Method for discriminating and evaluating alternating injection-production instability mode of coated sand layer of air energy storage well

Abstract

The invention provides an air energy storage well coated sand layer alternating injection-production instability mode discrimination and evaluation method, which comprises the following steps of: 1, determining an initial state parameter of an evaluation object, and determining flow in experimental evaluation according to a similarity criterion; 2, collecting parameters of two ends of the coated sand filling layer in the experiment process, classifying alternating injection-production instability failure forms of the coated sand filling layer of the air energy storage well, and identifying instability failure modes; step 3, calculating each index according to the collected parameters; and 4, carrying out production regulation and control and coated sand filling layer evaluation according to an index calculation result. According to the air energy storage well coated sand layer alternating injection-production instability mode distinguishing and evaluating method, the stability of a coated sand filling layer in the experiment (production) process is evaluated through a simple method, the underground production state of the coated sand filling layer is simulated, instability mode distinguishing is carried out, and certain guiding significance is achieved for actual well safety production.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and natural gas development and exploitation, and in particular to a method for distinguishing and evaluating an instability mode of alternating injection and production of a coated sand layer in an air energy storage well. Background Art

[0002] Air energy storage involves using an air compressor to compress high-pressure gas during the nighttime off-peak hours and inject it into a reservoir for storage. During the day, when electricity is needed, the high-pressure gas inside the reservoir is released to discharge the gas. Compressed air energy storage wells are wellbore channels that inject compressed air into underground reservoirs and then extract the compressed air. Due to the high-frequency, short-cycle alternating injection and production conditions of air energy storage wells and the looseness of the reservoir, sand production is prone to occur. A common sand control method for air energy storage wells is a composite sand coating and screen pipe sand control. This involves using a sand-carrying fluid to squeeze coated sand particles into the formation. Solid particles then fill the sand-producing areas, forming a coated sand coating. This serves to prevent sand production while maintaining fluidity and productivity. Under these high-frequency, high-volume injection and production conditions, the coated sand coating can become unstable and fail. However, there are currently no technical methods to identify and evaluate the instability patterns of coated sand coatings.

[0003] Chinese patent application number CN201910986668.0 discloses a multi-stage, long-term, stable sand control process for sandstone reservoirs in the late stage of high water cut. The process includes the following steps: 1. establishing a reservoir instability model and determining the degree of instability; 2. preventing reservoir instability using real-time fluid velocity control; 3. in-situ stabilization and reservoir skeleton reconstruction using a high-efficiency chemical coupled physicochemical method; 4. reconstructing a high-strength, high-permeability artificial wellbore wall to prevent near-wellbore collapse; 5. using a filter to prevent high-permeability wellbore blockage; and 6. restoring reservoir permeability. This process effectively reduces the destruction of the reservoir skeleton sand and the degree of sand production during the high-water-cut period, eliminates near-wellbore blockage after water flooding and polymer flooding, improves fluid flow, and achieves efficient development of unconsolidated sandstone reservoirs in the oilfield. However, this application is only aimed at multi-stage stable and long-term sand control in the late stage of high water content in sandstone reservoirs, and does not involve the identification and evaluation of the instability mode of alternating injection and production in the coated sand layer of air energy storage wells.

[0004] In the Chinese patent application with application number: CN202110285745.7, a method for evaluating the magnitude of ground stress based on mechanical instability and collapse of the wellbore is involved, including screening and data classification of mechanically unstable and collapsed well sections, expressing the magnitude of deep ground stress and wellbore stress based on the structural strain coefficient, establishing a structural strain coefficient equation based on the stress limit equilibrium condition, solving the structural strain coefficient based on the least squares method and calculating the horizontal principal stress, and evaluating the rationality of the ground stress estimation results; the present invention screens the wellbore stress instability and collapse well section data, classifies the collapse data, constructs a stress limit equilibrium equation based on the strain coefficient, and solves the overdetermined equation based on the critical collapse formation information constraint, calculates and evaluates the deep in-situ horizontal maximum principal stress and minimum principal stress, and provides a method for evaluating the rationality of the in-situ stress results, thereby realizing the quantitative calculation and evaluation of the magnitude of the horizontal principal stress of the deep formation, and providing the necessary deep formation mechanics basic parameters for deep underground engineering, especially oil and gas well engineering, oil and gas extraction engineering, etc. However, this application is aimed at the evaluation of ground stress based on mechanical instability and collapse of the well wall, and does not involve the identification and evaluation of the instability mode of alternating injection and production of the coated sand layer of the air energy storage well.

[0005] The Chinese patent application with application number CN202010081980.8 involves a method for determining the risk of erosion failure of injection and production tubing in a gas reservoir-type gas storage facility, which belongs to the technical field of underground gas storage risk assessment. A method for determining the risk of erosion failure of injection and production tubing in a gas reservoir-type gas storage facility comprises the following steps: 1) obtaining the initial state parameters of the injection and production well to be measured; 2) calculating the average temperature and average pressure of the micro-element section of the injection and production tubing; 3) calculating the natural gas flow velocity under the average temperature and average pressure of the micro-element section; 4) calculating the probability of erosion failure of the micro-element section; 5) calculating the probability of erosion failure of the injection and production tubing in the entire well section. The invented method for determining the risk of erosion failure of injection and production tubing in a gas reservoir-type gas storage facility characterizes the risk of erosion failure of injection and production wells in a gas reservoir-type gas storage facility in a probabilistic form, and corrects the probability of erosion failure of injection and production wells based on well logging data, which is of great significance for ensuring the safe operation of gas storage facilities. However, this application is aimed at the determination of the erosion failure risk of injection and production tubing in gas reservoir-type gas storage facilities, and does not involve the identification and evaluation of the alternating injection and production instability mode of the coated sand layer in air energy storage wells.

[0006] The above existing technologies are significantly different from the present invention and fail to solve the technical problem we want to solve. To this end, we have invented a new method for identifying and evaluating the instability mode of alternating injection and production in coated sand layers of air energy storage wells. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for distinguishing and evaluating the alternating injection and production instability mode of the coated sand layer of an air energy storage well, which increases the stability performance index of the filling layer and can evaluate the performance of the coated sand filling layer in each cycle.

[0008] The purpose of the present invention can be achieved by the following technical measures: a method for distinguishing and evaluating the instability mode of alternating injection and production of a coated sand layer in an air energy storage well, the method comprising:

[0009] Step 1: Determine the initial state parameters of the evaluation object and determine the flow rate in the experimental evaluation based on the similarity criterion;

[0010] Step 2: Collect parameters at both ends of the coated sand filling layer during the experiment to classify the instability and failure forms of the alternating injection and production of the coated sand filling layer of the air energy storage well, and identify the instability and failure modes;

[0011] Step 3, calculate various indicators based on the collected parameters;

[0012] Step 4: Conduct production control and evaluate the coated sand filling layer based on the index calculation results.

[0013] The purpose of the present invention can also be achieved by the following technical measures:

[0014] In step 1, the similarity of flow phenomena requires the equality of the Nusselt criterion numbers, which can be derived from the momentum differential equation:

[0015]

[0016] Where, μ′ is the actual reservoir fluid viscosity, mPa·s; μ″ is the experimental fluid viscosity, mPa·s; l′ is the actual reservoir thickness, m; l″ is the experimental reservoir thickness, m; v′ is the actual reservoir fluid flow rate, m / s; v″ is the experimental fluid flow rate, m / s;

[0017] Right now:

[0018] Re′=Re″ (1-2)

[0019] Where Re is the Reynolds number, Re′ is the Reynolds number of the actual reservoir, and Re″ is the Reynolds number during experimental evaluation, which is dimensionless.

[0020] This shows that the Reynolds criterion of two fluids with similar motion phenomena must be equal, and the same can be derived:

[0021]

[0022] Where Q' is the actual fluid flow rate, m 3 / h; Q″ is the experimental fluid flow rate, m 3 / h; determine the flow rate in the experimental evaluation based on similarity criteria.

[0023] In step 2, the collected parameters include: displacement flow rate, displacement pressure difference, sand flow rate, and particle size.

[0024] In step 2, when classifying the instability and failure forms of the alternating injection and production of the coated sand filling layer in the air energy storage well, the coated sand filling layer is consolidated to the screen surface and converted to the experimental conditions based on the actual consolidation conditions and injection and production conditions on site using the similarity principle. After the experimental test, the container cover is opened and different instability forms of the coated sand are observed. According to the instability and failure forms in the experimental cavity, the instability and failure forms of the coated sand filling layer are classified, including the gravel intrusion and blockage failure mode of the coated sand filling layer, the extrusion plastic crushing mode of the coated sand filling layer, and the rupture instability mode of the coated sand filling layer.

[0025] In step 2, when identifying the instability and failure mode of the alternating injection and production of the coated sand filling layer of the air energy storage well, the pressure difference and displacement flow rate at both ends of the coated sand filling layer during the experiment or production process are collected, and the permeability curves of both ends of the coated sand filling layer in the injection and production stage in each cycle are calculated using Darcy's law. The instability and failure mode of the coated sand filling layer is identified based on the dynamic changes of the experimental or production pressure difference and permeability curve.

[0026] In step 3, the stability of the coated sand filling layer under the production conditions of the air energy storage well is evaluated. According to the parameters of the sand retaining medium permeability, sand particle size and gas production intensity in the displacement process, the filling layer stability index, sand retaining performance index, flow performance index, anti-clogging performance index and comprehensive performance index of each cycle of the coated sand filling layer are calculated to evaluate the performance of the coated sand filling layer. According to the evaluation of the comprehensive performance index of each cycle, a coated sand sample suitable for the production conditions of the air energy storage well is obtained. Based on the on-site production conditions and sand production characteristics, the changes in the performance of the coated sand in each cycle are evaluated, providing a reliable experimental basis for regulating the pressure difference at both ends of the coated sand in the actual production process.

[0027] In step 3, when calculating the sand retention performance index of the alternating injection-production cycle, the sand retention performance during the alternating injection-production cycle is characterized by the amount of sand passing through and the maximum sand particle size. The greater the amount of sand passing through during the experiment, or the larger the maximum sand particle size, the weaker the sand retention capacity. The theoretical sand passing ratio R is used to represent the mass ratio of the formation sand with a particle size smaller than the coating sand particle size accuracy in the experimental formation sand to the total sand volume. The sand passing rate R during the experimental test cycle is m(j) for:

[0028]

[0029] Where m t is the total formation sand mass of the experiment, g; m s(j) is the mass of sand passing through the screen tube in a certain period, g; R is the theoretical sand passing ratio, dimensionless; R m is the sand passing rate of the screen tube, dimensionless;

[0030] Define the periodic sand particle size ratio R d(j)The ratio of the maximum sand particle size in the jth cycle to the median of the nominal particle size of the coating sand:

[0031]

[0032] Where, d pmax is the maximum particle size of the formation sand passing through the coating sand filling layer, mm; w f R is the nominal accuracy of the coated sand filling layer, mm; d is the sand particle size ratio, dimensionless;

[0033] The larger the sand passing rate and the larger the sand passing particle size ratio, the worse the sand retaining capacity. The sand retaining performance evaluation index is proposed to be the weighted average of the above two dimensionless indicators:

[0034]

[0035] Where S d(j) is the evaluation index of periodic sand retaining performance, dimensionless; X d is the weighted average coefficient;

[0036] Evaluation index S of sand retaining performance in alternating injection-production cycle d(j) The amount and particle size of the formation sand blocked by the sand retaining medium are taken into consideration at the same time. Its value is between 0 and 1. The larger the index value, the better the sand retaining performance.

[0037] In step 3, when evaluating the flow performance of the alternating injection-production cycle, the experimental data mainly tested or collected were the displacement flow rate, the pressure difference between the screen and the coated sand filling layer, and the sand flow rate. Based on the pressure difference between the outer side of the simulated filling layer and the inner wall of the screen sub, the flow rate, and the geometric parameters of the wellbore and the screen sub, Darcy's law was used to calculate the comprehensive permeability of the screen and filling section. The calculation formula is shown in Equation 1-7:

[0038]

[0039] Where k si is the permeability of the coated sand filling layer, D; q i is the flow rate through the sand retaining medium at the i-th moment, cm 3 ·s -1 ; μ is the fluid viscosity, mPa·s; r0 is the inner radius of the coated sand filling layer, cm; r i is the outer radius of the coated sand filling layer, cm; h is the effective height of the sand retaining medium, cm; ΔP i is the pressure difference at both ends of the sand retaining medium at a certain moment, MPa;

[0040] The permeability during the alternating injection-production cycle, that is, the fluid flow capacity of the coated sand filling layer during a certain production cycle, can be expressed by permeability; the better the overall permeability of the coated sand layer, the smaller the flow resistance.

[0041] In step 3, when calculating the permeability index of the alternating injection-production cycle, the permeability of the sand retaining medium in a certain production / test process is expressed as the comprehensive permeability k s It depends on the final permeability k of a certain experimental cycle. s0 and the permeability change during a production / test cycle; the end-of-use permeability k s0 and the average permeability k over the entire cycle sa The weighted average calculation yields the comprehensive permeability k s :

[0042] k s(j) =(1-X s )·k sa(j) +X s k s0(j) (1-8)

[0043]

[0044] Where, X s is the weighted average calculation coefficient; k s (j) is the comprehensive permeability of the sand retaining medium in the gas production stage of the jth cycle, μm 2 ;k s0 The permeability of the coated sand layer at the end of a certain period of the jth period is obtained by experimental test, and the permeability in each period is obtained by testing the quasi-stable stage, μm 2 ;k sa is the average permeability obtained during the entire experiment, μm 2 ;

[0045] In order to facilitate the comparison of the permeability performance of the coated sand filling layer in each cycle and the calculation of various subsequent dimensionless indicators, the dimensionless permeability performance index S of the coated sand filling layer in different cycles is proposed. l(j) The calculation formula is:

[0046]

[0047] Where k s(j) —Comprehensive permeability in the jth cycle μm 2 ;k smax —The maximum comprehensive permeability of the sand retaining medium in the jth cycle, μm 2 ;S l(j) —Dimensionless permeability evaluation index within the jth cycle.

[0048] In step 3, when evaluating the anti-clogging performance of the alternating injection-production cycle, the result of the blockage of the coated sand filling layer is an increase in the displacement pressure or pressure difference, or a decrease in the permeability or permeability ratio, and finally reaching a basically stable state, indicating that the blockage process is complete. The speed of change of the displacement pressure difference or permeability / permeability ratio over time and the final maintenance degree reflect the blockage status of the sand retaining medium, that is, the anti-clogging performance of the screen.

[0049] According to the above analysis, the anti-blocking performance can be qualitatively characterized by the curves of displacement pressure difference and permeability ratio over time. In order to facilitate quantitative evaluation, the periodic anti-blocking performance evaluation index S is proposed. k(j) ;

[0050] When the experimental flow rate is basically constant, the anti-clogging evaluation index can be calculated using the displacement pressure difference change curve:

[0051]

[0052] Where, is the average displacement pressure difference in the initial stage. It is recommended to take the first 1 / 4 of the displacement time for calculation, MPa; is the average displacement pressure difference in the final stage. It is recommended to take the last 1 / 4 of the displacement time for calculation, MPa; S k(j) is the anti-blocking performance evaluation index of the jth cycle, dimensionless;

[0053] For situations where the experimental flow rate is basically constant or not constant, the permeability ratio change curve can be used to calculate the anti-clogging evaluation index:

[0054]

[0055] Where, is the average permeability in the initial stage. It is recommended to calculate the first 1 / 4 of the displacement time, μm 2 ; The average permeability in the final stage is recommended to be calculated based on the last 1 / 4 of the displacement time, μm 2 ;

[0056] Anti-blocking performance evaluation index S k (j) is between 0 and 1. The larger the index value, the better the anti-blocking performance.

[0057] In step 3, when calculating the stability index of the alternating injection-production cycle, experimental tests show that after a certain period, as the physical properties of the filling layer change, its sand retaining effect decreases, which may cause the sand particle size to become larger. For the target air energy storage well, the critical sand particle size is 5μm. When the sand particle size is greater than 5μm, through analysis and processing of the experimental data, if the average permeability after the experiment is reduced to 80% of the initial permeability, then the production condition at this time is the critical production condition of the coating layer.

[0058] In step 3, when calculating the stability index, when the sand filling layer experiences gravel intrusion and clogging failure and full consolidation plastic extrusion failure, the critical instability period is W1, and the total experimental period is W t , the initial permeability k in the first cycle s01 , the critical instability period permeability is recorded as k s0z , then the stability index S w(j) The calculation method is:

[0059]

[0060] The stability index indicates the overall stability of the coated sand filling layer during the entire experiment / production process, ranging from 0 to 1. The larger the index, the better the stability of the coated sand filling layer.

[0061] In step 3, when calculating the periodic sand control function index, the periodic sand control function index S1 is a comprehensive reflection of the stability index, permeability, sand retaining performance and anti-blocking performance. d , penetration performance index S l , anti-blocking performance index S k and stability index S w Calculated by weighted average:

[0062] s 1(j) =W k s k(j) +W l s l(j) +W d s d(j) +W w s w(j) (1-14)

[0063] W k +W l +W d +W w =1 (1-15)

[0064] Where W d W is the sand retaining performance weight coefficient, dimensionless; l is the permeability weight coefficient, dimensionless; W k is the anti-blocking performance weight coefficient, W w is the dimensionless stability performance weight coefficient; S 1(j) It is a dimensionless indicator of sand control function in a certain period.

[0065] In step 3, when calculating the periodic equilibrium performance index, a well-performing coated sand filling medium requires not only a high weighted average value of stability, permeability, sand retention, and anti-blocking performance evaluation indicators, but also a relatively balanced performance of the above four to meet the long-term production needs of oil and gas wells. Based on this, the periodic equilibrium performance index S is defined. 2(j) for:

[0066]

[0067] The larger the periodic balance performance index S2 is, the more balanced the various performances of the sand retaining medium are; the larger the periodic sand control function index S1 and the periodic balance performance index S2 are, the better the comprehensive performance is.

[0068] In step 3, the comprehensive performance index S of the sand retaining medium within a certain period j The calculation formula is:

[0069] S j =S 1j ×0.7+S 2j ×0.3 (1-17)

[0070] Where S 2(j) is the equilibrium performance index within a certain period, dimensionless; S is the comprehensive performance index, dimensionless.

[0071] In step 3, the comprehensive performance index S within the cycle j The larger the value, the greater the weighted average value of each individual performance, and the more balanced the individual performance. The calculation formula for the comprehensive performance index of each cycle is:

[0072]

[0073] Where S is the weighted average value of the comprehensive indicators of each period, dimensionless;

[0074] The larger the comprehensive performance evaluation index S is, the better the properties of the coated sand filling layer are in each cycle. The final comprehensive performance evaluation index can be used to accurately and quantitatively compare the sand control effects of the coated sand filling layer.

[0075] In step 4, for the instability and failure morphology of the coated sand in step 2, the device is opened after the experiment to observe the instability morphology of the coated sand filling layer and the formation sand. Different instability states can be observed. The performance of the coated sand decreases in sequence from the gravel intrusion and blockage failure mode of the coated sand filling layer, the extrusion plastic crushing mode of the coated sand filling layer, and the rupture instability mode of the coated sand filling layer, and its performance can be judged.

[0076] In step 4, based on the pressure difference collected during the experiment in step 2 and the calculated permeability, the instability mode existing in the production process can be judged. If the failure mode is gravel intrusion and blockage of the coated sand filling layer, it means that the coated sand filling layer has not completely failed, and safe production can be carried out without adjusting the injection and production volume; if the mode is extrusion plastic crushing of the coated sand filling layer, it means that the coated sand filling layer has not completely failed, and the output needs to be reduced for production; if the mode is rupture and instability of the coated sand filling layer, it means that the underground coated sand filling layer has completely failed, the risk of sand production increases, and it will affect normal production.

[0077] In step 4, for each indicator calculated in step 3, a larger value of the periodic sand retaining performance indicator indicates better sand retaining performance in each cycle; the periodic flow performance indicator indicates that the better the overall permeability of the coated sand layer, the smaller the flow resistance, and the smaller the production capacity loss in a certain cycle; the periodic anti-blocking performance evaluation indicates that a larger value of the indicator indicates better anti-blocking performance and less blockage by formation sand in a certain cycle; the larger the periodic performance stability indicator indicates that the period of stable production of the coated sand filling layer is longer and the better the stability; the larger the periodic balance indicator indicates that the various properties of the sand retaining medium are more balanced, and the larger the periodic sand control function indicator indicates that the sand control performance of the coated sand layer is better; the larger the comprehensive performance indicator within the cycle indicates that the performance of the coated sand is better within a certain cycle and the bottom hole production is more stable, and a lower value indicates that the coated sand filling layer is at risk of instability and that the production needs to be reduced to maintain the stability of the coated sand filling layer; the same experimental evaluation is carried out on different coated sand samples, and their adaptability to the air energy storage production conditions is evaluated based on the calculated periodic comprehensive indicators, and the larger the periodic comprehensive indicator indicates that the performance is better.

[0078] The purpose of the present invention can also be achieved through the following technical measures: an air energy storage well coated sand layer alternating injection and production instability mode discrimination and evaluation system, characterized in that the air energy storage well coated sand layer alternating injection and production instability mode discrimination and evaluation system adopts an air energy storage well coated sand layer alternating injection and production instability mode discrimination and evaluation method to control sand production during the production process of the air energy storage well.

[0079] The method for distinguishing and evaluating the instability mode of alternating injection and production of coated sand layers in air energy storage wells in the present invention belongs to the technical field of sand control and completion, and is mainly used for the sand production control problem in the production process of air energy storage wells. The method for distinguishing and evaluating the instability mode of alternating injection and production of coated sand layers in air energy storage wells gives different instability and destruction states in specific injection and production stages, which are used to characterize the pore throat characteristics and internal structure changes of the instability of the coated sand filling layer; a method for distinguishing the instability mode based on the dynamic changes of the pressure difference or permeability at both ends of the coated sand filling layer in different injection and production cycles during the experiment (production) process is proposed; the innovation of the method lies in that the internal instability state can be simply judged by the pressure difference and permeability of a certain experimental (production) cycle; a method is proposed to evaluate the performance of the coated sand filling layer by experimentally testing the pressure difference, permeability and sand particle size at both ends of the alternating injection and production, and calculating the filling layer stability index, sand retaining performance index, flow performance index, anti-blocking performance index and comprehensive performance index of each cycle of the coated sand filling layer; compared with other evaluation methods, the advantage is that the filling layer stability performance index is added, and the performance of the coated sand filling layer in each cycle can be evaluated.

[0080] Since the stability of the underground sand control process during the alternating injection and production of air energy storage wells is the guarantee for the safe and efficient production of air energy storage wells, the present invention proposes a stability evaluation index and conducts a stability evaluation for air energy storage wells that use a coated sand filling layer as the main sand control method. The purpose is to evaluate the stability of the coated sand filling layer during the experiment (production) process in a simple way. According to actual production conditions such as: the degree of consolidation of the coated sand, the production alternating cycle, the injection and production volume and other parameters, the experimental parameters in the experimental process are fitted according to the similarity principle, the production status of the coated sand filling layer in the well is simulated, and the instability mode is identified, which has certain guiding significance for the safe production of actual wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 Schematic diagram of a failure mode of gravel intrusion and clogging in a coated sand filling layer according to a specific embodiment of the present invention;

[0082] Figure 2 Schematic diagram of the extrusion plastic crushing mode of the coated sand filling layer in a specific embodiment of the present invention;

[0083] Figure 3 Schematic diagram of the cracking and instability mode of the coated sand filling layer in a specific embodiment of the present invention;

[0084] Figure 4 A schematic diagram of the main experimental implementation plan and test data in a specific embodiment of the present invention;

[0085] Figure 5 A typical dynamic curve diagram of an intrusion and blockage failure mode of a coated sand filling layer in a specific embodiment of the present invention;

[0086] Figure 6 This is a dynamic diagram of a typical curve of plastic extrusion failure of a fully consolidated coated sand filling layer in a specific embodiment of the present invention;

[0087] Figure 7 A dynamic diagram of a typical curve of a cracking and instability mode of a coated sand filling layer in a specific embodiment of the present invention;

[0088] Figure 8 The present invention is a flow chart of a specific embodiment of the method for distinguishing and evaluating the instability mode of alternating injection and production of coated sand layers in air energy storage wells. DETAILED DESCRIPTION

[0089] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0090] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations and / or combinations thereof.

[0091] The present invention mainly addresses the problems of classification method for the instability and damage morphology of alternating injection and production of sand-coated filling layers in air-deficient energy storage wells, instability identification method for filling sand-control completion systems during production of air-deficient energy storage reservoirs, and stability evaluation method for filling sand-control layers after cyclic production of air-deficient energy storage reservoirs. A method for evaluating the instability and damage of alternating injection and production of sand-coated filling layers in air-deficient energy storage wells is proposed.

[0092] like Figure 8 As shown, Figure 8 This is a flow chart of the method for distinguishing and evaluating the instability mode of alternating injection and production in the coated sand layer of an air energy storage well according to the present invention. The method for distinguishing and evaluating the instability mode of alternating injection and production in the coated sand layer of an air energy storage well comprises:

[0093] Step 1: Determine the initial state parameters of the evaluation object.

[0094] The flow rate in the experimental evaluation is determined based on the similarity criterion.

[0095] The similarity of flow phenomena requires the equality of the Nusselt criterion number, which can be derived from the momentum differential equation:

[0096]

[0097] Where, μ′ is the actual reservoir fluid viscosity, mPa·s; μ″ is the experimental fluid viscosity, mPa·s; l′ is the actual reservoir thickness, m; l″ is the experimental reservoir thickness, m; v′ is the actual reservoir fluid flow rate, m / s; v″ is the experimental fluid flow rate, m / s;

[0098] Right now:

[0099] Re′=Re″ (1-2)

[0100] Where Re is the Reynolds number, Re′ is the Reynolds number of the actual reservoir, and Re″ is the Reynolds number during experimental evaluation, all dimensionless. In the present invention, superscript 1 refers to the physical property parameters used in experimental evaluation, and superscript 2 refers to the reservoir physical property parameters and injection and production gas volumes during actual production.

[0101] This shows that the Reynolds criterion of two fluids with similar motion phenomena must be equal. It can also be derived that:

[0102]

[0103] Where Q' is the actual fluid flow rate, m 3 / h; Q″ is the experimental fluid flow rate, m 3 / h;

[0104] The flow rate in the experimental evaluation is determined based on the similarity criterion.

[0105] Step 2: Collect parameters at both ends of the coated sand filling layer during the experiment.

[0106] The collected parameters include: displacement flow, displacement pressure difference, sand flow rate, and particle size.

[0107] S21: Classification of instability and failure forms of alternating injection and production of coated sand filling layers in air energy storage wells.

[0108] The coated sand filling layer was consolidated to the screen surface and converted to experimental conditions based on the actual on-site consolidation conditions and injection-production conditions using similarity principles. After the experimental test, the container lid was opened and different instability forms of the coated sand were observed. According to its instability failure form in the experimental cavity, the instability failure of the coated sand filling layer was classified, including the gravel intrusion and blockage failure mode of the coated sand filling layer, the extrusion plastic crushing mode of the coated sand filling layer, and the rupture instability mode of the coated sand filling layer.

[0109] S22: Identification of instability failure modes of alternating injection and production in coated sand filling layers of air energy storage wells

[0110] The pressure difference and displacement flow rate at both ends of the coated sand filling layer are collected during the experiment (production). The permeability curves at both ends of the coated sand filling layer during the injection and production stages of each cycle are calculated using Darcy's law. The instability and failure mode of the coated sand filling layer are identified based on the dynamic changes of the experimental (production) pressure difference and permeability curves.

[0111] Step 3: Calculate various indicators based on the collected parameters.

[0112] The calculated indicators include: sand retaining performance index, flow performance index, anti-blocking performance index, and stability index.

[0113] Comprehensive performance evaluation of sand filling layer in air energy storage wells

[0114] For the stability evaluation of the coated sand filling layer under the production conditions of air energy storage wells, according to the parameters such as the permeability of the sand retaining medium, the sand particle size, and the gas production intensity in the displacement process, the filling layer stability index, sand retaining performance index, flow performance index, anti-clogging performance index of the coated sand filling layer in a certain period and the comprehensive performance index of each period are calculated to evaluate the performance of the coated sand filling layer. According to the evaluation of the comprehensive performance index of each period, a coated sand sample suitable for the production conditions of air energy storage wells is obtained. Based on the on-site production conditions and sand production characteristics, the changes in the performance of the coated sand in each period are evaluated, providing a reliable experimental basis for regulating the pressure difference at both ends of the coated sand in the actual production process.

[0115] Calculation method of sand retention performance index during alternating injection and production cycle: The sand retention performance during the alternating injection and production cycle is characterized by the amount of sand passing through and the maximum sand particle size. The greater the amount of sand passing through during the experiment, or the larger the maximum sand particle size, the weaker the sand retention capacity. The theoretical sand passing ratio R is used to represent the mass ratio of the formation sand with a particle size smaller than the coating sand particle size accuracy in the experimental formation sand to the total sand volume. The sand passing rate R during the experimental test cycle is m(j) for:

[0116]

[0117] Where m t is the total formation sand mass of the experiment, g; m s(j) is the mass of sand passing through the screen tube in a certain period, g; R is the theoretical sand passing ratio, dimensionless. m is the sand passing rate of the screen tube, dimensionless.

[0118] Define the periodic sand particle size ratio R d(j) The ratio of the maximum sand particle size in the jth cycle to the median of the nominal particle size of the coating sand:

[0119]

[0120] Where, d pmaxis the maximum particle size of the formation sand passing through the coating sand filling layer, mm; w f R is the nominal accuracy of the coated sand filling layer, mm; d is the sand particle size ratio, dimensionless.

[0121] The larger the sand passing rate and the larger the sand passing particle size ratio, the worse the sand retaining capacity. The sand retaining performance evaluation index is proposed to be the weighted average of the above two dimensionless indicators:

[0122] S d(j) =(1-R m(j) )X d +(1-R d(j) )(1-X d ) (1-6)

[0123] Where S d(j) is the evaluation index of periodic sand retaining performance, dimensionless; X d It is the weighted average coefficient, which generally focuses on the amount of sand passing through. It is recommended to take X d =0.65.

[0124] Evaluation index S of sand retaining performance in alternating injection-production cycle d(j) The amount and particle size of the formation sand blocked by the sand retaining medium are taken into consideration at the same time. Its value is between 0 and 1. The larger the index value, the better the sand retaining performance.

[0125] Evaluation method for flow performance of alternating injection-production cycle

[0126] The main test (collection) data in the experiment are displacement flow rate, pressure difference between the screen and coated sand packing layer, and sand flow rate. Based on the pressure difference between the outer side of the simulated packing layer and the inner wall of the screen sub, flow rate, and geometric parameters of the wellbore wall and screen sub, Darcy's law is used to calculate the comprehensive permeability of the screen and packing section. The calculation formula is shown in Equation 1-7:

[0127]

[0128] Where k si is the permeability of the coated sand filling layer, D; q i is the flow rate through the sand retaining medium at the i-th moment, cm 3 ·s -1 ; μ is the fluid viscosity, mPa·s; r0 is the inner radius of the coated sand filling layer, cm; r i is the outer radius of the coated sand filling layer, cm; h is the effective height of the sand retaining medium, cm; ΔP i It is the pressure difference at both ends of the sand retaining medium at a certain moment, MPa.

[0129] The permeability of a sand-coated fill layer during an alternating injection-production cycle, or the fluid flow capacity of the fill layer during a production cycle, can be expressed as permeability. Better overall permeability of the sand-coated fill layer indicates lower flow resistance.

[0130] Calculation of permeability index during alternating injection and production cycle: The permeability of the sand retaining medium in a certain production / test process is calculated using the comprehensive permeability k s It depends on the final permeability k of a certain experimental cycle. s0 and the permeability change during a production / test cycle. End-of-use permeability k s0 and the average permeability k over the entire cycle sa The weighted average calculation yields the comprehensive permeability k s .

[0131] k s(j) =(1-X s )·k sa(j) +X s k s0(j) (1-8)

[0132]

[0133] Where, X s k is the weighted average calculation coefficient, and 0.5 is recommended; s(j) is the comprehensive permeability of the sand retaining medium in the gas production stage of the jth cycle, μm 2 ;k s0 The permeability of the coated sand layer at the end of a certain period of the jth period is obtained by experimental test, and the permeability in each period is obtained by testing the quasi-stable stage, μm 2 ;k sa is the average permeability obtained during the entire experiment, μm 2 .

[0134] In order to facilitate the comparison of the permeability performance of the coated sand filling layer in each cycle and the calculation of various subsequent dimensionless indicators, the dimensionless permeability performance index S of the coated sand filling layer in different cycles is proposed. l(j) The calculation formula is:

[0135]

[0136] Where k s(j) —Comprehensive permeability in the jth cycle μm 2 ;k smax —The maximum comprehensive permeability of the sand retaining medium in the jth cycle, μm 2 ;S l(j) —Dimensionless permeability evaluation index within the jth cycle.

[0137] Evaluation method for anti-blocking performance of alternating injection-production cycle

[0138] The result of the blockage of the coated sand filling layer is an increase in the displacement pressure or pressure difference (when the displacement flow rate remains basically unchanged), or a decrease in the permeability or permeability ratio, and finally reaches a basically stable state, indicating that the blockage process is completed. The speed of change of the displacement pressure difference or permeability / permeability ratio over time and the final maintenance degree reflect the blockage situation of the sand retaining medium, that is, the anti-blockage property of the screen.

[0139] According to the above analysis, the anti-blocking performance can be qualitatively characterized by the curves of displacement pressure difference and permeability ratio over time. In order to facilitate quantitative evaluation, the periodic anti-blocking performance evaluation index S is proposed. k(j) .

[0140] When the experimental flow rate is basically constant, the anti-clogging evaluation index can be calculated using the displacement pressure difference change curve:

[0141]

[0142] Where, is the average displacement pressure difference in the initial stage. It is recommended to take the first 1 / 4 of the displacement time for calculation, MPa; is the average displacement pressure difference in the final stage. It is recommended to take the last 1 / 4 of the displacement time for calculation, MPa; S k(j) is the anti-blocking performance evaluation index of the j-th cycle, dimensionless.

[0143] For situations where the experimental flow rate is basically constant or not constant, the permeability ratio change curve can be used to calculate the anti-clogging evaluation index:

[0144]

[0145] Where, is the average permeability in the initial stage. It is recommended to calculate the first 1 / 4 of the displacement time, μm 2 ; The average permeability in the final stage is recommended to be calculated based on the last 1 / 4 of the displacement time, μm 2 .

[0146] Anti-blocking performance evaluation index S k(j) The value is between 0 and 1. The larger the value, the better the anti-blocking performance.

[0147] Stability index of alternating injection-production cycle

[0148] Through experimental tests, it is found that after a certain period, as the physical properties of the filling layer change, its sand retaining effect decreases, which may cause the sand particle size to become larger. For the target air energy storage well, the critical sand particle size is 5μm. When the sand particle size is greater than 5μm, through analysis and processing of the experimental data, if the average permeability after the experiment is reduced to 80% of the initial permeability, then the production conditions at this time are the critical production conditions of the coating layer.

[0149] Stability index calculation method: When the sand filling layer experiences gravel intrusion and blockage failure instability mode and full consolidation plastic extrusion failure, the critical instability period is W1, and the total experimental period is W t , the initial permeability k in the first cycle s01 , the critical instability period permeability is recorded as k s0z , then the stability index S w(j) The calculation method is:

[0150]

[0151] The stability index indicates the overall stability of the coated sand filling layer during the entire experiment / production process, ranging from 0 to 1. The larger the index, the better the stability of the coated sand filling layer.

[0152] Calculation method of comprehensive performance index: Sand control function index S1 is a comprehensive reflection of stability index, permeability, sand retaining performance and anti-blocking performance. d , penetration performance index S l , anti-blocking performance index S k and stability index S w Calculated by weighted average:

[0153] s 1(j) =W k s k(j) +W l s l(j) +W d s d(j) +W w s w(j) (1-14)

[0154] W k +W l +W d +W w =1 (1-15)

[0155] Where W d W is the sand retaining performance weight coefficient, dimensionless; l is the permeability weight coefficient, dimensionless; W k is the anti-blocking performance weight coefficient, W w is the dimensionless stability performance weight coefficient; S 1(j)It is a dimensionless indicator of sand control function in a certain period.

[0156] The above weight coefficients are empirical coefficients, determined based on subjective experience, and are used to adjust the requirements of a specific sand control reservoir or block for sand control technology in terms of sand retention performance, anti-clogging performance, and permeability. In general, the primary function of a mechanical screen is to retain and control sand, while also taking into account flowability and anti-clogging performance. Therefore, when setting the above weight coefficients, sand retention performance plays an absolutely primary role, and it is generally recommended to take W d =0.4,W k =0.2,W l =0.2,W w =0.2. On this basis, it can be flexibly adjusted according to specific sand control needs and evaluation purposes.

[0157] A well-performing coated sand filling medium requires not only a high weighted average of stability, permeability, sand retention, and anti-blocking performance evaluation indicators, but also requires the above four properties to be relatively balanced to meet the long-term production needs of oil and gas wells. Based on this, the balanced performance index S is defined. 2(j) for:

[0158]

[0159] The larger the balance index S2, the more balanced the performance of the sand retaining medium; the larger the functional index S1 and the balance index S2, the better the overall performance.

[0160] Define the comprehensive performance index S of the sand retaining medium within a certain period j for:

[0161] S j =S 1j ×0.7+S 2j ×0.3 (1-17)

[0162] Where S 2(j) is the equilibrium performance index within a certain period, dimensionless; S is the comprehensive performance index, dimensionless.

[0163] Comprehensive performance index S within the cycle j The larger it is, the larger the weighted average of each individual performance is, and the more balanced the individual performance is.

[0164]

[0165] Where S is the weighted average value of the comprehensive indicators of each period and is dimensionless.

[0166] The larger the comprehensive performance evaluation index S is, the better the properties of the coated sand filling layer are in each cycle. The final comprehensive performance evaluation index can be used to accurately and quantitatively compare the sand control effects of the coated sand filling layer.

[0167] Step 4: Conduct production control and evaluate the coated sand filling layer based on the index calculation results.

[0168] Regarding the instability and failure morphology of the coated sand in S21, the device was opened after the experiment to observe the instability morphology of the coated sand filling layer and the formation sand. Different instability states can be observed. The performance of the coated sand decreases in sequence from the gravel intrusion and blockage failure mode of the coated sand filling layer, the extrusion plastic crushing mode of the coated sand filling layer, and the rupture instability mode of the coated sand filling layer, and its performance can be easily judged.

[0169] Based on the pressure difference collected during the experiment in S22 and the calculated permeability, the instability mode existing in the production process can be judged. If it is the failure mode of gravel intrusion and blockage of the coated sand filling layer, it means that the coated sand filling layer has not completely failed, and safe production can be carried out without adjusting the injection and production volume; if it is the extrusion plastic crushing mode of the coated sand filling layer, it means that the coated sand filling layer has not completely failed, and the output needs to be reduced for production; if it is the rupture and instability mode of the coated sand filling layer, it means that the underground coated sand filling layer has completely failed, the risk of sand production has increased, and it will affect normal production.

[0170] For each indicator calculated in step 3, the following are the cyclic sand retention performance index: A larger value indicates better sand retention performance within each cycle. The cyclic flow performance index: Better overall permeability of the coated sand layer indicates lower flow resistance and less production loss within a cycle. The cyclic anti-blocking performance evaluation: A larger value indicates better anti-blocking performance and less formation sand blockage within a cycle. The cyclic performance stability index: A larger value indicates a longer stable production cycle for the coated sand layer and better stability. A larger cyclic balance index indicates a more balanced performance of the sand retention medium. A larger cyclic sand control function index indicates better sand control performance of the coated sand layer. A larger cyclic comprehensive performance index indicates better performance within a cycle and more stable bottomhole production. A lower value indicates a risk of instability in the coated sand layer and requires production reduction to maintain stability. The same experimental evaluation was conducted on different coated sand samples. The calculated cyclic comprehensive index was used to evaluate their adaptability to air energy storage production conditions. A larger cyclic comprehensive index indicates better performance.

[0171] The classification method for the instability and failure morphology of the alternating injection and production of the coated sand filling layer of the air energy storage well proposed in the present invention solves the key problem of the current lack of characterization of the failure morphology of the coated sand. The identification method for the instability and failure mode of the alternating injection and production of the coated sand filling layer of the air energy storage well proposed in the present invention solves the current problem of the lack of judgment of the instability morphology of the coated sand through experimental (production) pressure difference and permeability dynamic curve. The comprehensive performance evaluation method of the coated sand filling layer of the air energy storage well proposed in the present invention solves the current problem of the lack of quantitative evaluation of the performance of the coated sand filling layer through experiments.

[0172] The following are several specific embodiments of the present invention:

[0173] Example 1

[0174] In a specific embodiment 1 of the present invention, the method for distinguishing and evaluating the instability mode of alternating injection and production in the coated sand layer of an air energy storage well includes the following steps:

[0175] (1) Classification method of instability failure forms of alternating injection and production of coated sand filling layers in air energy storage wells

[0176] Preferably, according to the present invention, in step S1, the coating sand filling layer has the following classification method of instability failure forms.

[0177] a Failure mode of gravel intrusion and clogging in the coated sand filling layer

[0178] At present, the solid control method of air energy storage wells mainly uses screen media and coated sand filling layer mechanical barrier. However, for production conditions where the coated sand filling layer is not fully consolidated, its failure mode is similar to the gravel filling sand control method under the production conditions of alternating injection and production. The repeated flow direction of the fluid will cause the sand retaining medium to become unstable after the blockage balance, and the sand retaining barrier will fail and the sand control will fail. During the gas injection stage, the formation sand on the surface of the coated sand filling layer will migrate to the reservoir, such as Figure 1 As shown in (a); During the gas production stage, a mixed zone of formation sand and coating sand filling layer is gradually produced, such as Figure 1 As shown in (b), with the change of injection-production cycle, the mixing of the coating sand filling layer and the formation sand becomes increasingly serious, the sand retaining bridge is formed slowly, and the stability of the coating sand filling layer is significantly reduced.

[0179] b Extrusion plastic crushing mode of coated sand filling layer

[0180] Figure 2 (a) is the state of the coating sand filling layer when no plastic extrusion occurs. During the gas injection stage, the injection of high gas volume will cause the consolidated coating sand filling layer and the reservoir to undergo plastic compression, which will deteriorate the overall permeability of the coating sand filling layer. During the gas production stage, the formation sand enters the coating sand filling layer, invading the entire coating sand filling layer, such as Figure 2 As shown in (b), the unstable longitudinal section of the coated sand filling layer is as follows Figure 2 As shown in (c), the permeability of the coated sand filling layer decreases significantly. As the cycle increases, the coated sand filling layer is gradually compacted and eventually plastic failure occurs.

[0181] c. Cracking and instability mode of coated sand filling layer

[0182] During the gas injection stage, there are high-flow locations in the fully consolidated coated sand filling layer, and under high-intensity gas injection conditions, a deficit area will gradually appear. During the gas production stage, the fluid will carry the formation sand along the high-flow area, gradually causing the particles of the coated sand filling layer to peel off, and eventually causing the coated sand filling layer to rupture or break. The rupture phenomenon will eventually cause sand breakthrough, and the breakage will cause the coating layer to fall off in pieces, and mixing with the formation sand will cause blockage, such as Figure 3 shown.

[0183] (2) Identification method of instability failure mode of alternating injection and production of coated sand filling layer in air energy storage well

[0184] Preferably, according to the present invention, in step S2, three dynamic identification methods based on different experimental / production curves are invented for the three instability modes of the coated sand filling layer.

[0185] The main test (collection) data of the experiment are displacement flow, pressure difference between the screen and the unstable medium, and sand passing rate. Figure 4 As shown in (a), the gas production stage is as follows Figure 4 As shown in (b), the Darcy law is used to calculate the comprehensive permeability of the screen and filling section based on the flow rate of the simulation test and the geometric parameters of the wellbore and screen short section.

[0186] a. Failure mode identification method for gravel intrusion and blockage in coated sand filling layer

[0187] The coated sand filling layer will fail due to gravel intrusion and blockage due to its own properties and injection and production conditions. In a single injection or production cycle, the experiment observed that the pressure difference at both ends of the filling layer slowly increased with time, and the pressure difference rising trend gradually became flat, and eventually tended to a stable value with the increase of production time. This is because the gravel filling layer and the near-well reservoir deformed and mixed, and finally reached a stable state. With the switching of injection and production cycles, the pressure difference at both ends of the filling layer continued to change, but its overall trend tended to increase, and the gravel filling layer and the near-well reservoir continued to deform and mix. After reaching a certain injection and production cycle, the gravel layer and the near-well formation are completely mixed, and the injection and production cycle is switched, and the pressure difference at both ends of the filling layer will no longer change. Eventually, a state of equilibrium is formed, at which time the permeability of the filling layer will gradually stabilize as shown in the figure. Figure 5 shown.

[0188] b. Recognition method of plastic crushing pattern of coated sand filling layer

[0189] The coated sand filling layer will be squeezed and plastically crushed due to its own properties and injection and production conditions. When the experiment / production observes that the pressure difference at both ends of the filling layer continues to increase over time, it may be that the filling layer is affected by the alternating stress and undergoes plastic extrusion, which causes the original filling layer to be compacted and the permeability of the filling layer to change. When the experiment observes that the pressure difference at both ends of the filling layer increases in this cycle and the stabilization trend is not obvious, it means that the displacement pressure generated by the fluid flow is continuously compacting the coated sand layer and gradually tightening it, resulting in a decrease in the permeability of the filling layer, which eventually tends to be stable. The permeability change is as follows: Figure 6 shown.

[0190] c. Identification method of cracking and instability pattern of coated sand filling layer

[0191] The coated sand filling layer will break and become unstable due to its own properties and injection and production conditions. When the experiment / production observes that the pressure difference at both ends of the filling layer fluctuates over time, it may be that the filling layer is broken by the influence of alternating stress, causing the original filling layer structure to change and causing the permeability of the filling layer to change; when the experiment observes that the pressure difference at both ends of the filling layer suddenly drops, it may be because the filling layer is broken and fractured by the influence of alternating stress, and gas breakthrough occurs within a certain range, and the permeability of the filling layer increases. When the experiment observes that the pressure difference at both ends of the filling layer rises slowly, it may be because the filling layer is plastically compacted by the influence of alternating stress and formation sand invades, resulting in a decrease in the permeability of the filling layer. The permeability change is as follows: Figure 7 shown.

[0192] (3) Evaluation method of comprehensive performance index of coated sand properties

[0193] Preferably, according to the present invention, in step S3, a set of experimental evaluation methods for the performance of the coated sand filling layer is invented based on the production conditions of the air energy storage well.

[0194] a. Establishment of experimental conditions for filling layer stability evaluation

[0195] The flow rate in the experimental evaluation is determined based on the similarity criterion.

[0196] The similarity of flow phenomena requires the equality of the Nusselt criterion number, which can be derived from the momentum differential equation:

[0197]

[0198] Wherein, μ′ is the actual fluid viscosity, mPa·s; μ″ is the experimental fluid viscosity, mPa·s; l′ is the actual reservoir thickness, m; l″ is the experimental reservoir thickness, m; v′ is the actual fluid flow rate, m / s; v″ is the experimental fluid flow rate, m / s;

[0199] Right now:

[0200] Re′=Re″ (1-2)

[0201] Where Re is the Reynolds number.

[0202] This shows that the Reynolds criterion of two fluids with similar motion phenomena must be equal. It can also be derived that:

[0203]

[0204] Where Q' is the actual fluid flow rate, m 3 / h; Q″ is the experimental fluid flow rate, m 3 / h;

[0205] The flow rate in the experimental evaluation is determined based on the similarity criterion.

[0206] b. Evaluation method of sand retaining performance in alternating injection-production cycles

[0207] Calculation method of sand retention performance index during alternating injection and production cycle: The sand retention performance during the alternating injection and production cycle is characterized by the amount of sand passing through and the maximum sand particle size. The greater the amount of sand passing through during the experiment, or the larger the maximum sand particle size, the weaker the sand retention capacity. The theoretical sand passing ratio R is used to represent the mass ratio of the formation sand with a particle size smaller than the coating sand particle size accuracy in the experimental formation sand to the total sand volume. The sand passing rate R during the experimental test cycle is m(j) for:

[0208]

[0209] Where m t is the total formation sand mass of the experiment, g; m s(j) is the mass of sand passing through the screen tube in a certain period, g; R is the theoretical sand passing ratio, dimensionless. m is the sand passing rate of the screen tube, dimensionless.

[0210] Define the periodic sand particle size ratio R d(j) The ratio of the maximum sand particle size in the jth cycle to the median of the nominal particle size of the coating sand:

[0211]

[0212] Where, d pmax is the maximum particle size of the formation sand passing through the coating sand filling layer, mm; w f R is the nominal accuracy of the coated sand filling layer, mm; d is the sand particle size ratio, dimensionless.

[0213] The larger the sand passing rate and the larger the sand passing particle size ratio, the worse the sand retaining capacity. The sand retaining performance evaluation index is proposed to be the weighted average of the above two dimensionless indicators:

[0214] S d(j) =(1-Rm(j) )X d +(1-R d(j) )(1-X d ) (1-6)

[0215] Where S d(j) is the evaluation index of periodic sand retaining performance, dimensionless; X d It is the weighted average coefficient, which generally focuses on the amount of sand passing through. It is recommended to take X d =0.65.

[0216] Evaluation index S of sand retaining performance in alternating injection-production cycle d(j) The amount and particle size of the formation sand blocked by the sand retaining medium are taken into consideration at the same time. Its value is between 0 and 1. The larger the index value, the better the sand retaining performance.

[0217] c. Evaluation method for flow performance of alternating injection-production cycles

[0218] The main test (collection) data in the experiment are displacement flow rate, pressure difference between the screen and coated sand packing layer, and sand flow rate. Based on the pressure difference between the outer side of the simulated packing layer and the inner wall of the screen sub, flow rate, and geometric parameters of the wellbore wall and screen sub, Darcy's law is used to calculate the comprehensive permeability of the screen and packing section. The calculation formula is shown in Equation 1-7:

[0219]

[0220] Where k si is the permeability of the coated sand filling layer, D; q i is the flow rate through the sand retaining medium at the i-th moment, cm 3 ·s -1 ; μ is the fluid viscosity, mPa·s; r0 is the inner radius of the coated sand filling layer, cm; r i is the outer radius of the coated sand filling layer, cm; h is the effective height of the sand retaining medium, cm; ΔP i It is the pressure difference at both ends of the sand retaining medium at a certain moment, MPa.

[0221] The permeability of a sand-coated fill layer during an alternating injection-production cycle, or the fluid flow capacity of the fill layer during a production cycle, can be expressed as permeability. Better overall permeability of the sand-coated fill layer indicates lower flow resistance.

[0222] Calculation of permeability index during alternating injection and production cycle: The permeability of the sand retaining medium in a certain production / test process is calculated using the comprehensive permeability k s It depends on the final permeability k of a certain experimental cycle. s0 and the permeability change during a production / test cycle. End-of-use permeability k s0 and the average permeability k over the entire cycle saThe weighted average calculation yields the comprehensive permeability k s .

[0223] k s(j) =(1-X s )·k sa(j) +X s k s0(j) (1-8)

[0224]

[0225] Where, X s k is the weighted average calculation coefficient, and 0.5 is recommended; s(j) is the comprehensive permeability of the sand retaining medium in the gas production stage of the jth cycle, μm 2 ;k s0 The permeability of the coated sand layer at the end of a certain period of the jth period is obtained by experimental test, and the permeability in each period is obtained by testing the quasi-stable stage, μm 2 ;k sa is the average permeability obtained during the entire experiment, μm 2 .

[0226] In order to facilitate the comparison of the permeability performance of the coated sand filling layer in each cycle and the calculation of various subsequent dimensionless indicators, the dimensionless permeability performance index S of the coated sand filling layer in different cycles is proposed. l(j) The calculation formula is:

[0227]

[0228] Where k s(j) —Comprehensive permeability in the jth cycle μm 2 ;k smax —The maximum comprehensive permeability of the sand retaining medium in the jth cycle, μm 2 ;S l(j) —Dimensionless permeability evaluation index within the jth cycle.

[0229] d. Evaluation method for anti-blocking performance of alternating injection-production cycles

[0230] The result of the blockage of the coated sand filling layer is an increase in the displacement pressure or pressure difference (when the displacement flow rate remains basically unchanged), or a decrease in the permeability or permeability ratio, and finally reaches a basically stable state, indicating that the blockage process is completed. The speed of change of the displacement pressure difference or permeability / permeability ratio over time and the final maintenance degree reflect the blockage situation of the sand retaining medium, that is, the anti-blockage property of the screen.

[0231] According to the above analysis, the anti-blocking performance can be qualitatively characterized by the curves of displacement pressure difference and permeability ratio over time. In order to facilitate quantitative evaluation, the periodic anti-blocking performance evaluation index S is proposed. k(j) .

[0232] When the experimental flow rate is basically constant, the anti-clogging evaluation index can be calculated using the displacement pressure difference change curve:

[0233]

[0234] Where, is the average displacement pressure difference in the initial stage. It is recommended to take the first 1 / 4 of the displacement time for calculation, MPa; is the average displacement pressure difference in the final stage. It is recommended to take the last 1 / 4 of the displacement time for calculation, MPa; S k(j) is the anti-blocking performance evaluation index of the j-th cycle, dimensionless.

[0235] For situations where the experimental flow rate is basically constant or not constant, the permeability ratio change curve can be used to calculate the anti-clogging evaluation index:

[0236]

[0237] Where, is the average permeability in the initial stage. It is recommended to calculate the first 1 / 4 of the displacement time, μm 2 ; The average permeability in the final stage is recommended to be calculated based on the last 1 / 4 of the displacement time, μm 2 .

[0238] Anti-blocking performance evaluation index S k(j) The value is between 0 and 1. The larger the value, the better the anti-blocking performance.

[0239] f. Stability index of alternating injection and production cycle

[0240] Through experimental tests, it is found that after a certain period, as the physical properties of the filling layer change, its sand retaining effect decreases, which may cause the sand particle size to become larger. For the target air energy storage well, the critical sand particle size is 5μm. When the sand particle size is greater than 5μm, through analysis and processing of the experimental data, if the average permeability after the experiment is reduced to 80% of the initial permeability, then the production conditions at this time are the critical production conditions of the coating layer.

[0241] Stability index calculation method: When the sand filling layer experiences gravel intrusion and blockage failure instability mode and full consolidation plastic extrusion failure, the critical instability period is W1, and the total experimental period is W t , the initial permeability k in the first cycle s01 , the critical instability period permeability is recorded as k s0z , then the stability index S w(j) The calculation method is:

[0242]

[0243] The stability index indicates the overall stability of the coated sand filling layer during the entire experiment / production process, ranging from 0 to 1. The larger the index, the better the stability of the coated sand filling layer.

[0244] e. Comprehensive evaluation method for alternating injection and production

[0245] Calculation method of comprehensive performance index: Sand control function index S1 is a comprehensive reflection of stability index, permeability, sand retaining performance and anti-blocking performance. d , penetration performance index S l , anti-blocking performance index S k and stability index S w Calculated by weighted average:

[0246] s 1(j) =W k s k(j) +W l s l(j) +W d s d(j) +W w s w(j) (1-14)

[0247] W k +W l +W d +W w =1 (1-15)

[0248] Where W d W is the sand retaining performance weight coefficient, dimensionless; l is the permeability weight coefficient, dimensionless; W k is the anti-blocking performance weight coefficient, W w is the dimensionless stability performance weight coefficient; S 1(j) It is a dimensionless indicator of sand control function in a certain period.

[0249] The above weight coefficients are empirical coefficients, determined based on subjective experience, and are used to adjust the requirements of a specific sand control reservoir or block for sand control technology in terms of sand retention performance, anti-clogging performance, and permeability. In general, the primary function of a mechanical screen is to retain and control sand, while also taking into account flowability and anti-clogging performance. Therefore, when setting the above weight coefficients, sand retention performance plays an absolutely primary role, and it is generally recommended to take W d =0.4,W k =0.2,W l =0.2,W w =0.2. On this basis, it can be flexibly adjusted according to specific sand control needs and evaluation purposes.

[0250] A well-performing coated sand filling medium requires not only a high weighted average of stability, permeability, sand retention, and anti-blocking performance evaluation indicators, but also requires the above four properties to be relatively balanced to meet the long-term production needs of oil and gas wells. Based on this, the balanced performance index S is defined. 2(j) for:

[0251]

[0252] The larger the balance index S2, the more balanced the performance of the sand retaining medium; the larger the functional index S1 and the balance index S2, the better the overall performance.

[0253] Define the comprehensive performance index S of the sand retaining medium within a certain period j for:

[0254] S j =S 1j ×0.7+S 2j ×0.3 (1-17)

[0255] Where S 2(j) is the equilibrium performance index within a certain period, dimensionless; S is the comprehensive performance index, dimensionless.

[0256] Comprehensive performance index S within the cycle j The larger it is, the larger the weighted average of each individual performance is, and the more balanced the individual performance is.

[0257]

[0258] Where S is the weighted average value of the comprehensive indicators of each period and is dimensionless.

[0259] The larger the comprehensive performance evaluation index S is, the better the properties of the coated sand filling layer are in each cycle. The final comprehensive performance evaluation index can be used to accurately and quantitatively compare the sand control effects of the coated sand filling layer.

[0260] Example 2

[0261] In this application example 2, a certain energy storage well is taken as an example. The average daily gas injection volume is 240,000 cubic meters, the daily gas production volume is 160,000 cubic meters, the reservoir thickness of the gas well is 40m, the reservoir pressure is 13MPa, and the reservoir temperature is 58.3°C. For example, the laboratory temperature is 20°C, the simulated reservoir thickness is 30cm, and the pressure is the experimental pressure 1MPa. Considering the compressibility of gas inside the reservoir due to temperature and pressure, the gas injection volume in the gas injection stage is 16.8m3 / h, and the gas volume in the gas production stage is 11.2m 3 / h.

[0262] Calculation of periodic sand retaining performance index:

[0263] The filling volume of formation sand in the experiment mt =17200g, the median particle size of the coated sand is 150μm, and within three experimental cycles, the sand production is m1=4.7854g, m2=5.142g, and m3=4.646g. According to the formation sand sieving curve of actual formation sand production, R=0.43.

[0264] By calculating R m1 =0.0278%, R m2 =0.0299%, R m3 =0.027%.

[0265] After the experimental sieve analysis curve analysis, the maximum sand particle size in each cycle is d pmax1 =125μm,d p max2 =130μm,d p max3 =110μm

[0266] By calculating R d1 =0.83, R d2 =0.87, R d3 =0.73.

[0267] By calculating S d1 =0.7582,S d2 =0.7365,S d3 =0.8232.

[0268] Through calculation, it is found that after periodic injection and production, the sand retaining performance at both ends of the coated sand filling layer will change with the continuous injection and production, showing an overall increasing trend, and the sand retaining effect of the coated sand filling layer gradually improves.

[0269] Calculation of permeability performance index:

[0270] The calculation results of the permeability of the pressure difference between the two ends of the coated sand in the experiment are as follows: sa1 =141.52, k sa2 =125.3, k sa3 =175.5μm 2 , we can get k s1 =142.13, k s2 =126.54, k s3 =183.13μm 2 .

[0271] By calculating the comprehensive permeability, the dimensionless permeability calculation results in different sand retention cycles are as follows: l1 =0.7761,s l2 =0.6908,s l3 =0.8889.

[0272] The experimental results show that after the end of each injection and production cycle, the initial permeability of the coated sand filling layer changes. The greater the initial permeability of the coated sand filling layer in this cycle, the greater the permeability change at both ends of the coated sand filling layer, the greater the calculated dimensionless permeability performance index, the greater the average permeability of the coated sand filling layer in this cycle, and the better the seepage performance of the coated sand filling layer.

[0273] Cycle anti-blocking performance indicators:

[0274] The anti-blocking performance of each cycle is calculated experimentally as follows: k1 =0.705s k2 =0.7709,s k3 =0.6161, which is opposite to the permeability change trend of the coated sand filling layer.

[0275] Cycle stability performance indicators:

[0276] When the third cycle of coating sand filling layer is damaged, s w3 =0,s w1 =0.268,s w2 =0.476.

[0277] Comprehensive performance indicators of the cycle:

[0278] The periodic sand control function index is calculated and obtained:

[0279] s 11 =0.6531,s 12 =0.68214,s 13 =0.63028;

[0280] The calculation results of the balance index are as follows: 21 =0.7371,s 22 =0.8449,s 23 =0.521. When the coated sand filling layer becomes unstable at the bottom of the well, its sand control function index and balance index will change significantly, which can be used as a method for identifying the instability pattern of the well.

[0281] Comprehensive performance index S within the cycle j for:

[0282] s1 = 0.6783, s2 = 0.731, s3 = 0.598. The coated sand filling layer became unstable, and its sand control capacity decreased significantly, indicating that the production conditions had a significant impact on the coated sand filling layer. The production pressure difference should be appropriately reduced to ensure stable long-term production.

[0283] For different types of coated sand samples, experimental simulation should be carried out under the same production conditions to calculate the overall comprehensive performance of each cycle, for example:A =0.865,s B =0.95,s C =0.96, then sample C is more suitable for the production conditions of air energy storage wells.

[0284] Example 3

[0285] In this application example 3, a certain energy storage well is taken as an example. The average daily gas injection volume is 400,000 cubic meters, the daily gas production volume is 320,000 cubic meters, the reservoir thickness of the gas well is 40m, the reservoir pressure is 13MPa, and the reservoir temperature is 58.3°C. For example, the laboratory temperature is 20°C, the simulated reservoir thickness is 30cm, and the pressure is the experimental pressure 1MPa. Considering the compressibility of gas inside the reservoir due to temperature and pressure, the gas injection volume in the gas injection stage is calculated according to the similarity principle to be 28m 3 / h, the gas volume in the gas production stage is 22.4m 3 / h.

[0286] Calculation of periodic sand retaining performance index:

[0287] The filling volume of formation sand in the experiment m t =17200g, the median particle size of the coated sand is 150μm, and within three experimental cycles, the sand production is m1=4.231g, m2=4.772g, and m3=3.824g. According to the formation sand sieving curve of actual formation sand production, R=0.43.

[0288] By calculating R m1 =0.0246%, R m2 =0.0277%, R m3 =0.0222%.

[0289] After the experimental sieve analysis curve analysis, the maximum sand particle size in each cycle is d pmax1 =90μm,d p max2 =95μm,d p max3 =70μm

[0290] By calculating R d1 =0.6, R d2 =0.63, R d3 =0.47.

[0291] By calculating S d1 =0.774,S d2 =0.7603,S d3 =0.8222.

[0292] Through calculation, it is found that after periodic injection and production, the sand retaining performance at both ends of the coated sand filling layer will change with the continuous injection and production, showing an overall increasing trend, and the sand retaining effect of the coated sand filling layer gradually improves.

[0293] Calculation of permeability performance index:

[0294] The calculation results of the permeability of the pressure difference between the two ends of the coated sand in the experiment are as follows: sa1 =69.3, k sa2 =74.1, k sa3 =63.5μm 2 , we can get k s1 =64.05,k s2 =71.04, k s3 =62.6μm 2 .

[0295] By calculating the comprehensive permeability, the dimensionless permeability calculation results in different sand retention cycles are as follows: l1 =0.8567,s l2 =0.954,s l3 =0.846.

[0296] The experimental results show that the lower the initial permeability of the coated sand layer, the greater the permeability change at both ends of the coated sand layer, the larger the calculated dimensionless permeability performance index, and the more serious the mixing change of the coated sand filling layer in this period.

[0297] Cycle anti-blocking performance indicators:

[0298] The anti-blocking performance of each cycle is calculated experimentally as follows: k1 =0.6035,s k2 =0.7355,s k3 =0.7587, which is opposite to the permeability change trend of the coated sand filling layer.

[0299] Cycle stability performance indicators:

[0300] When the third cycle of coating sand filling layer is damaged, s w3 =0,s w1 =

[0301] 0.374,s w2 =0.579. As the injection-production cycle increases, the anti-clogging performance of the coated sand layer improves. As the sand retaining cycle progresses, the internal sand retaining bridge of the coated sand layer gradually forms, and the anti-clogging ability gradually increases.

[0302] Comprehensive performance indicators of the cycle:

[0303] The periodic sand control function index is calculated and obtained:

[0304] s 11 =0.6764,s 12 =0.7578,s 13=0.6498; the destruction and instability of the coating sand layer has a great impact on the overall sand control function, and the sand control performance decreases rapidly.

[0305] The calculation results of the balance index are as follows: 21 =0.7302,s 22 =0.8084,s 23 =0.566. When the coated sand filling layer becomes unstable at the bottom of the well, its sand control function index and balance index will change significantly, which can be used as a method for identifying the instability pattern of the well.

[0306] Comprehensive performance index S within the cycle j for:

[0307] s1 = 0.6925, s2 = 0.773, s3 = 0.6248. The coated sand filling layer became unstable, and its sand control ability decreased significantly, indicating that the production conditions had a significant impact on the coated sand filling layer. The production pressure difference should be appropriately reduced to ensure stable long-term production.

[0308] For different types of coated sand samples, experimental simulation should be carried out under the same production conditions to calculate the overall comprehensive performance of each cycle, for example: A =0.87,s B =0.92,s C =0.91, then sample B is more suitable for the production condition of air energy storage wells.

[0309] The present invention proposes a classification method for the instability and failure morphologies of the coated sand filling layer in the alternating injection and production of air energy storage wells, which fully considers the failure and deformation morphologies of the coated sand filling layer in different injection and production alternating production processes, and solves the current problem of the lack of characterization methods for the instability and failure of the coated sand filling layer.

[0310] The present invention proposes a method for utilizing parameters such as pressure difference permeability in the production process to judge the instability of the coated sand filling layer, so as to formulate control measures for the production process and improve the safe production regulation of air energy storage wells.

[0311] The present invention proposes a comprehensive performance index evaluation standard for the properties of air energy storage near-wellbore sand-proof coating sand. The standard can simply and quickly calculate the stability indexes of the coated sand filling layer at both ends after injection and production in different injection and production cycles based on parameters such as the permeability of the sand retaining medium, the sand particle size, and the gas production intensity during the displacement process and after the experiment, and evaluate the indexes in each cycle of the coated sand; and different coated sand samples can be compared during the experiment to optimize the coated sand samples suitable for the production condition of air energy storage.

[0312] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art may modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features therein. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

[0313] Except for the technical features described in the specification, all other technical features are known technologies to those skilled in the art.

Claims

1. A method for distinguishing and evaluating the instability mode of alternating injection and production in the coated sand layer of an air energy storage well, characterized by: The method for distinguishing and evaluating the instability mode of alternating injection and production in the coated sand layer of the air energy storage well includes: Step 1: Determine the initial state parameters of the evaluation object and determine the flow rate in the experimental evaluation based on the similarity criterion; Step 2: Collect parameters at both ends of the coated sand filling layer during the experiment to classify the instability and failure forms of the alternating injection and production of the coated sand filling layer of the air energy storage well, and identify the instability and failure modes; Step 3, calculate various indicators based on the collected parameters; Step 4: Conduct production control and evaluate the coated sand filling layer based on the index calculation results.

2. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of the air energy storage well according to claim 1 is characterized in that: In step 1, the similarity of flow phenomena requires the equality of the Nusselt criterion numbers, which can be derived from the momentum differential equation: Where, μ′ is the actual reservoir fluid viscosity, mPa·s; μ″ is the experimental fluid viscosity, mPa·s; l′ is the actual reservoir thickness, m; l″ is the experimental reservoir thickness, m; v′ is the actual reservoir fluid flow rate, m / s; v″ is the experimental fluid flow rate, m / s; Right now: Re′=Re″ (1-2) Where Re is the Reynolds number, Re′ is the Reynolds number of the actual reservoir, and Re″ is the Reynolds number during experimental evaluation, which is dimensionless. This shows that the Reynolds criterion of two fluids with similar motion phenomena must be equal, and the same can be derived: Where Q' is the actual fluid flow rate, m 3 / h; Q″ is the experimental fluid flow rate, m 3 / h; determine the flow rate in the experimental evaluation based on similarity criteria.

3. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of the air energy storage well according to claim 1 is characterized in that: In step 2, the collected parameters include: displacement flow rate, displacement pressure difference, sand flow rate, and particle size.

4. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 1 is characterized in that: In step 2, when classifying the instability and failure forms of the alternating injection and production of the coated sand filling layer in the air energy storage well, the coated sand filling layer is consolidated to the screen surface and converted to the experimental conditions based on the actual consolidation conditions and injection and production conditions on site using the similarity principle. After the experimental test, the container cover is opened and different instability forms of the coated sand are observed. According to the instability and failure forms in the experimental cavity, the instability and failure forms of the coated sand filling layer are classified, including the gravel intrusion and blockage failure mode of the coated sand filling layer, the extrusion plastic crushing mode of the coated sand filling layer, and the rupture instability mode of the coated sand filling layer.

5. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of the air energy storage well according to claim 1 is characterized in that: In step 2, when identifying the instability and failure mode of the alternating injection and production of the coated sand filling layer of the air energy storage well, the pressure difference and displacement flow rate at both ends of the coated sand filling layer during the experiment or production process are collected, and the permeability curves of both ends of the coated sand filling layer in the injection and production stage in each cycle are calculated using Darcy's law. The instability and failure mode of the coated sand filling layer is identified based on the dynamic changes of the experimental or production pressure difference and permeability curve.

6. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 1 is characterized in that: In step 3, the stability of the coated sand filling layer under the production conditions of the air energy storage well is evaluated. According to the parameters of the sand retaining medium permeability, sand particle size and gas production intensity in the displacement process, the filling layer stability index, sand retaining performance index, flow performance index, anti-clogging performance index and comprehensive performance index of each cycle of the coated sand filling layer are calculated to evaluate the performance of the coated sand filling layer. According to the evaluation of the comprehensive performance index of each cycle, a coated sand sample suitable for the production conditions of the air energy storage well is obtained. Based on the on-site production conditions and sand production characteristics, the changes in the performance of the coated sand in each cycle are evaluated, providing a reliable experimental basis for regulating the pressure difference at both ends of the coated sand in the actual production process.

7. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 6 is characterized in that: In step 3, when calculating the sand retention performance index of the alternating injection-production cycle, the sand retention performance during the alternating injection-production cycle is characterized by the amount of sand passing through and the maximum sand particle size. The greater the amount of sand passing through during the experiment, or the larger the maximum sand particle size, the weaker the sand retention capacity. The theoretical sand passing ratio R is used to represent the mass ratio of the formation sand with a particle size smaller than the coating sand particle size accuracy in the experimental formation sand to the total sand volume. The sand passing rate R during the experimental test cycle is m(j) for: Where m t is the total formation sand mass of the experiment, g; m s(j) is the mass of sand passing through the screen tube in a certain period, g; R is the theoretical sand passing ratio, dimensionless; R m is the sand passing rate of the screen tube, dimensionless; Define the periodic sand particle size ratio R d(j) The ratio of the maximum sand particle size in the jth cycle to the median of the nominal particle size of the coating sand: Where, d pmax is the maximum particle size of the formation sand passing through the coating sand filling layer, mm; w f R is the nominal accuracy of the coated sand filling layer, mm; d is the sand particle size ratio, dimensionless; The larger the sand passing rate and the larger the sand passing particle size ratio, the worse the sand retaining capacity. The sand retaining performance evaluation index is proposed to be the weighted average of the above two dimensionless indicators: S d(j )=(1-R m(j) )X d +(1-R d(j) )(1-X d ) (1-6) Where S d(j) is the evaluation index of periodic sand retaining performance, dimensionless; X d is the weighted average coefficient; Evaluation index S of sand retaining performance in alternating injection-production cycle d(j) The amount and particle size of the formation sand blocked by the sand retaining medium are taken into consideration at the same time. Its value is between 0 and 1. The larger the index value, the better the sand retaining performance.

8. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 7 is characterized in that: In step 3, when evaluating the flow performance of the alternating injection-production cycle, the experimental data mainly tested or collected were the displacement flow rate, the pressure difference between the screen and the coated sand filling layer, and the sand flow rate. Based on the pressure difference between the outer side of the simulated filling layer and the inner wall of the screen sub, the flow rate, and the geometric parameters of the wellbore and the screen sub, Darcy's law was used to calculate the comprehensive permeability of the screen and filling section. The calculation formula is shown in Equation 1-7: Where k si is the permeability of the coated sand filling layer, D; q i is the flow rate through the sand retaining medium at the i-th moment, cm 3 ·s -1 ; μ is the fluid viscosity, mPa·s; r0 is the inner radius of the coated sand filling layer, cm; r i is the outer radius of the coated sand filling layer, cm; h is the effective height of the sand retaining medium, cm; ΔP i is the pressure difference at both ends of the sand retaining medium at a certain moment, MPa; The permeability during the alternating injection-production cycle, that is, the fluid flow capacity of the coated sand filling layer during a certain production cycle, can be expressed by permeability; the better the overall permeability of the coated sand layer, the smaller the flow resistance.

9. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 8 is characterized in that: In step 3, when calculating the permeability index of the alternating injection-production cycle, the permeability of the sand retaining medium in a certain production / test process is expressed as the comprehensive permeability k s It depends on the final permeability k of a certain experimental cycle. s0 and the permeability change during a production / test cycle; the end-of-use permeability k s0 and the average permeability k over the entire cycle sa The weighted average calculation yields the comprehensive permeability k s : k s(j) =(1-Xs)·k sa(j) +X s k s0(j) (1-8) Where, X s is the weighted average calculation coefficient; k s(j) is the comprehensive permeability of the sand retaining medium in the gas production stage of the jth cycle, μm 2 ;k s0 The permeability of the coated sand layer at the end of a certain period of the jth period is obtained by experimental test, and the permeability in each period is obtained by testing the quasi-stable stage, μm 2 ;k sa is the average permeability obtained during the entire experiment, μm 2 ; In order to facilitate the comparison of the permeability performance of the coated sand filling layer in each cycle and the calculation of various subsequent dimensionless indicators, the dimensionless permeability performance index S of the coated sand filling layer in different cycles is proposed. l(j) The calculation formula is: Where k s(j) —Comprehensive permeability in the jth cycle μm 2 ;k smax —The maximum comprehensive permeability of the sand retaining medium in the jth cycle, μm 2 ; S l(j) —Dimensionless permeability evaluation index within the jth cycle.

10. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 9 is characterized in that: In step 3, when evaluating the anti-clogging performance of the alternating injection-production cycle, the result of the blockage of the coated sand filling layer is an increase in the displacement pressure or pressure difference, or a decrease in the permeability or permeability ratio, and finally reaching a basically stable state, indicating that the blockage process is complete. The speed of change of the displacement pressure difference or permeability / permeability ratio over time and the final maintenance degree reflect the blockage status of the sand retaining medium, that is, the anti-clogging performance of the screen. According to the above analysis, the time-varying curves of displacement pressure difference and permeability ratio can be used to qualitatively characterize the anti-clogging performance. In order to facilitate quantitative evaluation, the periodic anti-clogging evaluation index S is proposed. k(j) ; When the experimental flow rate is basically constant, the anti-clogging evaluation index can be calculated using the displacement pressure difference change curve: Where, is the average displacement pressure difference in the initial stage. It is recommended to take the first 1 / 4 of the displacement time for calculation, MPa; The average displacement pressure difference in the final stage is recommended to be calculated based on the last 1 / 4 of the displacement time, MPa; S k(j) is the anti-blocking performance evaluation index of the jth cycle, dimensionless; For situations where the experimental flow rate is basically constant or not constant, the permeability ratio change curve can be used to calculate the anti-clogging evaluation index: Where, is the average permeability in the initial stage. It is recommended to calculate the first 1 / 4 of the displacement time, μm 2 ; The average permeability in the final stage is recommended to be calculated based on the last 1 / 4 of the displacement time, μm 2 ; Anti-blocking performance evaluation index S k(j) The value is between 0 and 1. The larger the value, the better the anti-blocking performance.

11. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 10, characterized in that: In step 3, when calculating the stability index of the alternating injection-production cycle, experimental tests show that after a certain period, as the physical properties of the filling layer change, its sand retaining effect decreases, which may cause the sand particle size to become larger. For the target air energy storage well, the critical sand particle size is 5μm. When the sand particle size is greater than 5μm, through analysis and processing of the experimental data, if the average permeability after the experiment is reduced to 80% of the initial permeability, then the production condition at this time is the critical production condition of the coating layer.

12. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 11, characterized in that: In step 3, when calculating the stability index, when the sand filling layer experiences gravel intrusion and clogging failure and full consolidation plastic extrusion failure, the critical instability period is W1, and the total experimental period is W t , the initial permeability k in the first cycle s01 , the critical instability period permeability is recorded as k s0z , then the stability index S w(j) The calculation method is: The stability index indicates the overall stability of the coated sand filling layer during the entire experiment / production process, ranging from 0 to 1. The larger the index, the better the stability of the coated sand filling layer.

13. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 12, characterized in that: In step 3, when calculating the periodic sand control function index, the periodic sand control function index S1 is a comprehensive reflection of the stability index, permeability, sand retaining performance and anti-blocking performance. d , penetration performance index S l , anti-blocking performance index S k and stability index S w Calculated by weighted average: s 1(j) =W k s k(j) +W l s l(j) +W d s d(j) +W w s w(j) (1-14) IN k +W l +W d +W w =1 (1-15) Where W d is the weight coefficient of sand retaining performance, dimensionless; W l is the permeability weight coefficient, dimensionless; W k is the anti-blocking performance weight coefficient, W w is the dimensionless stability performance weight coefficient; S 1(j) It is a dimensionless indicator of sand control function in a certain period.

14. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 13, characterized in that: In step 3, when calculating the periodic equilibrium performance index, a well-performing coated sand filling medium requires not only a high weighted average value of stability, permeability, sand retention, and anti-blocking performance evaluation indicators, but also a relatively balanced performance of the above four to meet the long-term production needs of oil and gas wells. Based on this, the periodic equilibrium performance index S is defined. 2(j) for: The larger the periodic balance performance index S2 is, the more balanced the various performances of the sand retaining medium are; the larger the periodic sand control function index S1 and the periodic balance performance index S2 are, the better the comprehensive performance is.

15. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 14, characterized in that: In step 3, the comprehensive performance index S of the sand retaining medium within a certain period j The calculation formula is: Sj=S1j×0.7+S2j×0.3 (1-17) Where S 2(j) is the equilibrium performance index within a certain period, dimensionless; S is the comprehensive performance index, dimensionless.

16. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 15, characterized in that: In step 3, the comprehensive performance index S within the cycle j The larger the value is, the larger the weighted average value of each individual performance is, and the more balanced the individual performance is. The calculation formula for the comprehensive performance index of each cycle is: Where S is the weighted average value of the comprehensive indicators of each period, dimensionless; The larger the comprehensive performance evaluation index S is, the better the properties of the coated sand filling layer are in each cycle. The final comprehensive performance evaluation index can be used to accurately and quantitatively compare the sand control effects of the coated sand filling layer.

17. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 1 is characterized in that: In step 4, for the instability and failure morphology of the coated sand in step 2, the device is opened after the experiment to observe the instability morphology of the coated sand filling layer and the formation sand. Different instability states can be observed. The performance of the coated sand decreases in sequence from the gravel intrusion and blockage failure mode of the coated sand filling layer, the extrusion plastic crushing mode of the coated sand filling layer, and the rupture instability mode of the coated sand filling layer, and its performance can be judged.

18. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 1 is characterized in that: In step 4, based on the pressure difference collected during the experiment in step 2 and the calculated permeability, the instability mode existing in the production process can be judged. If the failure mode is gravel intrusion and blockage of the coated sand filling layer, it means that the coated sand filling layer has not completely failed, and safe production can be carried out without adjusting the injection and production volume; if the mode is extrusion plastic crushing of the coated sand filling layer, it means that the coated sand filling layer has not completely failed, and the output needs to be reduced for production; if the mode is rupture and instability of the coated sand filling layer, it means that the underground coated sand filling layer has completely failed, the risk of sand production increases, and it will affect normal production.

19. The method for distinguishing and evaluating the instability mode of alternating injection and production of the coated sand layer of an air energy storage well according to claim 1 is characterized in that: In step 4, for each indicator calculated in step 3, a larger value of the periodic sand retaining performance indicator indicates better sand retaining performance in each cycle; the periodic flow performance indicator indicates that the better the overall permeability of the coated sand layer, the smaller the flow resistance, and the smaller the production capacity loss in a certain cycle; the periodic anti-blocking performance evaluation indicates that a larger value of the indicator indicates better anti-blocking performance and less blockage by formation sand in a certain cycle; the larger the periodic performance stability indicator indicates that the period of stable production of the coated sand filling layer is longer and the better the stability; the larger the periodic balance indicator indicates that the various properties of the sand retaining medium are more balanced, and the larger the periodic sand control function indicator indicates that the sand control performance of the coated sand layer is better; the larger the comprehensive performance indicator within the cycle indicates that the performance of the coated sand is better within a certain cycle and the bottom hole production is more stable, and a lower value indicates that the coated sand filling layer is at risk of instability and that the production needs to be reduced to maintain the stability of the coated sand filling layer; the same experimental evaluation is carried out on different coated sand samples, and their adaptability to the air energy storage production conditions is evaluated based on the calculated periodic comprehensive indicators, and the larger the periodic comprehensive indicator indicates that the performance is better.

20. Air energy storage well coated sand layer alternating injection and production instability mode discrimination and evaluation system, characterized by: The air energy storage well coated sand layer alternating injection and production instability mode discrimination and evaluation system adopts the air energy storage well coated sand layer alternating injection and production instability mode discrimination and evaluation method described in any one of claims 1-19 to control sand production during the production process of the air energy storage well.

Images