A method, application method, and apparatus for selecting the particle size of pre-crosslinked gel particles.

Abstract

This paper provides a method, application method, and apparatus for selecting the particle size of pre-crosslinked gel particles. The method includes: constructing pore size probability distribution equations for high-permeability and low-permeability cores; constructing particle size probability distribution equations for the pre-crosslinked gel particles; constructing reconstructed particle size probability distribution equations for different particle size distribution intervals based on the particle size probability distribution equations; obtaining the plugging probabilities of high-permeability and low-permeability layers corresponding to different particle size distribution intervals based on the high-permeability cores, low-permeability cores, and the reconstructed particle size probability distribution equations for different particle size distribution intervals; and selecting a particle size distribution interval that simultaneously satisfies a high-permeability layer plugging rate higher than a first threshold and a low-permeability layer plugging rate lower than a second threshold. This method can displace residual oil in low-permeability layers while reducing damage to the rock, thus reducing costs and increasing efficiency.

Description

Technical Field

[0001] This invention relates to the petroleum industry, and in particular to a method, application method, and apparatus for selecting the particle size of pre-crosslinked gel particles. Background Technology

[0002] Most oilfields have now entered the medium-to-high water-cut stage, but a large amount of residual oil remains untapped, especially in reservoirs with interlayer heterogeneity. When water is injected into these reservoirs, it rushes through high-permeability layers, failing to displace the residual oil in low-permeability layers, significantly impacting the efficient development of the entire reservoir. Pre-crosslinked gel particles, due to their elastic deformation and deep-sealing capabilities, are widely used in major oilfields. Their main mechanism of action is to block high-permeability water migration, allowing subsequent injected water to enter the low-permeability layers rich in residual oil, thereby displacing the residual oil in the low-permeability layers.

[0003] However, in heterogeneous reservoirs, during particle injection, the particles simultaneously come into contact with both high and low permeability layers. Pre-crosslinked gel particles with unsuitable particle sizes may block the high-permeability layer, but they also block the low-permeability layer to some extent, causing damage. Existing technologies include acidizing and other unblocking methods, but these suffer from drawbacks such as high cost, wellbore corrosion, and secondary damage.

[0004] Therefore, there is an urgent need for a method for selecting the particle size of pre-crosslinked gel particles, which can select pre-crosslinked gel particles with appropriate particle size so that the particles only block the high-permeability layer and not the low-permeability layer. This will allow the residual oil in the low-permeability layer to be displaced during subsequent water injection, while reducing damage to the rock and improving efficiency. Summary of the Invention

[0005] The purpose of this embodiment is to provide a method, application method and device for selecting the particle size of pre-crosslinked gel particles, so as to displace the residual oil in the low-permeability layer, while reducing damage to the rock and reducing costs and increasing efficiency.

[0006] To achieve the above objectives, this embodiment provides a method for selecting the particle size of pre-crosslinked gel particles, including:

[0007] High-permeability cores and low-permeability cores of the same size were obtained from the same target reservoir, wherein the permeability of the high-permeability core was higher than that of the low-permeability core.

[0008] A pore size probability distribution equation is constructed for the high-permeability core and a low-permeability core, wherein the pore size probability distribution equation is used to characterize the probability of occurrence of different pore sizes in the core.

[0009] A particle size probability distribution equation is constructed for pre-crosslinked gel particles, wherein the particle size probability distribution equation is used to characterize the probability of different particle sizes appearing in the pre-crosslinked gel particles;

[0010] Multiple particle size distribution intervals are divided based on a preset interval, and the reconstructed particle size probability distribution equations corresponding to different particle size distribution intervals are constructed according to the particle size probability distribution equation.

[0011] Based on the pore size probability distribution equation of the high-permeability core, the pore size probability distribution equation of the low-permeability core, and the reconstructed particle size probability distribution equation under different particle size distribution ranges, the high-permeability layer plugging probability and the low-permeability layer plugging probability corresponding to different particle size distribution ranges are obtained.

[0012] Based on the high-permeability layer plugging probability corresponding to different particle size distribution intervals and the low-permeability layer plugging probability corresponding to different particle size distribution intervals, a selected particle size distribution interval is chosen that simultaneously satisfies the condition that the high-permeability layer plugging rate is higher than the first threshold and the low-permeability layer plugging rate is lower than the second threshold.

[0013] Preferably, the construction of the pore size probability distribution equations for the high-permeability core and the low-permeability core further includes:

[0014] Mercury intrusion porosimetry was performed on the high-permeability core and the low-permeability core to obtain the pore size distribution in the high-permeability core and the low-permeability core, respectively.

[0015] Based on the pore size distribution in the high-permeability core and the low-permeability core, the pore size probability distribution equations for the high-permeability core and the low-permeability core are fitted to obtain the pore size probability distribution equations.

[0016] Preferably, the step of fitting the pore size probability distribution equations of the high-permeability core and the low-permeability core based on the pore size distribution of the high-permeability core further includes:

[0017] The pore size probability distribution equation for high-permeability cores or low-permeability cores is characterized by the following formula:

[0018]

[0019] Where, d p σ represents the pore size of a high-permeability or low-permeability core. p The standard deviation of pore size for high-permeability or low-permeability rock cores. ψ(d) represents the median pore size of a high-permeability or low-permeability core. p ) represents the pore size d in high-permeability or low-permeability rock cores. p The probability of its occurrence.

[0020] Preferably, the particle size probability distribution equation for constructing the pre-crosslinked gel particles further includes:

[0021] Obtain the particle size distribution of the pre-crosslinked gel particles;

[0022] Based on the particle size distribution, a particle size probability distribution equation is obtained by fitting.

[0023] Preferably, the step of fitting the particle size probability distribution equation based on the particle size distribution further includes:

[0024] The particle size probability distribution equation is characterized by the following formula:

[0025]

[0026] Where, d d σ represents the particle size of the pre-crosslinked gel particles. d The standard deviation of the particle size of the pre-crosslinked gel particles. The median particle size of the pre-crosslinked gel particles. The particle size d in the pre-crosslinked gel particles d The probability of its occurrence.

[0027] Preferably, the step of dividing multiple particle size distribution intervals based on a preset interval and constructing reconstructed particle size probability distribution equations corresponding to different particle size distribution intervals according to the particle size probability distribution equation further includes:

[0028]

[0029] Where, d d The particle size of the pre-crosslinked gel particles. The particle size d in the pre-crosslinked gel particles d The probability of occurrence, d da and d db These are two boundary values ​​for any particle size distribution range, dd d For d d The differential, The reconstructed particle size probability distribution equation is given for any particle size distribution interval.

[0030] Preferably, the step of obtaining the high-permeability layer plugging probability and the low-permeability layer plugging probability corresponding to different particle size distribution ranges based on the pore size probability distribution equation of the high-permeability core, the pore size probability distribution equation of the low-permeability core, and the reconstructed particle size probability distribution equation under different particle size distribution ranges further includes:

[0031] The probability of plugging a high-permeability layer or a low-permeability layer corresponding to different particle size distribution ranges can be calculated using the following formulas:

[0032]

[0033] Where, dp ψ(d) represents the pore size of a high-permeability or low-permeability core. p ) represents the pore size d in high-permeability or low-permeability rock cores. p The probability of occurrence, dd p For d p The differential, d d The particle size of the pre-crosslinked gel particles. For any particle size distribution interval, the reconstructed particle size probability distribution equation is given by dd. d For d d The differential, d da and d db These are two boundary values ​​for any particle size distribution range, Φ(d) d ) represents the probability of plugging a high-permeability layer or a low-permeability layer for any particle size distribution range.

[0034] On the other hand, the embodiments of this article provide a method for applying the particle size of pre-crosslinked gel particles, which, based on the particle size selection method of pre-crosslinked gel particles described above, obtains a selected particle size distribution range, including:

[0035] Obtain target pre-crosslinked gel particles, wherein the particle size of the target pre-crosslinked gel particles belongs to the selected particle size distribution range;

[0036] The target pre-crosslinked gel particles are used to plug the target reservoir, wherein the pore throats of the high-permeability layer are plugged but the pore throats of the low-permeability layer are not plugged;

[0037] Water is injected into the target reservoir to displace crude oil in the low-permeability rock layer.

[0038] Furthermore, this embodiment also provides a particle size selection device for pre-crosslinked gel particles, the device comprising:

[0039] The acquisition module is used to acquire high-permeability cores and low-permeability cores of the same size from the same target reservoir, wherein the permeability of the high-permeability core is higher than that of the low-permeability core.

[0040] The first construction module is used to construct the pore size probability distribution equation of the high-permeability core and the low-permeability core, wherein the pore size probability distribution equation is used to characterize the probability of occurrence of different pore sizes in the core.

[0041] The second construction module is used to construct the particle size probability distribution equation of the pre-crosslinked gel particles, wherein the particle size probability distribution equation is used to characterize the probability of different particle sizes appearing in the pre-crosslinked gel particles.

[0042] The reconstruction module is used to divide multiple particle size distribution intervals based on a preset interval, and to construct the reconstructed particle size probability distribution equations corresponding to different particle size distribution intervals according to the particle size probability distribution equation.

[0043] The plugging probability determination module is used to obtain the plugging probability of the high-permeability layer and the plugging probability of the low-permeability layer corresponding to different particle size distribution ranges based on the pore size probability distribution equation of the high-permeability core, the pore size probability distribution equation of the low-permeability core, and the reconstructed particle size probability distribution equation under different particle size distribution ranges.

[0044] The selection module is used to select a particle size distribution range that simultaneously satisfies the following conditions: the high permeability layer blocking probability corresponding to the different particle size distribution ranges and the low permeability layer blocking probability corresponding to the different particle size distribution ranges.

[0045] In another aspect, embodiments of this document also provide a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the computer program, when executed by the processor, performs instructions according to any of the methods described above.

[0046] As can be seen from the technical solutions provided in the embodiments above, the embodiments of this paper obtain target pre-crosslinked gel particles belonging to the selected particle size distribution range, and use the target pre-crosslinked gel particles to plug the target reservoir. The pore throats of the high-permeability layer are plugged, but the pore throats of the low-permeability layer are not plugged. In this way, water can be injected into the target reservoir. Since the pore throats of the high-permeability layer are plugged, the water can only enter the low-permeability layer and displace the remaining oil in the low-permeability layer. This process will not damage the rock and has high oil displacement efficiency and good effect.

[0047] To make the above and other objects, features and advantages of this document more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments or prior art described herein, the accompanying drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this article. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 A schematic flowchart of a method for selecting the particle size of pre-crosslinked gel particles provided in the embodiments of this article is shown;

[0050] Figure 2The flowchart illustrating the pore size probability distribution equations for constructing high-permeability cores and low-permeability cores provided in the embodiments of this article is shown.

[0051] Figure 3 A schematic diagram of the process for constructing the particle size probability distribution equation of pre-crosslinked gel particles provided in the embodiments of this article is shown;

[0052] Figure 4 A schematic diagram of the pore size probability distribution equation of the high-permeability core provided in the embodiments of this article is shown;

[0053] Figure 5 An image showing the pore size probability distribution equation of the low-permeability core provided in the embodiments of this article is illustrated.

[0054] Figure 6 An image showing the particle size probability distribution equation of the pre-crosslinked gel particles provided in the embodiments of this article is illustrated.

[0055] Figure 7 An image of the reconstructed particle size probability distribution equation provided in the embodiments of this article is shown;

[0056] Figure 8 The examples provided in this paper show the low-permeability layer plugging rate and high-permeability layer plugging rate corresponding to the selected particle size distribution ranges.

[0057] Figure 9 A schematic flowchart of a method for applying particle size to pre-crosslinked gel particles provided in the embodiments of this article is shown.

[0058] Figure 10 This document shows a schematic diagram of the module structure of a particle size selection device for pre-crosslinked gel particles provided in an embodiment of the invention.

[0059] Figure 11 A schematic diagram of the module structure of a particle size application device for pre-crosslinked gel particles provided in the embodiments of this article is shown.

[0060] Figure 12 A schematic diagram of the structure of the computer device provided in the embodiments of this article is shown.

[0061] Explanation of symbols in the attached drawings:

[0062] 100. Acquisition Module;

[0063] 200. First building block;

[0064] 300. Second building block;

[0065] 400. Refactoring the module;

[0066] 500. Blocking probability determination module;

[0067] 600. Select module;

[0068] 700. Particle Acquisition Module;

[0069] 800, Blocking Module;

[0070] 900, Displacement Module;

[0071] 1202. Computer equipment;

[0072] 1204, Processor;

[0073] 1206. Memory;

[0074] 1208. Drive mechanism;

[0075] 1210. Input / output module;

[0076] 1212. Input devices;

[0077] 1214. Output devices;

[0078] 1216. Presentation equipment;

[0079] 1218. Graphical User Interface;

[0080] 1220. Network interface;

[0081] 1222. Communication link;

[0082] 1224. Communication bus. Detailed Implementation

[0083] The technical solutions in the embodiments described below will be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments described herein, and not all of the embodiments. Based on the embodiments described herein, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this document.

[0084] Most oilfields have now entered the medium-to-high water-cut stage, but a large amount of residual oil remains untapped, especially in reservoirs with interlayer heterogeneity. When water is injected into these reservoirs, it rushes through high-permeability layers, failing to displace the residual oil in low-permeability layers, significantly impacting the efficient development of the entire reservoir. Pre-crosslinked gel particles, due to their elastic deformation and deep-sealing capabilities, are widely used in major oilfields. Their main mechanism of action is to block high-permeability water migration, allowing subsequent injected water to enter the low-permeability layers rich in residual oil, thereby displacing the residual oil in the low-permeability layers.

[0085] However, in heterogeneous reservoirs, during particle injection, the particles simultaneously come into contact with both high and low permeability layers. Pre-crosslinked gel particles with unsuitable particle sizes may block the high-permeability layer, but they also block the low-permeability layer to some extent, causing damage. Existing technologies include acidizing and other unblocking methods, but these suffer from drawbacks such as high cost, wellbore corrosion, and secondary damage.

[0086] To address the aforementioned issues, this embodiment provides a method for selecting the particle size of pre-crosslinked gel particles. Figure 1 This is a flowchart illustrating a method for selecting the particle size of pre-crosslinked gel particles provided in the embodiments of this document. This specification provides the operational steps of the method described in the embodiments or flowcharts, but based on conventional or non-inventive labor, more or fewer operational steps may be included. The order of steps listed in the embodiments is merely one possible execution order among many and does not represent the only possible execution order. In actual system or device products, the methods shown in the embodiments or accompanying drawings can be executed sequentially or in parallel.

[0087] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings herein are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, apparatus, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0088] Reference Figure 1 This paper provides a method for selecting the particle size of pre-crosslinked gel particles, including:

[0089] S101: Obtain high-permeability cores and low-permeability cores of the same size from the same target reservoir, wherein the permeability of the high-permeability core is higher than that of the low-permeability core;

[0090] S102: Construct the pore size probability distribution equation for the high-permeability core and the low-permeability core, wherein the pore size probability distribution equation is used to characterize the probability of different pore sizes appearing in the core.

[0091] S103: Construct a particle size probability distribution equation for pre-crosslinked gel particles, wherein the particle size probability distribution equation is used to characterize the probability of different particle sizes appearing in the pre-crosslinked gel particles;

[0092] S104: Divide multiple particle size distribution intervals based on a preset interval, and construct the reconstructed particle size probability distribution equations corresponding to different particle size distribution intervals according to the particle size probability distribution equation.

[0093] S105: Based on the pore size probability distribution equation of the high-permeability core, the pore size probability distribution equation of the low-permeability core, and the reconstructed particle size probability distribution equation under different particle size distribution ranges, the high-permeability layer plugging probability and the low-permeability layer plugging probability corresponding to different particle size distribution ranges are obtained.

[0094] S106: Based on the high-permeability layer blocking probability corresponding to the different particle size distribution intervals and the low-permeability layer blocking probability corresponding to the different particle size distribution intervals, select a particle size distribution interval that simultaneously satisfies the condition that the high-permeability layer blocking rate is higher than the first threshold and the low-permeability layer blocking rate is lower than the second threshold.

[0095] The target reservoir is an oil reservoir requiring oil recovery and development. It contains high-permeability and low-permeability layers, with the high-permeability layer having a higher permeability than the low-permeability layer. When water is injected into the target reservoir, it rushes along the high-permeability layer, failing to displace the remaining oil in the low-permeability layer, significantly impacting the efficient development of the entire reservoir. The method presented in this paper selects pre-crosslinked gel particles with appropriate particle size to seal the pore throats of the high-permeability layer, while not blocking the pore throats of the low-permeability layer. This allows for the reinjection of water into the target reservoir. Because the pore throats of the high-permeability layer are blocked, water can only enter the low-permeability layer, displacing the remaining oil there. This process does not damage the rock and has high oil displacement efficiency and good results.

[0096] The key to the above process is how to select pre-crosslinked gel particles with appropriate particle size. In this embodiment, the pore size probability distribution equations of high-permeability cores and low-permeability cores are constructed to characterize the probability of different pore sizes in high-permeability and low-permeability cores. In addition, the particle size probability distribution equation of pre-crosslinked gel particles is also constructed to characterize the probability of different particle sizes in pre-crosslinked gel particles. Generally, pre-crosslinked gel particles are obtained by absorbing water and swelling dry powder. Dry powder is prepared in advance, and after the dry powder absorbs water and swells, usable pre-crosslinked gel particles are obtained. However, the particle size of pre-crosslinked gel particles is not fixed. Due to different water absorption and other reasons, the particle size of pre-crosslinked gel particles is different.

[0097] Furthermore, it is necessary to correlate the probability of different pore sizes in high-permeability core samples with the probability of different particle sizes in pre-crosslinked gel particles, and similarly, to correlate the probability of different pore sizes in low-permeability core samples with the probability of different particle sizes in pre-crosslinked gel particles, thereby obtaining the plugging probability of high-permeability and low-permeability layers under different particle sizes of pre-crosslinked gel particles. However, due to the random size distribution of pre-crosslinked gel particles (e.g., a minimum particle size of 150 micrometers and a maximum of 750 micrometers), to achieve the above objective, it is necessary to divide the particle size distribution into multiple ranges, for example, with a preset interval of 20 micrometers, particle size distribution ranges of 150-170 micrometers, 170-190 micrometers, etc., and determine the probability of different particle sizes in pre-crosslinked gel particles within each particle size distribution range, thus obtaining the reconstructed particle size probability distribution equation.

[0098] Based on the pore size probability distribution equations for high-permeability cores, low-permeability cores, and reconstructed particle size probability distribution equations for different particle size distribution ranges, the plugging probabilities of high-permeability layers and low-permeability layers corresponding to different particle size distribution ranges are obtained. When selecting a particle size distribution range, a first threshold value and a second threshold value can be determined. Since the plugging probabilities of high-permeability layers differ for different particle size distribution ranges, the first threshold value can be a first set multiple of the maximum plugging probability of high-permeability layers. However, the first set multiple is generally greater than 0.5 and less than 1, such as 0.7 times or 0.6 times. Similarly, the plugging probabilities of low-permeability layers also differ for different particle size distribution ranges. The second threshold value can be a second set multiple of the maximum plugging probability of high-permeability layers. However, the second set multiple is generally greater than 0 and less than 0.5, such as 0.3 times or 0.4 times. Furthermore, a selected particle size distribution range can be chosen that simultaneously satisfies the conditions that the plugging rate of high-permeability layers is higher than the first threshold value and the plugging rate of low-permeability layers is lower than the second threshold value.

[0099] In the embodiments described herein, reference is made to Figure 2 The construction of the pore size probability distribution equations for the high-permeability core and the low-permeability core further includes:

[0100] S201: Mercury intrusion porosimetry was performed on the high-permeability core and the low-permeability core respectively to obtain the pore size distribution in the high-permeability core and the low-permeability core.

[0101] S202: Based on the pore size distribution in the high-permeability core and the low-permeability core, the pore size probability distribution equations for the high-permeability core and the low-permeability core are fitted to obtain the pore size probability distribution equations.

[0102] Specifically, the step of fitting the pore size probability distribution equations for the high-permeability core and the low-permeability core based on the pore size distribution in the high-permeability core further includes:

[0103] The pore size probability distribution equation for high-permeability cores or low-permeability cores is characterized by the following formula:

[0104]

[0105] Where, d p σ represents the pore size of a high-permeability or low-permeability core. p The standard deviation of pore size for high-permeability or low-permeability rock cores. ψ(d) represents the median pore size of a high-permeability or low-permeability core. p ) represents the pore size d in high-permeability or low-permeability rock cores. p The probability of its occurrence.

[0106] In the embodiments described herein, reference is made to Figure 3 The particle size probability distribution equation for constructing the pre-crosslinked gel particles further includes:

[0107] S301: Obtain the particle size distribution of the pre-crosslinked gel particles;

[0108] S302: Based on the particle size distribution, a particle size probability distribution equation is fitted.

[0109] The pre-crosslinked gel particles are obtained by absorbing water and swelling pre-prepared dry powder to form usable pre-crosslinked gel particles. The particle size distribution is tested using a micron laser particle size analyzer to obtain the particle size distribution of the pre-crosslinked gel particles.

[0110] Specifically, the step of fitting the particle size probability distribution equation based on the particle size distribution further includes:

[0111] The particle size probability distribution equation is characterized by the following formula:

[0112]

[0113] Where, d d σ represents the particle size of the pre-crosslinked gel particles. d The standard deviation of the particle size of the pre-crosslinked gel particles. The median particle size of the pre-crosslinked gel particles. The particle size d in the pre-crosslinked gel particles d The probability of its occurrence.

[0114] In this embodiment, the step of dividing multiple particle size distribution intervals based on a preset interval and constructing reconstructed particle size probability distribution equations corresponding to different particle size distribution intervals according to the particle size probability distribution equation further includes:

[0115]

[0116] Where, d d The particle size of the pre-crosslinked gel particles. The particle size d in the pre-crosslinked gel particles d The probability of occurrence, d da and d db These are two boundary values ​​for any particle size distribution range, dd d For d d The differential, The reconstructed particle size probability distribution equation is given for any particle size distribution interval.

[0117] Furthermore, the step of obtaining the high-permeability layer plugging probability and the low-permeability layer plugging probability corresponding to different particle size distribution intervals based on the pore size probability distribution equation of the high-permeability core, the low-permeability core, and the reconstructed particle size probability distribution equation under different particle size distribution intervals further includes:

[0118] The probability of plugging a high-permeability layer or a low-permeability layer corresponding to different particle size distribution ranges can be calculated using the following formulas:

[0119]

[0120] Where, d p ψ(d) represents the pore size of a high-permeability or low-permeability core. p ) represents the pore size d in high-permeability or low-permeability rock cores. p The probability of occurrence, dd p For d p The differential, d d The particle size of the pre-crosslinked gel particles. For any particle size distribution interval, the reconstructed particle size probability distribution equation is given by dd. d For d d The differential, d da and d db These are two boundary values ​​for any particle size distribution range, Φ(d) d ) represents the probability of plugging a high-permeability layer or a low-permeability layer for any particle size distribution range.

[0121] In addition, in this embodiment, high-permeability cores and low-permeability cores of the same size as those in S101 can be obtained again, and experiments can be conducted using parallel injection and separate production methods to verify the degree of crude oil recovery after plugging with pre-crosslinked gel particles of selected particle size distribution range.

[0122] Specifically, when applying the methods described in the embodiments of this article, a median pore size of 300 micrometers is selected for the high-permeability layer of a heterogeneous oil reservoir, and a median pore size of 100 micrometers is selected for the low-permeability layer. A pre-crosslinked gel particle dry powder with a mesh size of 100-200 is selected for field use in oilfields. The particles are prepared into a solution at a concentration of 2000 mg / L, and after absorbing water and swelling for 12 hours, the particle size distribution is tested using a micron laser particle size analyzer.

[0123] Reference Figure 4 The pore size probability distribution equation for high-permeability core layers is further constructed as follows:

[0124]

[0125] Where, d p The pore size is the diameter of the high-permeability rock core.

[0126] Reference Figure 5 The pore size probability distribution equation for low-permeability cores is as follows:

[0127]

[0128] Where, d p The pore size of the core sample in the low-permeability layer or the core sample in the low-permeability layer.

[0129] Reference Figure 6 The particle size probability distribution equation for the pre-crosslinked gel particles is as follows:

[0130]

[0131] Where, d d The particle size is denoted as .

[0132] Multiple particle size distribution ranges are divided based on preset intervals. The minimum particle size is 100 mesh, and the maximum is 200 mesh, which is 150-750 micrometers. The particle size is further divided into 30 portions with a preset interval of 20 micrometers. The particle size distribution ranges are (150, 170), (170, 190), ..., (730, 750). Taking the particle size distribution range (150, 170) as an example... Figure 7 The reconstructed particle size probability distribution equation is:

[0133]

[0134] Taking the particle size distribution range (150, 170) as an example, the probability of high permeability layer blockage in this range is as follows:

[0135]

[0136] Where, d d d represents the particle size of the pre-crosslinked gel particles. p The pore size is the diameter of the high-permeability rock core.

[0137] Taking the particle size distribution range (150, 170) as an example, the probability of blocking low-permeability layers in this range is as follows:

[0138]

[0139] Where, d d d represents the particle size of the pre-crosslinked gel particles. p The pore size is the diameter of the core sample from the low-permeability layer.

[0140] Further calculations revealed that the first threshold value was 0.7 times the maximum high-permeability layer sealing rate, and the second threshold value was 0.3 times the minimum low-permeability layer sealing rate. Figure 8 The selectable range shown is the selected particle size distribution range.

[0141] In addition, the same high-permeability cores and low-permeability cores as mentioned above were selected, and experiments were conducted using a parallel, combined injection and separate extraction method. The experimental steps were as follows:

[0142] (1) Use artificial core clamping device models to clamp high-permeability cores and low-permeability cores respectively;

[0143] (3) Vacuuming, water saturation, and oil saturation were performed according to the displacement test criteria, and the porosity and initial oil saturation were calculated.

[0144] (4) Water flooding is carried out at a displacement rate of 0.1 to 0.5 mL / min, and the produced fluid is collected to obtain the first degree of recovery;

[0145] (5) After the moisture content reaches a certain value (determined according to the site standard), inject a certain amount of pre-crosslinked gel particles (determined according to the site standard);

[0146] (6) Perform subsequent water flooding, collect the produced fluid from subsequent water flooding, and calculate the second recovery degree;

[0147] (7) The increased extraction degree is calculated by subtracting the first extraction degree from the second extraction degree.

[0148] Reference Figure 9 Based on the selected particle size distribution range obtained by the particle size selection method for pre-crosslinked gel particles described above, this paper also provides a method for applying the particle size of pre-crosslinked gel particles, including:

[0149] S401: Obtain target pre-crosslinked gel particles, wherein the particle size of the target pre-crosslinked gel particles belongs to the selected particle size distribution range;

[0150] S402: The target pre-crosslinked gel particles are used to plug the target reservoir, wherein the pore throats of the high-permeability layer are plugged but the pore throats of the low-permeability layer are not plugged;

[0151] S403: Inject water into the target reservoir to displace crude oil in the low-permeability rock layer.

[0152] By obtaining target pre-crosslinked gel particles belonging to the selected particle size distribution range, the target reservoir is plugged using the target pre-crosslinked gel particles. The pore throats of the high-permeability layer are plugged, but the pore throats of the low-permeability layer are not plugged. In this way, water can be injected into the target reservoir. Since the pore throats of the high-permeability layer are plugged, water can only enter the low-permeability layer and displace the remaining oil in the low-permeability layer. This process does not damage the rock and has high oil displacement efficiency and good effect.

[0153] Based on the above-described method for selecting the particle size of pre-crosslinked gel particles, this embodiment also provides a device for selecting the particle size of pre-crosslinked gel particles. The device may include a system (including a distributed system), software (application), module, component, server, client, etc., using the method described in this embodiment, combined with necessary hardware implementation. Based on the same innovative concept, the devices in one or more embodiments provided in this embodiment are as described in the following embodiments. Since the implementation schemes and methods for solving the problem are similar, the implementation of the specific devices in this embodiment can refer to the implementation of the aforementioned method, and repeated details will not be elaborated further. As used below, the terms "unit" or "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0154] Specifically, Figure 10 This is a schematic diagram of the module structure of one embodiment of the particle size selection device for pre-crosslinked gel particles provided in this article, with reference to... Figure 10 As shown in the embodiments herein, a particle size selection device for pre-crosslinked gel particles includes: an acquisition module 100, a first construction module 200, a second construction module 300, a reconstruction module 400, a blocking probability determination module 500, and a selection module 600.

[0155] The acquisition module 100 is used to acquire high-permeability cores and low-permeability cores of the same size from the same target reservoir, wherein the permeability of the high-permeability core is higher than that of the low-permeability core.

[0156] The first construction module 200 is used to construct the pore size probability distribution equation of the high-permeability core and the pore size probability distribution equation of the low-permeability core, wherein the pore size probability distribution equation is used to characterize the probability of occurrence of different pore sizes in the core.

[0157] The second building module 300 is used to build a particle size probability distribution equation for pre-crosslinked gel particles, wherein the particle size probability distribution equation is used to characterize the probability of different particle sizes appearing in the pre-crosslinked gel particles.

[0158] The reconstruction module 400 is used to divide multiple particle size distribution intervals based on a preset interval, and to construct the reconstructed particle size probability distribution equations corresponding to different particle size distribution intervals according to the particle size probability distribution equation.

[0159] The plugging probability determination module 500 is used to obtain the plugging probability of the high-permeability layer and the plugging probability of the low-permeability layer corresponding to different particle size distribution ranges based on the pore size probability distribution equation of the high-permeability core, the pore size probability distribution equation of the low-permeability core, and the reconstructed particle size probability distribution equation under different particle size distribution ranges.

[0160] The selection module 600 is used to select a particle size distribution range that simultaneously satisfies the following conditions: the high permeability layer blocking probability corresponding to the different particle size distribution ranges and the low permeability layer blocking probability corresponding to the different particle size distribution ranges.

[0161] Reference Figure 11 Based on the above-described method for applying the particle size of pre-crosslinked gel particles, this paper also provides a corresponding device for applying the particle size of pre-crosslinked gel particles, the device comprising:

[0162] The particle acquisition module 700 is used to acquire target pre-crosslinked gel particles, wherein the particle size of the target pre-crosslinked gel particles belongs to the selected particle size distribution range.

[0163] The plugging module 800 is used to plug the target reservoir using the target pre-crosslinked gel particles, wherein the pore throats of the high-permeability layer are plugged but the pore throats of the low-permeability layer are not plugged.

[0164] The displacement module 900 is used to inject water into the target reservoir to displace crude oil in low-permeability rock layers.

[0165] Reference Figure 12As shown, based on the above-described method for selecting the particle size of pre-crosslinked gel particles or the method for applying the particle size of pre-crosslinked gel particles, one embodiment of this document also provides a computer device 1202, wherein the above-described method is run on the computer device 1202. The computer device 1202 may include one or more processors 1204, such as one or more central processing units (CPUs) or graphics processing units (GPUs), each processing unit capable of implementing one or more hardware threads. The computer device 1202 may also include any memory 1206 for storing any kind of information such as code, settings, data, etc. In one specific embodiment, a computer program is stored on the memory 1206 and can run on the processor 1204. When the computer program is run by the processor 1204, it can execute instructions according to the above-described method. Non-limitingly, for example, the memory 1206 may include any type of RAM, any type of ROM, flash memory, hard disk, optical disk, etc. More generally, any memory can use any technology to store information. Furthermore, any memory can provide volatile or non-volatile retention of information. Furthermore, any memory can represent a fixed or removable component of the computer device 1202. In one case, when the processor 1204 executes associated instructions stored in any memory or combination of memories, the computer device 1202 can perform any operation of the associated instructions. The computer device 1202 also includes one or more drive mechanisms 1208 for interacting with any memory, such as a hard disk drive, an optical disk drive, etc.

[0166] Computer device 1202 may further include an input / output module 1210 (I / O) for receiving various inputs (via input device 1212) and providing various outputs (via output device 1214). A specific output mechanism may include a presentation device 1216 and an associated graphical user interface 1218 (GUI). In other embodiments, the input / output module 1210 (I / O), input device 1212, and output device 1214 may be omitted, and the device may function solely as a computer device within a network. Computer device 1202 may also include one or more network interfaces 1220 for exchanging data with other devices via one or more communication links 1222. One or more communication buses 1224 couple the components described above together.

[0167] Communication link 1222 can be implemented in any way, such as via a local area network, a wide area network (e.g., the Internet), a point-to-point connection, or any combination thereof. Communication link 1222 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc., governed by any protocol or combination of protocols.

[0168] Corresponding to Figures 1-3 and Figure 9 In addition to the methods described above, this embodiment also provides a computer-readable storage medium storing a computer program that, when executed by a processor, performs the steps of the above-described methods.

[0169] This embodiment also provides a computer-readable instruction, wherein when a processor executes the instruction, the program therein causes the processor to perform the following: Figures 1-3 and Figure 9 The method shown.

[0170] It should be understood that in the various embodiments of this document, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this document.

[0171] It should also be understood that, in the embodiments herein, the term "and / or" is merely a description of the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following associated objects have an "or" relationship.

[0172] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this document.

[0173] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0174] In the embodiments provided herein, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the couplings or direct couplings or communication connections shown or discussed may be indirect couplings or communication connections through some interfaces, devices, or units, or they may be electrical, mechanical, or other forms of connection.

[0175] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments described herein, depending on actual needs.

[0176] Furthermore, the functional units in the various embodiments of this document can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0177] If the integrated unit is implemented as 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 this paper, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this paper. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0178] This document uses specific embodiments to illustrate the principles and implementation methods of this document. The descriptions of the embodiments above are only for the purpose of helping to understand the methods and core ideas of this document. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this document. Therefore, the content of this specification should not be construed as a limitation of this document.

Claims

1. A method for selecting the particle size of pre-crosslinked gel particles, characterized in that, include: High-permeability cores and low-permeability cores of the same size were obtained from the same target reservoir, wherein the permeability of the high-permeability core was higher than that of the low-permeability core. A pore size probability distribution equation is constructed for the high-permeability core and a low-permeability core, wherein the pore size probability distribution equation is used to characterize the probability of different pore sizes appearing in the core. A particle size probability distribution equation is constructed for pre-crosslinked gel particles, wherein the particle size probability distribution equation is used to characterize the probability of different particle sizes appearing in the pre-crosslinked gel particles; Multiple particle size distribution intervals are divided based on a preset interval, and the reconstructed particle size probability distribution equations corresponding to different particle size distribution intervals are constructed according to the particle size probability distribution equation. Based on the pore size probability distribution equation of the high-permeability core, the pore size probability distribution equation of the low-permeability core, and the reconstructed particle size probability distribution equation under different particle size distribution ranges, the high-permeability layer plugging probability and the low-permeability layer plugging probability corresponding to different particle size distribution ranges are obtained. Based on the high-permeability layer blocking probability corresponding to different particle size distribution intervals and the low-permeability layer blocking probability corresponding to different particle size distribution intervals, a selected particle size distribution interval is chosen that simultaneously satisfies the high-permeability layer blocking rate being higher than the first threshold and the low-permeability layer blocking rate being lower than the second threshold. The step of dividing multiple particle size distribution intervals based on a preset interval and constructing reconstructed particle size probability distribution equations corresponding to different particle size distribution intervals according to the particle size probability distribution equation further includes: ； Where, d d The particle size of the pre-crosslinked gel particles. The particle size d in the pre-crosslinked gel particles d The probability of occurrence, d da and d db These are two boundary values ​​for any particle size distribution range, dd d For d d The differential, For any particle size distribution interval, reconstruct the particle size probability distribution equation; The step of obtaining the high-permeability layer plugging probability and the low-permeability layer plugging probability corresponding to different particle size distribution ranges based on the pore size probability distribution equation of the high-permeability core, the low-permeability core, and the reconstructed particle size probability distribution equation under different particle size distribution ranges further includes: The probability of plugging a high-permeability layer or a low-permeability layer corresponding to different particle size distribution ranges can be calculated using the following formulas: ； Where, d p The pore size is the diameter of the core sample from a high-permeability or low-permeability layer. The pore size d in high-permeability or low-permeability rock cores p The probability of occurrence, dd p For d p The differential, d d The particle size of the pre-crosslinked gel particles. For any particle size distribution interval, the reconstructed particle size probability distribution equation is given by dd. d For d d The differential, d da and d db These are the two boundary values ​​for any particle size distribution interval. This represents the probability of sealing a high-permeability layer or a low-permeability layer for any particle size distribution range.

2. The method for selecting the particle size of pre-crosslinked gel particles according to claim 1, characterized in that, The construction of the pore size probability distribution equations for the high-permeability core and the low-permeability core further includes: Mercury intrusion porosimetry was performed on the high-permeability core and the low-permeability core to obtain the pore size distribution in the high-permeability core and the low-permeability core, respectively. Based on the pore size distribution in the high-permeability core and the low-permeability core, the pore size probability distribution equations for the high-permeability core and the low-permeability core are fitted to obtain the pore size probability distribution equations.

3. The method for selecting the particle size of pre-crosslinked gel particles according to claim 2, characterized in that, The step of fitting the pore size probability distribution equations for the high-permeability core and the low-permeability core based on the pore size distribution in the high-permeability core further includes: The pore size probability distribution equation for high-permeability cores or low-permeability cores is characterized by the following formula: ； Where, d p σ represents the pore size of a high-permeability or low-permeability core. p This represents the standard deviation of pore size in high-permeability or low-permeability rock cores. The median pore size is for high-permeability or low-permeability core samples. The pore size d in high-permeability or low-permeability rock cores p The probability of its occurrence.

4. The method for selecting the particle size of pre-crosslinked gel particles according to claim 1, characterized in that, The particle size probability distribution equation for constructing the pre-crosslinked gel particles further includes: Obtain the particle size distribution of the pre-crosslinked gel particles; Based on the particle size distribution, a particle size probability distribution equation is obtained by fitting.

5. The method for selecting the particle size of pre-crosslinked gel particles according to claim 4, characterized in that, The step of fitting the particle size probability distribution equation based on the particle size distribution further includes: The particle size probability distribution equation is characterized by the following formula: ； Where, d d σ represents the particle size of the pre-crosslinked gel particles. d The standard deviation of the particle size of the pre-crosslinked gel particles. The median particle size of the pre-crosslinked gel particles. The particle size d in the pre-crosslinked gel particles d The probability of its occurrence.

6. A method for applying particle size to pre-crosslinked gel particles, characterized in that, The particle size selection method for pre-crosslinked gel particles based on any one of claims 1-5, obtaining a selected particle size distribution range, includes: Obtain target pre-crosslinked gel particles, wherein the particle size of the target pre-crosslinked gel particles belongs to the selected particle size distribution range; The target pre-crosslinked gel particles are used to plug the target reservoir, wherein the pore throats of the high-permeability layer are plugged but the pore throats of the low-permeability layer are not plugged; Water is injected into the target reservoir to displace crude oil in the low-permeability rock layer.

7. A particle size selection device for pre-crosslinked gel particles, characterized in that, The device includes: The acquisition module is used to acquire high-permeability cores and low-permeability cores of the same size from the same target reservoir, wherein the permeability of the high-permeability core is higher than that of the low-permeability core. The first construction module is used to construct the pore size probability distribution equation of the high-permeability core and the low-permeability core, wherein the pore size probability distribution equation is used to characterize the probability of occurrence of different pore sizes in the core. The second construction module is used to construct the particle size probability distribution equation of the pre-crosslinked gel particles, wherein the particle size probability distribution equation is used to characterize the probability of different particle sizes appearing in the pre-crosslinked gel particles. The reconstruction module is used to divide multiple particle size distribution intervals based on a preset interval, and to construct reconstructed particle size probability distribution equations corresponding to different particle size distribution intervals according to the particle size probability distribution equation; wherein, the reconstructed particle size probability distribution equation is: ； Where, d d The particle size of the pre-crosslinked gel particles. The particle size d in the pre-crosslinked gel particles d The probability of occurrence, d da and d db These are two boundary values ​​for any particle size distribution range, dd d For d d The differential, For any particle size distribution interval, reconstruct the particle size probability distribution equation; The plugging probability determination module is used to obtain the plugging probability of the high-permeability layer and the plugging probability of the low-permeability layer corresponding to different particle size distribution ranges based on the pore size probability distribution equation of the high-permeability core, the pore size probability distribution equation of the low-permeability core, and the reconstructed particle size probability distribution equation under different particle size distribution ranges; wherein, the plugging probability of the high-permeability layer or the plugging probability of the low-permeability layer corresponding to different particle size distribution ranges is calculated by the following formula: ； Where, d p The pore size is the diameter of the core sample from a high-permeability or low-permeability layer. The pore size d in high-permeability or low-permeability rock cores p The probability of occurrence, dd p For d p The differential, d d The particle size of the pre-crosslinked gel particles. For any particle size distribution interval, the reconstructed particle size probability distribution equation is given by dd. d For d d The differential, d da and d db These are the two boundary values ​​for any particle size distribution interval. For any particle size distribution range, this represents the probability of plugging a high-permeability layer or a low-permeability layer. The selection module is used to select a particle size distribution range that simultaneously satisfies the following conditions: the high permeability layer blocking probability corresponding to the different particle size distribution ranges and the low permeability layer blocking probability corresponding to the different particle size distribution ranges.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that, When the computer program is run by the processor, it executes the instructions of the method according to any one of claims 1-6.

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