram of an apparatus for testing CO2 recovery rate in edge-bottom water-gas reservoirs in some exemplary embodiments;

[0017] Figure 4 The cumulative water intrusion curves are simulated in some exemplary embodiments;

[0018] Figure 5 The cumulative gas extraction curve is simulated in some exemplary embodiments;

[0019] Figure 6 For example, the recovery rate curves of simulated tests in some exemplary embodiments;

[0020] Figure 7 The cumulative CO2 injection curves are simulated tests in some exemplary embodiments;

[0021] Figure 8 The cumulative water production curves are simulated in some exemplary embodiments;

[0022] Figure 9 CO2 burial curves are simulated for testing in some exemplary embodiments. Detailed Implementation

[0023] This application describes several embodiments, but these descriptions are exemplary and not restrictive, and it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with, or may replace, any feature or element of any other embodiment.

[0024] This application includes and contemplates combinations of features and elements known to those skilled in the art. The embodiments, features, and elements disclosed in this application may also be combined with any conventional features or elements to form a unique inventive scheme as defined by the claims. Any feature or element of any embodiment may also be combined with features or elements from other inventive schemes to form another unique inventive scheme as defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in this application may be implemented individually or in any suitable combination. Therefore, the embodiments are not limited except by the limitations imposed by the appended claims and their equivalents. Furthermore, various modifications and changes may be made within the scope of the appended claims.

[0025] Furthermore, in describing representative embodiments, the specification may have presented methods and / or processes as a specific sequence of steps. However, the method or process should not be limited to the specific order of steps described herein, to the extent that it does not depend on such a specific order. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation of the claims. Moreover, the claims concerning the method and / or process should not be limited to the steps performed in the written order, and those skilled in the art will readily understand that these orders can be varied and still remain within the spirit and scope of the embodiments of this application.

[0026] This invention provides an apparatus for testing CO2 recovery rates in edge-bottom water-gas reservoirs, such as... Figure 1 As shown, the device includes: a core holder 1, a first container 2 and a second container 3 respectively connected to the input end of the core holder, a third container 4 connected to a plurality of CO2 injection points provided on the core holder, a fourth container 5 connected to the output end of the core holder, a first pressure sensor 6, and a data processing device 7.

[0027] The number and location of CO2 injection points set on the core holder 1 are set according to experimental requirements;

[0028] The first container 2 and the second container 3 are respectively used to hold different simulated edge-bottom water-gas reservoir materials to simulate edge-bottom water-gas reservoirs;

[0029] The third container 4 is used to hold CO2 gas for CO2 injection into the simulated edge-bottom water gas reservoir to develop the gas reservoir.

[0030] The fourth container 5 is used to collect the products from CO2 injection into the simulated edge-bottom water gas reservoir for gas development, and to remove CO2 gas from the products.

[0031] The first pressure sensor 6 is used to collect the pressure of the gas in the fourth container and transmit it to the data processing device 7 to calculate the recovery rate of CO2 injection development in the edge-bottom water-gas reservoir.

[0032] In one exemplary embodiment, the core holder 1 is provided with multiple CO2 injection points, and the input end of each CO2 injection point is connected to a pressure sensor.

[0033] In one exemplary embodiment, the first container 2 is used to hold simulated formation water; the second container 3 is used to hold methane gas.

[0034] In one exemplary embodiment, a first pressure sensor is connected to the output of a fourth container;

[0035] The second pressure sensor is connected to the output end of the core holder;

[0036] The third pressure sensor is connected to the input end of the core holder;

[0037] The fourth pressure sensor is connected to the outlet end of the first container.

[0038] In one exemplary embodiment, the fourth container is further used to hold a NaOH solution to absorb CO2 from the product.

[0039] In one exemplary embodiment, the apparatus further includes an ISCO pump, a confining pressure pump, a six-way valve, a back pressure regulating valve, and a thermostatic chamber;

[0040] An ISCO pump is used to pressurize the third container;

[0041] A confining pressure pump is used to apply confining pressure to the core holder;

[0042] A six-way valve is connected to the output ends of the first container, the second container, and the third container, respectively;

[0043] A back pressure regulating valve is used to control the gas outflow rate at the outlet end of the core holder;

[0044] A constant temperature chamber is used to provide a constant temperature for experiments.

[0045] In one exemplary embodiment, the apparatus further includes:

[0046] The first valve is located between the first container and the six-way valve;

[0047] The second valve is located between the second container and the six-way valve;

[0048] The third valve is located between the third container and the six-way valve;

[0049] The fourth valve is located between the six-way valve and the core holder;

[0050] The fifth valve is located between the outlet end of the core holder and the back pressure regulating valve;

[0051] The sixth valve is located between the core holder and the confining pressure pump;

[0052] The seventh valve is located between the back pressure regulating valve and the fourth container.

[0053] The experimental equipment used in this example is mostly conventional, and the operation process is simple. The experiment greatly improves the accuracy, efficiency, and functionality of CO2 injection enhanced oil recovery model tests in edge and bottom water gas reservoirs, and provides basic data for the design of gas reservoir development methods.

[0054] This invention provides a method for testing CO2 recovery rate in edge-bottom water-gas reservoirs, such as... Figure 2 As shown, the method includes steps 200-220:

[0055] Step 200: Through the first and second containers, inject different simulated edge-bottom water-gas reservoir materials into the core held by the core holder to simulate the edge-bottom water-gas reservoir;

[0056] Step 210: Inject CO2 gas into a selected injection point among multiple CO2 injection points set on the core holder through the third container to simulate CO2 injection development of the edge-bottom water-gas reservoir;

[0057] Step 220: During the simulated CO2 injection development of the edge-bottom water-gas reservoir, collect relevant pressure data and use data processing equipment to calculate the recovery rate of CO2 injection in the edge-bottom water-gas reservoir.

[0058] In one exemplary embodiment, the step of sequentially injecting different simulated edge-bottom water-gas reservoir materials into the core held by the core holder through the first and second containers to simulate the edge-bottom water-gas reservoir includes:

[0059] A preset confining pressure value is applied to the core holder by a confining pressure pump;

[0060] Methane gas is injected into the core held by the core holder using the first container until the saturation pressure of the current simulated edge-bottom water gas reservoir reaches the original formation pressure of the edge-bottom water gas reservoir.

[0061] Simulated formation water is injected into the simulated bottom water gas reservoir using the second container until water is seen at the outlet end of the core holder.

[0062] In one exemplary embodiment, the CO2 recovery rate of the edge-bottom water-gas reservoir is:

[0063]

[0064] In the above formula, Gp is ​​the volume of CH4 methane gas in the simulated CO2 injection development stage of the edge-bottom water gas reservoir, η is the recovery rate of CO2 injection in the simulated edge-bottom water gas reservoir, and G is the saturated natural gas volume in the simulated edge-bottom water gas reservoir.

[0065] In one exemplary embodiment, the volume of CH4 methane gas during the CO2 injection development stage of the simulated edge-bottom water-gas reservoir is:

[0066] G p =10(V4-W) p P7

[0067] In the above formula, Gp is ​​the volume of CH4 methane gas during the simulated CO2 injection development stage of the edge-bottom water-gas reservoir, V4 is the volume of the fourth container after removing the NaoH solution, Wp is the cumulative water production during the simulated CO2 injection development stage of the edge-bottom water-gas reservoir, and P7 is the pressure value monitored by the first sensor.

[0068] In one exemplary embodiment, the cumulative water production Wp during the CO2 injection development phase of the simulated edge-bottom water-gas reservoir is:

[0069]

[0070] In the formula, Wp represents the cumulative water production during the simulated CO2 injection development phase of the edge-bottom water-gas reservoir. To simulate the pressure of the first container at the start of the CO2 injection development phase of a bottom-water gas reservoir, P1 is the simulated pressure of the first container during the CO2 injection development phase of the bottom-water gas reservoir, and V w Let C be the volume of the first container. w The coefficient of formation water compressibility;

[0071] The saturated natural gas content of the simulated edge-bottom water-gas reservoir is:

[0072]

[0073] In the formula: G is the saturated natural gas quantity of the simulated edge-bottom water-gas reservoir, V2 is the volume of the second container, and P 21 To simulate the pressure in the second container of a bottom-water gas reservoir before pressurization saturation, P 22 To simulate the pressure in the second container when the pressure saturation of the edge-bottom water gas reservoir is completed, Z 21 To simulate the compressibility factor of natural gas in the second container before pressurization saturation in a side-bottom water gas reservoir, Z 22 To simulate the compressibility factor of natural gas in the second container when the pressure saturation of the edge-bottom water gas reservoir is completed.

[0074] Example 1

[0075] This example demonstrates the experimental process of testing CO2 injection to enhance oil recovery in a side-floor water-gas reservoir, as shown below:

[0076] Step 1: Assemble an experimental device for CO2 injection to enhance oil recovery in edge-bottom water-gas reservoirs.

[0077] The experimental setup includes: an ISCO pump, a core holder, four containers, seven pressure sensors, a confining pressure pump, seven valves, a six-way valve, a back pressure regulating valve, and a data processing device.

[0078] In this embodiment, the first container and the second container are respectively connected to the input end of the core holder; the third container is connected to multiple CO2 injection points set on the core holder; and the fourth container is connected to the output end of the multi-point core holder.

[0079] In this embodiment, a multi-test core holder is used to hold the experimental rock sample. The multi-test core holder has multiple CO2 injection points, the number and location of which are set according to experimental requirements.

[0080] In this embodiment, the first container 1 is used to hold high-pressure simulated formation water to simulate a marginal water gas reservoir; the second container 2 is used to hold high-pressure CH4; the third container 3 is used to hold high-pressure CO2; and the fourth container 4 collects the products from CO2 injection into the simulated marginal water gas reservoir to develop the gas reservoir. The fourth container 4 contains NaOH solution to absorb the CO2 in the products from CO2 injection into the gas reservoir, thereby separating the produced gas at the outlet.

[0081] In this embodiment, pressure sensor 1 is disposed at the output end of the first container to monitor water pressure;

[0082] Pressure sensor 2 is installed at the inlet end of the multi-point core holder to monitor the pressure at the inlet end of the multi-point core holder;

[0083] Pressure sensor 3, pressure sensor 4 and pressure sensor 5 are respectively installed at the first CO2 injection point, the second CO2 injection point and the third CO2 injection point, and are used to monitor the pressure at the first CO2 injection point, the second CO2 injection point and the third CO2 injection point respectively;

[0084] Pressure sensor 6 is installed at the outlet end of the core holder to monitor the pressure at the outlet end of the core holder;

[0085] Pressure sensor 7 is located at the output end of the fourth container and is used to monitor the pressure of the fourth container.

[0086] ISCO Pump I is used to pressurize a third container;

[0087] The confining pressure pump is used to apply confining pressure to the multi-point core holder;

[0088] The six-way valve is connected to the output ends of the first container, the second container and the third container respectively, and is used to coordinate the connection between the first container 1, the second container 2 and the third container 3 and the core holder.

[0089] The back pressure regulating valve is used to control the gas outflow rate at the outlet end of the multi-point core holder;

[0090] A constant temperature chamber is used to provide a constant temperature for experiments.

[0091] In this embodiment, the experimental apparatus also includes 7 valves:

[0092] Valve 1 is located between the first intermediate container and the six-way valve, and is used to control the connection between the first intermediate container and the six-way valve;

[0093] Valve 2 is located between the second intermediate container and the six-way valve, and is used to control the connection between the second intermediate container and the six-way valve;

[0094] Valve 3 is located between the third intermediate container and the six-way valve, and is used to control the connection between the third intermediate container and the six-way valve.

[0095] Valve 4 is located between the six-way valve and the multi-measuring-point core holder, and is used to control the connection of the third intermediate container to the injection point through the six-way valve;

[0096] Valve 5 is located between the output end of the multi-point core holder and the back pressure regulating valve, and is used to control the connection between the outlet end of the multi-point core holder and the fourth container.

[0097] Valve 6 is located between the multi-point core holder and the confining pressure pump, and is used to control the connection between the multi-point core holder and the confining pressure pump.

[0098] Valve 7 is located between the back pressure regulating valve and the fourth intermediate container, and is used to control the connection between the output end of the multi-point core holder and the fourth intermediate container.

[0099] The second step is to initialize the experimental setup for testing CO2 recovery rate in edge-bottom water-gas reservoirs.

[0100] Step 201: Connect the experimental setup for testing CO2 recovery rate in the edge-bottom water-gas reservoir and close all valves;

[0101] Step 202: Activate each pressure sensor and begin recording the pressure data collected by each pressure sensor.

[0102] In this step, the known porosity Permeability K, Length L, Diameter D, and Water Saturation S wi The core samples for the experiment were placed in a multi-point core holder, according to... Figure 3 Connect the experimental setup, close all valves, start the data processing equipment, and record the pressure of each pressure sensor. The core sample used in the experiment is used to simulate the edge-bottom water-gas reservoir.

[0103] The third step is to simulate the original edge-bottom water-gas reservoir, specifically the reservoir depletion and development stage. The specific operational steps are as follows:

[0104] Step 301: Use a confining pressure pump to increase the confining pressure of the core holder to the preset confining pressure value;

[0105] The specific steps for this process are as follows:

[0106] Open valve 6 and use the confining pressure pump to apply confining pressure to the core holder to the required confining pressure for the experiment, then close valve 4. In this step, the confining pressure required for the experiment is determined based on the burial depth of the gas reservoir to which the experimental core sample belongs.

[0107] Step 302: Inject the simulated pressure-saturated natural gas volume of the edge-bottom water gas reservoir into the core holder using the second container 2;

[0108] The specific steps for this process are as follows:

[0109] Open valve 2 and use the second container 2 to pressurize and saturate the simulated edge-bottom water gas reservoir in the multi-point core holder until the saturation pressure reaches the initial flow pressure required for the simulated edge-bottom water gas reservoir. Then close valve 2. The saturation gas volume is determined based on the volume of the second container 2 and the pressure before and after saturation pressurization, as shown in the following expression:

[0110]

[0111] Where: G is the simulated pressurized saturated natural gas volume in the edge-bottom water gas reservoir, mL; V2 is the volume of the second container 2, mL; P 21 To simulate the pressure of the second container 2 before pressurization saturation in a bottom-water gas reservoir, MPa; P 22 To simulate the pressure of the second container 2 when the pressure saturation of the edge-bottom water gas reservoir is completed, in MPa; Z 21 To simulate the compressibility factor of natural gas in the second container 2 before pressurization saturation in a bottom-water gas reservoir, f; ω 22 To simulate the compressibility factor f of natural gas in the second container 2 when the pressure saturation of the edge-bottom water gas reservoir is completed.

[0112] Step 303: Use the high-pressure simulated formation water in the first container 1 to increase the pressure on the pressure core holder until the pressure value of the core holder reaches the initial flowing pressure of the simulated edge-bottom water gas reservoir.

[0113] The specific steps for this process are as follows:

[0114] Open valve 1 to establish the connection between the first container 1 and the core holder, inject formation water into the sample core in the core holder to simulate the edge-bottom water gas reservoir, and pressurize it to be consistent with the initial flow pressure of the simulated edge-bottom water gas reservoir.

[0115] Step 304: Simulate the depletion and development stage of edge-bottom water gas reservoirs;

[0116] The specific steps for this process are as follows:

[0117] Open valve 5 and use the back pressure regulating valve to control the gas outflow rate at the outlet of the core holder until water flows out of the outlet of the core holder and then close valve 5.

[0118] In the simulated depletion development phase of the edge-bottom water gas reservoir, the cumulative water intrusion, cumulative gas production, and recovery rate of the simulated edge-bottom water gas reservoir were calculated based on monitoring data from various pressure sensors. Figure 4 , Figure 5 , Figure 6 The calculation expression is as follows:

[0119] W e =V w C w (P i -P1) (2)

[0120] G p =10V4P7 (3)

[0121]

[0122] In the formula: V w The volume of the first container 1 is in mL; C w P is the formation water compressibility coefficient, 1 / MPa; i P1 is the initial formation water pressure, MPa; P2 is the formation water pressure in container 1, MPa; V4 is the remaining volume of container 4 after deducting the NaOH solution, mL; P7 is the fluid pressure in container 4, MPa; Gp is ​​the cumulative CH4 gas production in the simulated edge-bottom water gas reservoir, mL; η is the CH4 recovery rate in the simulated edge-bottom water gas reservoir, %.

[0123] Step 4: Simulate the CO2 injection development stage of the edge-bottom water-gas reservoir.

[0124] Inject the accumulated amount of CO2 gas into the core holder until the pressure of the pressure sensor corresponding to the fourth container 4 remains constant. The specific operation of this step can be as follows:

[0125] Step 401: Turn on the ISCO pump and open valves 2 and 4. Carbon dioxide gas in the third container 3 is injected into the experimental core sample through CO2 injection point 2.

[0126] The cumulative CO2 injection rate of the simulated bottom water gas reservoir is determined based on the ISCO pump injection rate, the volume of the third container 3, and the pressure. The calculation expression is as follows:

[0127]

[0128] In the formula: G CO2 V3 represents the cumulative CO2 injection volume into the edge-bottom water-gas reservoir (mL); V3 is the volume of the third container (mL); Vz is the water injection volume into the intermediate container (mL) by the ISCO pump; P 31 To simulate the pressure in intermediate container 3 before CO2 injection into the edge-bottom water-gas reservoir, (MPa); Z 31To simulate the CO2 compressibility factor (f; P) in intermediate container 3 before CO2 injection into the edge-bottom water-gas reservoir. 32 To simulate the CO2 injection process in the intermediate container 3 during the bottom water-gas reservoir, the pressure was measured in MPa; Z. 32 f is the CO2 compressibility factor in intermediate container 3 during the CO2 injection process.

[0129] Step 402: When the pressure sensor 7 monitors that the pressure remains constant, the process of injecting CO2 into the experimental core sample through injection point 2 is completed. Stop the experiment, close all valves, and complete the test experiment on the effect of CO2 injection to enhance the recovery rate of simulated edge-bottom water-gas reservoir.

[0130] Step 5: Calculate the recovery rate

[0131] Step 501: Export the monitoring data of each pressure sensor from the data acquisition system. Calculate the cumulative water intrusion and cumulative water production during the CO2 injection development stage of the simulated edge-bottom water-gas reservoir based on the monitoring pressure of pressure sensor 1, the volume of the first container 1, equations (1) and (6), and plot the cumulative water intrusion curve during the CO2 injection development stage of the simulated edge-bottom water-gas reservoir. Figure 4 ) and cumulative water production curve ( Figure 8 The formula for calculating cumulative water production is as follows:

[0132]

[0133] Where: Wp is the cumulative water production during the simulated CO2 injection development stage of the edge-bottom water-gas reservoir, in mL; The pressure of intermediate container 1 was measured in MPa at the end of the depletion development phase of a bottom-water gas reservoir.

[0134] Step 502: Calculate the cumulative gas production and recovery rate (i.e., recovery rate) of the simulated bottom water gas reservoir during the CO2 injection development stage based on the remaining volume of pressure sensor 7, the fourth container 4 after deducting the NaOH solution, and the cumulative water production of the simulated bottom water gas reservoir. Figure 5 , Figure 6 The formula for calculating the cumulative gas production during the CO2 injection development stage of the simulated bottom water gas reservoir is shown in Equation (7), and the recovery rate is still calculated using Equation (4).

[0135] G p =10(V4-W) p P7 (7)

[0136] Step 503: Based on the pressure data monitored by pressure sensors 2, 3, 4, 5, and 6, the cumulative gas production, cumulative water intrusion, and cumulative water production during the simulated CO2 injection development stage of the edge-bottom water-gas reservoir, and the basic data from the experimental core samples, calculate the CO2 burial curve during the simulated CO2 injection development stage of the edge-bottom water-gas reservoir. Figure 9 The CO2 storage curve from the simulation test is calculated using the following expression:

[0137] Simulated mean pressure of edge-bottom water-gas reservoir:

[0138]

[0139] To simulate the average pressure of the edge-bottom water-gas reservoir, P2 is pressure sensor 2 monitoring pressure data, P3 is pressure sensor 3 monitoring pressure data, P4 is pressure sensor 4 monitoring pressure data, P5 is pressure sensor 5 monitoring pressure data, and P6 is pressure sensor 6 monitoring pressure data.

[0140] Simulated CO2 burial volume during the CO2 injection development phase of a water-gas reservoir at the edge and bottom:

[0141]

[0142] Simulated CO2 storage during the CO2 injection development phase of a water-gas reservoir at the edge and bottom:

[0143]

[0144] In the formula: To simulate the average pressure of the edge-bottom water-gas reservoir, P2 is the pressure monitored by pressure sensor 2, MPa; P3 is the pressure monitored by pressure sensor 3, MPa; P4 is the pressure monitored by pressure sensor 4, MPa; P5 is the pressure monitored by pressure sensor 5, MPa; P6 is the pressure monitored by pressure sensor 6, MPa; Z iCH4 To simulate the initial state CH4 compressibility factor of a side-bottom water-gas reservoir, f; To simulate the CH4 compressibility factor f;S under the mean pressure of a bottom-water gas reservoir. wi To simulate the initial water saturation of a bottom-water gas reservoir, f; V CO2 β represents the simulated CO2 volume in a bottom-water gas reservoir, expressed in mL; β represents the simulated CO2 PV number in a bottom-water gas reservoir, expressed in f.

[0145] Step 504: Based on the simulated recovery rate curve of the edge-bottom water-gas reservoir (i.e., the recovery degree). Figure 6 ) and CO2 burial curve ( Figure 9 The study determined the overall effect of CO2 injection on the edge and bottom water-gas reservoirs to enhance recovery and storage.

[0146] This testing method has the following technical advantages in enhancing oil recovery through CO2 injection in edge and bottom water gas reservoirs:

[0147] ① It can simulate the depletion development and CO2 injection development process of edge and bottom water gas reservoirs;

[0148] ② By changing the pumping speed of the ISCO pump and utilizing multiple pressure measurement points, physical simulation of CO2 injection development of gas reservoirs with different injection-production ratios, timings, and injection locations can be achieved. Moreover, the operation is relatively simple and easy to implement.

[0149] ③ Based on the results of physical simulation experiments and formula calculations, dynamic curves such as cumulative water intrusion, cumulative water production, cumulative gas production, recovery rate, and CO2 storage during the development of edge and bottom water gas reservoirs can be obtained. These curves can be used to analyze the entire life cycle development process of edge and bottom water gas reservoirs and to more comprehensively evaluate the enhanced oil recovery rate and storage effect of CO2 injection in edge and bottom water gas reservoirs.

[0150] Example 2

[0151] This example demonstrates the calculation process for CO2 recovery in a test of a side-floor water-gas reservoir; the specific experimental procedure is as follows:

[0152] Step 1: Given the porosity Permeability K, Length L, Diameter D, and Water Saturation S wi The experimental rock sample was placed into the core holder, according to... Figure 3 Connect the experimental setup, close all valves, start the data processing equipment, and record the current pressure values ​​of each pressure sensor. The purpose of this is to record the pressure data in advance to prevent the experiment from starting before the pressure data is recorded.

[0153] In this example, the core porosity of the experimental rock sample The core has a permeability of 14.5%, a permeability K of 4.3 mD, a core length L of 30.032 cm, a diameter D of 3.667 cm, and a water saturation S. wi It is 28.88%.

[0154] Step 2: Open valve 6 and use the confining pressure pump to increase the confining pressure of the core holder to the predetermined experimental confining pressure value, then close valve 4.

[0155] In this example, the predetermined experimental confining pressure is 30 MPa.

[0156] Step 3: Simulate the edge-bottom water-gas reservoir;

[0157] Open valve 2 and use the second container 2 (which is used to hold high-pressure CH4) to pressurize and saturate the simulated edge-bottom water gas reservoir in the core holder until the saturation pressure reaches the initial flow pressure required for the simulated edge-bottom water gas reservoir. Then close valve 2.

[0158] In this example, the initial flow pressure is determined based on the simulated reservoir pressure, for example, 16 MPa, and the example saturated gas volume is calculated to be 6534.5 mL according to Equation (1).

[0159] Step 4: Simulate the depletion and development stage of edge-bottom water gas reservoirs;

[0160] Open valve 5 and use the back pressure regulating valve to control the gas outflow rate at the outlet of the multi-point core holder to simulate the depletion development of the edge and bottom water gas reservoir until the back pressure regulating valve sees water and closes valve 5.

[0161] Acquire monitoring data from each pressure sensor during the time period from when gas begins to flow out of the core holder outlet to when water begins to flow out of the core holder outlet; calculate the cumulative water intrusion, cumulative gas production, and production rate of the simulated edge-bottom water gas reservoir based on the monitoring data from each pressure sensor and equations (2) to (4); specifically as follows Figure 4 , Figure 5 and Figure 6 As shown.

[0162] Step 5: Turn on the ISCO pump, open valves 2 and 4, and inject CO2 from intermediate container 3 into the experimental rock sample through pressure measurement point 2 to simulate the CO2 injection development stage of the edge-bottom water-gas reservoir.

[0163] The cumulative CO2 injection rate of the simulated bottom water gas reservoir is determined based on the ISCO pump injection rate, the volume of the third container 3, the pressure, and equation (5). The cumulative CO2 injection rate of the simulated bottom water gas reservoir (e.g., Figure 7 ).

[0164] Step 6: When the pressure sensor 7 monitors that the pressure remains constant, the process of injecting CO2 into the experimental rock sample through pressure measuring point 2 is completed. Stop the experiment, close all valves, and complete the CO2 enhanced oil recovery effect test of the edge and bottom water gas reservoirs. This stage is called the simulated edge and bottom water gas reservoir CO2 injection development stage.

[0165] Step 7: Export the monitoring data of each pressure sensor from the data acquisition system, calculate the cumulative water intrusion and cumulative water production during the CO2 injection development stage of the simulated edge-bottom water gas reservoir based on the monitoring pressure of pressure sensor 1, the volume of the first container 1, equations (1) and (6), and plot the cumulative water intrusion curve during the CO2 injection development stage of the simulated edge-bottom water gas reservoir. Figure 4 ) and cumulative water production curve ( Figure 8 ).

[0166] Step 8: Based on the pressure data monitored by pressure sensors 2, 3, 4, 5, and 6, the cumulative gas production, cumulative water intrusion, and cumulative water production during the simulated CO2 injection development stage of the edge-bottom water-gas reservoir, and the basic core data from Step 1, calculate the CO2 burial curve during the simulated CO2 injection development stage of the edge-bottom water-gas reservoir. Figure 9 )

[0167] Step 9: Based on the simulated edge-bottom water-gas reservoir recovery curve (e.g.) Figure 6 The recovery curve from the simulation test) and the CO2 storage curve (such as the recovery curve) and the CO2 storage curve) Figure 9The simulated CO2 storage curves show that recovery rate and recovery extent have the same meaning. The study determined the overall effect of CO2 injection on improving recovery rate and storage in edge and bottom water-gas reservoirs. For example, CO2 injection in an edge and bottom water-gas reservoir improved the recovery rate by 28.9 percentage points and stored 0.25 PVCO2, demonstrating a good overall effect on improving recovery rate and storing CO2.

[0168] This example demonstrates a method and apparatus for testing the enhanced oil recovery (EOR) effect of CO2 injection in edge-water gas reservoirs. Using this method and apparatus, researchers can simulate and test the EOR effect of CO2 injection in edge-water gas reservoirs under different water body energies, reservoir properties, injection timings, and injection locations. This innovative achievement is highly challenging. The test conditions are consistent with the gas reservoir conditions, making the test results more representative. It is significantly superior to existing techniques that use idealized numerical simulations to evaluate the EOR effect of CO2 injection in edge-water gas reservoirs. The evaluation results are more consistent with actual production, which is of great significance for the development of edge-water gas reservoirs.

[0169] It will be understood by those skilled in the art that all or some of the steps, systems, or apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software may be distributed on a computer-readable medium, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

Claims

1. An apparatus for testing CO2 recovery rate in edge-bottom water-gas reservoirs, characterized in that, The device includes: a core holder, a first container and a second container respectively connected to the input end of the core holder, a third container connected to a plurality of CO2 injection points provided on the core holder, a fourth container connected to the output end of the core holder, a first pressure sensor, and a data processing device. The number and location of CO2 injection points set on the core holder are set according to experimental requirements; The first container and the second container are used to hold different simulated edge-bottom water-gas reservoir materials to simulate edge-bottom water-gas reservoirs; The third container is used to hold CO2 gas for CO2 injection into the simulated edge-bottom water gas reservoir to develop the gas reservoir. The fourth container is used to collect the products from CO2 injection into the simulated edge-bottom water gas reservoir for gas development, and to remove CO2 gas from the products. The first pressure sensor is used to collect the pressure of the gas in the fourth container and transmit it to the data processing device to calculate the recovery rate of CO2 injection development in the edge-bottom water-gas reservoir.

2. The apparatus for testing CO2 recovery rate of edge-bottom water-gas reservoirs according to claim 1, characterized in that, A pressure sensor is connected to the input of each CO2 injection point.

3. The apparatus for testing CO2 recovery rate of edge-bottom water-gas reservoirs according to claim 1, characterized in that, The first container is used to hold simulated formation water; The second container is used to hold methane gas.

4. The apparatus for testing CO2 recovery rate of edge-bottom water-gas reservoirs according to claim 1, characterized in that, Also includes: The first pressure sensor is connected to the output of the fourth container; The second pressure sensor is connected to the output end of the core holder; The third pressure sensor is connected to the input end of the core holder; The fourth pressure sensor is connected to the outlet end of the first container.

5. The apparatus for testing CO2 recovery rate of edge-bottom water-gas reservoirs according to claim 1, characterized in that, The fourth container is also used to hold NaOH solution, so that the NaOH solution can absorb CO2 from the product.

6. The apparatus for testing CO2 recovery rate of edge-bottom water-gas reservoirs according to claim 1, characterized in that, The device further includes: An ISCO pump is used to pressurize the third container; A confining pressure pump is used to apply confining pressure to the core holder; A six-way valve is connected to the output ends of the first container, the second container, and the third container, respectively; A back pressure regulating valve is used to control the gas outflow rate at the output end of the core holder; A constant temperature chamber is used to provide a constant temperature for experiments.

7. The apparatus for testing CO2 recovery rate of edge-bottom water-gas reservoirs according to claim 6, characterized in that, The device further includes: A first valve is disposed between the first container and the six-way valve; A second valve is disposed between the second container and the six-way valve; A third valve is disposed between the third container and the six-way valve; The fourth valve is located between the six-way valve and the core holder; The fifth valve is located between the output end of the core holder and the back pressure regulating valve; The sixth valve is located between the core holder and the confining pressure pump; The seventh valve is located between the back pressure regulating valve and the fourth container.

8. A method for testing CO2 recovery rate in edge-bottom water-gas reservoirs, characterized in that, The method comprises: applying the apparatus of any one of claims 1-7; Different simulated edge-bottom water-gas reservoir materials are injected into the core held by the core holder through the first and second containers to simulate the edge-bottom water-gas reservoir. CO2 gas is injected into a selected injection point among multiple CO2 injection points set on the core holder through a third container to simulate the CO2 injection development of a side-bottom water-gas reservoir. During the simulated CO2 injection development of the edge-bottom water-gas reservoir, relevant pressure data were collected, and the recovery rate of CO2 injection in the edge-bottom water-gas reservoir was calculated using data processing equipment.

9. The method for testing CO2 recovery rate of edge-bottom water-gas reservoirs according to claim 8, characterized in that, The process involves sequentially injecting different simulated edge-bottom water-gas reservoir materials into the core held by the core holder through the first and second containers, simulating an edge-bottom water-gas reservoir, including: A preset confining pressure value is applied to the core holder by a confining pressure pump; Methane gas is injected into the core held by the core holder using the second container until the saturation pressure of the current simulated edge-bottom water gas reservoir reaches the original formation pressure of the edge-bottom water gas reservoir. Simulated formation water is injected into the simulated bottom water gas reservoir using the first container until water is seen at the outlet end of the core holder.

10. The method for testing CO2 recovery rate in water-driven gas reservoirs according to claim 8, characterized in that, The CO2 recovery rate of the aforementioned bottom water-gas reservoir is: In the above formula, Gp is ​​the volume of CH4 methane gas in the simulated CO2 injection development stage of the edge-bottom water gas reservoir, η is the recovery rate of CO2 injection in the simulated edge-bottom water gas reservoir, and G is the saturated natural gas volume in the simulated edge-bottom water gas reservoir.

11. The method for testing CO2 recovery rate in a water-driven gas reservoir according to claim 10, characterized in that, The volume of CH4 methane gas during the simulated CO2 injection development stage of the edge-bottom water-gas reservoir is: G p =10(V4-W p )P7 In the above formula, Gp is ​​the volume of CH4 methane gas during the simulated CO2 injection development stage of the edge-bottom water-gas reservoir, V4 is the volume of the fourth container after removing the NaoH solution, Wp is the cumulative water production during the simulated CO2 injection development stage of the edge-bottom water-gas reservoir, and P7 is the pressure value monitored by the first sensor.

12. The method for testing CO2 recovery rate in water-driven gas reservoirs according to claim 11, characterized in that, The cumulative water production Wp during the CO2 injection development phase of the simulated edge-bottom water-gas reservoir is: In the formula, Wp represents the cumulative water production during the simulated CO2 injection development stage of the edge-bottom water-gas reservoir, and V... w Let C be the volume of the first container. w The compressibility coefficient of formation water is . To simulate the pressure of the first container at the start of the CO2 injection development phase of the edge-bottom water-gas reservoir, P1 is the simulated pressure of the first container during the CO2 injection development phase of the edge-bottom water-gas reservoir. The saturated natural gas content of the simulated edge-bottom water-gas reservoir is: In the formula: G is the saturated natural gas quantity of the simulated edge-bottom water-gas reservoir, V2 is the volume of the second container, and P 21 To simulate the pressure in the second container of a bottom-water gas reservoir before pressurization saturation, P 22 To simulate the pressure in the second container when the pressure saturation of the edge-bottom water gas reservoir is completed, Z 21 To simulate the compressibility factor of natural gas in the second container before pressurization saturation in a side-bottom water gas reservoir, Z 22 To simulate the compressibility factor of natural gas in the second container when the pressure saturation of the edge-bottom water gas reservoir is completed.

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