Method and device for improving recovery efficiency based on CO2 microbubbles and forward pressure driving

Abstract

The embodiment of the invention provides a method and device for improving the recovery efficiency based on CO2 microbubbles and forward pressure driving. The method comprises the steps that on-site injection parameters are obtained, the on-site injection parameters comprise the pressure flooding agent injection amount, the pressure flooding agent injection speed, the soaking time and the CO2 microbubble gas-liquid ratio, and the on-site injection parameters are injection parameters corresponding to the target recovery ratio in multiple recovery ratios; the multiple recovery rates are obtained by conducting petroleum simulation recovery on the target well based on different injection parameters; the target recovery rate is the highest recovery rate in the maximum change rate; according to the pressure flooding agent injection amount and the pressure flooding agent injection speed, a pressure flooding agent is injected into the target well; according to the soaking time, soaking treatment is conducted on the target well injected with the pressure flooding agent; cO2 microbubbles are injected into the target well subjected to soaking treatment, and the CO2 microbubbles are obtained according to the gas-liquid ratio of the CO2 microbubbles; and oil recovery is conducted on the target well injected with the CO2 microbubbles. According to the method, the recovery efficiency can be improved.

Description

Technical Field

[0001] The present application relates to the field of exploitation of low-permeability and ultra-low-permeability oil reservoirs, and in particular to a method and device for improving oil recovery based on CO2 microbubbles and forward pressure drive. Background Art

[0002] In recent years, the development of conventional oil and gas reservoirs has entered the final stage, and the development targets of oil and gas reservoirs have been continuously shifted to unconventional reservoir types such as low permeability and ultra-low permeability. The reserves of low permeability and ultra-low permeability reservoirs account for a relatively high proportion of the proven oil and gas reserves, so the efficient development of such oil and gas resources is of great strategic significance to ensure the sustainable development of oil and gas. The geological environment of low permeability and ultra-low permeability reservoirs is complex, with the characteristics of poor reservoir properties, large seepage resistance, poor natural flow capacity of bottom fluids, and low single well production capacity.

[0003] In order to achieve efficient development of low-permeability and ultra-low-permeability reservoirs, the oil field site proposed forward pressure drive technology. Conventional forward pressure drive technology injects pressure drive agent into the reservoir at a pressure slightly higher than the reservoir fracture pressure, forming micro-cracks in the reservoir while increasing the degree of crude oil utilization in the reservoir. Finally, conventional water injection is resumed at the injection end to collect and drive the remaining oil to the production end.

[0004] However, in the conventional water injection production process at the later stage of pressure drive, crude oil is mobilized only by water injection, which has a poor recovery effect on low-permeability and ultra-low-permeability oil and gas reservoirs, resulting in a low recovery rate. Summary of the invention

[0005] The embodiments of the present application provide a method and device for improving oil recovery based on CO2 microbubbles and forward pressure drive, which are used to improve the oil recovery effect.

[0006] In a first aspect, an embodiment of the present application provides a method for improving oil recovery based on CO2 microbubbles and forward pressure drive, comprising:

[0007] Obtaining field injection parameters, wherein the field injection parameters include the injection amount of the pressure-displacing agent, the injection speed of the pressure-displacing agent, the well soaking time, and the CO2 microbubble gas-liquid ratio. The field injection parameters are injection parameters corresponding to the target recovery rate among multiple recovery rates. The multiple recovery rates are obtained by simulating oil recovery of the target well based on different injection parameters; the target recovery rate is the highest recovery rate among the maximum change rates;

[0008] Inject the pressure-displacing agent into the target well according to the pressure-displacing agent injection amount and pressure-displacing agent injection speed;

[0009] According to the well shut-in time, the target well injected with the pressure-displacing agent is shut-in treated;

[0010] Inject CO2 microbubbles into the target well after well soaking treatment, and the CO2 microbubbles are obtained according to the gas-liquid ratio of CO2 microbubbles;

[0011] Oil recovery is performed on the target well after CO2 microbubbles are injected.

[0012] In one possible implementation,

[0013] Obtain the injection parameter range corresponding to the target well obtained by the experiment;

[0014] Perform numerical conversion on the injection parameter range corresponding to the target well to obtain the injection parameter range for simulated oil recovery;

[0015] Based on the injection parameter range of simulated oil recovery, simulated oil recovery is performed on the target well, and multiple recovery factors corresponding to different injection parameters of simulated oil recovery are obtained;

[0016] According to the injection parameters corresponding to the target recovery factor among the multiple recovery factors, the field injection parameters are obtained.

[0017] In a possible implementation manner, the injection parameter range corresponding to the target well obtained by experiment includes:

[0018] Obtain experimental cores from target wells;

[0019] Determine the comparative experimental parameters of the target group number; wherein the target group number is consistent with the number of field injection parameters, and only the target parameter is different in each group of comparative experimental parameters, and the target parameter can be any one of the injection amount of the pressure drive agent, the injection speed, the soaking time and the CO2 microbubble gas-liquid ratio; the comparative experimental parameters are consistent with the field injection parameters;

[0020] The injection parameter range of the target parameter of each group of comparative experiments is determined; wherein the injection parameter range represents that the recovery factor obtained when the comparative experiment is carried out with the value in the injection parameter range satisfies the preset change rate.

[0021] In a possible implementation, when the target parameter of the comparative experiment is the gas-liquid ratio of CO2 microbubbles, determining the injection parameter range of the target parameter of each group of comparative experiments includes:

[0022] Inject the pressure-displacing agent into the experimental core at the same pressure-displacing agent injection amount and injection speed;

[0023] According to the same soaking time, soaking treatment was carried out on the experimental cores injected with pressure displacement agent;

[0024] According to the preset multiple different CO2 microbubble gas-liquid ratios, CO2 microbubbles are injected into the experimental core;

[0025] Obtain the recovery factor of the experimental core corresponding to each CO2 microbubble gas-liquid ratio;

[0026] According to the recovery factor of the experimental core, the CO2 microbubble gas-liquid ratio corresponding to the preset change rate is used as the optimal parameter value of the CO2 microbubble gas-liquid ratio; wherein there are multiple optimal parameter values;

[0027] According to the optimal parameter value of the CO2 microbubble gas-liquid ratio, the injection parameter range of the CO2 microbubble gas-liquid ratio is obtained.

[0028] In a possible implementation, according to the optimal parameter value of the CO2 microbubble gas-liquid ratio, the injection parameter range of the CO2 microbubble gas-liquid ratio is obtained, including:

[0029] The target CO2 microbubble gas-liquid ratio within the injection parameter range of the CO2 microbubble gas-liquid ratio is determined through numerical simulation.

[0030] In a possible implementation, the injection parameter range corresponding to the target well is numerically converted to obtain the injection parameter range for simulated oil recovery, including:

[0031] The shut-in time in the injection parameter corresponding to the target well is determined as the shut-in time in the injection parameter of the simulated oil recovery;

[0032] The CO2 microbubble gas-liquid ratio in the injection parameters corresponding to the target well is determined as the CO2 microbubble gas-liquid ratio in the parameters of the simulated oil recovery;

[0033] Determine the injection amount of the pressure-displacing agent in the injection parameters of the simulated oil recovery according to the pressure-displacing agent injection amount in the injection parameters corresponding to the target well and the first related parameters of the target well, wherein the first related parameters include the target well transformation radius, the experimental core radius, the experimental core length, and the reservoir thickness;

[0034] The injection rate of the pressure-displacing agent in the injection parameters corresponding to the target well and the second related parameters of the target well are determined, and the injection rate of the pressure-displacing agent in the injection parameters of the simulated oil recovery is determined. The second related parameters include the number of perforation holes, the area of ​​a single hole, the radius of the experimental core, and the porosity of the experimental core.

[0035] In a possible implementation, it further includes:

[0036] Obtain construction parameters in real time, including construction pressure, bottom hole pressure and instantaneous displacement;

[0037] If the real-time construction parameter is greater than the corresponding construction parameter threshold, the real-time construction parameter is reduced to below the corresponding construction parameter threshold, and the construction parameter threshold is determined based on the historical construction parameter.

[0038] In a second aspect, the present application provides an enhanced oil recovery device based on CO2 microbubbles and forward pressure drive, comprising:

[0039] An acquisition module is used to acquire field injection parameters, wherein the field injection parameters include the injection amount of the pressure-displacing agent, the injection speed of the pressure-displacing agent, the well-insertion time, and the CO2 microbubble gas-liquid ratio. The field injection parameters are injection parameters corresponding to the target recovery factor among multiple recovery factors. The multiple recovery factors are obtained by simulating oil recovery of the target well based on different injection parameters;

[0040] An injection module, used for injecting the pressure-displacing agent into the target well according to the pressure-displacing agent injection amount and pressure-displacing agent injection speed;

[0041] Well shut-in treatment module, used to perform well shut-in treatment on the target well injected with pressure-displacing agent according to the well shut-in time;

[0042] A module is obtained, which is used to inject CO2 microbubbles into the target well after the well soaking treatment, and the CO2 microbubbles are obtained according to the gas-liquid ratio of the CO2 microbubbles;

[0043] The recovery module is used to recover oil from the target well after the CO2 microbubbles are injected.

[0044] In a third aspect, an embodiment of the present application provides an electronic device, including: a memory, a processor;

[0045] Memory stores computer-executable instructions;

[0046] The processor executes the computer-executable instructions stored in the memory, so that the processor executes the above first aspect and / or various possible implementations of the first aspect.

[0047] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, they are used to implement the first aspect above and / or various possible implementations of the first aspect.

[0048] In a fifth aspect, an embodiment of the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the above first aspect and / or various possible implementation methods of the first aspect.

[0049] The embodiments of the present application provide a method and device for improving oil recovery based on CO2 microbubbles and forward pressure drive, by obtaining field injection parameters, wherein the field injection parameters include injection amount of pressure drive agent, injection speed of pressure drive agent, well shut-in time and CO2 microbubble gas-liquid ratio, the field injection parameters are injection parameters corresponding to a target recovery rate among multiple recovery rates, and the multiple recovery rates are obtained by simulating oil recovery of target wells based on different injection parameters; the target recovery rate is the highest recovery rate among the maximum change rates; according to the injection amount of pressure drive agent and the injection speed of pressure drive agent, the target well is injected into the pressure drive according to the injection amount of pressure drive agent and the injection speed of pressure drive agent. Inject pressure-displacing agent into the target well; according to the well soaking time, soak the target well injected with pressure-displacing agent; inject CO2 microbubbles into the target well after soaking treatment. CO2 microbubbles are obtained according to the gas-liquid ratio of CO2 microbubbles; at the same time, according to the gas-liquid ratio of CO2 microbubbles obtained by petroleum simulation, the recovered oil can be higher during actual injection, and CO2 microbubbles are obtained. CO2 microbubbles have strong injectability. After entering the reservoir, the microbubbles are subjected to less buoyancy due to their small volume and stable system, and can migrate to deeper parts of the reservoir. When flowing in a high-permeability channel, CO2 microbubbles can produce a "Jiamin effect", block large pores, and allow subsequent fluids to enter the low-permeability layer, thereby improving sweep efficiency. In addition, microbubbles can carry CO2 by dissolving, exerting the miscibility of CO2 and crude oil, expanding the volume of crude oil, breaking the capillary pressure balance and other mechanisms to recover the remaining oil and improve the oil washing efficiency in the pores. Thereby improving the final recovery rate. The target well after injecting CO2 microbubbles is used for oil recovery. At the same time, CO2 microbubbles can avoid the problem of gas channeling, that is, the injected CO2 gas flows rapidly along high permeability channels or cracks, bypassing the oil in the oil layer and directly reaching the production well, resulting in a reduced recovery rate. At the same time, the method based on CO2 microbubbles and forward pressure drive can not only effectively improve the crude oil recovery rate, but also bury CO2 underground during the oil recovery process, reducing CO2 emissions, and providing an optimization direction for the future pressure drive development of low permeability and ultra-low permeability oil reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0051] Figure 1 A schematic flow chart of a method for improving oil recovery based on CO2 microbubbles and forward pressure drive provided in this application;

[0052] Figure 2 A schematic diagram of the relationship between the injection rate of a pressure-displacement agent and the recovery factor provided in this application;

[0053] Figure 3 A schematic diagram of the change of CO2 microbubble gas-liquid ratio and recovery rate provided in this application;

[0054] Figure 4 A schematic diagram of the change of the gas-liquid ratio and gas-oil ratio of CO2 microbubbles provided in this application;

[0055] Figure 5 A schematic flow chart of another method for improving oil recovery based on CO2 microbubbles and forward pressure drive provided in this application;

[0056] Figure 6 A schematic diagram of the process flow based on CO2 microbubbles and forward pressure drive improved for this application;

[0057] Figure 7 A schematic diagram of the structure of the enhanced oil recovery device based on CO2 microbubbles and forward pressure drive provided in this application;

[0058] Figure 8 A schematic diagram of the structure of the electronic device provided in this application.

[0059] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0060] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0061] At present, in order to achieve efficient development of low-permeability and ultra-low-permeability oil reservoirs, forward pressure-driven technology has been proposed in oil fields. Conventional forward pressure-driven technology injects pressure-driven agents into the reservoir at a pressure slightly higher than the reservoir fracture pressure, forms microcracks in the reservoir and increases the degree of crude oil production in the reservoir. Finally, conventional water injection is restored at the injection end to collect and displace the remaining oil to the production end. However, conventional forward pressure-driven technology often has the following problems: (1) Low-permeability and ultra-low-permeability oil reservoirs have developed natural fractures, and the microcracks formed during the pressure-driven process lead to the development of local fractures. The injected water in the later stage is easy to advance along the fractures, causing water channeling and flooding, resulting in ineffective water injection, resulting in unsatisfactory final pressure-driven recovery rate; (2) The later water injection only plays a role in mobilizing the remaining oil, and cannot further improve the oil washing efficiency and sweep efficiency, so the recovery rate of the reservoir crude oil is limited; (3) Low-permeability and ultra-low-permeability oil reservoirs have small pore throats and strong heterogeneity, which limits the use of foam drive, chemical drive and other recovery enhancement technologies.

[0062] The embodiments of the present application provide a method and device for improving oil recovery based on CO2 microbubbles and forward pressure drive. The method uses CO2 microbubble drive to replace the water drive stage in the conventional pressure drive process. While avoiding CO2 gas channeling, the performance of microbubbles and CO2 is used to enhance the oil recovery process of forward pressure drive, thereby further improving the crude oil recovery rate of low permeability and ultra-low permeability oil reservoirs.

[0063] First, the terms involved in this application are explained:

[0064] Recovery rate: It is one of the important indicators to measure the efficiency of oil and gas field development, which indicates the ratio of the actual amount of oil and gas extracted from the reservoir to the original geological reserves in the reservoir.

[0065] Figure 1 A schematic flow chart of a method for improving oil recovery based on CO2 microbubbles and forward pressure drive provided in this application is shown in FIG. Figure 1 As shown, the method includes:

[0066] S101. Obtaining field injection parameters, wherein the field injection parameters include the injection amount of the pressure-displacing agent, the injection speed of the pressure-displacing agent, the soaking time, and the CO2 microbubble gas-liquid ratio. The field injection parameters are injection parameters corresponding to a target recovery rate among multiple recovery rates. The multiple recovery rates are obtained by simulating oil recovery of the target well based on different injection parameters; the target recovery rate is the highest recovery rate among the maximum change rates.

[0067] Among them, forward pressure drive refers to the process of injecting pressure drive agent - well soaking treatment - oil recovery.

[0068] The pressure displacement agent injection volume refers to the volume of the pressure displacement agent injected into the target well.

[0069] The pressure drive injection rate refers to the injection rate into the target well.

[0070] Well shut-in time refers to the time the well is temporarily shut down during the production process.

[0071] The CO2 microbubble gas-liquid ratio refers to the gas-liquid ratio of CO2 microbubble foaming, which is the ratio or ratio between CO2 and formation water. During the actual injection process, the volume ratio of CO2 to formation water can be converted into a flow rate ratio.

[0072] Oil recovery simulation refers to: using electronic equipment to simulate the process of oil recovery by CO2 microbubbles and forward pressure drive to determine the on-site injection parameters, which can be specifically reservoir numerical simulation, mathematical modeling, etc.

[0073] Based on the experimental principle of controlling a single variable, multiple groups of control experiments can be set up. Each group of experiments only adjusts the value of one parameter among the pressure-displacement agent injection amount, pressure-displacement agent injection rate, well-insertion time, and CO2 microbubble gas-liquid ratio during the experiment. Then, the crude oil recovery rate of each group of experiments is recorded to obtain the indoor test results, that is, when the recovery rate target in each group of experiments is reached, the pressure-displacement agent injection amount parameter range, pressure-displacement agent injection rate parameter range, well-insertion time parameter range, and CO2 microbubble gas-liquid ratio parameter range. The parameter range includes the change process of the recovery rate from large to small. Based on the indoor experimental results, the reservoir numerical simulation model of the target well is established and the production data history fitting is performed. Through numerical simulation, the field injection parameters are determined. The field injection parameters are the inflection points in the process of the recovery rate change from large to small.

[0074] S102: Inject the pressure-displacing agent into the target well according to the pressure-displacing agent injection amount and pressure-displacing agent injection speed.

[0075] Among them, according to the reservoir characteristics of the reservoir where the target well is located, a pressure-displacing agent suitable for the reservoir is configured.

[0076] Specifically, the appropriate pressure-displacement agent for the reservoir can be determined based on the rock type (such as sandstone, shale, limestone, etc.), porosity and permeability, natural fractures in the reservoir, oil-water ratio, viscosity, temperature and pressure. For example: Water-based pressure-displacement agent: commonly used in low-temperature, low-pressure reservoirs, suitable for most sandstone reservoirs. Oil-based pressure-displacement agent: suitable for water-sensitive reservoirs or high-temperature and high-pressure conditions. Foam pressure-displacement agent: used in low-permeability reservoirs, with good fluidity and sand-carrying capacity.

[0077] According to the reservoir characteristics of the target well, configure the pressure-displacing agent suitable for the reservoir, then confirm the injection volume of the pressure-displacing agent, and inject the pressure-displacing agent into the target well according to the injection speed of the pressure-displacing agent. The injection volume of a single well is 30,000 to 60,000 m 3 The injection rate of a single well is 0.1~2.0m 3 / min.

[0078] S103, according to the well shut-in time, the target well into which the pressure-displacing agent is injected is shut-in treated.

[0079] If the well soaking time is T, then the target well injected with the pressure displacement agent is soaked for T. T can be 30 to 40 days.

[0080] S104, injecting CO2 microbubbles into the target well after the well soaking treatment, wherein the CO2 microbubbles are obtained based on the gas-liquid ratio of the CO2 microbubbles.

[0081] Among them, formation water with the same mineralization as the target well is configured, and then the formation water and CO2 are passed through a bubbler according to the CO2 microbubble gas-liquid ratio to obtain CO2 microbubbles, and the CO2 microbubbles are injected into the target well after the well soaking treatment. The CO2 microbubble gas-liquid ratio can be 1:1.

[0082] S105, recovering oil from the target well after the CO2 microbubbles are injected.

[0083] When CO2 microbubbles are injected into a target well, the prepared CO2 microbubbles will drive out the oil in the target well, thereby enabling oil recovery. The distribution of microbubbles is generally 10 microns to 100 microns.

[0084] The method for improving oil recovery based on CO2 microbubbles and forward pressure drive provided in the embodiment of the present application injects a pressure drive agent into the target well, performs a well-smothering treatment on the target well injected with the pressure drive agent, and injects CO2 microbubbles into the well after the well-smothering treatment, and then drives out the oil through the CO2 microbubbles, thereby recovering the oil. Compared with driving out the oil directly through CO2, driving out the oil through CO2 microbubbles can avoid the problem of the injected CO2 gas flowing rapidly along high-permeability channels or cracks, bypassing the oil in the oil layer and directly reaching the production well, resulting in a reduced recovery rate. At the same time, CO2 microbubbles are physically foamed and have strong injectability. After entering the reservoir, the microbubbles are subjected to less buoyancy due to their small size and stable system, and can migrate to deeper parts of the reservoir while blocking large pores, so that

[0085] In the above embodiments of the present application, the field injection parameters are determined in the following manner:

[0086] Obtain the injection parameter range corresponding to the target well obtained by the experiment;

[0087] Perform numerical conversion on the injection parameter range corresponding to the target well to obtain the injection parameter range for simulated oil recovery;

[0088] Based on the injection parameter range of simulated oil recovery, simulated oil recovery is performed on the target well, and multiple recovery factors corresponding to different injection parameters of simulated oil recovery are obtained;

[0089] According to the injection parameters corresponding to the target recovery factor among the multiple recovery factors, the field injection parameters are obtained.

[0090] The injection parameter range corresponding to the target well refers to: the value range of the parameter corresponding to the process of the recovery factor change rate from large to small.

[0091] The field injection parameter can be used to determine a value or to confirm a range.

[0092] The injection parameter range can be determined through indoor experiments → the parameter range determined by the indoor experiments can be converted into the oil simulation recovery injection parameter range → through the oil simulation recovery injection parameters, oil simulation recovery is carried out to determine the field injection parameters, wherein the oil simulation recovery can be similar to the field development, and the parameter scale used is the field injection parameters, and the oil simulation recovery can be a numerical simulation of the reservoir.

[0093] Based on the experimental principle of a single variable, an indoor experiment of CO2 microbubble enhanced forward pressure drive was carried out to obtain the experimental results, namely: the injection parameter range of the target well, which includes the pressure drive agent injection amount parameter range, the pressure drive agent injection rate range, the well soaking time and the CO2 microbubble gas-liquid ratio range. The values ​​in the injection parameter range of each target well were substituted into the preset formula for numerical conversion processing to obtain the numerical simulation injection parameter range, and then numerical simulation research was carried out based on the indoor experimental results to determine the recovery rate corresponding to each value in each numerical simulation injection parameter range. Then the values ​​of each injection parameter corresponding to the target recovery rate were determined.

[0094] In another embodiment, the injection parameter range is confirmed through literature or reports, and then based on the experimental principle of a single variable, the pressure-displacing agent injection amount, pressure-displacing agent injection rate, well-insertion time, and CO2 microbubble gas-liquid ratio are adjusted each time during the experiment, and experiments are conducted and the crude oil production is recorded. The corresponding parameter values ​​at the highest recovery rate in each group of single variable experiments are determined as initial injection parameters. The initial injection parameters include: pressure-displacing agent injection amount, pressure-displacing agent injection rate, well-insertion time, and CO2 microbubble gas-liquid ratio. The initial injection parameters are then converted into numerical values ​​to obtain field injection parameters.

[0095] The advantage of this setting is that combining experiments with simulated oil recovery makes the obtained on-site injection parameters more accurate. Experiments are relatively complex and time-consuming, so obtaining a rule and range through experiments, and then determining the on-site injection parameters through simulated oil recovery can reduce time and improve efficiency.

[0096] As a possible implementation of the present application, the injection parameter range corresponding to the target well obtained by experiment includes:

[0097] Obtain experimental cores from target wells;

[0098] Determine the comparative experimental parameters of the target group number; wherein the target group number is consistent with the number of field injection parameters, and only the target parameter is different in each group of comparative experimental parameters, and the target parameter can be any one of the injection amount of the pressure drive agent, the injection speed, the soaking time and the CO2 microbubble gas-liquid ratio; the comparative experimental parameters are consistent with the field injection parameters;

[0099] The injection parameter range of the target parameter of each group of comparative experiments is determined; wherein the injection parameter range represents that the recovery factor obtained when the comparative experiment is carried out with the value in the injection parameter range satisfies the preset change rate.

[0100] The core is obtained from the target well, cleaned and dried, and the porosity and permeability of the experimental core are measured by experimental instruments, and then the core is saturated with crude oil, and the saturated oil volume w1 is recorded at this time, so as to obtain the experimental core.

[0101] The recovery factor meeting the preset change rate means: including the process of the recovery factor change rate changing from large to small.

[0102] There are four parameters, namely, the injection amount of the pressure-displacing agent, the injection rate of the pressure-displacing agent, the soaking time and the gas-liquid ratio of CO2 microbubbles. Therefore, based on the single variable principle, four comparative experimental groups A, B, C and D are set up. Each group studies the effect of a single parameter change on the recovery factor. Specifically, Group A studies the effect of the pressure-displacing agent injection amount on the recovery factor change. The other parameters remain unchanged, and only the pressure-displacing agent injection amount is changed. Group B studies the effect of the pressure-displacing agent injection rate on the recovery factor change. The other parameters remain unchanged, and only the pressure-displacing agent injection rate is changed. Groups C and D are analogous to each other. Through the comparative experimental group A, the recovery factor corresponding to each pressure-displacing agent injection amount is obtained, and then the range of the pressure-displacing agent injection amount is confirmed according to the recovery factor corresponding to each pressure-displacing agent injection amount.

[0103] Figure 2 A schematic diagram of the relationship between the injection rate of a pressure-displacement agent and the recovery factor provided in this application is shown in FIG. Figure 2 As shown in the figure, when the injection rate is between 0ml / min and 2.4ml / min, as the injection rate increases, the recovery rate decreases from large to small. Therefore, 0ml / min-2.4ml / min is the injection parameter range of the pressure-displacing agent. During the experiment, since the experiment is relatively complicated and time-consuming, only a few injection rates of the pressure-displacing agent are preset to determine the change trend of the recovery rate. For example, the recovery rate of the pressure-displacing agent injection rate of 1.5ml / min is greater than the recovery rate of the pressure-displacing agent injection rate of 0.6ml / min. At the same time, the change rate of the recovery rate of 1.2ml / min-1.5ml / min is less than the change rate of 0.6ml / min-0.8ml / min. Then, through numerical simulation, a large number of pressure-displacing agent injection rates are set to determine the inflection point of the injection parameter of 1.2ml / min. In this way, the efficiency can be improved while ensuring accuracy. When the pressure-displacing agent injection rate is greater than the inflection point, the recovery rate is small, and the pressure-displacing agent injection rate is too fast, which will bring excessive pressure, leading to safety problems of the target well.

[0104] The advantage of such a setting is that by setting up comparative experiments and determining the injection parameter range of the target parameters of each set of comparative experiments, the accuracy of the obtained injection parameters can be improved, thereby improving the recovery rate.

[0105] On the basis of the above-mentioned embodiment of the present application, when the target parameter of the comparative experiment is the gas-liquid ratio of CO2 microbubbles, the injection parameter range of the target parameter of each group of comparative experiments is determined, including:

[0106] Inject the pressure-displacing agent into the experimental core at the same pressure-displacing agent injection amount and injection speed;

[0107] According to the same soaking time, soaking treatment is carried out on the experimental cores injected with pressure displacement agent;

[0108] According to a plurality of preset CO2 microbubble gas-liquid ratios, CO2 microbubbles are obtained and injected into the experimental core;

[0109] Obtain the recovery factor of the experimental core corresponding to each CO2 microbubble gas-liquid ratio;

[0110] According to the recovery factor of the experimental core, the CO2 microbubble gas-liquid ratio corresponding to the preset change rate is used as the optimal parameter value of the CO2 microbubble gas-liquid ratio; wherein there are multiple optimal parameter values;

[0111] According to the optimal parameter value of the CO2 microbubble gas-liquid ratio, the injection parameter range of the CO2 microbubble gas-liquid ratio is obtained.

[0112] The recovery factor meeting the preset change rate means that the change rate of the recovery factor between different CO2 microbubble gas-liquid ratios is a change process from large to small.

[0113] (1) Clean and dry the experimental core, measure the porosity and permeability of the experimental core with experimental instruments, and then saturate the core with crude oil. Record the saturated oil volume w1 at this time.

[0114] (2) Set multiple different CO2 microbubble gas-liquid ratios A, B, and C.

[0115] (3) Inject the pressure-displacing agent into the experimental core at a flow rate of Q1.

[0116] When the injection volume of the pressure-displacing agent reaches V, the inlet and outlet of the core holder are closed to carry out well soaking and imbibition. The well soaking time is T.

[0117] (5) After the soaking is completed, CO2 microbubbles are prepared using a foamer according to the CO2 microbubble gas-liquid ratio A. The valves at the outlet and inlet of the core holder are opened, and CO2 microbubbles are injected into the core holder through a constant pressure and constant speed pump until no oil is produced at the outlet. The displacement is stopped and the crude oil production w2 at this time is recorded.

[0118] Adjust the CO2 microbubble gas-liquid ratio A to CO2 microbubble gas-liquid ratio B, and repeat the above experimental steps (1) to (4).

[0119] (6) Compare the oil recovery factors under different CO2 microbubble gas-liquid ratios, and select the parameters with higher recovery factors (i.e., the change rate of recovery factors between different CO2 microbubble gas-liquid ratios, which is a change process from large to small) as the optimal parameter range, laying the foundation for the subsequent numerical simulation research. The recovery factor calculation formula is as follows:

[0120]

[0121] Where: E is the oil recovery factor; w1 is the saturated crude oil volume before the experiment; w2 is the produced oil volume under different CO2 microbubble gas-liquid ratios.

[0122] When the target parameters are the injection volume of the pressure-displacing agent, the injection speed of the pressure-displacing agent, and the well-keeping time, the process is the same.

[0123] The advantage of this setting is that the target parameters can be found to maximize the recovery rate.

[0124] Furthermore, according to the optimal parameter value of the CO2 microbubble gas-liquid ratio, the injection parameter range of the CO2 microbubble gas-liquid ratio is obtained, including:

[0125] The target CO2 microbubble gas-liquid ratio within the injection parameter range of the CO2 microbubble gas-liquid ratio is determined through numerical simulation.

[0126] Among them, the target CO2 microbubble gas-liquid ratio can be 1:1 or 2:1.

[0127] Through numerical simulation, the target CO2 microbubble gas-liquid ratio within the injection parameter range of the microbubble gas-liquid ratio can be obtained. The target CO2 microbubble gas-liquid ratio can be obtained based on the recovery factor comparison, or it can be obtained by combining the factor and the gas-oil ratio.

[0128] Figure 3 A schematic diagram of the change of CO2 microbubble gas-liquid ratio and recovery rate provided in this application is as follows: Figure 3 As shown in the figure, when the CO2 microbubble gas-liquid ratio is between 1:4 and 2:1, the recovery factor increases with the increase of the gas-liquid ratio, and when it exceeds 2:1, the recovery factor decreases with the increase of the gas-liquid ratio. When the CO2 microbubble gas-liquid ratio is 2:1, the change rate of the recovery factor is the largest, and the recovery factor is the highest, so the CO2 microbubble gas-liquid ratio can be 2:1.

[0129] Figure 4 A schematic diagram of the changes in the gas-liquid ratio and gas-oil ratio of CO2 microbubbles is provided. Figure 4As shown, as the CO2 microbubble gas-liquid ratio increases (the more CO2, i.e., the Gas liquid ratio in the figure), the recovery rate increases. As the mining time increases, CO2 with a high gas-liquid ratio is prone to break through in advance (referring to the injected CO2 gas flowing rapidly along high permeability channels or cracks, bypassing the oil in the oil layer and directly reaching the production well), resulting in a relatively high gas-oil ratio at the production end (i.e., the Gas oil ratio in the figure), that is, the proportion of recovered CO2 in oil is high, resulting in increased subsequent separation costs, reduced economic benefits, and is not conducive to carbon sequestration. Therefore, based on the results corresponding to the gas-oil ratio and the gas-liquid ratio, the optimal gas-liquid ratio is 1:1.

[0130] The advantage of this setting is that the recovery rate can be improved by determining the target CO2 microbubble gas-liquid ratio. Combining the recovery rate and gas-oil ratio corresponding to the CO2 microbubble gas-liquid ratio, the gas-oil ratio can be reduced while ensuring the recovery rate, thereby saving costs.

[0131] Furthermore, the injection parameter range corresponding to the target well is numerically converted to obtain the injection parameter range for simulated oil recovery, including:

[0132] The shut-in time in the injection parameter corresponding to the target well is determined as the shut-in time in the injection parameter of the simulated oil recovery;

[0133] The CO2 microbubble gas-liquid ratio in the injection parameters corresponding to the target well is determined as the CO2 microbubble gas-liquid ratio in the parameters of the simulated oil recovery;

[0134] Determine the injection amount of the pressure-displacing agent in the injection parameters of the simulated oil recovery according to the pressure-displacing agent injection amount in the injection parameters corresponding to the target well and the first related parameters of the target well, wherein the first related parameters include the target well transformation radius, the experimental core radius, the experimental core length, and the reservoir thickness;

[0135] The injection rate of the pressure-displacing agent in the injection parameters corresponding to the target well and the second related parameters of the target well are determined, and the injection rate of the pressure-displacing agent in the injection parameters of the simulated oil recovery is determined. The second related parameters include the number of perforation holes, the area of ​​a single hole, the radius of the experimental core, and the porosity of the experimental core.

[0136] The shut-in time range corresponding to the target well obtained in the experiment is used as the shut-in time range for simulated oil recovery.

[0137] The CO2 microbubble gas-liquid ratio range corresponding to the target well obtained in the experiment is used as the CO2 microbubble gas-liquid ratio range for oil simulation recovery.

[0138] Substituting the pressure-displacing agent injection amount corresponding to the target well obtained from the experiment into the preset formula, the pressure-displacing agent injection amount in the oil simulation recovery injection parameter can be obtained:

[0139]

[0140] Among them: V1 is the injection volume of the pressure-driven agent in the oil simulation recovery injection parameters; V2 is the pressure-driven injection volume of the experimental core; r1 is the transformation radius of the on-site water injection well; r2 is the radius of the experimental core; l is the length of the experimental core; H is the reservoir thickness; φ1 is the reservoir core porosity; φ2 is the experimental core porosity.

[0141] Substituting the pressure-displacement agent injection rate corresponding to the target well obtained from the experiment into the preset formula, the pressure-displacement agent injection rate in the oil simulation recovery injection parameter can be obtained:

[0142]

[0143] Among them, Q1 is the injection rate of the pressure-displacing agent in the oil simulation recovery injection parameters; Q2 is the injection rate of the pressure-displacing agent corresponding to the target well obtained in the experiment; n is the number of perforations; S is the area of ​​a single perforation; r2 is the radius of the experimental core; φ2 is the porosity of the experimental core.

[0144] In another embodiment, the injection parameter range is confirmed through literature or reports, and then based on the experimental principle of a single variable, after the initial injection parameters are obtained, the initial injection parameters include: well soaking time, CO2 microbubble gas-liquid ratio, pressure-displacing agent injection rate, and pressure-displacing agent injection amount. The well soaking time in the initial injection parameter is used as the well soaking time in the field injection parameter. The CO2 microbubble gas-liquid ratio in the initial injection parameter is used as the CO2 microbubble gas-liquid ratio in the field injection parameter, and then the pressure-displacing agent injection amount in the initial injection parameter is substituted into the preset formula to obtain the pressure-displacing agent injection rate in the field injection parameter:

[0145]

[0146] Among them: V1 is the injection volume of the pressure-displacing agent in the field injection parameters; V2 is the injection volume of the pressure-displacing agent in the initial injection parameters; r1 is the transformation radius of the field injection well; r2 is the experimental core radius; l is the experimental core length; H is the reservoir thickness; φ1 is the reservoir core porosity; φ2 is the experimental core porosity.

[0147] Substituting the injection amount of the pressure-displacing agent in the initial injection parameters into the preset formula, the pressure-displacing agent injection rate in the field injection parameters can be obtained:

[0148]

[0149] Among them, Q1 is the injection rate of the pressure-displacing agent in the field injection parameters; Q2 is the injection rate of the pressure-displacing agent in the initial injection parameters; n is the number of perforations; S is the area of ​​a single perforation; r2 is the radius of the experimental core; φ2 is the porosity of the experimental core.

[0150] The advantage of this setting is that this method can effectively improve the efficiency and recovery rate of CO2 flooding by converting laboratory parameters into injection parameters suitable for oil simulation recovery, and has significant technical and economic benefits.

[0151] Furthermore, it also includes:

[0152] The construction parameters are obtained in real time, wherein the construction parameters include the construction pressure, the bottom hole pressure and the instantaneous displacement; if the construction parameters obtained in real time are greater than the corresponding construction parameter threshold, the real-time construction parameters are reduced to below the corresponding construction parameter threshold, and the construction parameter threshold is determined based on the historical construction parameters.

[0153] Among them, the injection pressure, bottom hole pressure, and displacement changes are used to determine whether they are within a reasonable range (i.e., below the corresponding construction parameter threshold). If the construction parameters are unreasonable, it is necessary to consider whether there are unexpected situations, such as leakage, a drop in bottom hole pressure, and an increase in instantaneous displacement. Parameter optimization and adjustment are carried out in combination with previous construction parameters and changes in parameters such as pressure. For example, if the injection pressure is much greater than the fracture pressure of the reservoir, the injection pressure needs to be reduced as appropriate.

[0154] The advantage of this setting is that it can ensure the safety of oil extraction.

[0155] Figure 5 A schematic flow chart of another method for improving oil recovery based on CO2 microbubbles and forward pressure drive provided in this application is as follows: Figure 5 As shown, the method includes:

[0156] S501. Determine the on-site injection parameters, wherein the on-site injection parameters include the injection amount of the pressure-displacing agent, the injection speed of the pressure-displacing agent, the well soaking time, and the CO2 microbubble gas-liquid ratio.

[0157] (1) Based on the experimental principle of controlling a single variable, the injection volume and speed of the pressure-displacing agent, the soaking time, and the CO2 microbubble gas-liquid ratio were adjusted during the experiment. The experiments were conducted and the crude oil production was recorded to determine the most appropriate range of relevant parameters.

[0158] (2) Based on the laboratory experimental results and the reservoir parameters obtained in the early stage, a reservoir numerical simulation model of the target reservoir is established and production data history matching is performed to lay the foundation for the subsequent determination of the field injection plan;

[0159] (3) Using the range of injection volume, injection rate, well soaking time, and CO2 microbubble gas-liquid ratio determined in the previous experiments, a numerical simulation study of the optimal injection scheme was carried out to determine the field injection parameters during the field injection process.

[0160] S502, injecting the pressure-displacing agent into the water injection well for fracturing according to the injection amount and injection speed of the pressure-displacing agent.

[0161] (1) According to the reservoir characteristics of the target reservoir, a pressure-displacement agent suitable for the reservoir is configured to reduce damage to the target reservoir on the basis of improving the crude oil recovery rate of the reservoir and realize sustainable development of the reservoir;

[0162] (2) Determine the injection volume of the pressure-displacement agent in the early stage (the injection volume of a single well can be 30,000 to 60,000 m 3 ) and injection rate (the injection rate of a single well can be 0.1 to 2.0 m 3 / min, and ensure that the injection pressure is slightly higher than the reservoir fracture pressure), calculate the time required for on-site injection, and inject the pressure-displacing agent through on-site fracturing equipment or ultra-high pressure equipment. Within the range of construction pressure limit and injection pressure limit, the displacement can be appropriately increased to reduce the construction time;

[0163] (3) During the construction process, real-time monitoring of construction parameters such as construction pressure, bottom hole pressure, and instantaneous displacement is performed to avoid unexpected situations and provide reference for subsequent optimization design.

[0164] S503, performing well soaking operation of the water injection well according to the well soaking time.

[0165] (1) After the injection of the displacement agent is completed, the water injection well is closed and the well is shut down for percolation to achieve oil-water replacement in the reservoir and to play the role of the displacement agent in improving the recovery rate;

[0166] (2) The well-insertion time is determined by preliminary experiments and numerical simulations (the reference well-insertion time is 30 to 40 days). During the well-insertion process, the bottom hole pressure changes are recorded in real time to determine the state of pressure propagation to prevent excessive pressure diffusion caused by too long well-insertion time. The well-insertion time is adjusted in real time according to the pressure changes to reduce development costs.

[0167] S504, injecting CO2 microbubbles into the water well to recover oil.

[0168] (1) Formation water with the same salinity as the target reservoir is used as the CO2 microbubble foaming base fluid, and CO2 microbubbles are prepared through a foamer according to a certain ratio of CO2 to formation water (the reference gas-liquid ratio is 1:1);

[0169] (2) After the well soaking operation is completed, the injection wells resume continuous injection, and the production wells resume production;

[0170] (3) The prepared CO2 microbubbles are injected into the reservoir to displace the crude oil, thereby exerting the recovery-enhancing effect of CO2 and microbubbles to further improve the crude oil recovery rate.

[0171] Another method for improving oil recovery based on CO2 microbubbles and forward pressure drive provided in an embodiment of the present application is to prepare CO2 microbubbles into CO2 microbubbles through a foamer according to a certain ratio and inject them into the reservoir through a water injection well. CO2 microbubbles are small in size and have good injectability, and are suitable for low-permeability and ultra-low-permeability oil reservoirs, and have outstanding advantages over conventional water drive. On the one hand, CO2 can improve oil recovery efficiency under reservoir conditions by replenishing formation energy, expanding crude oil, reducing crude oil viscosity, changing reservoir wettability, mixing with crude oil, and extracting light and medium components; on the other hand, microbubbles can improve the mobility ratio, selectively block high permeability layers, and reduce inter-layer or intra-layer interference, thereby expanding the swept volume and improving the recovery of low-permeability and ultra-low-permeability oil reservoirs.

[0172] Figure 6 The schematic diagram of the process flow based on CO2 microbubbles and forward pressure drive improved for this application is as follows: Figure 6 As shown in the figure, the pressure-driven agent is injected into the well to drive the fractures in the target reservoir. The pressure-driven process has a larger construction displacement (0.1-2.0m 3 / min) can effectively supplement the formation energy and make up for the problem of insufficient natural energy in low-permeability and ultra-low-permeability reservoirs. The pressure-displacing agent used in forward pressure-displacing is usually composed of clean water and surfactants. Compared with the viscosity of fracturing fluid, it is injected into the reservoir under the condition slightly higher than the reservoir fracture pressure, which can form a large number of micro-cracks in the reservoir, connect natural cracks and increase the size of pore throats, improve the seepage channel, and reduce the resistance of subsequent oil recovery. Then carry out a 15-60-day well soaking operation. During the soaking process, oil-water imbibition and displacement occur under the action of the capillary force of the reservoir rock. The pressure-displacing agent enters the small pores of the reservoir in this process, and plays its role in reducing surface tension and reducing crude oil viscosity to enhance the oil washing efficiency. The displaced crude oil enters the high-permeability area formed by pressure-displacing, which increases the oil saturation in the area. After the well soaking operation is completed, the water injection well resumes continuous water injection to mobilize the reservoir crude oil, and CO2 and formation water are prepared into CO2 microbubbles through a foamer in a certain proportion and injected into the reservoir through the water injection well. CO2 microbubbles are small in size and have good injectability. They are suitable for low-permeability and ultra-low-permeability reservoirs and have outstanding advantages over conventional water flooding. On the one hand, CO2 can improve the oil recovery efficiency under reservoir conditions by replenishing formation energy, expanding crude oil, reducing crude oil viscosity, changing reservoir wettability, mixing with crude oil, and extracting light and medium components; on the other hand, microbubbles can improve the mobility ratio, selectively plug high-permeability layers, reduce inter-layer or intra-layer interference, thereby expanding the swept volume and improving the recovery rate of low-permeability and ultra-low-permeability reservoirs.

[0173] Figure 7 The schematic diagram of the structure of the enhanced oil recovery device based on CO2 microbubbles and forward pressure drive provided in this application is as follows: Figure 7As shown, the enhanced oil recovery device 70 based on CO2 microbubbles and forward pressure drive provided in this embodiment includes:

[0174] The acquisition module 701 is used to acquire the field injection parameters, wherein the field injection parameters include the injection amount of the pressure driving agent, the injection speed of the pressure driving agent, the well soaking time and the CO2 microbubble gas-liquid ratio. The field injection parameters are the injection parameters corresponding to the target recovery rate among multiple recovery rates. The multiple recovery rates are obtained by simulating oil recovery of the target well based on different injection parameters; the target recovery rate is the highest recovery rate among the maximum change rates;

[0175] An injection module 702 is used to inject a pressure-displacing agent into a target well according to a pressure-displacing agent injection amount and a pressure-displacing agent injection speed;

[0176] Well shut-in treatment module 703, used for shut-in treatment of the target well injected with the pressure displacement agent according to the well shut-in time;

[0177] Obtaining module 704, for injecting CO2 microbubbles into the target well after well soaking treatment, wherein the CO2 microbubbles are obtained according to the gas-liquid ratio of the CO2 microbubbles;

[0178] The recovery module 705 is used to recover oil from the target well after the CO2 microbubbles are injected.

[0179] In a possible implementation, the acquisition module 701 is further configured to:

[0180] Obtain the injection parameter range corresponding to the target well obtained by the experiment;

[0181] Based on the injection parameter range, simulate oil recovery for the target well and obtain multiple recovery factors corresponding to different injection parameters;

[0182] The injection parameters corresponding to the target recovery factors among the multiple recovery factors are numerically converted to obtain the field injection parameters.

[0183] In a possible implementation, the acquisition module 701 is further configured to:

[0184] Obtain the injection parameter range corresponding to the target well obtained by the experiment;

[0185] Perform numerical conversion on the injection parameter range corresponding to the target well to obtain the injection parameter range for simulated oil recovery;

[0186] Based on the injection parameter range of simulated oil recovery, simulated oil recovery is performed on the target well, and multiple recovery factors corresponding to different injection parameters of simulated oil recovery are obtained;

[0187] According to the injection parameters corresponding to the target recovery factor among the multiple recovery factors, the field injection parameters are obtained.

[0188] In a possible implementation, the acquisition module 701 is further used to:

[0189] Inject the pressure-displacing agent into the experimental core at the same pressure-displacing agent injection amount and injection speed;

[0190] According to the same soaking time, soaking treatment is carried out on the experimental cores injected with pressure displacement agent;

[0191] According to the preset multiple different CO2 microbubble gas-liquid ratios, CO2 microbubbles are injected into the experimental core;

[0192] Obtain the recovery factor of the experimental core corresponding to each CO2 microbubble gas-liquid ratio;

[0193] According to the recovery factor value of the experimental core, the CO2 microbubble gas-liquid ratio corresponding to the preset change rate is satisfied, which is used as the optimal parameter value of the CO2 microbubble gas-liquid ratio; wherein there are multiple optimal parameter values;

[0194] According to the optimal parameter value of the CO2 microbubble gas-liquid ratio, the injection parameter range of the CO2 microbubble gas-liquid ratio is obtained.

[0195] In a possible implementation, the acquisition module 701 is further used to:

[0196] The target CO2 microbubble gas-liquid ratio within the injection parameter range of the CO2 microbubble gas-liquid ratio is determined through numerical simulation.

[0197] In a possible implementation, the acquisition module 701 is further used to:

[0198] The shut-in time in the injection parameter corresponding to the target well is determined as the shut-in time in the injection parameter of the simulated oil recovery;

[0199] The CO2 microbubble gas-liquid ratio in the injection parameters corresponding to the target well is determined as the CO2 microbubble gas-liquid ratio in the parameters of the simulated oil recovery;

[0200] Determine the injection amount of the pressure-displacing agent in the injection parameters of the simulated oil recovery according to the pressure-displacing agent injection amount in the injection parameters corresponding to the target well and the first related parameters of the target well, wherein the first related parameters include the target well transformation radius, the experimental core radius, the experimental core length, and the reservoir thickness;

[0201] According to the injection rate of the pressure-displacing agent in the injection parameters corresponding to the target well and the second related parameter of the target well, the injection rate of the pressure-displacing agent in the injection parameters of the oil simulation recovery is determined, and the second related parameter includes the number of perforation holes, the area of ​​a single hole, the radius of the experimental core, and the porosity of the experimental core. In a possible implementation, the acquisition module 701 is also used to:

[0202] The construction parameters are obtained in real time, wherein the construction parameters include the construction pressure, the bottom hole pressure and the instantaneous displacement; if the construction parameters obtained in real time are greater than the corresponding construction parameter threshold, the real-time construction parameters are reduced to below the corresponding construction parameter threshold, and the construction parameter threshold is determined based on the historical construction parameters.

[0203] The device for enhancing oil recovery based on CO2 microbubbles and forward pressure drive provided in this embodiment can execute the method provided in the above method embodiment, and its implementation principle and technical effect are similar, so this embodiment will not be described in detail here.

[0204] Figure 8 This is a schematic diagram of the structure of the electronic device provided in this application. Figure 8 As shown, the electronic device 80 provided in this embodiment includes: at least one processor 801 and a memory 802. Optionally, the device 80 also includes a communication component 803. The processor 801, the memory 802 and the communication component 803 are connected via a bus 804.

[0205] In a specific implementation process, at least one processor 801 executes the computer-executable instructions stored in the memory 802, so that at least one processor 801 executes the above method.

[0206] The specific implementation process of the processor 801 can be found in the above method embodiment, and its implementation principle and technical effect are similar, so this embodiment will not be repeated here.

[0207] In the above embodiments, it should be understood that the processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in the invention can be directly implemented as a hardware processor, or can be implemented by a combination of hardware and software modules in the processor.

[0208] The memory may include a high-speed memory (Random Access Memory, RAM), and may also include a non-volatile memory (Non-volatile Memory, NVM), such as at least one disk memory.

[0209] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, the bus in the drawings of the present application is not limited to only one bus or one type of bus.

[0210] The present application also provides a computer program product, including a computer program, which implements the above method when executed by a processor.

[0211] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the above method is implemented.

[0212] The above-mentioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special-purpose computer.

[0213] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (Application Specific Integrated Circuits, referred to as: ASIC). Of course, the processor and the readable storage medium can also exist in the device as discrete components.

[0214] The division of units is only a logical function division, and there may be other divisions in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

[0215] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0216] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0217] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0218] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, disk or optical disk and other media that can store program codes.

[0219] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for improving oil recovery based on CO2 microbubbles and forward pressure drive, characterized in that: include: Acquire field injection parameters, wherein the field injection parameters include the injection amount of the pressure-displacing agent, the injection speed of the pressure-displacing agent, the well soaking time, and the CO2 microbubble gas-liquid ratio. The field injection parameters are injection parameters corresponding to a target recovery rate among multiple recovery rates. The multiple recovery rates are obtained by simulating oil recovery of the target well based on different injection parameters; the target recovery rate is the highest recovery rate among the maximum change rates; Injecting a pressure-displacing agent into the target well according to the pressure-displacing agent injection amount and the pressure-displacing agent injection speed; According to the well soaking time, the target well into which the pressure displacement agent is injected is soaked; Injecting CO2 microbubbles into the target well after the well soaking treatment, wherein the CO2 microbubbles are obtained according to the gas-liquid ratio of the CO2 microbubbles; Oil recovery is performed on the target well after CO2 microbubbles are injected.

2. The method according to claim 1, characterized in that: The field injection parameters are determined in the following manner: Obtaining the injection parameter range corresponding to the target well obtained by experiment; Performing numerical conversion processing on the injection parameter range corresponding to the target well to obtain the injection parameter range for simulated oil recovery; Based on the injection parameter range of the simulated oil recovery, simulated oil recovery is performed on the target well to obtain a plurality of recovery factors corresponding to different injection parameters of simulated oil recovery; The field injection parameter is obtained according to the injection parameter corresponding to the target recovery factor among the multiple recovery factors.

3. The method according to claim 2, characterized in that The injection parameter range corresponding to the target well obtained by the experiment includes: Obtaining an experimental core of the target well; Determine the comparative experimental parameters of the target group number; wherein the target group number is consistent with the number of the field injection parameters, and only the target parameter is different in each group of comparative experimental parameters, and the target parameter can be any one of the injection amount of the pressure drive agent, the injection speed, the soaking time and the CO2 microbubble gas-liquid ratio; the comparative experimental parameters are consistent with the field injection parameters; The injection parameter range of the target parameter of each group of comparative experiments is determined; wherein the injection parameter range represents that the recovery factor obtained when the comparative experiment is carried out with the value in the injection parameter range satisfies the preset change rate.

4. The method according to claim 3, characterized in that: When the target parameter of the comparative experiment is the CO2 microbubble gas-liquid ratio, the injection parameter range of the target parameter of each group of comparative experiments is determined, including: Injecting the pressure-displacing agent into the experimental core at the same pressure-displacing agent injection amount and injection speed; According to the same soaking time, the experimental core injected with the pressure displacement agent is soaked; According to a plurality of preset CO2 microbubble gas-liquid ratios, CO2 microbubbles are generated, and the CO2 microbubbles are injected into the experimental core; Obtaining the recovery factor of the experimental core corresponding to each CO2 microbubble gas-liquid ratio; According to the recovery factor value of the experimental core, the CO2 microbubble gas-liquid ratio corresponding to the preset change rate is satisfied, as the optimal parameter value of the CO2 microbubble gas-liquid ratio; wherein there are multiple optimal parameter values; According to the optimal parameter value of the CO2 microbubble gas-liquid ratio, the injection parameter range of the CO2 microbubble gas-liquid ratio is obtained.

5. The method according to any one of claims 2 to 4, characterized in that The step of obtaining the injection parameter range of the CO2 microbubble gas-liquid ratio according to the optimal parameter value of the CO2 microbubble gas-liquid ratio comprises: The target CO2 microbubble gas-liquid ratio within the injection parameter range of the CO2 microbubble gas-liquid ratio is determined through numerical simulation.

6. The method according to any one of claims 2 to 4, characterized in that The injection parameter range corresponding to the target well is numerically converted to obtain the injection parameter range for simulated oil recovery, including: Determine the shut-in time in the injection parameter corresponding to the target well as the shut-in time in the injection parameter of the simulated oil recovery; The CO2 microbubble gas-liquid ratio in the injection parameters corresponding to the target well is determined as the CO2 microbubble gas-liquid ratio in the parameters of the simulated oil recovery; Determine the injection amount of the pressure-displacing agent in the injection parameters of the simulated oil recovery according to the injection amount of the pressure-displacing agent in the injection parameters corresponding to the target well and the first related parameter of the target well, wherein the first related parameter includes the transformation radius of the target well, the radius of the experimental core, the length of the experimental core, and the reservoir thickness; The pressure-displacing agent injection rate in the injection parameters of the simulated oil recovery is determined according to the pressure-displacing agent injection rate in the injection parameters corresponding to the target well and the second related parameters of the target well, wherein the second related parameters include the number of perforation holes, the area of ​​a single hole, the experimental core radius, and the experimental core porosity.

7. The method according to any one of claims 1 to 4, characterized in that: Also includes: Acquire construction parameters in real time, wherein the construction parameters include construction pressure, bottom hole pressure and instantaneous displacement; If the real-time acquired construction parameter is greater than the corresponding construction parameter threshold, the real-time construction parameter is reduced to below the corresponding construction parameter threshold, and the construction parameter threshold is determined based on the historical construction parameter.

8. An enhanced oil recovery device based on CO2 microbubbles and forward pressure drive, characterized in that: include: An acquisition module is used to acquire field injection parameters, wherein the field injection parameters include the injection amount of the pressure-displacing agent, the injection speed of the pressure-displacing agent, the well soaking time and the CO2 microbubble gas-liquid ratio. The field injection parameters are injection parameters corresponding to a target recovery rate among multiple recovery rates. The multiple recovery rates are obtained by simulating oil recovery of the target well based on different injection parameters; the target recovery rate is the highest recovery rate among the maximum change rates; An injection module, used for injecting a pressure-displacing agent into the target well according to the pressure-displacing agent injection amount and the pressure-displacing agent injection speed; A well shut-in treatment module, used for performing a well shut-in treatment on the target well injected with the pressure-displacing agent according to the well shut-in time; An obtaining module is used to inject CO2 microbubbles into the target well after the well soaking treatment, wherein the CO2 microbubbles are obtained according to the gas-liquid ratio of the CO2 microbubbles; The recovery module is used to recover oil from the target well after the CO2 microbubbles are injected.

9. An electronic device, characterized in that: include: Memory, processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory, so that the processor performs the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, which are used to implement the method according to any one of claims 1 to 7 when executed by a processor.

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