Unconventional oil reservoir water injection huff-puff development effect evaluation method, equipment and product

Abstract

The invention discloses an unconventional oil reservoir water injection huff-puff development effect evaluation method, equipment and a product, and relates to the field of oil-gas field development. Firstly, according to the oil reservoir property of a target oil reservoir and construction parameters of a water injection huff-puff well, a water injection huff-puff development effect evaluation index system and a grading standard are established, and on the basis, single-index evaluation of all indexes can be conducted; obtaining a basic condition index evaluation result and a dynamic response index evaluation result of the target water injection throughput well by using a fuzzy comprehensive evaluation method, and comparing the two results to evaluate the effectiveness of the current water injection throughput measure; and further calculating a comprehensive evaluation index of the target water injection huff-puff well by utilizing a fuzzy comprehensive evaluation method, and carrying out overall evaluation on the water injection huff-puff development effect according to the comprehensive evaluation index. The rationality and accuracy of evaluation of the unconventional oil reservoir water injection huff and puff development effect can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas field development, and in particular to a method, equipment and product for evaluating the effect of water injection and huff-and-puff development of unconventional oil reservoirs. Background Art

[0002] At present, there are three main methods commonly used to evaluate the effect of water injection development in oil reservoirs, namely, development dynamic analysis method, water drive characteristic curve analysis method and injection-production correspondence analysis method. The development dynamic analysis method mainly analyzes the changes in parameters such as daily liquid production, daily oil production, cumulative liquid production, cumulative oil production, and water content of different wells through the development dynamic curve of injection-production well groups or well points, and qualitatively evaluates the effectiveness of water injection and the development effect. The water drive characteristic curve analysis method calculates the sweep coefficient of water drive reservoirs by establishing a curve of changes in recovery degree and water content, and quantitatively evaluates the effect of water injection. The injection-production correspondence analysis method mainly combines geological stratification data to judge the corresponding conditions of the injection and production layers in the well group, and semi-quantitatively evaluates the effect of injection and production. However, these methods are mainly aimed at the water drive process of conventional oil reservoirs, and are less applicable to the water injection and huff-and-puff process of unconventional oil reservoirs such as tight oil and shale oil.

[0003] Unconventional oil reservoirs such as tight oil and shale oil have extremely poor physical properties, and their permeability is generally 3 to 5 orders of magnitude lower than that of conventional oil reservoirs. Therefore, conventional oil reservoirs are mainly developed by water flooding, that is, the water injection well and the oil production well are different wells, and the injected water displaces the oil to the oil production well and produces it; however, the ultra-low permeability characteristics of the reservoir make it difficult for unconventional oil reservoirs to form an injection-production pressure system, so unconventional oil reservoirs are often developed by water injection, that is, the water injection well and the oil production well are the same well. The difference in the seepage laws and development methods between conventional and unconventional oil reservoirs makes the currently commonly used water injection development effect evaluation method unsuitable for the water injection and production process of unconventional oil reservoirs. Summary of the invention

[0004] The purpose of this application is to provide a method, equipment and product for evaluating the effect of water injection and huff-and-puff development in unconventional oil reservoirs, so as to improve the rationality and accuracy of the evaluation of the effect of water injection and huff-and-puff development in unconventional oil reservoirs.

[0005] To achieve the above objectives, this application provides the following solutions.

[0006] In a first aspect, the present application provides a method for evaluating the effect of water injection huff and puff development in unconventional oil reservoirs, comprising: establishing a water injection huff and puff development effect evaluation index system according to the reservoir properties of the target oil reservoir and the construction parameters of the water injection huff and puff wells; the water injection huff and puff development effect evaluation index system comprises a plurality of basic condition indicators and a plurality of dynamic response indicators; determining a grading standard for evaluating each basic condition indicator and each dynamic response indicator according to the value range of actual data of the water injection huff and puff wells in the target oil reservoir; performing a single indicator evaluation according to the grading standard for evaluating each basic condition indicator and each dynamic response indicator, and determining the target oil reservoir. The single indicator evaluation results of each basic condition indicator and each dynamic response indicator of the water injection well; based on the water injection injection development effect evaluation index system, the fuzzy comprehensive evaluation method is used to obtain the basic condition indicator evaluation results and dynamic response indicator evaluation results of the target water injection injection well; the basic condition indicator evaluation results and dynamic response indicator evaluation results of the target water injection well are compared to evaluate the effectiveness of the current water injection measures; based on the water injection injection development effect evaluation index system, the fuzzy comprehensive evaluation method is used to calculate the comprehensive evaluation index of the target water injection well, and the water injection injection development effect is evaluated as a whole.

[0007] Optionally, a water injection huff and puff development effect evaluation index system is established according to the reservoir properties of the target oil reservoir and the construction parameters of the water injection huff and puff wells, specifically comprising: selecting Class I reservoir reserves, Class II reservoir reserves, fracturing cluster spacing, horizontal well single-stage sand addition intensity, horizontal well single-stage fluid usage intensity and crude oil viscosity as multiple basic condition indicators of the water injection huff and puff development effect evaluation index system according to the reservoir properties of the target oil reservoir and the construction parameters of the water injection huff and puff wells; selecting tons of water oil exchange rate, cumulative throughput oil increase, cumulative injection-production ratio, recovery degree, first-year cumulative oil production and fracture network complexity as multiple dynamic response indicators of the water injection huff and puff development effect evaluation index system.

[0008] Optionally, the grading standard for evaluating each basic condition indicator and each dynamic response indicator is determined based on the value range of actual data of water injection wells in the target oil reservoir, specifically including: based on the actual data of water injection wells in the target oil reservoir, integrating one or more means of adaptive clustering, factor analysis, mine statistics and industry standards, determining the value range of each basic condition indicator and each dynamic response indicator into one, two or three categories as the grading standard for evaluating each basic condition indicator and each dynamic response indicator.

[0009] Optionally, the water injection huff and puff development effect evaluation index system is based on the use of a fuzzy comprehensive evaluation method to obtain basic condition index evaluation results and dynamic response index evaluation results of the target water injection huff and puff well, specifically including: based on the water injection huff and puff development effect evaluation index system, using the fuzzy analytic hierarchy process to respectively establish judgment matrices for basic condition indexes and dynamic response indexes; calculating weight sets of basic condition indexes and dynamic response indexes according to the judgment matrices of the basic condition indexes and dynamic response indexes respectively; calculating the membership of each basic condition index and each dynamic response index relative to each grading standard, and constructing a membership judgment matrix corresponding to the basic condition index and the dynamic response index; calculating the basic condition index evaluation results of the target water injection huff and puff well according to the weight set of the basic condition index and the membership judgment matrix corresponding to the basic condition index; calculating the dynamic response index evaluation results of the target water injection huff and puff well according to the weight set of the dynamic response index and the membership judgment matrix corresponding to the dynamic response index.

[0010] Optionally, the water injection throughput development effect evaluation index system is based on which judgment matrices for basic condition indicators and dynamic response indicators are established respectively using fuzzy hierarchical analysis method, specifically including: comparing each basic condition indicator in the water injection throughput development effect evaluation index system in pairs, and constructing a judgment matrix for basic condition indicators based on the importance scale obtained by comparison; comparing each dynamic response indicator in the water injection throughput development effect evaluation index system in pairs, and constructing a judgment matrix for dynamic response indicators based on the importance scale obtained by comparison.

[0011] Optionally, respectively calculating the membership of each basic condition indicator and each dynamic response indicator relative to each grading standard, and constructing a membership evaluation matrix corresponding to the basic condition indicator and the dynamic response indicator, specifically includes: substituting the specific numerical value of each basic condition indicator into a trapezoidal membership function, calculating the membership of each basic condition indicator relative to each grading standard by using the trapezoidal membership function, and forming a membership evaluation matrix corresponding to the basic condition indicator; substituting the specific numerical value of each dynamic response indicator into the trapezoidal membership function, calculating the membership of each dynamic response indicator relative to each grading standard by using the trapezoidal membership function, and forming a membership evaluation matrix corresponding to the dynamic response indicator.

[0012] Optionally, the basic condition index evaluation result and the dynamic response index evaluation result of the target water injection well are compared to evaluate the effectiveness of the current water injection throughput measures, specifically including: if the dynamic response index evaluation result is greater than 1.2 times the basic condition index evaluation result, it indicates that the current water injection throughput measures are very effective; if the dynamic response index evaluation result is between 0.8 and 1.2 times the basic condition index evaluation result, it indicates that the current water injection throughput measures are relatively effective; if the dynamic response index evaluation result is less than 0.8 times the basic condition index evaluation result, it indicates that the current water injection throughput measures are poor.

[0013] Optionally, the water injection huff and puff development effect evaluation index system is based on which a fuzzy comprehensive evaluation method is used to calculate a comprehensive evaluation index of a target water injection huff and puff well, and an overall evaluation of the water injection huff and puff development effect is performed, specifically including: calculating a comprehensive weight matrix of all indicators based on a weight set of basic condition indicators and dynamic response indicators; calculating a comprehensive evaluation index of the target water injection huff and puff well based on the comprehensive weight matrix of all indicators and a membership judgment matrix corresponding to all indicators; and performing an overall evaluation of the water injection huff and puff development effect based on the comprehensive evaluation index of the target water injection huff and puff well.

[0014] In a second aspect, the present application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for evaluating the development effect of water injection in unconventional oil reservoirs.

[0015] In a third aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the method for evaluating the development effect of water injection in unconventional oil reservoirs.

[0016] According to the specific embodiments provided in this application, this application discloses the following technical effects: The present application provides a method, equipment and product for evaluating the development effect of water injection and huff-and-puff in unconventional oil reservoirs. It comprehensively considers the particularity of the seepage law and development mode of unconventional oil reservoirs, combines the basic condition indicators with the dynamic response indicators within the well control range, establishes a water injection and huff-and-puff development effect evaluation index system, clarifies the grading standards for the evaluation of different indicators, and performs single indicator evaluation based on this. On the other hand, based on the fuzzy comprehensive evaluation method, the basic condition indicator evaluation results, the dynamic response indicator evaluation results and the comprehensive evaluation index can be calculated. By comparing the calculated basic condition indicator evaluation results with the dynamic response indicator evaluation results, the effectiveness of the current water injection and huff-and-puff measures can be evaluated. According to the comprehensive evaluation index of the target water injection and huff-and-puff well, the water injection and huff-and-puff development effect can be evaluated as a whole. The present application combines the above methods to achieve a scientific, comprehensive, objective, true, reasonable and accurate evaluation of the development effect of water injection and huff-and-puff in unconventional oil reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1The present invention is a flow chart of a method for evaluating the effect of water injection and huff-and-puff development in unconventional oil reservoirs for this application. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] The purpose of this application is to provide a method, equipment and product for evaluating the effect of water injection and huff-and-puff development in unconventional oil reservoirs, so as to improve the rationality and accuracy of the evaluation of the effect of water injection and huff-and-puff development in unconventional oil reservoirs.

[0021] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0022] In an exemplary embodiment, Figure 1 As shown, a method for evaluating the development effect of water injection in unconventional oil reservoirs is provided, including the following steps 1 to 6.

[0023] Step 1: Establish a water injection huff and puff development effect evaluation index system according to the reservoir properties of the target reservoir and the construction parameters of the water injection huff and puff well; the water injection huff and puff development effect evaluation index system includes multiple basic condition indicators and multiple dynamic response indicators.

[0024] Unconventional oil reservoirs refer to oil reservoir resources with poor oil and gas quality, poor fluidity, low porosity and permeability, no natural production capacity, and difficult to exploit or poor exploitation efficiency using existing technologies, such as tight oil and shale oil. These reservoirs usually require special technologies and processes to achieve efficient exploitation. This application takes unconventional oil reservoirs such as tight oil and shale oil as target reservoirs to study the evaluation method of their water injection and huff-and-puff development effect.

[0025] Specifically, this application selects Class I reservoir reserves, Class II reservoir reserves, fracturing cluster spacing, horizontal well single-stage sand addition intensity, horizontal well single-stage fluid intensity and crude oil viscosity as multiple basic condition indicators of the water injection and huff development effect evaluation index system according to the reservoir properties of the target oil reservoir and the construction parameters of the water injection and huff well. The oil-for-oil ratio per ton of water, the cumulative increase in oil production through throughput, the cumulative injection-production ratio, the degree of recovery, the cumulative oil production in the first year and the complexity of the seam network are selected as multiple dynamic response indicators of the water injection and huff development effect evaluation index system. The following is a detailed introduction to the above basic condition indicators and dynamic response indicators in the water injection and huff development effect evaluation index system. In the following text, the basic condition indicators and dynamic response indicators are also collectively referred to as evaluation indicators, or indicators for short.

[0026] The various basic condition indicators are introduced as follows.

[0027] Class I and II reservoir reserves: Class I and II reservoirs are crude oil-rich areas and are important indicators for evaluating the richness of reservoir resources. They represent the reserve potential within the well control range. The size of reserves directly affects the feasibility and potential production capacity of water injection and huff-and-puff development, so it is one of the required indicators.

[0028] Fracturing cluster spacing: refers to the distance between horizontal well fracturing clusters. Since unconventional oil reservoirs are mainly developed by multi-stage horizontal well fracturing, the fracturing cluster spacing is directly related to the density and uniformity of horizontal well fracturing cracks in water injection and throughput. Reasonable fracturing cluster spacing can ensure effective water injection in horizontal wells, thereby achieving better throughput effects, and is therefore an important factor affecting development results.

[0029] Single-stage sanding intensity and single-stage fluid intensity of horizontal wells: These two indicators reflect the quality of proppant (sand) added and injected fracturing fluid per unit length of horizontal wells. The greater the single-stage fluid intensity, the more fracturing fluid enters the single stage during the fracturing process, and the larger the fracturing transformation volume; the greater the single-stage sanding intensity, the better the proppant laying effect in the fracture, the less likely the fracture is to close, and the long-term conductivity of the fracture can be effectively maintained. Therefore, the single-stage fluid intensity and the single-stage sanding intensity respectively evaluate the fracturing transformation effect and the conductivity retention before the water injection and huff-and-puff of the reservoir, which are crucial to ensuring the development effect of water injection and huff-and-puff.

[0030] Crude oil viscosity: an important indicator for measuring the fluidity of crude oil, which directly affects the difficulty of oil reservoir exploitation and the effect of water injection. The higher the viscosity, the weaker the oil-water displacement effect during water injection, and the more difficult it is to exploit the oil reservoir.

[0031] The above six evaluation indicators mainly reflect the information of geological characteristics, reserve size, fracture network transformation degree of oil reservoirs, etc. For example, the reserves of Class I and II reservoirs and crude oil viscosity reflect the geological characteristics of oil reservoirs, the reserves of Class I and II reservoirs also reflect the reserve size of oil reservoirs, and the spacing of fracturing clusters, the sand addition intensity of single stage of horizontal wells and the fluid intensity of single stage of horizontal wells reflect the fracture network transformation degree of oil reservoirs. Although the above six basic condition indicators themselves do not directly involve the dynamic changes in the production process, they are very important for whether the potential of water injection and huff-and-puff measures can be fully utilized.

[0032] Each dynamic response indicator is introduced as follows.

[0033] Ton of water to oil rate: One of the important indicators to measure the effect of water injection and huff and puff development, indicating the volume of underground crude oil replaced by a unit volume of injected water. The higher the ton of water to oil rate, the greater the amount of oil produced during the water injection and huff and puff process, and the greater the potential for oilfield production increase.

[0034] Cumulative throughput oil increase and cumulative injection-production ratio: These two indicators reflect the cumulative effect of water injection and huff development. Cumulative throughput oil increase is the cumulative throughput oil increase obtained by the reservoir through water injection and huff development, and the cumulative injection-production ratio is the ratio of the cumulative water injection volume to the cumulative liquid production volume of the reservoir, reflecting the overall effect of water injection and huff development and measuring the degree of formation energy replenishment.

[0035] Recovery degree: the ratio of cumulative oil production to geological reserves. It reflects the extent to which crude oil in the reservoir has been recovered, is directly related to the remaining recoverable reserves and production effect of the reservoir, and is of great significance for evaluating the effect of water injection and huff-and-puff development.

[0036] Cumulative oil production in the first year: One of the key indicators for evaluating the initial effects of water injection and huff-and-puff development, which can reflect the production capacity and efficiency in the initial stage of development.

[0037] Fracture network complexity: usually used to evaluate the degree of fracture development and the connectivity of the fracture network in the reservoir. During the fracturing process, excessive extension pressure causes the fractures to communicate with the surrounding natural fractures, thus forming a complex fracture network. The more developed and densely distributed the fractures are, the more complex the fracture network is, the higher the degree of oil-water mixing and replacement is, and the more conducive it is to improving the water injection effect.

[0038] During the development of oil reservoirs, measures such as water injection and repeated fracturing will change the underground pressure distribution and fracture network state of the reservoir, thereby affecting the degree of fracture development. Therefore, the complexity of the fracture network may change at different stages, and this indicator also reflects the dynamic evolution of the fracture network during the development of the oil reservoir. According to the dynamic response characteristics of the on-site fracturing section, this application establishes a classification standard for the complexity of the fracture network based on the characteristics of changes in pressure, oil volume, liquid volume, and water content, thereby using indicators that are easily obtained on-site to achieve quantitative evaluation of the complexity of the fracture network. The specific classification standards for the complexity of the fracture network are shown in Table 1. According to the complexity of the fracture network, it can be divided into four types, namely, complex fracture network type, developed fracture network type, micro-fracture communication type, and main fracture communication type.

[0039] Table 1 Classification standard of seam network complexity

[0040] In Table 1, the unit of pressure change is megapascal (MPa), the unit of oil volume change is ton (t), and the unit of liquid volume change is cubic meter (m 3 ), the water content change is in percentage (%). The complexity of the seam network is obtained by comprehensive evaluation of single indicators such as pressure change, oil volume change, liquid volume change, and water content change in Table 1, namely: (1). Among them, For each indicator (e.g. pressure change, oil volume change, liquid volume change, water content change), For each indicator The weight of . In order to measure the number of indicators for the complexity of the seam network, the embodiment shown in Table 1 ,but They correspond to changes in pressure, oil volume, liquid volume and water content respectively. is the calculated complexity of the seam network.

[0041] Among them, the membership The calculation of is based on the corresponding levels in Table 1. For example, if the indicator If the single index evaluation result is a complex fracture network type, the membership degree is 4; if the single index evaluation result is a developed fracture network type, the membership degree is 3; if the single index evaluation result is a micro-fracture communication type, the membership degree is 2; if the single index evaluation result is a main fracture communication type, the membership degree is 1. Weight The distribution calculation is based on the correlation between the indicators, and the weights of each indicator are determined by the hierarchical analysis method: 0.5, 0.3, 0.1, and 0.1.

[0042] Step 2: According to the value range of the actual data of water injection wells in the target reservoir, determine the grading standards for the evaluation of each basic condition index and each dynamic response index.

[0043] Specifically, this application integrates multiple means such as adaptive clustering, factor analysis, mine statistics and industry standards, combines qualitative and quantitative methods, determines the value range of each basic condition indicator and each dynamic response indicator, and organizes them into the grading standards of each indicator in the water injection and huff and puff development effect evaluation index system shown in Table 2.

[0044] Table 2 Evaluation index system and classification standards of each index for reservoir water injection huff-and-puff development effect

[0045] In Table 2, the unit t represents tons, m represents meters, mPa·s represents millipascal·seconds, and % represents percentage. The evaluation results of reservoir water injection huff-and-puff development effects are divided into three categories, among which Category I (category one) is the parameter value range that is most conducive to production or optimal dynamic response, followed by Category II (category two), and Category III (category three).

[0046] Step 3: Perform single indicator evaluation according to the grading standards for evaluation of each basic condition indicator and each dynamic response indicator, and determine the single indicator evaluation results of each basic condition indicator and each dynamic response indicator of the target water injection well.

[0047] Before conducting a comprehensive evaluation of the development effect of water injection and huff-and-puff, a single indicator evaluation can be conducted for each basic condition index and each dynamic response index of the target water injection and huff-and-puff well (hereinafter referred to as the target well). Specifically, the measured data (actual values) of each index of the target well are compared with the classification standards in Table 2, and the single indicator evaluation results of each evaluation index can be obtained by judging whether it belongs to Class I, Class II or Class III according to the interval of the actual value. Among them, the reserves of Class I and Class II reservoirs, the spacing between fracturing clusters, the sand addition intensity of a single stage of a horizontal well and the liquid intensity of a single stage of a horizontal well, the viscosity of crude oil, and the cumulative oil production in the first year can be directly obtained based on the measured data of the target well. Ton-water oil exchange rate = cumulative oil increase in each cycle of water injection and huff-and-puff / cumulative water injection in each cycle of water injection and huff-and-puff. Cumulative injection-production ratio = ratio of cumulative water injection to cumulative liquid production. Cumulative oil increase after huff-and-puff = cumulative oil production predicted to be abandoned after water injection and huff-cumulative oil production predicted to be abandoned before water injection and huff-and-puff. Recovery degree = ratio of cumulative oil production to geological reserves. The calculation of the complexity of the seam network is shown in formula (1).

[0048] The step 3 specifically includes the following steps 3.1 to 3.12.

[0049] Step 3.1: When the reserves of a type of reservoir in the target water injection well are greater than 11×10 4 t, the single index evaluation result of the first-class reservoir reserves is determined as the first-class; when the first-class reservoir reserves of the target water injection well are 5×10 4 t to 11×10 4 t, the single index evaluation result of the first-class reservoir reserves is determined to be the second class; when the first-class reservoir reserves of the target water injection well are less than 5×10 4 At t, the single index evaluation results of the reserves of a type of reservoir are determined to be three categories.

[0050] Step 3.2: When the reserves of the second-class reservoir of the target water injection well are greater than 15×10 4 t, the single index evaluation result of the Class II reservoir reserves is determined to be Class I; when the Class II reservoir reserves of the target water injection well are between 9×10 4 t to 15×10 4 t, the single index evaluation result of the Class II reservoir reserves is determined to be Class II; when the Class II reservoir reserves of the target water injection well are less than 9×10 4 At t, the single index evaluation result of the reserves of the second type of reservoir is determined to be three types.

[0051] Step 3.3: When the fracturing cluster spacing of the target water injection well is less than 9m, the single index evaluation result of the fracturing cluster spacing is determined to be Class I; when the fracturing cluster spacing of the target water injection well is between 9m and 12m, the single index evaluation result of the fracturing cluster spacing is determined to be Class II; when the fracturing cluster spacing of the target water injection well is greater than 12m, the single index evaluation result of the fracturing cluster spacing is determined to be Class III.

[0052] Step 3.4: When the horizontal well single-stage sand addition intensity of the target water injection well is greater than 2.5m 3 ·m -1 When the single index evaluation result of the single-stage sand addition strength of the horizontal well is determined to be Class I; when the single-stage sand addition strength of the horizontal well of the target water injection well is 2m 3 ·m -1 Up to 2.5m 3 ·m -1 When the single index evaluation result of the horizontal well single-stage sand addition strength is determined to be Class II; when the horizontal well single-stage sand addition strength of the target water injection well is less than 2m 3 ·m -1 When determining the single index evaluation results of the single-stage sand addition strength of horizontal wells, it is determined that the results are divided into three categories.

[0053] Step 3.5: When the single-stage fluid intensity of the horizontal well of the target water injection well is greater than 35m 3 ·m -1 When the single index evaluation result of the single-stage fluid intensity of the horizontal well is determined to be Class I; when the single-stage fluid intensity of the horizontal well of the target water injection well is 25m 3 ·m -1 Up to 35m 3 ·m -1 When the single index evaluation result of the horizontal well single-stage fluid intensity is between 25m and 35m, the single index evaluation result of the horizontal well single-stage fluid intensity is determined to be Class II; when the horizontal well single-stage fluid intensity of the target water injection well is less than 25m 3 ·m -1 When determining the single index evaluation results of the single-stage fluid intensity of horizontal wells, it is determined that the results are divided into three categories.

[0054] Step 3.6: When the crude oil viscosity of the target water injection huff and puff well is less than 200 mPa·s, the single index evaluation result of the crude oil viscosity is determined to be Class I; when the crude oil viscosity of the target water injection huff and puff well is between 200 mPa·s and 300 mPa·s, the single index evaluation result of the crude oil viscosity is determined to be Class II; when the crude oil viscosity of the target water injection huff and puff well is greater than 300 mPa·s, the single index evaluation result of the crude oil viscosity is determined to be Class III.

[0055] Step 3.7: When the oil change rate per ton of water of the target water injection well is greater than 0.08 m 3 ·m -3 When the single indicator evaluation result of the oil-exchange rate per ton of water is determined to be Class I; when the oil-exchange rate per ton of water of the target water injection well is 0.04m 3 ·m -3 Up to 0.08m 3 ·m -3 When the single indicator evaluation result of the oil-exchange rate per ton of water is between 0.04m 3 ·m-3 When determining the single indicator evaluation results of oil change rate per ton of water, it is determined that the results are divided into three categories.

[0056] Step 3.8: When the cumulative oil increase by throughput of the target water injection well is greater than 500t, the single index evaluation result of the cumulative oil increase by throughput is determined to be Class I; when the cumulative oil increase by throughput of the target water injection well is between 150t and 500t, the single index evaluation result of the cumulative oil increase by throughput is determined to be Class II; when the cumulative oil increase by throughput of the target water injection well is less than 150t, the single index evaluation result of the cumulative oil increase by throughput is determined to be Class III.

[0057] Step 3.9: When the cumulative injection-production ratio of the target water injection well is greater than 2.3, the single index evaluation result of the cumulative injection-production ratio is determined to be Class I; when the cumulative injection-production ratio of the target water injection well is between 1.6 and 2.3, the single index evaluation result of the cumulative injection-production ratio is determined to be Class II; when the cumulative injection-production ratio of the target water injection well is less than 1.6, the single index evaluation result of the cumulative injection-production ratio is determined to be Class III.

[0058] Step 3.10: When the recovery degree of the target water injection well is greater than 3.2%, the single indicator evaluation result of the recovery degree is determined to be Class I; when the recovery degree of the target water injection well is between 2.5% and 3.2%, the single indicator evaluation result of the recovery degree is determined to be Class II; when the recovery degree of the target water injection well is less than 2.5%, the single indicator evaluation result of the recovery degree is determined to be Class III.

[0059] Step 3.11: When the first-year cumulative oil production of the target water injection well is greater than 0.3×10 4 t, the single indicator evaluation result of the first-year cumulative oil production is determined to be Class I; when the first-year cumulative oil production of the target water injection well is 0.2×10 4 t to 0.3×10 4 t, the single indicator evaluation result of the first-year cumulative oil production is determined to be Class II; when the first-year cumulative oil production of the target water injection well is less than 0.2×10 4 At t, the single indicator evaluation results of the cumulative oil production in the first year are determined to be divided into three categories.

[0060] Step 3.12: When the fracture network complexity of the target water injection huff and puff well is greater than 3, the single index evaluation result of the fracture network complexity is determined to be Class I; when the fracture network complexity of the target water injection huff and puff well is between 2 and 3, the single index evaluation result of the fracture network complexity is determined to be Class II; when the fracture network complexity of the target water injection huff and puff well is less than 2, the single index evaluation result of the fracture network complexity is determined to be Class III.

[0061] Step 4: Based on the water injection huff and puff development effect evaluation index system, the fuzzy comprehensive evaluation method is used to obtain the basic condition index evaluation results and dynamic response index evaluation results of the target water injection huff and puff wells.

[0062] When conducting a comprehensive evaluation of the effects of water injection and huff-and-puff development in unconventional oil reservoirs, this application uses a fuzzy comprehensive evaluation method. The fuzzy comprehensive evaluation method is a comprehensive evaluation method based on fuzzy mathematics theory. According to the membership calculation of fuzzy mathematics, qualitative evaluation can be converted into quantitative evaluation. It is particularly suitable for the comprehensive evaluation (or comprehensive judgment) of things or objects that are constrained by multiple factors. It has the characteristics of rigorous logic, clear results, and strong systematicity, and can effectively solve fuzzy and uncertain problems. Therefore, this application uses a fuzzy comprehensive evaluation method for analysis based on the reservoir water injection and huff-and-puff development effect evaluation index system.

[0063] First, the principle of fuzzy comprehensive evaluation method is introduced.

[0064] The weight represents the importance of a certain evaluation factor to the evaluation result, and the size of the weight has a direct impact on the final evaluation result. The comments represent the various evaluation results of the evaluated factors. Given two finite sets and , represents the weight set, Represents the evaluation set.

[0065] (2).

[0066] (3).

[0067] In the formula, The weight of the evaluation factor (referred to as the factor), for this application, refers to the weight of the evaluation indicator; is the number of evaluation indicators, in the embodiment of the present application . Evaluation level, for this application, refers to the evaluation results, i.e., Class I, Class II, and Class III; is the grade number of the evaluation result, in the embodiment of the present application .

[0068] is the evaluation matrix. By quantifying each indicator of the evaluated object, that is, calculating the membership degree of a single indicator, the fuzzy relationship matrix is ​​obtained as follows: (4). In the formula, For the evaluation matrix No. Line Column elements, representing indicators Relative to the rating The index in this application It includes 12 evaluation indicators shown in Table 2. They correspond to category one, category two and category three in the evaluation results respectively.

[0069] Fuzzy comprehensive evaluation can be expressed by the following fuzzy transformation: (5). In the formula, the comprehensive evaluation vector For evaluation set In this application, the weight set is determined and the judging matrix After that, we can multiply them to get the comprehensive evaluation vector According to the maximum membership principle, the largest fuzzy subset The corresponding evaluation level is the comprehensive evaluation result.

[0070] From the above introduction, it can be seen that it is very important to determine the weight reasonably, which determines the importance of each evaluation index in the comprehensive evaluation. At present, the commonly used weight determination methods mainly include expert scoring method, fuzzy hierarchical analysis method, entropy weight method, principal component analysis method, etc. This application uses fuzzy hierarchical analysis method to determine the weight of each index.

[0071] Fuzzy Analytic Hierarchy Process (FAHP) is a method that combines the analytic hierarchy process (AHP) with fuzzy mathematics theory, and is used to deal with situations where evaluation indicators are fuzzy. It combines qualitative analysis with quantitative calculation in the AHP method, allowing decision makers to use fuzzy language when judging the importance of indicators. It has strong applicability and flexibility, and at the same time solves the problem of difficult consistency testing in traditional analytic hierarchy process, and improves the reliability of decision-making.

[0072] Using the fuzzy hierarchical analysis method, we must first establish a fuzzy consistent judgment matrix to reflect the relative importance of each level factor (corresponding to the indicators of this application) and other factors. Table 3 shows the fuzzy quantification method of the weights of each evaluation indicator, based on which the fuzzy judgment matrix (referred to as the judgment matrix) can be obtained. Each element : (6). In the formula, is the judgment matrix No. Line Column elements, indicating indicators Comparison indicators The importance of the factor is shown in Table 3. The larger the value, the greater the Ratio Factor The more important. ,index , It includes 12 evaluation indicators shown in Table 2, namely .

[0073] Table 3 Fuzzy quantification method of each evaluation index weight

[0074] The following example illustrates the judgment matrix of this application The establishment method of the 12 evaluation indicators of this application (class I reservoir reserves, class II reservoir reserves, fracturing cluster spacing, horizontal well single-stage sand addition intensity, horizontal well single-stage fluid intensity, crude oil viscosity, ton water oil exchange rate, cumulative throughput increase, cumulative injection-production ratio, recovery degree, first-year cumulative oil production, and fracture network complexity) is used. Any two indicators , , if the water injection huff and puff development effect of the reservoir is concerned, the indicator , Equally important, the corresponding If the indicator than another indicator Slightly more important, then the corresponding If the indicator , Compared with the same importance, the importance is between equally important and slightly important, then the corresponding If the indicator With indicators In comparison, the above three cases The scales are 1, 1 / 3 and 1 / 2 respectively.

[0075] Furthermore, the fuzzy consistency test method in fuzzy mathematics is used to perform consistency test on the fuzzy judgment matrix to ensure the rationality of the established fuzzy judgment matrix. Based on the fuzzy weighted average method in fuzzy mathematics, the fuzzy weights of each indicator at each level are calculated, and the fuzzy weights that pass the consistency test are summarized and corrected to obtain the final weights of each factor in the decision-making.

[0076] Specifically, in the established judgment matrix Based on Perform normalization to obtain the normalized judgment matrix , and then calculate the indicators Weight , forming a weight set .

[0077] For each element The formula for normalization is as follows: (7).

[0078] The normalized judgment matrix is ​​obtained : (8). is the judgment matrix after normalization No. Line Column elements, also The normalized processing result.

[0079] Each indicator can be further calculated Weight : (9). This is the judgment matrix after normalization No. The indicator weight calculated by the row.

[0080] The step 4 specifically includes the following steps 4.1 to 4.5.

[0081] Step 4.1: Based on the reservoir water injection huff-and-puff development effect evaluation index system, the fuzzy analytic hierarchy process is used to establish the judgment matrices of the basic condition index and the dynamic response index.

[0082] The above is an introduction to the judgment matrix and indicator weight calculation method using all 12 indicators as an example. For the six basic condition indicators and six dynamic response indicators, the calculation principle of the judgment matrix and indicator weight is the same, which is to first determine the judgment matrix using the fuzzy quantification method of the evaluation indicator weights shown in Table 3. Each element , and then in the judgment matrix Based on Perform normalization to obtain the normalized judgment matrix , and then calculate the indicators Weight , forming a weight set ,at this time .

[0083] Step 4.2: Calculate the weight sets of the basic condition index and the dynamic response index according to the judgment matrices of the basic condition index and the dynamic response index respectively.

[0084] As mentioned above, each element in the judgment matrix of the basic condition indicators is normalized to obtain a normalized judgment matrix; the weight of a basic condition indicator is calculated according to each row of the normalized judgment matrix, and the weights of each basic condition indicator together constitute a weight set of the basic condition indicators.

[0085] Each element in the judgment matrix of the dynamic response index is normalized to obtain a normalized judgment matrix; the weight of a dynamic response index is calculated according to each row of the normalized judgment matrix, and the weights of each dynamic response index together constitute a weight set of the dynamic response index.

[0086] Step 4.3: Calculate the membership of each basic condition index and each dynamic response index relative to each grading standard, and construct the membership evaluation matrix corresponding to the basic condition index and the dynamic response index.

[0087] The calculation of indicator membership is a key step in the fuzzy comprehensive evaluation method, which maps the actual value of the evaluation indicator to the fuzzy set to reflect its corresponding fuzzy degree.

[0088] Before calculating the indicator membership, you first need to select a suitable membership function. Common membership functions include triangular membership function, trapezoidal membership function, Gaussian membership function, etc. To select a suitable membership function, you need to consider the characteristics of the indicator and the shape of the membership curve. Based on the characteristics of the 12 selected indicators, this application selects the trapezoidal membership function for calculation. Evaluation indicators are divided into the larger the better type, the smaller the better type, and the intermediate optimal type according to the differences in their intervals and levels.

[0089] The larger the index value of the "bigger is better", the better it is. Usually, its membership function is monotonically increasing. As the index value increases, its membership also increases, such as the reserves of Class I and II reservoirs, the oil exchange rate per ton of water, etc. The smaller the index value, the better it is. Its membership function is usually monotonically decreasing. As the index value decreases, its membership increases, such as crude oil viscosity, fracturing cluster spacing, etc. The intermediate optimal index membership contributes the most to the target as the index value changes within a certain range, that is, the index value is the best within a certain intermediate range. In this case, the membership function is usually monotonically increasing or monotonically decreasing within a certain range, and reaches the maximum value at a certain point or within a range. This situation does not exist in the indicators selected in this application. The trapezoidal membership function used in this application is shown in Table 4.

[0090] Table 4 Trapezoidal membership function

[0091] in Represents the specific numerical value (actual value) corresponding to a certain indicator of the target well. Represents the dividing point between the first and second category classification standards. The dividing points representing the second and third category classification standards can be found in Table 2. The degree to which the value of a certain indicator belongs to a certain level (for example, the degree to which the specific value of a type of reservoir reserves belongs to three types), that is, the degree of membership.

[0092] The evaluation matrix shown in formula (4) This is the membership evaluation matrix of this application. For each indicator in Table 2 First, select a suitable membership function. This application selects a trapezoidal membership function. Then, according to the index The characteristics of (smaller is better or larger is better) select different empirical formulas (10) or (11) and query the index from Table 2 The corresponding dividing point , , and the indicator The actual value of By inserting it, we can calculate the index Membership , calculated The value is each The specific value of each indicator Evaluation level The degree of membership.

[0093] Taking the single-stage fluid intensity of the horizontal well of the target well as an example, the value of the single-stage fluid intensity of the horizontal well of the target well, 31.9, is substituted into the calculation formula (11) of the trapezoidal membership function, and its membership is 0.69. Similarly, the corresponding membership can be obtained by substituting the value of each indicator (basic condition indicator or dynamic response indicator) into the corresponding formula, and finally the membership evaluation matrix corresponding to the basic condition indicator or dynamic response indicator can be obtained. .

[0094] Step 4.4: Calculate the basic condition index evaluation result of the target water injection well according to the weight set of the basic condition index and the membership evaluation matrix corresponding to the basic condition index.

[0095] Specifically, the basic condition indicators of the target water injection well Substitute the specific value of into the trapezoidal membership function, use the trapezoidal membership function to calculate the membership of each basic condition index relative to each grading standard, and form the membership evaluation matrix corresponding to the basic condition index , similar to formula (4), at this time, ; Then, similar to formula (5), the weight set of basic condition indicators is Membership evaluation matrix corresponding to basic condition indicators Multiply them together to get the comprehensive evaluation vector . Further, the comprehensive evaluation vector The value obtained by adding each element in is the basic condition index evaluation result of the target water injection well.

[0096] Step 4.5: Calculate the dynamic response index evaluation result of the target water injection huff and puff well according to the weight set of the dynamic response index and the membership evaluation matrix corresponding to the dynamic response index.

[0097] Similarly, the dynamic response indicators of the target water injection well are Substitute the specific value of into the trapezoidal membership function, use the trapezoidal membership function to calculate the membership of each dynamic response index relative to each grading standard, and form the membership evaluation matrix corresponding to the dynamic response index ; Then the weight set of dynamic response indicators Membership evaluation matrix corresponding to dynamic response index Multiply them together to get the comprehensive evaluation vector , the comprehensive evaluation vector By adding each element in , we can get the dynamic response index evaluation result of the target water injection well.

[0098] Step 5: Compare the basic condition index evaluation results and dynamic response index evaluation results of the target water injection well to evaluate the effectiveness of the current water injection and huff-and-puff measures.

[0099] The calculated basic condition index evaluation results and dynamic response index evaluation results are both in numerical form. If the calculated dynamic response index evaluation result is greater than 1.2 times the basic condition index evaluation result, the dynamic response of the target well's water injection throughput is better than the basic condition, indicating that the oil well potential has been fully released and the current water injection throughput measures are very effective.

[0100] If the calculated dynamic response index evaluation result is between 0.8 and 1.2 times the basic condition index evaluation result, the dynamic response of the target well's water injection throughput is close to the basic condition, indicating that the current water injection throughput measures are relatively effective and can be maintained but also have room for improvement.

[0101] If the calculated dynamic response index evaluation result is less than 0.8 times the basic condition index evaluation result, the dynamic response of the target well's water injection throughput is poor compared with the basic conditions, indicating that the current water injection throughput measures are poorly effective and the target well needs to be further regulated to improve the water injection throughput effect.

[0102] Step 6: Based on the water injection huff and puff development effect evaluation index system, the fuzzy comprehensive evaluation method is used to calculate the comprehensive evaluation index of the target water injection huff and puff well, and the water injection huff and puff development effect is evaluated as a whole.

[0103] The step 6 specifically includes the following steps 6.1 to 6.3.

[0104] Step 6.1: Calculate the comprehensive weight matrix of all indicators based on the weight sets of basic condition indicators and dynamic response indicators.

[0105] Furthermore, the influence of basic condition indicators and dynamic response indicators on the comprehensive evaluation of water injection huff-and-puff development effects was analyzed based on the field measured data, and the proportion of the overall weight of basic condition indicators to the overall weight of all indicators was obtained. , the overall weight of the dynamic response index accounts for the overall weight of all indicators , the comprehensive weights of the 12 evaluation indicators can be calculated according to the following formula: (12). As a basic condition indicator The weight of As a basic condition indicator The comprehensive weight of Dynamic response index The weight of Dynamic response index The comprehensive weight of and The collection of is used as the comprehensive weight matrix of all indicators.

[0106] Step 6.2: Calculate the comprehensive evaluation index of the target water injection well based on the comprehensive weight matrix of all indicators and the membership evaluation matrix corresponding to all indicators.

[0107] For any of the 12 evaluation indicators of this application (class I reservoir reserves, class II reservoir reserves, fracturing cluster spacing, horizontal well single-stage sand addition intensity, horizontal well single-stage fluid intensity, crude oil viscosity, ton water oil exchange rate, cumulative throughput increase, cumulative injection-production ratio, recovery degree, first-year cumulative oil production, and fracture network complexity) , refer to the method described in step 4.3 to determine the membership evaluation matrix corresponding to all indicators. Then, the comprehensive weight matrix of all indicators is multiplied and superimposed with the membership evaluation matrix corresponding to all indicators (similar to the calculation method of the evaluation results of dynamic response indicators and basic condition indicators), and the comprehensive evaluation index F of the target water injection well can be calculated.

[0108] Step 6.3: Conduct an overall evaluation of the water injection huff and puff development effect based on the comprehensive evaluation index of the target water injection huff and puff well.

[0109] According to the final comprehensive evaluation index, the value range (classification boundary) of the comprehensive evaluation of water injection huff-and-puff development effect of unconventional oil reservoirs is obtained, as shown in Table 5.

[0110] Table 5 Classification boundaries for comprehensive evaluation of water injection huff-and-puff development effects in unconventional oil reservoirs

[0111] By comparing the value range of the classification shown in Table 5, the comprehensive evaluation result of the water injection huff and puff development effect of the target well can be obtained, that is, whether it belongs to Class I, Class II or Class III. Specifically, if 0.7≤F≤1, the water injection huff and puff development effect of the target water injection huff and puff well is determined to be Class I; if 0.45≤F<0.7, the water injection huff and puff development effect of the target water injection huff and puff well is determined to be Class II; if 0≤F<0.45, the water injection huff and puff development effect of the target water injection huff and puff well is determined to be Class III. Further, the water injection huff and puff development effect can be evaluated as a whole based on the comprehensive evaluation results of the target water injection huff and puff well, where Class I indicates that the water injection huff and puff development effect is the best, Class II is second, and Class III is third.

[0112] Based on the actual data of water injection wells in the target reservoir, this application combines the basic condition indicators such as reserves and fracturing process parameters within the well control range with dynamic response indicators such as oil-for-oil ratio per ton of water and oil increase, establishes an evaluation index system for water injection development effects, and conducts single factor evaluation to clarify the classification standards for different indicators. At the same time, a weight set is established based on the fuzzy analytic hierarchy process, and a membership evaluation matrix is ​​obtained through the fuzzy comprehensive evaluation method. Finally, a comprehensive evaluation result is calculated, which can conduct a scientific, comprehensive, objective, true, reasonable and accurate evaluation of the water injection development effects of unconventional reservoirs.

[0113] A specific implementation process of the present application method is provided below. Based on the above-mentioned evaluation method for the effect of water injection huff and puff development of unconventional oil reservoirs, the effect of water injection huff and puff wells in unconventional oil reservoirs in Block M of L Oilfield is evaluated, and the process is as follows.

[0114] S1: Establishing a water injection huff and puff development effect evaluation index system according to the reservoir properties of the target reservoir and the construction parameters of the water injection huff and puff well; the water injection huff and puff development effect evaluation index system includes a plurality of basic condition indicators and a plurality of dynamic response indicators.

[0115] S2: According to the value range of the actual data of the water injection wells in the target reservoir, the grading standards for the evaluation of each basic condition index and each dynamic response index are determined, as shown in Table 2.

[0116] S3: Perform single index evaluation according to the grading standards for evaluation of each basic condition index and each dynamic response index, and determine the single index evaluation results of each basic condition index and each dynamic response index of the target water injection huff and puff well.

[0117] Well M1 in Block M is taken as one of the target wells and is used as an example for specific introduction. The actual geological and production dynamic data of Well M1 are obtained, and the 12 indicators of Well M1 are evaluated by single indicators in combination with the classification standards shown in Table 2. The single indicator evaluation results are shown in Table 6.

[0118]

[0119] S4: Based on the water injection huff and puff development effect evaluation index system, the fuzzy comprehensive evaluation method is used to obtain the basic condition index evaluation results and dynamic response index evaluation results of the target water injection huff and puff wells.

[0120] Taking the dynamic response index as an example, based on the water injection huff-and-puff development effect evaluation index system, the dynamic response index judgment matrix established by the fuzzy hierarchical analysis method is shown in Table 7.

[0121]

[0122] The dynamic response index weights calculated according to the dynamic response index judgment matrix are shown in Table 8. All the values ​​in Table 8 constitute the weight set of the dynamic response index.

[0123] Table 8 Dynamic response index weights

[0124] Similarly, the weights of the basic condition indicators are shown in Table 9. All the values ​​in Table 9 constitute the weight set of the basic condition indicators.

[0125] Table 9 Weights of basic condition indicators

[0126] As mentioned above, the calculation process of indicator weights is to first establish a judgment matrix based on the fuzzy hierarchical analysis method, then normalize each element to obtain the normalized judgment matrix, and then calculate the weight of each indicator according to each row to obtain the weight set. , each value in the weight set represents the weight of each indicator.

[0127] Taking the dynamic response index as an example, the fuzzy quantification method of the weights of each evaluation index shown in Table 3 is used to determine the judgment matrix: (13).

[0128] Then, each element in the judgment matrix is ​​normalized using formula (7), for example: (14).

[0129] Similarly, calculate other normalized processing results to obtain the judgment matrix after normalization: (15).

[0130] Formula (9) is used to calculate the weight, for example: (16).

[0131] The same goes for 0.3641, 0.0744, 0.1323, 0.1361, 0.0744, rounded to two decimal places, as shown in Table 8.

[0132] Furthermore, the membership is calculated using the trapezoidal membership function, and the membership evaluation matrix corresponding to the basic condition index and the dynamic response index is constructed. The basic condition index evaluation result of the M1 well is calculated based on the weight set of the basic condition index and the membership evaluation matrix corresponding to the basic condition index, and the dynamic response index evaluation result of the M1 well is calculated based on the weight set of the dynamic response index and the membership evaluation matrix corresponding to the dynamic response index. Specifically, the membership evaluation matrix is ​​multiplied and superimposed with the weight set to obtain the final basic condition index evaluation result and dynamic response index evaluation result.

[0133] S5: Compare the basic condition index evaluation results and dynamic response index evaluation results of M1 well to evaluate the effectiveness of the current water injection and huff-and-puff measures.

[0134] If the calculated dynamic response index evaluation result is greater than 1.2 times the basic condition index evaluation result, it indicates that the potential of the oil well has been fully released and the current water injection and huff-and-puff measures are very effective. If the calculated dynamic response index evaluation result is between 0.8 and 1.2 times the basic condition index evaluation result, it indicates that the existing measures are relatively effective and can be maintained, but at the same time there is room for improvement. If the calculated dynamic response index evaluation result is less than 0.8 times the basic condition index evaluation result, it indicates that the current water injection and huff-and-puff measures are poor in effect, and further regulation of the target well is required to improve the water injection and huff-and-puff effect. Table 10 shows the comparison of the basic condition index evaluation results and the dynamic response index evaluation results of multiple water injection and huff-and-puff wells in the M block of the L oilfield. For example, the basic condition index evaluation result of the M1 well is 0.29, which belongs to the third category, and the dynamic response index evaluation result is 0.78, which belongs to the first category, indicating that the current measures have fully exerted the potential of the M1 well, and the current water injection and huff-and-puff measures are very effective and can be maintained.

[0135] Table 10 Comparison of the evaluation results of basic condition indicators and dynamic response indicators for each target well in Block M

[0136] S6: Based on the water injection huff and puff development effect evaluation index system, the fuzzy comprehensive evaluation method is used to calculate the comprehensive evaluation index of the target water injection huff and puff well, and the water injection huff and puff development effect is evaluated as a whole.

[0137] Analyze the influence of basic condition indicators and dynamic response indicators on the comprehensive evaluation of water injection huff-and-puff development effects based on field measured data, and determine the proportion of the overall weight of basic condition indicators to the overall weight of all indicators =0.33, the overall weight of the dynamic response index accounts for the overall weight of all indicators =0.67, combining the basic condition index and the dynamic response index, using formula (12) to calculate the comprehensive weights of the 12 evaluation indexes, and obtaining the comprehensive weight table for the evaluation of water injection huff-and-puff development effect, as shown in Table 11.

[0138] Table 11 Comprehensive weight table for water injection huff and puff development effect evaluation

[0139] Through the membership evaluation matrix and comprehensive weight matrix corresponding to all indicators, the comprehensive evaluation index of M1 well is calculated to be 0.67. The comprehensive evaluation index F is the sum of the comprehensive weight of each indicator (including basic condition indicators and dynamic response indicators) multiplied by the membership calculated from the specific value of the indicator.

[0140] Similarly, the comprehensive evaluation index is calculated for multiple target wells in Block M, and the water injection huff-and-puff development effect is evaluated overall. The comprehensive evaluation results are shown in Table 12.

[0141]

[0142] The results show that the comprehensive evaluation results of Wells M4, M5 and M6 are Class I, indicating that their current water injection and huffing measures have the best overall development effect; the comprehensive evaluation results of Wells M1, M2, M3 and M7 are Class II, indicating that their current water injection and huffing measures have a good overall development effect; the comprehensive evaluation result of Well M8 is Class III, indicating that the overall development effect of its current water injection and huffing measures is poor and urgently needs to be regulated.

[0143] This application conducts in-depth research on the evaluation method of water injection development effect. Based on the actual data of water injection wells in the target oil reservoir, the basic condition indicators such as Class I reservoir reserves, Class II reservoir reserves, fracturing cluster spacing, horizontal well single-stage sand addition intensity, horizontal well single-stage fluid intensity, crude oil viscosity, and dynamic response indicators such as ton water oil exchange rate, cumulative throughput increase, cumulative injection-production ratio, recovery degree, first-year cumulative oil production, and fracture network complexity are comprehensively considered to establish a water injection development effect evaluation index system. The weight set is established using the fuzzy hierarchical analysis method, and finally a method for evaluating the development effect of water injection in unconventional oil reservoirs is formed, which can evaluate whether the current water injection measures are effective. At the same time, this method also compares the evaluation results of basic condition indicators with the evaluation results of dynamic response indicators to screen out wells that need to take control measures in the next step, thereby ensuring the water injection effect of the reservoir.

[0144] In an exemplary embodiment, the present application also provides a computer device, which may be a server or a terminal. The computer device includes a processor, a memory, an input / output interface, and a communication interface. The processor, the memory, and the input / output interface are connected via a system bus, and the communication interface is connected to the system bus via the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, the method for evaluating the development effect of water injection throughput in unconventional oil reservoirs is implemented.

[0145] In an exemplary embodiment, the present application also provides a computer program product, including a computer program, which, when executed by a processor, implements the method for evaluating the development effect of water injection in unconventional oil reservoirs.

[0146] It can be understood by a person skilled in the art that all or part of the processes in the above-mentioned embodiment method can be completed by hardware related to computer program instructions, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the process of the embodiment of the above-mentioned method. Among them, any reference to the memory or other medium in each embodiment provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0147] It should be noted that the information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0148] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0149] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for evaluating the effect of water injection huff-and-puff development in unconventional oil reservoirs, characterized in that: include: According to the reservoir properties of the target reservoir and the construction parameters of the water injection well, a water injection well development effect evaluation index system is established; the water injection well development effect evaluation index system includes multiple basic condition indicators and multiple dynamic response indicators; According to the value range of actual data of water injection wells in the target reservoir, determine the grading standards for the evaluation of each basic condition index and each dynamic response index; Single index evaluation is performed according to the grading standards for evaluation of each basic condition index and each dynamic response index, and single index evaluation results of each basic condition index and each dynamic response index of the target water injection huff-and-puff well are determined; Based on the water injection huff and puff development effect evaluation index system, the fuzzy comprehensive evaluation method is used to obtain the basic condition index evaluation results and dynamic response index evaluation results of the target water injection huff and puff wells. Compare the basic condition index evaluation results and dynamic response index evaluation results of the target water injection well to evaluate the effectiveness of the current water injection measures; Based on the water injection huff and puff development effect evaluation index system, the fuzzy comprehensive evaluation method is used to calculate the comprehensive evaluation index of the target water injection huff and puff well, and the water injection huff and puff development effect is evaluated as a whole.

2. The method for evaluating the effect of water injection development in unconventional oil reservoirs according to claim 1, characterized in that: According to the reservoir properties of the target reservoir and the construction parameters of the water injection well, a water injection well development effect evaluation index system is established, which specifically includes: According to the reservoir properties of the target oil reservoir and the construction parameters of the water injection wells, the first-class reservoir reserves, the second-class reservoir reserves, the fracturing cluster spacing, the sand addition intensity of the horizontal well single stage, the liquid intensity of the horizontal well single stage and the crude oil viscosity are selected as multiple basic condition indicators of the water injection well development effect evaluation index system; the oil exchange rate per ton of water, the cumulative oil increase through throughput, the cumulative injection-production ratio, the recovery degree, the cumulative oil production in the first year and the complexity of the fracture network are selected as multiple dynamic response indicators of the water injection well development effect evaluation index system.

3. The method for evaluating the effect of water injection development in unconventional oil reservoirs according to claim 1, characterized in that: The grading standards for evaluating each basic condition index and each dynamic response index are determined based on the value range of the actual data of the water injection wells in the target oil reservoir, specifically including: Based on the actual data of water injection wells in the target oil reservoir, one or more methods including adaptive clustering, factor analysis, mine statistics and industry standards are integrated to determine the value range for dividing each basic condition indicator and each dynamic response indicator into one, two or three categories, which serves as the grading standard for the evaluation of each basic condition indicator and each dynamic response indicator.

4. The method for evaluating the effect of water injection development in unconventional oil reservoirs according to claim 1, characterized in that: The water injection huff and puff development effect evaluation index system uses a fuzzy comprehensive evaluation method to obtain the basic condition index evaluation results and dynamic response index evaluation results of the target water injection huff and puff well, specifically including: Based on the water injection huff-and-puff development effect evaluation index system, the judgment matrices of basic condition index and dynamic response index are established respectively by using fuzzy analytic hierarchy process. The weight sets of the basic condition index and the dynamic response index are calculated according to the judgment matrices of the basic condition index and the dynamic response index respectively; Calculate the membership of each basic condition index and each dynamic response index relative to each grading standard, and construct the membership evaluation matrix corresponding to the basic condition index and the dynamic response index; The basic condition index evaluation result of the target water injection well is calculated according to the weight set of the basic condition index and the membership evaluation matrix corresponding to the basic condition index; The dynamic response index evaluation result of the target water injection well is calculated according to the weight set of the dynamic response index and the membership evaluation matrix corresponding to the dynamic response index.

5. The method for evaluating the effect of water injection development in unconventional oil reservoirs according to claim 4, characterized in that: The water injection huff-and-puff development effect evaluation index system uses fuzzy analytic hierarchy process to establish judgment matrices for basic condition indexes and dynamic response indexes, specifically including: Each basic condition index in the water injection huff-and-puff development effect evaluation index system is compared pairwise, and a judgment matrix of basic condition index is constructed based on the importance scale obtained by the comparison. The dynamic response indicators in the water injection huff-and-puff development effect evaluation index system are compared pairwise, and a judgment matrix of the dynamic response indicators is constructed based on the importance scale obtained from the comparison.

6. The method for evaluating the effect of water injection huff-and-puff development of unconventional oil reservoirs according to claim 4, characterized in that: The step of calculating the membership of each basic condition index and each dynamic response index relative to each grading standard and constructing a membership evaluation matrix corresponding to the basic condition index and the dynamic response index specifically includes: Substitute the specific values ​​of each basic condition indicator into the trapezoidal membership function, use the trapezoidal membership function to calculate the membership of each basic condition indicator relative to each grading standard, and form a membership evaluation matrix corresponding to the basic condition indicator; Substitute the specific values ​​of each dynamic response index into the trapezoidal membership function, use the trapezoidal membership function to calculate the membership of each dynamic response index relative to each grading standard, and construct the membership evaluation matrix corresponding to the dynamic response index.

7. The method for evaluating the effect of water injection huff-and-puff development of unconventional oil reservoirs according to claim 4, characterized in that: The basic condition index evaluation results and dynamic response index evaluation results of the target water injection well are compared to evaluate the effectiveness of the current water injection well measures, specifically including: If the dynamic response index evaluation result is greater than 1.2 times the basic condition index evaluation result, it indicates that the current water injection and huff-and-puff measures are very effective; If the dynamic response index evaluation result is between 0.8 and 1.2 times the basic condition index evaluation result, it indicates that the current water injection and huff-and-puff measures are relatively effective; If the dynamic response index evaluation result is less than 0.8 times the basic condition index evaluation result, it indicates that the current water injection and huff-and-puff measures are less effective.

8. The method for evaluating the effect of water injection huff-and-puff development of unconventional oil reservoirs according to claim 4, characterized in that: The water injection huff and puff development effect evaluation index system is based on the fuzzy comprehensive evaluation method to calculate the comprehensive evaluation index of the target water injection huff and puff well, and the water injection huff and puff development effect is evaluated as a whole, specifically including: Calculate the comprehensive weight matrix of all indicators based on the weight sets of basic condition indicators and dynamic response indicators; The comprehensive evaluation index of the target water injection well is calculated based on the comprehensive weight matrix of all indicators and the membership evaluation matrix corresponding to all indicators; The water injection huff and puff development effect is evaluated overall based on the comprehensive evaluation index of the target water injection huff and puff well.

9. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for evaluating the effect of water injection development in unconventional oil reservoirs as claimed in any one of claims 1 to 8.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the method for evaluating the effect of water injection development in unconventional oil reservoirs according to any one of claims 1 to 8 is implemented.

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