An evaluation method, device and product for the development effect of water injection huff and puff in unconventional reservoirs

Abstract

The present application discloses a method, device and product for evaluating the development effect of water injection huff and puff in unconventional reservoirs, relating to the field of oil and gas field development. First, according to the reservoir properties of the target reservoir and the construction parameters of the water injection huff and puff wells, an evaluation index system and grading criteria for the development effect of water injection huff and puff are established, based on which single-index evaluation of each index can be carried out; then, the fuzzy comprehensive evaluation method is used to obtain the evaluation results of the basic condition index and the dynamic response index of the target water injection huff and puff well, and the two are compared to evaluate the effectiveness of the current water injection huff and puff measures; further, the fuzzy comprehensive evaluation method is used to calculate the comprehensive evaluation index of the target water injection huff and puff well, and based on this, the overall evaluation of the development effect of water injection huff and puff is carried out. The present application can improve the rationality and accuracy of the evaluation of the development effect of water injection huff and puff in unconventional reservoirs.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas field development, and particularly to a method, device and product for evaluating the development effect of cyclic water injection in unconventional reservoirs. Background Art

[0002] Currently, there are mainly three methods commonly used to evaluate the development effect of water injection in reservoirs, namely the development performance analysis method, the water drive characteristic curve analysis method, and the injection-production correspondence analysis method. The development performance analysis method mainly analyzes the changes in parameters such as liquid production per day, oil production per day, cumulative liquid production, cumulative oil production, and water cut of different wells through the development performance curves of injection-production well groups or well points, and qualitatively evaluates the water injection response status and development effect. The water drive characteristic curve analysis method calculates the sweep efficiency of the water drive reservoir by establishing the change curve of the recovery factor and the water cut, and quantitatively evaluates the quality of the water injection effect. The injection-production correspondence analysis method mainly combines the geological layer data to judge the correspondence status of the injection and production layers in the well group, and semi-quantitatively evaluates the quality of the injection-production effect. However, these methods mainly target the water drive process of conventional reservoirs and are less applicable to the cyclic water injection process of unconventional reservoirs such as tight oil and shale oil.

[0003] The physical properties of unconventional reservoirs such as tight oil and shale oil are extremely poor, and the permeability is generally 3 - 5 orders of magnitude lower than that of conventional reservoirs. Therefore, conventional reservoirs mainly adopt water drive development, that is, the injection well and the production well are different wells, and the injected water displaces the oil to the production well and is produced; however, the ultra-low permeability characteristics of the reservoir make it difficult to form an injection-production pressure system in unconventional reservoirs. Therefore, unconventional reservoirs often adopt cyclic water injection development, that is, the injection well and the production well are the same well. The differences in the seepage laws and development methods between conventional reservoirs and unconventional reservoirs result in the inapplicability of the currently commonly used water injection development effect evaluation methods to the cyclic water injection process of unconventional reservoirs. Summary of the Invention

[0004] The purpose of the present application is to provide a method, device and product for evaluating the development effect of cyclic water injection in unconventional reservoirs to improve the rationality and accuracy of the evaluation of the development effect of cyclic water injection in unconventional reservoirs.

[0005] To achieve the above purpose, the present application provides the following solutions.

[0006] In a first aspect, the present application provides a method for evaluating the development effect of water injection huff and puff in unconventional reservoirs, including: establishing an evaluation index system for the development effect of water injection huff and puff according to the reservoir properties of the target reservoir and the construction parameters of the water injection huff and puff wells; the evaluation index system for the development effect of water injection huff and puff includes multiple basic condition indexes and multiple dynamic response indexes; determining the grading criteria for the evaluation of each basic condition index and each dynamic response index according to the value range of the actual data of the water injection huff and puff wells in the target reservoir; conducting single-index evaluation according to the grading criteria for the evaluation of each basic condition index and each dynamic response index to 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; based on the evaluation index system for the development effect of water injection huff and puff, obtaining the evaluation results of the basic condition indexes and the evaluation results of the dynamic response indexes of the target water injection huff and puff well by using the fuzzy comprehensive evaluation method; comparing the evaluation results of the basic condition indexes and the evaluation results of the dynamic response indexes of the target water injection huff and puff well to evaluate the effectiveness of the current water injection huff and puff measures; based on the evaluation index system for the development effect of water injection huff and puff, calculating the comprehensive evaluation index of the target water injection huff and puff well by using the fuzzy comprehensive evaluation method to conduct an overall evaluation of the development effect of water injection huff and puff.

[0007] Optionally, the step of establishing an evaluation index system for the development effect of water injection huff and puff according to the reservoir properties of the target reservoir and the construction parameters of the water injection huff and puff wells specifically includes: selecting the reserves of Class I reservoirs, the reserves of Class II reservoirs, the fracture cluster spacing, the sand addition intensity per single stage of horizontal wells, the liquid usage intensity per single stage of horizontal wells, and the crude oil viscosity as multiple basic condition indexes of the evaluation index system for the development effect of water injection huff and puff according to the reservoir properties of the target reservoir and the construction parameters of the water injection huff and puff wells; selecting the oil production rate per ton of water, the cumulative incremental oil production by huff and puff, the cumulative injection-production ratio, the recovery degree, the cumulative oil production in the first year, and the fracture network complexity as multiple dynamic response indexes of the evaluation index system for the development effect of water injection huff and puff.

[0008] Optionally, the step of determining the grading criteria for the evaluation of each basic condition index and each dynamic response index according to the value range of the actual data of the water injection huff and puff wells in the target reservoir specifically includes: based on the actual data of the water injection huff and puff wells in the target reservoir, determining the value ranges for classifying each basic condition index and each dynamic response index into Class I, Class II, or Class III by integrating one or more of self-adaptive clustering, factor analysis, field statistics, and industry standards as the grading criteria for the evaluation of each basic condition index and each dynamic response index.

[0009] Optionally, for the evaluation index system of the development effect of water injection huff and puff, the evaluation results of the basic condition index and the dynamic response index of the target water injection huff and puff well are obtained by using the fuzzy comprehensive evaluation method, which specifically includes: based on the evaluation index system of the development effect of water injection huff and puff, the judgment matrices of the basic condition index and the dynamic response index are respectively established by using the fuzzy analytic hierarchy process; the weight sets of the basic condition index and the dynamic response index are respectively calculated according to the judgment matrices of the basic condition index and the dynamic response index; the membership degrees of each basic condition index and each dynamic response index relative to each grading standard are respectively calculated, and the membership degree judgment matrices corresponding to the basic condition index and the dynamic response index are constructed; the evaluation result of the basic condition index of the target water injection huff and puff well is calculated according to the weight set of the basic condition index and the membership degree judgment matrix corresponding to the basic condition index; the evaluation result of the dynamic response index of the target water injection huff and puff well is calculated according to the weight set of the dynamic response index and the membership degree judgment matrix corresponding to the dynamic response index.

[0010] Optionally, for the evaluation index system of the development effect of water injection huff and puff, the judgment matrices of the basic condition index and the dynamic response index are respectively established by using the fuzzy analytic hierarchy process, which specifically includes: each basic condition index in the evaluation index system of the development effect of water injection huff and puff is compared pairwise, and the judgment matrix of the basic condition index is constructed based on the importance scale obtained from the comparison; each dynamic response index in the evaluation index system of the development effect of water injection huff and puff is compared pairwise, and the judgment matrix of the dynamic response index is constructed based on the importance scale obtained from the comparison.

[0011] Optionally, the membership degrees of each basic condition index and each dynamic response index relative to each grading standard are respectively calculated, and the membership degree judgment matrices corresponding to the basic condition index and the dynamic response index are constructed, which specifically includes: substituting the specific values of each basic condition index into the trapezoidal membership function, and using the trapezoidal membership function to calculate the membership degrees of each basic condition index relative to each grading standard, so as to form the membership degree judgment matrix corresponding to the basic condition index; substituting the specific values of each dynamic response index into the trapezoidal membership function, and using the trapezoidal membership function to calculate the membership degrees of each dynamic response index relative to each grading standard, so as to form the membership degree judgment matrix corresponding to the dynamic response index.

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

[0013] Optionally, for the evaluation index system of the water injection huff and puff development effect, the fuzzy comprehensive evaluation method is used to calculate the comprehensive evaluation index of the target water injection huff and puff well, and the overall evaluation of the water injection huff and puff development effect is carried out, specifically including: calculating the comprehensive weight matrix of all indexes according to the weight set of the basic condition indexes and the dynamic response indexes; calculating the comprehensive evaluation index of the target water injection huff and puff well according to the comprehensive weight matrix of all indexes and the membership degree judgment matrix corresponding to all indexes; and carrying out the overall evaluation of the water injection huff and puff development effect according to 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 on the memory and executable on the processor, where the processor executes the computer program to implement the evaluation method for the water injection huff and puff development effect of the unconventional reservoir.

[0015] In a third aspect, the present application provides a computer program product, including a computer program, which implements the evaluation method for the water injection huff and puff development effect of the unconventional reservoir when executed by a processor.

[0016] According to the specific embodiments provided by the present application, the following technical effects are disclosed in the present application:

[0017] The present application provides an evaluation method, device and product for the water injection huff and puff development effect of an unconventional reservoir. Considering the seepage law and the particularity of the development mode of the unconventional reservoir comprehensively, the basic condition indexes within the well control range are combined with the dynamic response indexes, an evaluation index system for the water injection huff and puff development effect is established, the grading standards for different index evaluations are clarified, and single-index evaluations are carried out based on this. On the other hand, based on the fuzzy comprehensive evaluation method, the evaluation results of the basic condition indexes, the evaluation results of the dynamic response indexes and the comprehensive evaluation index can be calculated. By comparing the calculated evaluation results of the basic condition indexes with the evaluation results of the dynamic response indexes, the effectiveness of the current water injection huff and puff measures can be evaluated. According to the comprehensive evaluation index of the target water injection huff and puff well, the overall evaluation of the water injection huff and puff development effect can be carried out. The present application realizes the scientific, comprehensive, objective, true, reasonable and accurate evaluation of the water injection huff and puff development effect of the unconventional reservoir by integrating the above methods. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1It is a flow schematic diagram of an evaluation method for the development effect of water injection huff and puff in unconventional reservoirs in this application. Specific embodiments

[0020] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present application.

[0021] The purpose of this application is to provide an evaluation method, device and product for the development effect of water injection huff and puff in unconventional reservoirs, so as to improve the rationality and accuracy of the evaluation of the development effect of water injection huff and puff in unconventional reservoirs.

[0022] To make the above objects, features and advantages of the present application more obvious and understandable, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0023] In an exemplary embodiment, as Figure 1 shown, an evaluation method for the development effect of water injection huff and puff in unconventional reservoirs is provided, including the following steps 1 to 6.

[0024] Step 1: Establish an evaluation index system for the development effect of water injection huff and puff according to the reservoir properties of the target reservoir and the construction parameters of the water injection huff and puff wells; the evaluation index system for the development effect of water injection huff and puff includes multiple basic condition indexes and multiple dynamic response indexes.

[0025] An unconventional reservoir refers to a reservoir resource with poor oil and gas quality, poor fluidity, low porosity and permeability, no natural production capacity, and difficult to exploit or with poor exploitation efficiency using existing technologies. For example, tight oil, shale oil, etc. These reservoirs usually require special technologies and processes to achieve efficient exploitation. This application takes unconventional reservoirs such as tight oil and shale oil as target reservoirs and studies the evaluation method for their development effect of water injection huff and puff.

[0026] Specifically, according to the reservoir properties of the target reservoir and the construction parameters of the water injection huff and puff wells, this application selects the reserves of Class I reservoirs, the reserves of Class II reservoirs, the fracture cluster spacing, the sand addition intensity per single stage of horizontal wells, the liquid usage intensity per single stage of horizontal wells, and the crude oil viscosity as multiple basic condition indexes of the evaluation index system for the development effect of water injection huff and puff. The oil production rate per ton of water, the cumulative incremental oil production of huff and puff, the cumulative injection-production ratio, the recovery factor, the cumulative oil production in the first year, and the fracture network complexity are selected as multiple dynamic response indexes of the evaluation index system for the development effect of water injection huff and puff. The above basic condition indexes and dynamic response indexes in the evaluation index system for the development effect of water injection huff and puff will be introduced in detail below. In the following text, the basic condition indexes and dynamic response indexes are also collectively referred to as evaluation indexes, simply referred to as indexes.

[0027] The introduction of each basic condition index is as follows.

[0028] Reserves of Class I and Class II reservoirs: Class I and Class II reservoirs are areas rich in crude oil, which are important indicators for evaluating the richness of reservoir resources and represent the reserve potential within the well control range. The size of the reserves directly affects the feasibility of water injection and huff and puff development and the potential production capacity, so it is one of the mandatory indicators.

[0029] Fracture cluster spacing: It refers to the distance between fracture clusters in horizontal wells. Since unconventional reservoirs are mainly developed by multi-stage fracturing of horizontal wells, the fracture cluster spacing is directly related to the layout density and uniformity of the fracturing fractures in horizontal wells for water injection and huff and puff. A reasonable fracture cluster spacing can ensure the effective water injection of horizontal wells, thereby obtaining better huff and puff effects, so it is an important factor affecting the development effect.

[0030] Sand addition intensity per single stage and fluid injection intensity per single stage of horizontal wells: These two indicators reflect the mass of proppant (sand) added and fracturing fluid injected per unit length of the horizontal well. The greater the fluid injection intensity per single stage, the more fracturing fluid enters a single stage during the fracturing process, and the larger the fracturing treatment volume; the greater the sand addition intensity per single stage, the better the placement effect of the proppant in the fracture, the less likely the fracture is to close, and it can effectively maintain the long-term conductivity of the fracture. Therefore, the fluid injection intensity per single stage and the sand addition intensity per single stage respectively evaluate the fracturing treatment effect before water injection and huff and puff development of the reservoir and the maintenance situation of the conductivity, which are crucial for ensuring the development effect of water injection and huff and puff.

[0031] Crude oil viscosity: An important indicator to measure the fluidity of crude oil, which directly affects the difficulty of reservoir exploitation and the effect of water injection and huff and puff. The higher the viscosity, the weaker the oil-water displacement effect during water injection and huff and puff, and the greater the difficulty of reservoir exploitation.

[0032] The above six evaluation indicators mainly reflect information such as the geological characteristics, reserve size, and fracture network transformation degree of the reservoir. For example, the reserves of Class I and Class II reservoirs and the crude oil viscosity reflect the geological characteristics of the reservoir, the reserves of Class I and Class II reservoirs also reflect the reserve size of the reservoir, and the fracture cluster spacing, sand addition intensity per single stage of horizontal wells, and fluid injection intensity per single stage of horizontal wells reflect the fracture network transformation degree of the reservoir. Although the above six basic condition indicators do not directly involve the dynamic changes during the exploitation process, they are very important for whether the potential of water injection and huff and puff measures can be fully exerted.

[0033] The introduction of each dynamic response index is as follows.

[0034] Oil production per ton of water injected: One of the important indicators to measure the development effect of water injection and huff and puff, which represents the volume of underground crude oil displaced by unit volume of injected water. The higher the oil production per ton of water injected, the greater the amount of oil produced during water injection and huff and puff, and the greater the potential for oilfield production increase.

[0035] Cumulative oil production increase and cumulative injection-production ratio: These two indicators reflect the cumulative effects during the cyclic waterflooding development process. The cumulative oil production increase is the cumulative oil production increase obtained by the reservoir through cyclic waterflooding development. The cumulative injection-production ratio is the ratio of the cumulative water injection volume to the cumulative liquid production volume of the reservoir, which reflects the overall effect of cyclic waterflooding development and measures the degree of formation energy replenishment.

[0036] Recovery factor: The ratio of cumulative oil production to geological reserves. It reflects the degree to which crude oil in the reservoir has been produced, which is directly related to the remaining recoverable reserves and production effect of the reservoir and is of great significance for evaluating the cyclic waterflooding development effect.

[0037] Cumulative oil production in the first year: One of the key indicators for evaluating the initial effect of cyclic waterflooding development, which can reflect the production capacity and efficiency in the initial stage of development.

[0038] 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 fracturing cracks to communicate with the surrounding natural fractures, thus forming a complex fracture network. The more developed and densely distributed the fractures are, the higher the fracture network complexity, and the higher the degree of oil-water mixing and displacement, which is more conducive to improving the cyclic waterflooding effect.

[0039] During the reservoir development process, measures such as cyclic waterflooding and refracturing will change the underground pressure distribution and fracture network state of the reservoir, thus affecting the degree of fracture development. Therefore, the fracture network complexity may change at different stages, and this indicator also reflects the dynamic evolution process of the fracture network during the reservoir development process. According to the dynamic response characteristics of the on-site fracturing sections, this application establishes a classification standard for fracture network complexity based on the change characteristics of pressure, oil volume, liquid volume, and water cut, so as to realize the quantitative evaluation of fracture network complexity by using the indicators that are easy to obtain on-site. The specific classification standard of fracture network complexity is shown in Table 1. According to the fracture network complexity, 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.

[0040] Table 1 Classification standard of fracture network complexity

[0041]

[0042] In Table 1, the unit of pressure change is megapascal (MPa), the unit of oil volume change is ton (t), the unit of liquid volume change is cubic meter (m 3 )), and the unit of water cut change is percentage (%). The fracture network complexity is obtained by comprehensive evaluation of single indicators such as pressure change, oil volume change, liquid volume change, and water cut change in Table 1, that is: (1). Among them, is the membership degree of each indicator (such as pressure change, oil volume change, liquid volume change, water cut change), For each index weight. is the number of indexes for measuring the complexity of the fracture network. In the embodiments shown in Table 1 , then correspond to pressure change, oil volume change, liquid volume change and water cut change respectively. is the calculated complexity of the fracture network.

[0043] Among them, the membership degree is calculated using the corresponding grades in Table 1. For example, if the single-index evaluation result of index is fracture network complex type, the membership degree is 4; if the single-index evaluation result is fracture network developed type, the membership degree is 3; if the single-index evaluation result is micro-fracture communication type, the membership degree is 2; if the single-index evaluation result is main-fracture communication type, the membership degree is 1. The distribution calculation of the weight is determined according to the correlation between each index. Using the analytic hierarchy process, the weights of each index are respectively: 0.5, 0.3, 0.1, 0.1.

[0044] Step 2: According to the value range of the actual data of the water injection and huff and puff wells in the target reservoir, determine the grading criteria for the evaluation of each basic condition index and each dynamic response index.

[0045] Specifically, this application combines multiple methods such as comprehensive adaptive clustering, factor analysis, field statistics and industry standards, combines qualitative and quantitative methods, determines the value ranges of each basic condition index and each dynamic response index, and organizes them into the grading criteria of each index in the water injection and huff and puff development effect evaluation index system shown in Table 2.

[0046] Table 2 Oil reservoir water injection and huff and puff development effect evaluation index system and grading criteria for each index

[0047]

[0048] In Table 2, the unit t represents ton, m represents meter, mPa·s represents millipascal-second, and % represents percentage. The evaluation results of the water injection and huff and puff development effect of the oil reservoir are divided into three categories. Among them, Category I (Class I) is the parameter value range that is most favorable for exploitation or has the best dynamic response, Category II (Class II) is the second best, and Category III (Class III) is the third best.

[0049] Step 3: Conduct single-index evaluation according to the grading criteria for the 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 and huff and puff well.

[0050] Before conducting a comprehensive evaluation of the development effect of water injection huff and puff, a single-index evaluation can be carried out for each basic condition index and each dynamic response index of the target water injection huff and puff well (which can be simply referred to as the target well). Specifically, compare the measured data (actual values) of each index of the target well with the grading standards in Table 2, and judge whether it belongs to Class I, Class II or Class III according to the interval where the actual value is located, then the single-index evaluation results of each evaluation index can be obtained. Among them, the reserves of Class I and II reservoirs, the fracture cluster spacing, the sand addition intensity per single stage of the horizontal well and the liquid usage intensity per single stage of the horizontal well, the crude oil viscosity, and the cumulative oil production in the first year can be directly obtained from the measured data of the target well. The oil production rate per ton of water = the cumulative increased oil volume in each cycle of water injection huff and puff / the cumulative water injection volume in each cycle of water injection huff and puff. The cumulative injection-production ratio = the ratio of the cumulative water injection volume to the cumulative liquid production volume. The cumulative increased oil volume of huff and puff = the predicted cumulative oil production until abandonment after the water injection huff and puff measure - the predicted cumulative oil production until abandonment before the water injection huff and puff measure. The recovery factor = the ratio of the cumulative oil production to the geological reserves. The calculation of the fracture network complexity is shown in formula (1).

[0051] Step 3 specifically includes the following steps 3.1 to 3.12.

[0052] Step 3.1: When the reserves of Class I reservoirs in the target water injection huff and puff well are greater than 11×10 4 t, determine that the single-index evaluation result of the reserves of Class I reservoirs is Class I; when the reserves of Class I reservoirs in the target water injection huff and puff well are between 5×10 4 t and 11×10 4 t, determine that the single-index evaluation result of the reserves of Class I reservoirs is Class II; when the reserves of Class I reservoirs in the target water injection huff and puff well are less than 5×10 4 t, determine that the single-index evaluation result of the reserves of Class I reservoirs is Class III.

[0053] Step 3.2: When the reserves of Class II reservoirs in the target water injection huff and puff well are greater than 15×10 4 t, determine that the single-index evaluation result of the reserves of Class II reservoirs is Class I; when the reserves of Class II reservoirs in the target water injection huff and puff well are between 9×10 4 t and 15×10 4 t, determine that the single-index evaluation result of the reserves of Class II reservoirs is Class II; when the reserves of Class II reservoirs in the target water injection huff and puff well are less than 9×10 4 t, determine that the single-index evaluation result of the reserves of Class II reservoirs is Class III.

[0054] Step 3.3: When the fracture cluster spacing in the target water injection huff and puff well is less than 9 m, determine that the single-index evaluation result of the fracture cluster spacing is Class I; when the fracture cluster spacing in the target water injection huff and puff well is between 9 m and 12 m, determine that the single-index evaluation result of the fracture cluster spacing is Class II; when the fracture cluster spacing in the target water injection huff and puff well is greater than 12 m, determine that the single-index evaluation result of the fracture cluster spacing is Class III.

[0055] Step 3.4: When the sand addition intensity per single stage of the horizontal well in the target water injection huff and puff well is greater than 2.5 m 3 ·m -1 , determine that the single-index evaluation result of the sand addition intensity per single stage of the horizontal well is Class I; when the sand addition intensity per single stage of the horizontal well in the target water injection huff and puff well is between 2 m 3 ·m -1 and 2.5 m 3 ·m -1 , determine that the single-index evaluation result of the sand addition intensity per single stage of the horizontal well is Class II; when the sand addition intensity per single stage of the horizontal well in the target water injection huff and puff well is less than 2 m 3 ·m -1 , determine that the single-index evaluation result of the sand addition intensity per single stage of the horizontal well is Class III.

[0056] Step 3.5: When the liquid injection intensity per single stage of the horizontal well in the target water injection huff and puff well is greater than 35 m 3 ·m -1 , determine that the single-index evaluation result of the liquid injection intensity per single stage of the horizontal well is Class I; when the liquid injection intensity per single stage of the horizontal well in the target water injection huff and puff well is between 25 m 3 ·m -1 and 35 m 3 ·m -1 , determine that the single-index evaluation result of the liquid injection intensity per single stage of the horizontal well is Class II; when the liquid injection intensity per single stage of the horizontal well in the target water injection huff and puff well is less than 25 m 3 ·m -1 , determine that the single-index evaluation result of the liquid injection intensity per single stage of the horizontal well is Class III.

[0057] Step 3.6: When the crude oil viscosity of the target water injection huff and puff well is less than 200 mPa·s, determine that the single-index evaluation result of the crude oil viscosity is 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, determine that the single-index evaluation result of the crude oil viscosity is Class II; when the crude oil viscosity of the target water injection huff and puff well is greater than 300 mPa·s, determine that the single-index evaluation result of the crude oil viscosity is Class III.

[0058] Step 3.7: When the oil production per ton of water of the target water injection huff and puff well is greater than 0.08 m 3 ·m -3 , determine that the single-index evaluation result of the oil production per ton of water is Class I; when the oil production per ton of water of the target water injection huff and puff well is between 0.04 m 3 ·m -3 and 0.08 m 3 ·m -3 , determine that the single-index evaluation result of the oil production per ton of water is Class II; when the oil production per ton of water of the target water injection huff and puff well is less than 0.04 m 3 ·m-3 When the single - index evaluation result of the oil - to - water conversion rate is determined to be Class III.

[0059] Step 3.8: When the cumulative oil production increase of the target water - injection huff - puff well is greater than 500 t, the single - index evaluation result of the cumulative oil production increase is determined to be Class I; when the cumulative oil production increase of the target water - injection huff - puff well is between 150 t and 500 t, the single - index evaluation result of the cumulative oil production increase is determined to be Class II; when the cumulative oil production increase of the target water - injection huff - puff well is less than 150 t, the single - index evaluation result of the cumulative oil production increase is determined to be Class III.

[0060] Step 3.9: When the cumulative injection - production ratio of the target water - injection huff - puff 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 huff - puff 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 huff - puff well is less than 1.6, the single - index evaluation result of the cumulative injection - production ratio is determined to be Class III.

[0061] Step 3.10: When the recovery factor of the target water - injection huff - puff well is greater than 3.2%, the single - index evaluation result of the recovery factor is determined to be Class I; when the recovery factor of the target water - injection huff - puff well is between 2.5% and 3.2%, the single - index evaluation result of the recovery factor is determined to be Class II; when the recovery factor of the target water - injection huff - puff well is less than 2.5%, the single - index evaluation result of the recovery factor is determined to be Class III.

[0062] Step 3.11: When the cumulative oil production in the first year of the target water - injection huff - puff well is greater than 0.3×10 4 t, the single - index evaluation result of the cumulative oil production in the first year is determined to be Class I; when the cumulative oil production in the first year of the target water - injection huff - puff well is between 0.2×10 4 t and 0.3×10 4 t, the single - index evaluation result of the cumulative oil production in the first year is determined to be Class II; when the cumulative oil production in the first year of the target water - injection huff - puff well is less than 0.2×10 4 t, the single - index evaluation result of the cumulative oil production in the first year is determined to be Class III.

[0063] Step 3.12: When the fracture - network complexity of the target water - injection huff - 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 - 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 - puff well is less than 2, the single - index evaluation result of the fracture - network complexity is determined to be Class III.

[0064] Step 4: Based on the evaluation index system of water - injection huff - puff development effect, use the fuzzy comprehensive evaluation method to obtain the evaluation results of the basic condition index and the dynamic response index of the target water - injection huff - puff well.

[0065] 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.

[0066] First, the principle of fuzzy comprehensive evaluation method is introduced.

[0067] 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.

[0068] (2).

[0069] (3).

[0070] 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 .

[0071] 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.

[0072] The fuzzy comprehensive evaluation can be represented by the following fuzzy transformation: (5). In the formula, the comprehensive evaluation vector is a fuzzy subset on the evaluation set In this application, after determining the weight set and the judgment matrix , multiplying them can obtain the comprehensive evaluation vector . According to the principle of maximum membership degree, the evaluation level corresponding to the largest fuzzy subset is the comprehensive evaluation result.

[0073] As can be seen from the above introduction, it is very important to reasonably determine the weights, which determines the importance of each evaluation index in the comprehensive evaluation. Currently, the commonly used methods for determining weights mainly include the expert scoring method, the fuzzy analytic hierarchy process, the entropy weight method, the principal component analysis method, etc. In this application, the fuzzy analytic hierarchy process is used to determine the weights of each index.

[0074] The fuzzy analytic hierarchy process (FAHP) is a method that combines the analytic hierarchy process (AHP) with fuzzy mathematics theory and is used to handle the situation where evaluation indicators are fuzzy. It combines qualitative analysis and quantitative calculation in the AHP method, allows decision-makers to use fuzzy language when judging the importance between indicators, has strong applicability and flexibility, and at the same time solves the problem of difficult consistency testing in the traditional analytic hierarchy process, improving the reliability of decision-making.

[0075] To use the fuzzy analytic hierarchy process, it is first necessary to establish a fuzzy consistent judgment matrix to reflect the relative importance between factors at each level (corresponding to the indicators in this application) and other factors. Table 3 shows the fuzzy quantification method of the weights of each evaluation index, and based on this, the fuzzy judgment matrix (referred to as the judgment matrix) each element in : is the element in the th row and th column of the judgment matrix , indicating the importance degree of the index compared with the index . The value is the scale in Table 3, and the larger the value, the more important the factor is than the factor . In this application , the indexes , include the 12 evaluation indexes shown in Table 2, that is .

[0076] Table 3 Fuzzy Quantification Method for Weights of Each Evaluation Index

[0077]

[0078] The following is an example to illustrate the judgment matrix of the present application establishment method. For any two of the 12 evaluation indexes of the present application (class I reservoir reserves, class II reservoir reserves, fracture cluster spacing, proppant addition intensity per single stage of horizontal well, fluid injection intensity per single stage of horizontal well, crude oil viscosity, oil production rate per ton of water, cumulative incremental oil production from cyclic steam stimulation, cumulative injection-production ratio, recovery factor, cumulative oil production in the first year, and fracture network complexity) 、 , if for the development effect of reservoir water injection and cyclic steam stimulation, indexes 、 are equally important, then the corresponding ; if index is slightly more important than another index , then the corresponding ; if indexes 、 are compared, and the importance is between equally important and slightly more important, then the corresponding . If it is the comparison between index and index , then the scales of in the above three cases are 1, 1 / 3, and 1 / 2 respectively.

[0079] Furthermore, using the fuzzy consistency test method in fuzzy mathematics, the fuzzy judgment matrix is subjected to a consistency test 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 index at each level are calculated, and the fuzzy weights after passing the consistency test are summarized and corrected to obtain the final weights of each factor in the decision-making.

[0080] Specifically, on the basis of the established judgment matrix , each element is normalized to obtain the normalized judgment matrix , and then the weights of each index are calculated to form the weight set .

[0081] The formula for normalizing each element is as follows: (7).

[0082] Thus, the normalized judgment matrix is obtained: (8). It is the judgment matrix after normalization processing The th row and th column element, which is also The result of normalization processing

[0083] Furthermore, the weights of each index can be calculated: : (9). That is the weight of the index calculated from the th row of the judgment matrix after normalization processing

[0084] Step 4 specifically includes the following steps 4.1 to 4.5

[0085] Step 4.1: Based on the evaluation index system for the development effect of reservoir water injection huff and puff, use the fuzzy analytic hierarchy process to establish the judgment matrices of the basic condition index and the dynamic response index respectively

[0086] The above is an introduction to the judgment matrix and the index weight calculation method with all 12 indexes as examples. For the six basic condition indexes and six dynamic response indexes among them, the calculation method principles of their judgment matrices and index weights are the same. First, use the fuzzy quantification method of each evaluation index weight shown in Table 3 to determine each element in the judgment matrix , and then, based on the judgment matrix , normalize each element to obtain the judgment matrix after normalization processing , and then calculate the weights of each index , which constitute the weight set . At this time .

[0087] Step 4.2: Calculate the weight sets of the basic condition index and the dynamic response index respectively according to the judgment matrices of the basic condition index and the dynamic response index

[0088] As mentioned above, normalize each element in the judgment matrix of the basic condition index to obtain the judgment matrix after normalization processing; calculate the weight of a basic condition index according to each row of the judgment matrix after normalization processing, and the weights of each basic condition index together constitute the weight set of the basic condition index

[0089] Normalize each element in the judgment matrix of the dynamic response index to obtain the judgment matrix after normalization processing; calculate the weight of a dynamic response index according to each row of the judgment matrix after normalization processing, and the weights of each dynamic response index together constitute the weight set of the dynamic response index​

[0090] Step 4.3: Calculate the membership degrees of each basic condition index and each dynamic response index relative to each grading standard respectively, and construct the membership degree evaluation matrices corresponding to the basic condition indexes and the dynamic response indexes.

[0091] The calculation of index membership degree is a key step in the fuzzy comprehensive evaluation method, which maps the actual values of evaluation indexes into a fuzzy set to reflect their corresponding degrees of fuzziness.

[0092] Before calculating the index membership degree, it is first necessary to select a suitable membership function. Common membership functions include triangular membership function, trapezoidal membership function, Gaussian membership function, etc. Selecting a suitable membership function requires considering the characteristics of the index and the shape of the membership degree curve. Based on the characteristics of the 12 selected indexes, the trapezoidal membership function is selected for calculation in this application. Evaluation indexes are divided into three types according to the differences in their intervals and grade divisions: the larger-the-better type, the smaller-the-better type, and the intermediate-optimal type.

[0093] For the larger-the-better type of indexes, the larger the index value, the better. Generally, its membership function is monotonically increasing. As the index value increases, its membership degree also increases. For example, the reserves of the first and second types of reservoirs, the oil production rate per ton of water, etc. For the smaller-the-better type of indexes, it is exactly the opposite. The smaller the index value, the better. Its membership function is usually monotonically decreasing. As the index value decreases, its membership degree increases. For example, crude oil viscosity, fracture cluster spacing, etc. For the intermediate-optimal type of indexes, the membership degree changes with the index value within a certain range, and the contribution degree to the target is the largest, that is, the index value is the best within a certain intermediate range. In this case, the membership function is usually monotonically increasing or decreasing within a certain range and reaches the maximum value at a certain point or within a certain range. There is no such situation among the indexes selected in this application. The trapezoidal membership function adopted in this application is shown in Table 4.

[0094] Table 4 Trapezoidal membership function

[0095]

[0096] where represents the specific value (actual value) corresponding to a certain index of the target well. represents the demarcation point between the first and second grading standards, represents the demarcation point between the second and third grading standards, which can be obtained from Table 2. is the degree to which a certain index value belongs to a certain grade (for example, the degree to which the specific value of the reserves of the first type of reservoir belongs to the third type), that is, the membership degree.

[0097] The evaluation matrix shown in formula (4) is the membership degree evaluation matrix of this application. For each index in Table 2 , first select an appropriate membership degree function. In this application, the trapezoidal membership degree function is selected. Then, according to the characteristics of the index (the smaller-the-better type or the larger-the-better type), select different empirical formulas (10) or (11). Query from Table 2 to obtain the cut-off points corresponding to the index , , and use the actual value of the index as to substitute into the formula, then the membership degree of this index can be calculated. The calculated value is the specific value of each , representing the membership degree of each index to the evaluation level . Taking the liquid injection intensity per single stage of the horizontal well in the target well as an example, substitute the value 31.9 of the liquid injection intensity per single stage of the horizontal well in the target well into the larger-the-better type calculation formula (11) of the trapezoidal membership degree function, and its membership degree is obtained as 0.69. Similarly, substituting the values of each index (basic condition index or dynamic response index) into the corresponding formula can obtain the corresponding membership degree, and finally the membership degree evaluation matrix

[0098] corresponding to the basic condition index or dynamic response index can be obtained. .

[0099] Step 4.4: Calculate the evaluation result of the basic condition index of the target water injection huff and puff well according to the weight set of the basic condition index and the membership degree evaluation matrix corresponding to the basic condition index.

[0100] Specifically, substitute the specific values of each basic condition index of the target water injection huff and puff well into the trapezoidal membership degree function, and use the trapezoidal membership degree function to calculate the membership degree of each basic condition index relative to each grading standard, so as to form the membership degree evaluation matrix corresponding to the basic condition index. Similar to formula (4), at this time, ; . Then, similar to formula (5), multiply the weight set of the basic condition index by the membership degree evaluation matrix corresponding to the basic condition index to obtain the comprehensive evaluation vector . Further add up each element in the comprehensive evaluation vector , and the obtained value is the evaluation result of the basic condition index of the target water injection huff and puff well.

[0101] Step 4.5: Calculate the evaluation result of the dynamic response index of the target water injection huff and puff well according to the weight set of the dynamic response index and the membership degree evaluation matrix corresponding to the dynamic response index.

[0102] Similarly, substitute the specific values of each dynamic response index of the target water injection huff and puff well into the trapezoidal membership function, and use the trapezoidal membership function to calculate the membership degree of each dynamic response index relative to each grading standard, and form the membership degree evaluation matrix corresponding to the dynamic response index ; then multiply the weight set of the dynamic response index by the membership degree evaluation matrix corresponding to the dynamic response index to obtain the comprehensive evaluation vector , and add up each element in the comprehensive evaluation vector to obtain the evaluation result of the dynamic response index of the target water injection huff and puff well.

[0103] Step 5: Compare the evaluation result of the basic condition index of the target water injection huff and puff well with the evaluation result of the dynamic response index, and evaluate the effectiveness of the current water injection huff and puff measure.

[0104] The calculated evaluation results of the basic condition index and the dynamic response index are both in numerical form. If the calculated evaluation result of the dynamic response index is greater than 1.2 times the evaluation result of the basic condition index, it means that the dynamic response of the target well's water injection huff and puff is better than the basic condition, indicating that the potential of the oil well has been fully released and the current water injection huff and puff measure is very effective.

[0105] If the calculated evaluation result of the dynamic response index is between 0.8 and 1.2 times the evaluation result of the basic condition index, it means that the dynamic response of the target well's water injection huff and puff is close to the basic condition, indicating that the current water injection huff and puff measure is relatively effective and can be continued while having room for improvement.

[0106] If the calculated evaluation result of the dynamic response index is less than 0.8 times the evaluation result of the basic condition index, it means that the dynamic response of the target well's water injection huff and puff is worse than the basic condition, indicating that the current water injection huff and puff measure has poor effect and further regulation of the target well is needed to improve the water injection huff and puff effect.

[0107] Step 6: Based on the evaluation index system of water injection huff and puff development effect, use the fuzzy comprehensive evaluation method to calculate the comprehensive evaluation index of the target water injection huff and puff well, and conduct an overall evaluation of the water injection huff and puff development effect.

[0108] The specific steps of Step 6 include the following Steps 6.1 to 6.3.

[0109] Step 6.1: Calculate the comprehensive weight matrix of all indexes according to the weight sets of the basic condition index and the dynamic response index.

[0110] Furthermore, based on the on-site measured data, analyze the influence degree of the basic condition index and the dynamic response index on the comprehensive evaluation of the water injection huff and puff development effect, and obtain the proportion of the overall weight of the basic condition index in the overall weight of all indexes , and the proportion of the overall weight of the dynamic response index in the overall weight of all indexes is . Then, the comprehensive weight of the 12 evaluation indexes can be calculated according to the following formula: (12). Where is the weight of the basic condition index , is the comprehensive weight of the basic condition index ; is the weight of the dynamic response index , is the comprehensive weight of the dynamic response index . Combine with as the comprehensive weight matrix of all indexes.

[0111] Step 6.2: Calculate the comprehensive evaluation index of the target water injection huff and puff well according to the comprehensive weight matrix of all indexes and the membership degree judgment matrix corresponding to all indexes.

[0112] For any one of the 12 evaluation indexes (class I reservoir reserves, class II reservoir reserves, fracture cluster spacing, horizontal well single-stage sand addition intensity, horizontal well single-stage liquid usage intensity, crude oil viscosity, tons of water to oil conversion rate, cumulative huff and puff oil increment, cumulative injection-production ratio, recovery factor, cumulative oil production in the first year, and fracture network complexity) of this application , determine the membership degree judgment matrix corresponding to all indexes with reference to the method described in Step 4.3. Then multiply and superimpose the comprehensive weight matrix of all indexes and the membership degree judgment matrix corresponding to all indexes (similar to the calculation methods of the evaluation results of the dynamic response index and the basic condition index), and the comprehensive evaluation index F of the target water injection huff and puff well can be calculated.

[0113] Step 6.3: Conduct an overall evaluation of the water injection huff and puff development effect according to the comprehensive evaluation index of the target water injection huff and puff well.

[0114] Classify according to the finally obtained comprehensive evaluation index to obtain the value range (classification boundary) of the comprehensive evaluation of the water injection huff and puff development effect in unconventional oil reservoirs, as shown in Table 5.

[0115] Table 5 Classification boundary of comprehensive evaluation of water injection huff and puff development effect in unconventional oil reservoirs

[0116]

[0117] According to the value ranges of the classifications shown in Table 5, the comprehensive evaluation results 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, it is determined that the water injection huff and puff development effect of the target water injection huff and puff well is Class I; if 0.45 ≤ F < 0.7, it is determined that the water injection huff and puff development effect of the target water injection huff and puff well is Class II; if 0 ≤ F < 0.45, it is determined that the water injection huff and puff development effect of the target water injection huff and puff well is Class III. Further, the overall evaluation of the water injection huff and puff development effect can be carried out based on the comprehensive evaluation results of the target water injection huff and puff well, where Class I indicates the best water injection huff and puff development effect, Class II is the second best, and Class III is the third best.

[0118] Based on the actual data of the water injection huff and puff wells in the target reservoir, this application combines the basic condition indicators such as the reserves and fracturing process parameters within the well control range and the dynamic response indicators such as the oil production per ton of water and the increased oil production, establishes an evaluation index system for the water injection huff and puff development effect, and conducts single-factor evaluation to clarify the grading standards of different indicators. At the same time, a weight set is established based on the fuzzy analytic hierarchy process, and a membership degree judgment matrix is obtained through the fuzzy comprehensive evaluation method. Finally, the comprehensive evaluation result is calculated, which can scientifically, comprehensively, objectively, truly, reasonably and accurately evaluate the water injection huff and puff development effect of unconventional reservoirs.

[0119] The following provides a specific implementation process of the method of this application. Based on the above-mentioned evaluation method for the water injection huff and puff development effect of unconventional reservoirs, the effect evaluation is carried out for the water injection huff and puff wells in the M block of the L oilfield, and the process is as follows.

[0120] S1: According to the reservoir properties of the target reservoir and the construction parameters of the water injection huff and puff wells, establish an evaluation index system for the water injection huff and puff development effect; the evaluation index system for the water injection huff and puff development effect includes multiple basic condition indicators and multiple dynamic response indicators.

[0121] S2: According to the value ranges of the actual data of the water injection huff and puff wells in the target reservoir, determine the grading standards for the evaluation of each basic condition indicator and each dynamic response indicator, as shown in Table 2.

[0122] S3: Conduct single-index evaluation according to the grading standards for the evaluation of each basic condition indicator and each dynamic response indicator, and determine the single-index evaluation results of each basic condition indicator and each dynamic response indicator of the target water injection huff and puff well.

[0123] Take Well M1 in the M block as one of the target wells and introduce it specifically by way of example. Obtain the actual geological and production dynamic data of Well M1, and conduct single-index evaluation on the 12 indicators of Well M1 in combination with the grading standards shown in Table 2. The single-index evaluation results are shown in Table 6.

[0124]

[0125] S4: Based on the evaluation index system for the development effect of water injection huff and puff, the evaluation results of the basic condition index and the dynamic response index of the target water injection huff and puff well are obtained by using the fuzzy comprehensive evaluation method.

[0126] Taking the dynamic response index as an example, based on the evaluation index system for the development effect of water injection huff and puff, the judgment matrix of the dynamic response index established by using the fuzzy analytic hierarchy process is shown in Table 7.

[0127]

[0128] The weights of the dynamic response index calculated according to the judgment matrix of the dynamic response index are shown in Table 8, and all the values in Table 8 constitute the weight set of the dynamic response index.

[0129] Table 8 Weights of Dynamic Response Index

[0130]

[0131] Similarly, the weights of the basic condition index can be obtained as shown in Table 9, and all the values in Table 9 constitute the weight set of the basic condition index.

[0132] Table 9 Weights of Basic Condition Index

[0133]

[0134] As mentioned above, the calculation process of the index weights is to first establish a judgment matrix according to the fuzzy analytic hierarchy process, then normalize each element to obtain the normalized judgment matrix, and then calculate the weights of each index according to each row to obtain the weight set. Each value in the weight set represents the weight of each index.

[0135] Taking the dynamic response index as an example, the judgment matrix is determined by using the fuzzy quantification method of the weights of each evaluation index shown in Table 3:

[0136] (13).

[0137] Then, formula (7) is used to normalize each element in the judgment matrix. For example:

[0138] (14).

[0139] Similarly, the other normalization results are calculated to obtain the normalized judgment matrix:

[0140] (15).

[0141] The weight calculation is carried out by using formula (9). For example:

[0142] (16).

[0143] Similarly, we get 0.3641, 0.0744, 0.1323, 0.1361, 0.0744, rounded to two decimal places, as shown in Table 8.

[0144] Furthermore, the membership degrees are calculated using the trapezoidal membership function to construct the membership evaluation matrices corresponding to the basic condition indicators and dynamic response indicators. The evaluation results of the basic condition indicators of Well M1 are calculated based on the weight set of the basic condition indicators and the membership evaluation matrix corresponding to the basic condition indicators, and the evaluation results of the dynamic response indicators of Well M1 are calculated based on the weight set of the dynamic response indicators and the membership evaluation matrix corresponding to the dynamic response indicators. Specifically, the membership evaluation matrix is multiplied by the weight set and superimposed to obtain the final evaluation results of the basic condition indicators and dynamic response indicators.

[0145] S5: Compare the evaluation results of the basic condition indicators and dynamic response indicators of Well M1 to evaluate the effectiveness of the current water injection huff and puff measures.

[0146] If the calculated evaluation result of the dynamic response indicator is greater than 1.2 times the evaluation result of the basic condition indicator, it indicates that the potential of the oil well has been fully released and the current water injection huff and puff measures are very effective. If the calculated evaluation result of the dynamic response indicator is between 0.8 and 1.2 times the evaluation result of the basic condition indicator, it indicates that the existing measures are relatively effective and can be continued while there is room for improvement. If the calculated evaluation result of the dynamic response indicator is less than 0.8 times the evaluation result of the basic condition indicator, it indicates that the current water injection huff and puff measures are less effective and further regulation of the target well is required to improve the water injection huff and puff effect. Table 10 shows the comparison of the evaluation results of the basic condition indicators and dynamic response indicators of multiple water injection huff and puff wells in Block M of L Oilfield. For example, the evaluation result of the basic condition indicators of Well M1 is 0.29, belonging to Class III, and the evaluation result of the dynamic response indicators is 0.78, belonging to Class I, indicating that the current measures have fully exerted the potential of Well M1 and the current water injection huff and puff measures are very effective and can be continued.

[0147] Table 10 Comparison of the evaluation results of the basic condition indicators and dynamic response indicators of each target well in Block M

[0148]

[0149] S6: Based on the evaluation index system of water injection huff and puff development effect, use the fuzzy comprehensive evaluation method to calculate the comprehensive evaluation index of the target water injection huff and puff well and conduct an overall evaluation of the water injection huff and puff development effect.

[0150] Based on the on-site measured data, analyze the influence degree of the basic condition indicators and dynamic response indicators on the comprehensive evaluation of the development effect of water injection huff and puff, and determine the proportion of the overall weight of the basic condition indicators in the overall weight of all indicators = 0.33, and the proportion of the overall weight of the dynamic response indicators in the overall weight of all indicators is = 0.67. Combine the basic condition indicators and dynamic response indicators, and use formula (12) to calculate the comprehensive weights of the 12 evaluation indicators, and obtain the comprehensive weight table for the evaluation of the development effect of water injection huff and puff, as shown in Table 11

[0151] Table 11 Comprehensive weight table for the evaluation of the development effect of water injection huff and puff

[0152]

[0153] Through the membership degree judgment matrix and comprehensive weight matrix corresponding to all indicators, the comprehensive evaluation index of Well M1 is calculated to be 0.67. The comprehensive evaluation index F is the sum of the products of the comprehensive weight occupied by each indicator (including basic condition indicators and dynamic response indicators) and the membership degree calculated from the specific value of this indicator

[0154] Similarly, calculate the comprehensive evaluation index for multiple target wells in Block M, and conduct an overall evaluation of the development effect of water injection huff and puff. The comprehensive evaluation results are shown in Table 12

[0155]

[0156] The results show that the comprehensive evaluation results of Well M4, Well M5 and Well M6 are of the first category, indicating that the overall development effect of their current water injection huff and puff measures is the best; the comprehensive evaluation results of Well M1, Well M2, Well M3 and Well M7 are of the second category, indicating that the overall development effect of their current water injection huff and puff measures is better; the comprehensive evaluation result of Well M8 is of the third category, indicating that the overall development effect of its current water injection huff and puff measures is poor and urgent regulation is needed

[0157] This application has conducted in-depth research on the evaluation method of the development effect of water injection huff and puff. Based on the actual data of water injection huff and puff wells in the target reservoir, basic condition indicators such as the reserves of Class I reservoirs, the reserves of Class II reservoirs, the fracture cluster spacing, the sand addition intensity per single stage of horizontal wells, the liquid usage intensity per single stage of horizontal wells, and the crude oil viscosity, as well as dynamic response indicators such as the oil production rate per ton of water, the cumulative incremental oil production of huff and puff, the cumulative injection-production ratio, the recovery factor, the cumulative oil production in the first year, and the complexity of the fracture network, an evaluation index system for the development effect of water injection huff and puff has been established. The fuzzy analytic hierarchy process is used to establish the weight set, and finally, an evaluation method for the development effect of water injection huff and puff in unconventional reservoirs that can evaluate whether the current water injection huff and puff measures are effective is formed. At the same time, this method also screens out the wells that need to take control measures in the next step through the comparison of the evaluation results of basic condition indicators and dynamic response indicators, so as to ensure the water injection huff and puff effect of the reservoir.

[0158] In an exemplary embodiment, this application also provides a computer device, which can be a server or a terminal. The computer device includes a processor, a memory, an input / output interface, and a communication interface. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, 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 external devices. The communication interface of the computer device is used to communicate with external terminals through a network connection. When the computer program is executed by the processor, it implements the evaluation method for the development effect of water injection huff and puff in unconventional reservoirs.

[0159] In an exemplary embodiment, this application also provides a computer program product, including a computer program, which implements the evaluation method for the development effect of water injection huff and puff in unconventional reservoirs when executed by the processor.

[0160] Those of ordinary skill in the art will understand that all or part of the processes in the above-described example methods can be completed by hardware related to computer program instructions. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the example embodiments of the above methods. Among them, any reference to a memory or other medium provided in the embodiments of the present application can include at least one of non-volatile and volatile memories. 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 can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0161] 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 for analysis, stored data, displayed data, etc.) involved in the present application are all information and data that have been authorized by the user or fully authorized by all parties, and the collection, use, and processing of the relevant data need to comply with the relevant regulations.

[0162] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered to be within the scope described in this specification.

[0163] In this article, specific examples are used to elaborate on the principles and implementation manners of the present application. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation on the present 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 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 reservoir and the construction parameters of the water injection well, the reserves of the first type of reservoir, the reserves of the second type of reservoir, the spacing between fracturing clusters, the sand addition intensity of the single stage of the horizontal well, the fluid intensity of the single stage of the horizontal well, and the viscosity of crude oil 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 by throughput, the cumulative injection-production ratio, the degree of recovery, 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; 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; 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 reservoir, one or more methods including adaptive clustering, factor analysis, mine statistics and industry standards are integrated to determine the value range of each basic condition indicator and each dynamic response indicator as being classified into one, two or three categories, which are used as the grading standard for the evaluation of each basic condition indicator and each dynamic response indicator; 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; Specifically, the actual values ​​of each indicator of the target water injection well are compared with its classification standard, and the actual value range is used to determine whether it belongs to Class I, Class II or Class III, thus obtaining the single indicator evaluation results of each indicator. 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. 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 huff and puff well is calculated according to the weight set of the dynamic response index and the membership evaluation matrix corresponding to the dynamic response index; 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; 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; 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 overall. 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 overall evaluation of water injection huff and puff development effect is conducted based on the comprehensive evaluation index of the target water injection huff and puff wells; Classification is performed according to the final comprehensive evaluation index F; 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 based on the comprehensive evaluation results of the target water injection huff and puff well, the water injection huff and puff development effect is evaluated as a whole, among which Class I indicates that the water injection huff and puff development effect is the best, Class II is the second, and Class III is the third.

2. 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 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.

3. The method for evaluating the effect of water injection development in unconventional oil reservoirs according to claim 1, 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.

4. 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 development effect of water injection into unconventional oil reservoirs as claimed in any one of claims 1 to 3.

5. 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 3 is implemented.

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