Chemical system determination method, system and device for multi-layer oil reservoir and medium

Abstract

The invention relates to the technical field of oil and gas field development, and discloses a chemical system determination method, system and device for a multi-layer oil reservoir and a medium. The method comprises the steps that the current high-permeability layer seepage resistance of a chemical system existing in a core of the multi-layer oil reservoir is obtained; based on the seepage resistance of the current high-seepage layer and a first preset threshold value, whether the chemical system plays a resistance adjusting role or not is determined; under the condition that the chemical system exerts the resistance adjusting effect, the actual injection amount of the chemical system is obtained; determining whether the actual injection amount of the chemical system is greater than or equal to the set injection amount; under the condition that the actual injection amount is greater than or equal to the set injection amount, acquiring a small layer utilization coefficient; and under the condition that the small-layer utilization coefficient is smaller than or equal to a second preset threshold value, determining that the current chemical system is an effective chemical system of the multi-layer oil reservoir. The method is suitable for various reservoir types through the seepage capacity of different chemical systems in the reservoir and the requirements of all layers of the multi-layer oil reservoir for different seepage resistance systems.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas field development, in particular to a method, system and device for determining a chemical system for a multi-layer reservoir and a medium. BACKGROUND

[0002] Heterogeneity is generally strong in continental reservoirs, but the characteristics are different. In the process of improving recovery by a chemical system for a multi-layer reservoir, it is difficult to apply one chemical system to the whole process of developing a multi-layer reservoir. Selecting a chemical system and determining the combination mode of multiple chemical systems are the keys to chemical flooding of a multi-layer reservoir.

[0003] Existing methods for determining a chemical system for a multi-layer reservoir are mostly applicable to a specific reservoir type. Numerical simulation or core experiments are used to optimize the chemical system for a multi-layer reservoir. The process is cumbersome and has no universal guiding significance for field implementation. SUMMARY

[0004] The purpose of the embodiments of the present application is to provide a method, system, device and medium for determining a chemical system for a multi-layer reservoir, to solve the problem that existing methods for determining a chemical system for a multi-layer reservoir are mostly applicable to a specific reservoir type, and numerical simulation or core experiments are used to optimize the chemical system for a multi-layer reservoir. The process is cumbersome and has no universal guiding significance for field implementation.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a method for determining a chemical system for a multi-layer reservoir, comprising: obtaining the current high-permeability layer flow resistance of a core of a multi-layer reservoir in the presence of a chemical system; determining whether the chemical system plays a resistance adjustment role based on the current high-permeability layer flow resistance and a first preset threshold value; obtaining the actual injection amount of the chemical system in the case where the chemical system plays a resistance adjustment role; determining whether the actual injection amount of the chemical system is greater than or equal to a set injection amount; obtaining a small-layer producing coefficient in the case where the actual injection amount is greater than or equal to the set injection amount; determining that the current chemical system is an effective chemical system for the multi-layer reservoir in the case where the small-layer producing coefficient is less than or equal to a second preset threshold value.

[0006] In the embodiments of the present application, the current high-permeability layer flow resistance of the core of the multi-layer reservoir in the presence of the chemical system is obtained, comprising: obtaining the first low-permeability layer flow resistance and the first high-permeability layer flow resistance of the core filled with water; obtaining the first high-permeability layer flow distribution of the core in the presence of the chemical system based on the first low-permeability layer flow resistance and the first high-permeability layer flow resistance; Based on the flow distribution of the first high permeability layer, the fluid distribution of the first high permeability layer of the chemical system in the core is obtained; Based on the fluid distribution of the first high permeability layer, the seepage resistance of the high permeability layer with the chemical system in the core is obtained.

[0007] In the embodiment of the present application, based on the seepage resistance of the first low permeability layer and the seepage resistance of the first high permeability layer, the flow distribution of the first high permeability layer in the chemical system of the core is obtained, including: Based on the seepage resistance of the first low permeability layer, the seepage resistance of the first high permeability layer, and a first formula, the flow distribution of the first high permeability layer is obtained, wherein the first formula includes:

[0008] In the first formula, Show The flow distribution of the first high permeability layer at time express The seepage resistance of the first low permeability layer at time express The seepage resistance of the first high permeability layer at time t, Indicates the core injection rate.

[0009] In the embodiment of the present application, based on the fluid distribution of the first high permeability layer, the seepage resistance of the high permeability layer of the chemical system in the core is obtained, including: Based on the fluid distribution in the first high permeability layer and the second formula, the seepage resistance of the high permeability layer is obtained, wherein the second formula includes:

[0010] In the second formula, represents the seepage resistance of the hyperpermeable layer, represents the viscosity of the i-th chemical system, represents the fluid distribution of the i-th chemical system in the core in the high permeability layer, represents the fluid distribution of all chemical systems in the high permeability layer in the core, represents the core end area, represents the viscosity of the water phase, represents the core length, Indicates the maximum permeability.

[0011] In the embodiment of the present application, determining whether the chemical system plays a resistance adjustment role based on the seepage resistance of the hyperpermeability layer and the first preset threshold value includes: Based on the current seepage resistance of the high permeability layer and the seepage resistance of the high permeability layer at the previous moment, the relative change rate of the seepage resistance of the high permeability layer in adjacent time steps is obtained; When the relative change rate of the seepage resistance of the hyperpermeable layer is greater than or equal to a first preset threshold, determining that the chemical system plays a resistance adjustment role; When the relative change rate of the seepage resistance of the hyperpermeable layer is less than the first preset threshold, it is determined that the chemical system does not play a role in resistance adjustment.

[0012] In the embodiment of the present application, obtaining the small layer activation coefficient includes: Obtain high permeability layer diversion rate and core injection rate; Based on the diversion rate of the high permeability layer and the core injection rate, the small layer production coefficient is obtained.

[0013] In the embodiment of the present application, it also includes: If the chemical system does not play a role in adjusting the resistance or the small layer producing coefficient is greater than the second preset threshold, the chemical system is replaced until the actual injection volume is greater than or equal to the set injection volume and the small layer producing coefficient is less than or equal to the second preset threshold; Based on all effective chemical systems, determine the effective chemical system combination for multi-layer reservoirs.

[0014] A second aspect of the present application provides a chemical system determination system for a multi-layer oil reservoir, comprising: The first acquisition module is used to obtain the current seepage resistance of the high permeability layer of the chemical system in the core of the multi-layer oil reservoir; A first determination module is configured to determine whether the chemical system plays a resistance adjustment role based on the current seepage resistance of the hyperpermeability layer and a first preset threshold; The second acquisition module is used to obtain the actual injection amount of the chemical system when the chemical system plays a resistance adjustment role; The second determination module is used to determine whether the actual injection amount of the chemical system is greater than or equal to the set injection amount; The third acquisition module is used to obtain the small layer production coefficient when the actual injection volume is greater than or equal to the set injection volume; The third determination module is configured to determine that the current chemical system is an effective chemical system of the multi-layer oil reservoir when the small layer producing coefficient is less than or equal to a second preset threshold value.

[0015] A third aspect of the present application provides a device for determining a chemical system of a multi-layer oil reservoir, comprising: a memory configured to store instructions; The processor is configured to call the instructions from the memory and implement the method for determining the chemical system of a multi-layered oil reservoir according to the first aspect when executing the instructions.

[0016] A fourth aspect of the present application provides a machine-readable storage medium having stored thereon instructions for causing a machine to execute the method for determining the chemical system of a multi-layer oil reservoir according to the first aspect described above.

[0017] Through the above technical scheme, combined with the seepage capacity in the reservoir under different chemical systems and the requirements of each layer of the multi-layer oil reservoir for different seepage resistance systems, the design scheme of the chemical system of the multi-layer oil reservoir was determined.

[0018] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present application but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings: Figure 1 The following schematically shows a flow chart of a method for determining a chemical system of a multi-layer oil reservoir according to an embodiment of the present application; Figure 2 A schematic diagram of flow distribution during a chemical system injection process according to an embodiment of the present application is shown; Figure 3 A schematic diagram of a small layer activation coefficient according to an embodiment of the present application is shown schematically; Figure 4 Schematically shows a flow distribution diagram during another chemical system injection process according to an embodiment of the present application; Figure 5 Another schematic diagram of a small layer activation coefficient according to an embodiment of the present application is shown schematically; Figure 6 A schematic diagram of an effective chemical system design for a multi-layer oil reservoir according to an embodiment of the present application is shown schematically. DETAILED DESCRIPTION

[0020] To make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the embodiments of the present application and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0021] It should be noted that the acquisition, transmission, storage, use, and processing of data in the technical solution of this application are in compliance with the relevant provisions of laws and regulations. In the embodiments of this application, certain software, components, models, and other existing solutions in the industry may be mentioned. These should be considered as exemplary. Their purpose is only to illustrate the feasibility of implementing the technical solution of this application, but it does not mean that the applicant has or will necessarily use such solutions.

[0022] It should be noted that if the embodiments of the present application involve directionality indication (such as up, down, left, right, front, back, …), the directionality indication is only used to explain the relative position relationship, motion condition, etc. between components in a certain posture (as shown in the drawings), if the certain posture changes, the directionality indication also changes accordingly.

[0023] In addition, if the embodiments of the present application involve descriptions such as "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

[0024] Figure 1 The flowchart of the method for determining the chemical system of a multi-layer oil reservoir according to the embodiments of the present application is schematically shown. As shown in Figure 1 The embodiments of the present application provide a method for determining the chemical system of a multi-layer oil reservoir, which can include the following steps: Step S110: Obtain the current high-permeability layer flow resistance of the core of the multi-layer oil reservoir in the presence of the chemical system; Step S120: Determine whether the chemical system plays a resistance adjustment role based on the current high-permeability layer flow resistance and a first preset threshold value; Step S130: In the case that the chemical system plays a resistance adjustment role, obtain the actual injection amount of the chemical system; Step S140: Determine whether the actual injection amount of the chemical system is greater than or equal to the set injection amount; Step S150: In the case that the actual injection amount is greater than or equal to the set injection amount, obtain the small-layer producing coefficient; Step S160: In the case that the small-layer producing coefficient is less than or equal to a second preset threshold value, determine that the current chemical system is an effective chemical system for the multi-layer oil reservoir.

[0025] In step S110, the current high-permeability layer flow resistance of the core of the multilayer reservoir to the chemical system is determined. The multilayer reservoir refers to a plurality of independent or partially connected oil and gas reservoirs in an oil field or reservoir, which are usually composed of different lithology, physical properties (such as permeability, porosity) or fluid properties of geological layers, and may be separated by impermeable barriers (such as mudstone, shale) between each other. The chemical system (such as polymer, surfactant, alkali, etc.) is injected into the core to improve the oil flowability and enhance the displacement efficiency of the multilayer reservoir.

[0026] In step S120, the size relationship between the current high-permeability layer flow resistance and the first preset threshold value is determined to determine whether the chemical system plays a resistance adjustment role.

[0027] In step S130, if it is determined that the chemical system plays a resistance adjustment role, the actual injection amount of the chemical system is determined. The actual injection amount of the chemical system calculation formula includes:

[0028] In the actual injection amount of the chemical system calculation formula, represents the actual injection amount of the chemical system, represents the core liquid injection speed, represents the injection time.

[0029] In step S140, it is determined whether the actual injection amount of the chemical system reaches the set injection amount to determine whether the actual injection amount of the chemical system reaches the injection amount requirement.

[0030] In step S150, in the case that the actual injection amount of the chemical system is greater than or equal to the set injection amount, the small layer producing coefficient is determined.

[0031] In step S160, the second preset threshold value can be 0.3, and when the small layer producing coefficient is less than or equal to 0.3, it indicates that the interlayer displacement effect of the chemical system in the multilayer reservoir is small during the displacement process, the chemical system can uniformly enter each reservoir, and the displacement effect is good, that is, the current chemical system is determined to be an effective chemical system for the multilayer reservoir, and the chemical system can be used for chemical flooding development of the reservoir condition.

[0032] The above scheme determines the flow resistance of the chemical system in each layer of the reservoir, determines the migration state of the chemical system in the multilayer reservoir, and compares and determines according to the size of the small layer producing coefficient and the second preset threshold value, considers the flow capacity of the chemical system in the reservoir under different chemical systems, and also considers the demand of each layer of the multilayer reservoir for different flow resistance systems, which can provide guidance for the scheme design and agent selection of the field chemical system.

[0033] In an optional implementation, step S110 may include the following steps: Step S111: obtaining the seepage resistance of the first low permeability layer and the seepage resistance of the first high permeability layer of the core filled with water; Step S112: based on the seepage resistance of the first low permeability layer and the seepage resistance of the first high permeability layer, obtaining the flow distribution of the first high permeability layer in the chemical system of the core; Step S113: based on the flow distribution of the first high permeability layer, obtaining the fluid distribution of the first high permeability layer in the chemical system of the core; Step S114: Based on the fluid distribution of the first high permeability layer, the seepage resistance of the high permeability layer of the chemical system in the core is obtained.

[0034] In step S111, the seepage resistance of the first low permeability layer of the core filled with water is determined by a first low permeability layer seepage resistance calculation formula, wherein the first low permeability layer seepage resistance calculation formula includes:

[0035] In the calculation formula of the seepage resistance of the first low permeability layer, represents the seepage resistance of the first low-permeability layer, Indicates the pressure during water drive, Indicates the injection water flow rate, The viscosity of the core when it is filled with water. represents the core length, represents the minimum permeability, Represents the core end area.

[0036] The seepage resistance of the first high permeability layer of the core filled with water is determined by the seepage resistance calculation formula of the first high permeability layer, wherein the seepage resistance calculation formula of the first high permeability layer includes:

[0037] In the calculation formula of the seepage resistance of the first high permeability layer, represents the seepage resistance of the first high permeability layer, Indicates the pressure during water drive, Indicates the injection water flow rate, The viscosity of the core when it is filled with water. represents the core length, represents the maximum permeability, Represents the core end area.

[0038] In an optional implementation, step S112 may include the following steps: Step S112a: Based on the seepage resistance of the first low-permeability layer, the seepage resistance of the first high-permeability layer, and a first formula, the flow distribution of the first high-permeability layer is obtained, wherein the first formula includes:

[0039] In the first formula, Show The flow distribution of the first hypertonic layer at time t (the amount of liquid entering the hypertonic layer at time t+1), express The seepage resistance of the first low permeability layer at time express The seepage resistance of the first high permeability layer at time Indicates the core injection rate.

[0040] Step S112b: Based on the seepage resistance of the first low permeability layer, the seepage resistance of the first high permeability layer, and the flow distribution calculation formula of the first low permeability layer, the flow distribution calculation formula of the first low permeability layer is obtained, wherein the flow distribution calculation formula of the first low permeability layer includes:

[0041] In the calculation formula for flow distribution of the first low permeability layer, Show The flow distribution of the first low-permeability layer at time t (the amount of liquid entering the low-permeability layer at time t+1), express The seepage resistance of the first low permeability layer at time express The seepage resistance of the first high permeability layer at time t, Indicates the core injection rate.

[0042] In steps S112a-S112b, the flow distribution at the next moment (time t+1) can be determined using the proportional relationship of the seepage resistance at time t.

[0043] In an optional embodiment, taking a two-layer oil reservoir as an example, step S113 may include the following steps: Step S113a: Obtain the fluid distribution of the first high permeability layer in the chemical system of the core according to the flow distribution of the first high permeability layer and the calculation formula of the fluid distribution of the first high permeability layer, wherein the calculation formula of the fluid distribution of the first high permeability layer includes:

[0044] In the calculation formula of fluid distribution in the first high permeability layer, represents the fluid distribution of the i-th chemical system in the core in the high permeability layer, represents the flow distribution of the first hypertonic layer of the i-th chemical system entering the hypertonic layer at time t, represents the core length, represents the porosity of the high permeability layer, Represents the core end area.

[0045] Step S113b: Obtain the fluid distribution of the first low permeability layer in the chemical system of the core according to the flow distribution of the first low permeability layer and the calculation formula of the fluid distribution of the first low permeability layer, wherein the calculation formula of the fluid distribution of the first low permeability layer includes:

[0046] In the calculation formula of fluid distribution in the first low permeability layer, represents the fluid distribution of the i-th chemical system in the core in the low permeability layer, represents the flow distribution of the first low-permeability layer of the i-th chemical system entering the low-permeability layer at time t, represents the core length, represents the porosity of the low permeability layer, Represents the core end area.

[0047] In an optional implementation, step S114 may include the following steps: Step S114a: Based on the fluid distribution in the first high permeability layer and the second formula, the seepage resistance of the high permeability layer is obtained, wherein the second formula includes:

[0048] In the second formula, represents the seepage resistance of the hyperpermeable layer, represents the viscosity of the i-th chemical system, represents the fluid distribution of the i-th chemical system in the core in the high permeability layer, represents the fluid distribution of all chemical systems in the high permeability layer in the core, represents the core end area, represents the viscosity of the water phase, represents the core length, Represents the permeability of the high permeability layer.

[0049] Step S114b: Determine the seepage resistance of the low permeability layer in the chemical system of the core based on the fluid distribution of the low permeability layer and the calculation formula of the seepage resistance of the low permeability layer, wherein the calculation formula of the seepage resistance of the low permeability layer includes:

[0050] In the calculation formula of the seepage resistance of the low permeability layer, represents the seepage resistance of the first low-permeability layer, represents the viscosity of the i-th chemical system, represents the fluid distribution of the i-th chemical system in the core in the low permeability layer, represents the minimum permeability, represents the core end area, The viscosity of the core when it is filled with water. represents the core length, It represents the fluid distribution of all chemical systems in the low permeability layer in the core.

[0051] In the embodiment of the present application, the reservoir differential can be determined based on the ratio of the maximum permeability to the minimum permeability within the multi-layer oil reservoir. The reservoir differential refers to the significant difference in reservoir physical properties (mainly permeability) between different small layers (or single layers) within the same oil reservoir. Among them, the maximum permeability and minimum permeability reservoirs represent the maximum difference in the exploitation between the multi-layer oil reservoirs. Therefore, the minimum permeability and maximum permeability are selected to determine the seepage resistance of the low permeability layer and the seepage resistance of the high permeability layer of the multi-layer oil reservoir, respectively.

[0052] In an optional implementation, step S120 may include the following steps: Step S121: based on the current seepage resistance of the hyperpermeable layer and the seepage resistance of the hyperpermeable layer at the previous moment, obtaining the relative change rate of the seepage resistance of the hyperpermeable layer in adjacent time steps; Step S122: when the relative change rate of the seepage resistance of the hyperpermeable layer is greater than or equal to a first preset threshold, determining that the chemical system plays a resistance adjustment role; Step S123: when the relative change rate of the seepage resistance of the hyperpermeable layer is less than a first preset threshold, it is determined that the chemical system does not play a resistance adjustment role.

[0053] In step S121, the relative change rate of the high permeability layer seepage resistance at all adjacent time steps is calculated based on the current high permeability layer seepage resistance, the high permeability layer seepage resistance at the previous moment, and the calculation formula for the relative change rate of the high permeability layer seepage resistance. The calculation formula for the relative change rate of the high permeability layer seepage resistance includes:

[0054] In the calculation formula of the relative change rate of seepage resistance in the high permeability layer, It represents the relative change rate of seepage resistance in the high permeability layer. represents the seepage resistance of the hypertonic layer of the i-th chemical system at time t-1, represents the seepage resistance of the hypertonic layer of the i-th chemical system at time t.

[0055] In steps S122 and S123, the first preset threshold value may be 1%. If the relative change rate of the seepage resistance in the high-permeability layer is greater than or equal to 1%, the chemical system still functions to regulate the resistance in the multi-layer reservoir. If the relative change rate of the seepage resistance in the high-permeability layer is less than 1%, the chemical system's resistance regulation function in the multi-layer reservoir is nearly ineffective.

[0056] This embodiment of the present application determines whether the current chemical system still has resistance adjustment effects by comparing the relative change rate of the seepage resistance of the hyperpermeability layer with a first preset threshold. If resistance adjustment effects are not present, a new chemical system is required; if resistance adjustment effects are still present, the current chemical system is continued.

[0057] In an optional implementation, step S150 may include the following steps: Step S151: obtaining the diversion rate of the high permeability layer and the core injection rate; Step S152: Based on the diversion rate of the high permeability layer and the core injection rate, the small layer production coefficient is obtained.

[0058] In steps S151 to S152, the small layer production coefficient can be obtained by substituting the high permeability layer diversion rate and the core injection rate into the small layer production coefficient calculation formula. The small layer production coefficient calculation formula includes:

[0059] In the calculation formula of the small layer utilization coefficient, represents the small layer utilization coefficient, represents the diversion rate of the hypertonic layer, represents the core injection rate, Represents the number of reservoirs. Schematically, the small layer production coefficient = (high permeability layer diversion rate - average diversion rate) / average diversion rate, and the number of reservoirs is 2.

[0060] In an optional embodiment, the method further comprises the following steps: Step S210: If the chemical system does not play a role in regulating the resistance or the small layer producing coefficient is greater than a second preset threshold, the chemical system is replaced until the actual injection volume is greater than or equal to the set injection volume and the small layer producing coefficient is less than or equal to the second preset threshold; Step S220: Based on all effective chemical systems, determine an effective chemical system combination for the multi-layer oil reservoir.

[0061] In steps S210 to S220, when the chemical system does not play a role in resistance adjustment or the small layer utilization coefficient is greater than the second preset threshold, the chemical system is replaced and the above steps S110 to S160 are repeated until the actual injection volume of the chemical system is greater than or equal to the set injection volume and the small layer utilization coefficient is less than or equal to the second preset threshold. The replacement of the chemical system is stopped, and all effective chemical systems are determined as the effective chemical system combination of the multi-layer oil reservoir.

[0062] In the process of chemical system-based enhanced oil recovery in multi-layered reservoirs, it is often difficult to achieve optimal results by consistently using a single chemical system. Therefore, in the present embodiment, by replacing the chemical system and repeating steps S110 to S160, an effective chemical system combination for the multi-layered reservoir is obtained, and the optimal recovery rate is achieved by using the effective chemical system combination for the multi-layered reservoir.

[0063] In an optional embodiment, the method further comprises the following steps: Step S310: when the actual injection volume is less than the set injection volume, obtaining the viscosity of the chemical system at the current moment and the viscosity of the chemical system at the previous moment; Step S320: determining whether the chemical system should be changed based on the viscosity of the chemical system at the current moment and the viscosity of the chemical system at the previous moment; Step S330: When the chemical system is replaced, the quantity of the chemical system is recorded.

[0064] In steps S310-S330, if the current chemical system viscosity is equal to the previous chemical system viscosity, the chemical system has not been changed. If the current chemical system viscosity is not equal to the previous chemical system viscosity, the chemical system has been changed, and the number of chemical systems changed is recorded.

[0065] The following describes in detail the method for determining the chemical system of a multi-layer oil reservoir provided by the present application through three specific examples.

[0066] Example 1: Block information: minimum permeability of the reservoir , permeability difference The maximum permeability of the reservoir is the product of the minimum permeability and the permeability difference. The maximum permeability and minimum permeability reservoirs represent the maximum difference in exploitation between multi-layer reservoirs. Therefore, the maximum permeability layer and the minimum permeability layer in the multi-layer reservoir are selected for development.

[0067] Set the minimum permeability of the reservoir , permeability difference , the maximum permeability of the reservoir All reservoirs are of equal thickness, with a water phase viscosity of 1 mPa·s and an oil phase viscosity of 10 mPa·s. The set injection volume for the chemical system is 0.7 PV. The resistance coefficients and corresponding effective viscosities of different chemical systems in different reservoirs are shown in Table 1. Different chemical systems are defined by different permeabilities, and different reservoirs are defined by different viscosities. The initial viscosity of the chemical system is determined to be 65 mPa·s.

[0068] Table 1

[0069] Calculate the seepage resistance, flow distribution, and fluid distribution in each layer of the core. Figure 2 A schematic diagram of flow distribution during the injection of a chemical system according to an embodiment of the present application is shown. Figure 2 As shown, Figure 2 The horizontal axis represents the actual injection volume (PV), and the vertical axis represents the flow distribution.

[0070] Calculate the small layer utilization coefficient, Figure 3 A schematic diagram of a small layer activation coefficient according to an embodiment of the present application is shown schematically. Figure 3 As shown in the figure, the set displacement requirements (small layer utilization coefficient ≤ 0.3%) have been met at this time. There is no need to change the chemical system. Using a chemical system with an initial viscosity of 65 mPa·s to displace the permeability combination of 1000 mD and 3300 mD can meet the set displacement requirements (small layer utilization coefficient ≤ 0.3%).

[0071] Example 2: Set the minimum permeability of the reservoir , permeability difference , the maximum permeability of the reservoir The viscosity of the initial chemical system was selected to be 65 mPa·s, and the other basic parameter settings were consistent with those in Example 1 and will not be repeated here.

[0072] Calculate the seepage resistance, flow distribution, and fluid distribution in each layer of the core. Figure 4 A schematic diagram of flow distribution during injection of another chemical system according to an embodiment of the present application is shown. Figure 4 As shown, Figure 4 The horizontal axis represents the actual injection volume (PV), and the vertical axis represents the flow distribution.

[0073] When the actual injection volume reaches 0.17PV, the chemical system is switched to 22mPa·s; when the actual injection volume reaches 0.3PV, the chemical system is switched to 65mPa·s; when the actual injection volume is 0.52PV, the chemical system is switched to 22mPa·s. In this process, the small layer production coefficient is calculated. Figure 5 Another schematic diagram of a small layer activation coefficient according to an embodiment of the present application is shown schematically. Figure 5 As shown in the figure, the set displacement requirement (small layer utilization coefficient ≤ 0.3%) is finally met to obtain an effective chemical system combination for multi-layer oil reservoirs.

[0074] Example 3: Changing reservoir conditions Minimum permeability and reservoir grade difference By repeating the above steps S110 to S160 multiple times, an effective chemical system design for a multi-layer oil reservoir can be obtained. Figure 6A schematic diagram of an effective chemical system design for a multi-layer oil reservoir according to an embodiment of the present application is shown schematically. Figure 6 As shown, a single chemical system can meet the displacement requirements in the gray area; the scheme design for the circular area requires alternating chemical systems to adjust the seepage difference between high and low layers; the scheme design for the diamond area adopts a step-by-step viscosity reduction polymer flooding scheme; the scheme design for the star-shaped area belongs to high-quality oil reservoirs, where the permeability of both high and low permeability layers is high, and multiple uses of high-viscosity polymer flooding are required.

[0075] The present application also provides a chemical system determination system for a multi-layer oil reservoir, including: The first acquisition module is used to obtain the current seepage resistance of the high permeability layer of the chemical system in the core of the multi-layer oil reservoir; A first determination module is configured to determine whether the chemical system plays a resistance adjustment role based on the current seepage resistance of the hyperpermeability layer and a first preset threshold; The second acquisition module is used to obtain the actual injection amount of the chemical system when the chemical system plays a resistance adjustment role; The second determination module is used to determine whether the actual injection amount of the chemical system is greater than or equal to the set injection amount; The third acquisition module is used to obtain the small layer production coefficient when the actual injection volume is greater than or equal to the set injection volume; The third determination module is configured to determine that the current chemical system is an effective chemical system of the multi-layer oil reservoir when the small layer producing coefficient is less than or equal to a second preset threshold value.

[0076] It can be understood that the chemical system determination system for a multi-layer oil reservoir provided in the embodiment of the present application can implement each process of the chemical system determination method for a multi-layer oil reservoir in the above embodiment and can achieve the same technical effect. To avoid repetition, it will not be described here.

[0077] The present application also provides a device for determining a chemical system of a multi-layer oil reservoir, comprising: a memory configured to store instructions; The processor is configured to call instructions from the memory and implement the chemical system determination method of the multi-layered oil reservoir as described above when executing the instructions.

[0078] It can be understood that the chemical system determination device for a multi-layer oil reservoir provided in the embodiment of the present application can implement each process of the chemical system determination method for a multi-layer oil reservoir in the above embodiment and can achieve the same technical effect. To avoid repetition, it will not be described here.

[0079] An embodiment of the present application further provides a machine-readable storage medium having stored thereon instructions for causing a machine to execute the method for determining the chemical system of a multi-layer oil reservoir as described above.

[0080] It is understandable that the machine-readable storage medium provided in the embodiment of the present application can implement each process of the chemical system determination method of the multi-layer oil reservoir in the above embodiment and can achieve the same technical effect. To avoid repetition, it will not be described here.

[0081] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0082] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0083] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0084] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0085] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0086] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0087] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can be implemented using any method or technology for information storage. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change RAM (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media, such as modulated data signals and carrier waves.

[0088] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0089] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A method for determining the chemical system of a multi-layer oil reservoir, characterized in that: include: Obtaining the current seepage resistance of the high permeability layer of the chemical system existing in the core of the multi-layer oil reservoir; determining whether the chemical system plays a resistance adjustment role based on the current seepage resistance of the hyperpermeability layer and a first preset threshold; obtaining an actual injection amount of the chemical system when the chemical system plays a role in adjusting resistance; determining whether the actual injection volume of the chemical system is greater than or equal to the set injection volume; When the actual injection volume is greater than or equal to the set injection volume, obtaining a small layer producing coefficient; When the small layer producing coefficient is less than or equal to a second preset threshold, the current chemical system is determined to be an effective chemical system of the multi-layer oil reservoir.

2. The method according to claim 1, characterized in that The obtaining of the current high permeability layer seepage resistance of the chemical system in the core of the multi-layer oil reservoir includes: Obtain the seepage resistance of the first low permeability layer and the first high permeability layer filled with water in the core; Based on the seepage resistance of the first low-permeability layer and the seepage resistance of the first high-permeability layer, a flow distribution of the first high-permeability layer in the chemical system of the core is obtained; Based on the flow distribution of the first high permeability layer, a fluid distribution of the first high permeability layer in the chemical system of the core is obtained; Based on the fluid distribution of the first high permeability layer, the seepage resistance of the high permeability layer of the chemical system in the core is obtained.

3. The method according to claim 2, characterized in that The obtaining of the flow distribution of the first high permeability layer in the chemical system of the core based on the seepage resistance of the first low permeability layer and the seepage resistance of the first high permeability layer includes: Based on the seepage resistance of the first low-permeability layer, the seepage resistance of the first high-permeability layer, and a first formula, the flow distribution of the first high-permeability layer is obtained, wherein the first formula includes: In the first formula, Show The flow distribution of the first high permeability layer at time express The seepage resistance of the first low permeability layer at time express The seepage resistance of the first high permeability layer at time Indicates the core injection rate.

4. The method according to claim 2, characterized in that The obtaining of the seepage resistance of the high permeability layer of the chemical system in the core based on the fluid distribution of the first high permeability layer includes: Based on the fluid distribution in the first high permeability layer and the second formula, the seepage resistance of the high permeability layer is obtained, wherein the second formula includes: In the second formula, represents the seepage resistance of the hyperpermeable layer, represents the viscosity of the i-th chemical system, represents the fluid distribution of the i-th chemical system in the core of the high permeability layer, represents the fluid distribution of all chemical systems in the high permeability layer in the core, represents the core end area, represents the viscosity of the water phase, represents the core length, Indicates the maximum permeability.

5. The method according to claim 1, wherein The determining whether the chemical system plays a resistance adjustment role based on the seepage resistance of the hyperpermeability layer and a first preset threshold value includes: Based on the current seepage resistance of the hyperpermeable layer and the seepage resistance of the hyperpermeable layer at a previous moment, obtaining a relative change rate of the seepage resistance of the hyperpermeable layer at adjacent time steps; When the relative change rate of the seepage resistance of the hyperpermeable layer is greater than or equal to the first preset threshold, determining that the chemical system plays a resistance adjustment role; When the relative change rate of the seepage resistance of the hyperpermeability layer is less than the first preset threshold, it is determined that the chemical system does not play a resistance adjustment role.

6. The method according to claim 1, characterized in that The obtaining of the small layer utilization coefficient includes: Obtain high permeability layer diversion rate and core injection rate; The small layer production coefficient is obtained based on the high permeability layer diversion rate and the core injection rate.

7. The method according to claim 1, characterized in that Also includes: If the chemical system does not play a role in adjusting the resistance or the small layer producing coefficient is greater than a second preset threshold, replace the chemical system until the actual injection amount is greater than or equal to the set injection amount and the small layer producing coefficient is less than or equal to the second preset threshold; Based on all effective chemical systems, an effective chemical system combination of the multi-layered reservoir is determined.

8. A chemical system determination system for a multi-layer oil reservoir, characterized in that: include: A first acquisition module is used to obtain the current seepage resistance of the high permeability layer of the chemical system existing in the core of the multi-layer oil reservoir; a first determining module, configured to determine whether the chemical system plays a resistance adjustment role based on the current seepage resistance of the hyperpermeability layer and a first preset threshold; a second acquisition module, configured to acquire an actual injection volume of the chemical system when the chemical system plays a resistance adjustment role; A second determination module is used to determine whether the actual injection amount of the chemical system is greater than or equal to the set injection amount; A third acquisition module is used to obtain a small layer production coefficient when the actual injection amount is greater than or equal to the set injection amount; The third determining module is configured to determine that the current chemical system is an effective chemical system of the multi-layer oil reservoir when the small layer producing coefficient is less than or equal to a second preset threshold.

9. A device for determining the chemical system of a multi-layer oil reservoir, characterized in that: include: a memory configured to store instructions; A processor is configured to call the instructions from the memory and implement the chemical system determination method for a multi-layered oil reservoir according to any one of claims 1 to 7 when executing the instructions.

10. A machine-readable storage medium, characterized in that The machine-readable storage medium stores instructions for causing a machine to execute the method for determining a chemical system of a multi-layer oil reservoir according to any one of claims 1 to 7.

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