Method for evaluating productivity of reservoir particle migration damage and crack filling layer composite damage

Abstract

The invention discloses a reservoir particle migration damage and crack filling layer composite damage productivity evaluation method, which comprises the following steps of: predicting the damage degree of reservoir particle migration to reservoir permeability and productivity through a particle migration permeability damage evaluation method of a loose sandstone reservoir under different production conditions; evaluating the fracture flow conductivity damage and productivity damage degree through a flow conductivity damage evaluation method under the compaction-embedding-blocking composite action of the fracturing filling well; reservoir particle migration damage and fracture conductivity damage are comprehensively considered, and dynamic productivity prediction and evaluation are achieved. According to the method, reservoir particle migration damage and fracture conductivity damage are comprehensively considered, the production time effect is considered, all-factor productivity dynamic prediction and evaluation are achieved, and optimization and implementation of particle migration and sand production control countermeasures are supported.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and natural gas development and exploitation, and in particular relates to a method for evaluating the production capacity of reservoir particle migration damage and fracture filling layer composite damage. Background Art

[0002] Loose sandstone oil and gas reservoirs have high porosity and low cementation strength, and there are serious sand problems during production. For oil and gas reservoirs prone to sand production, during production, reservoir particles are carried by fluids and peeled off, migrated, and pore throats are blocked inside the near-well reservoir, affecting oil well production capacity. Especially in the middle and late stages of development, as water saturation increases, high water content causes the critical velocity of particle migration to decrease, further exacerbating the particle migration problem and causing production capacity damage.

[0003] At present, fracturing and filling is a major sand prevention and production increase process technology for loose sandstone reservoirs prone to sand production. For example, fracturing and filling technology has been widely used in loose sandstone oil and gas reservoirs prone to sand production in Bohai Oilfield, my country. The fracturing and filling process opens cracks in the near-well reservoir and fills them with proppants to achieve the purpose of sand prevention and production increase. However, in actual applications, it was found that after the fracturing and filling was put into production, the crack closure effect and the drop in formation pressure during the production process caused the proppant to be embedded in the crack wall more deeply. At the same time, the formation sand invaded the sand-blocking medium and synergistically caused the fracture conductivity to decrease, further significantly reducing the oil well production capacity.

[0004] According to the above analysis, for the fracturing and filling sand control of loose sandstone reservoirs prone to sand production, the migration of reservoir particles, the closing and compaction of proppants in fractures, the embedding of proppants into the formation and the blocking of formation sand will all cause damage to the production capacity of oil wells. Accurate production capacity prediction and evaluation are of great significance for controlling particle migration and optimizing fracturing and filling sand control parameters in such reservoirs. Therefore, it is very important to consider the production capacity prediction and evaluation of reservoir particle migration damage and the composite damage of fracture filling layer. However, there are still the following key issues:

[0005] 1. There is a lack of evaluation methods for reservoir capacity damage caused by reservoir particle migration, especially the impact of different water saturations on reservoir particle migration and the corresponding capacity damage evaluation method, which makes it impossible to consider the damage caused by reservoir particle migration in capacity evaluation, resulting in poor accuracy of the results.

[0006] 2. There is a lack of a method for evaluating the damage to the conductivity and productivity of medium-to-high permeability weakly cemented reservoirs, which comprehensively considers the combined effects of proppant compaction, proppant embedding in the formation, and formation sand plugging in the filling zone. In the prior art, the productivity evaluation method that mainly considers the plugging effect has poor accuracy.

[0007] 3. There is a lack of dynamic capacity prediction and evaluation methods for fracturing and filling wells in medium- and high-permeability loose sandstone reservoirs that comprehensively consider the damage to reservoir particle migration and fracture conductivity, resulting in poor prediction accuracy and difficulty in effectively guiding the optimization of control measures. Summary of the invention

[0008] The problem to be solved by the present invention is to provide a capacity evaluation method for reservoir particle migration damage and fracture filling layer composite damage. The method can predict the degree of damage to reservoir permeability and capacity caused by reservoir particle migration under different production conditions, especially under conditions of water saturation changes, and comprehensively consider the composite effects of proppant compaction, proppant embedding into the formation and formation sand blockage in the filling zone to evaluate the degree of conductivity damage and capacity impairment; comprehensively consider the reservoir particle migration damage and fracture conductivity damage to achieve dynamic capacity prediction and evaluation, and provide technical support for effectively controlling reservoir particle migration and wellbore sand production.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for evaluating the production capacity of reservoir particle migration damage and fracture filling layer composite damage, comprising the following steps:

[0010] S1: Through the particle migration permeability damage evaluation method under different production conditions of loose sandstone reservoirs, the degree of damage to reservoir permeability and production capacity caused by reservoir particle migration under different production conditions is predicted;

[0011] S2: The conductivity damage evaluation method under the combined effects of compaction-embedding-blocking of fracturing and filling wells is used to comprehensively consider the combined effects of proppant compaction, proppant embedding in the formation and sand blockage in the filling zone to evaluate the degree of fracture conductivity damage and production capacity damage;

[0012] S3: Comprehensively consider the damage of reservoir particle migration and fracture conductivity to achieve dynamic production capacity prediction and evaluation.

[0013] Furthermore, the method for evaluating the permeability damage of particle migration in loose sandstone reservoirs under different production conditions comprises the following steps:

[0014] S11: Initial water saturation S of the reservoir w0 Under these conditions, the critical velocity of particle migration is obtained through experiments, and the maximum radius r of the particle migration area is obtained according to the particle migration simulation results. max0 Then, the reservoir is divided into 0-j grids from near the well to far from the well, and the initial permeability K of different grid units in the initial situation is obtained by the particle migration simulation method. 0j ;

[0015] S12: According to Griffith's theory, the cohesive strength ratio of rock with increasing water saturation is calculated as follows:

[0016]

[0017] In the formula, β i The cohesive strength ratio of the reservoir rock is dimensionless; E0 is the elastic modulus of the rock, in MPa; a0 is the crack length of the rock, in m; E i is the elastic modulus of rock at different water saturations, in MPa; a i is the crack length at different water saturations of the rock, in meters; for medium- and high-permeability loose sandstone β i The value is 0.3-0.7;

[0018] S13: The critical velocity of reservoir particle migration is obtained as a function of water saturation. The formula is as follows:

[0019]

[0020] In the formula, v fci is the critical velocity under different water saturation conditions that change with time, in m / s; v fc0 is the critical velocity obtained by experimental test under the initial water saturation of the reservoir, in m / s; μ f0 is the experimental fluid viscosity, in Pa·s; μ f1 is the reservoir fluid viscosity, in Pa·s;

[0021] S14: Considering the influence of reservoir rock strength and porous media pore throat structure on solid phase particle spalling, the maximum particle migration radius with increasing water saturation is obtained. The formula is as follows:

[0022]

[0023] S15: At this time, the particle migration area expands, causing the reservoir permeability damage to increase. The grid is re-divided according to the maximum radius under the current water saturation. According to the empirical relationship between rock strength and reservoir permeability, the reservoir permeability after the particle migration damage intensifies in the grid from near well to far well is calculated. The formula is as follows;

[0024]

[0025] In the formula, K ij is the grid unit permeability after the particle migration damage increases with the increase of water saturation, in μm 2 .

[0026] Furthermore, the method for evaluating the damage to the flow conductivity of a fractured filling well under the combined action of compaction-embedding-plugging comprises the following steps:

[0027] S21: Calculate the permeability damage caused by proppant compaction based on the actual closure pressure generated by the fracture closure stress, bottom hole flow pressure and fracture pore pressure;

[0028] S22: Calculate the fracture width loss caused by the embedding of proppant into the formation based on the actual closure stress and the strength of proppant and reservoir rock;

[0029] S23: Based on the sand content of the reservoir fluid and the porosity parameters after the filling layer is closed and compacted, the degree of blockage of the fracture filling layer by the formation sand over the production time is calculated to evaluate the permeability damage;

[0030] S24: Comprehensively consider the above three effects and evaluate the damage to the fracture conductivity.

[0031] Further, the S21 includes the following steps:

[0032] S211: Calculate the actual closing pressure of the proppant as P c , the calculation formula is as follows,

[0033] P c =P-ΔP

[0034] Where P c is the actual closure pressure of the formation, in MPa; P is the pressure of the overlying rock formation, in MPa; △P (t) is the pore pressure, in MPa;

[0035] S212: The compaction permeability of proppants with different particle sizes under different pressures was measured experimentally. Based on the experimental results, the permeability damage coefficient caused by proppant compaction under different closure pressures was obtained as follows:

[0036]

[0037] In the formula, K Rc It is the permeability damage coefficient caused by proppant compaction of proppants with different particle sizes at different closure pressures, dimensionless.

[0038] Further, the S22 includes the following steps:

[0039] S221: Calculate the ideal contact radius between the proppant and the fracture wall. The calculation formula is:

[0040]

[0041] In the formula, S cg is the reservoir compressive strength, in MPa; r is the proppant radius, in mm; r x is the ideal contact radius between the proppant and the fracture wall under different closing pressure conditions, in mm;

[0042] S222: Calculate the fracture width loss caused by proppant embedment. The formula is as follows:

[0043]

[0044] In the formula, w f1 is the width of the crack where the proppant is embedded, in mm; r x0 is the actual contact radius between the proppant and the fracture wall, in mm; β is the embedded correction coefficient, when the closing pressure is large enough during the calculation process, r x It may be greater than r, so it is necessary to introduce an embedding correction coefficient β. The specific relationship is as follows:

[0045]

[0046] S223: Calculate the remaining effective seam width. The formula is as follows:

[0047] w f =w f0 -w f1

[0048] In the formula, w f is the crack width after proppant embedment, in mm; w f0 is the original crack width, in mm.

[0049] Further, the S23 includes the following steps:

[0050] S231: Calculate the dynamic blockage permeability damage coefficient. The calculation formula is as follows:

[0051]

[0052] In the formula, K Rs(t) is the dynamic plugging permeability damage coefficient, dimensionless; K Rmin is the minimum plugging permeability ratio at plugging equilibrium, dimensionless;

[0053] S232: Calculate the quasi-blocking equilibrium time. The calculation formula is as follows:

[0054]

[0055] Where, T pei is the proposed blocking equilibrium time, in days; V f is the volume of sand control medium, in m 3 ; φ g is the fracture porosity, unit is dimensionless; Q l is the fracture inflow, in m 3 ·sky -1 ; C s is the sand content of the fluid, in %; R si It is the volume ratio of formation sand that can invade fractures to produced sand, dimensionless.

[0056] Further, in S24, the fracture conductivity damage coefficient formula of the hydraulically fractured well under different production time and closure pressure conditions is:

[0057]

[0058] In the formula, C z(t) is the fracture conductivity and permeability damage coefficient under different production time and closure pressure conditions, dimensionless.

[0059] Further, the S3 comprises the following steps:

[0060] S31: Calculate the total skin factor of the reservoir area for particle migration;

[0061] S32: Calculate the fracture damage skin coefficient of the fracturing filling well;

[0062] S33: Calculate the dynamic production capacity of oil wells due to combined damage of particle migration and fracture filling layer.

[0063] Further, the S31 includes the following steps:

[0064] S311: Under the water saturation condition at a certain production time, according to the reservoir grid division, the particle migration damage permeability is obtained according to the geometric size of each unit body and the prediction, the skin coefficient of particle migration damage of each grid unit is calculated, the total skin coefficient is obtained by superposition, and then the production capacity ratio is calculated. The additional skin coefficient of the i-th grid unit is:

[0065]

[0066] In the formula, s d(i) , k d(i) 、r d(i) are the additional skin coefficient, permeability and outer radius of the ith grid unit, respectively, and the units are dimensionless and μm 2 and m;β s is the turbulence velocity coefficient; ρ l is the reservoir fluid density, in kg / m 3 ;μ f is the reservoir fluid viscosity, in Pa.s;

[0067] S312: Calculate the total skin factor of the water saturation area at different production times. The formula is as follows:

[0068]

[0069] Further, in S32, the calculation formula of the fracture damage skin coefficient of the fracturing filling well is as follows:

[0070]

[0071] Where C0 is the original conductivity of the fracture, in μm 2 cm; C x(t) To consider the fracture conductivity after embedding compaction and plugging damage, the unit is μm 2 cm;

[0072] In S33, the oil well productivity ratio is calculated according to the total additional skin factor:

[0073]

[0074] In the formula, r e is the reservoir control outer radius, in m; r w is the wellbore radius, in meters; S is the original inherent skin coefficient of the reservoir, such as the perforation skin coefficient, dimensionless; PR (t) is the capacity ratio that changes with production time, dimensionless.

[0075] The advantages and positive effects of the present invention are:

[0076] 1. The present invention provides a method for evaluating the permeability damage and capacity damage of particles migration in loose sandstone reservoirs under different production conditions. The method can be used to evaluate the damage to reservoir capacity caused by reservoir particles migration, especially to accurately evaluate the impact of different water saturations on reservoir particles migration and the corresponding capacity damage, so that the capacity evaluation of sand production and sand control wells can take into account the damage to reservoir particles migration, thereby greatly improving the accuracy of the results.

[0077] 2. The method for evaluating the conductivity and production capacity damage of a fracturing-filled well provided by the present invention can comprehensively consider the combined effects of the permeability damage caused by proppant compaction, the effective fracture width loss caused by proppant embedding into the formation, and the permeability loss caused by formation sand blockage in the filling zone for medium-to-high permeability weakly cemented reservoirs, thereby realizing the evaluation of conductivity damage and production capacity damage and improving the accuracy of the impact of fracturing-filling parameters on production capacity.

[0078] 3. The present invention provides a method for predicting and evaluating the dynamic production capacity of particles migration and composite damage to fracture filling layers in loose sandstone reservoir fracturing and filling wells. It comprehensively considers the damage to reservoir particles migration, composite conductivity of fracture filling, and production time effect, realizes dynamic prediction and evaluation of full-factor production capacity, and supports the optimization and implementation of particle migration and sand production control measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 It is an overall process flow chart of an embodiment of the present invention.

[0080] Figure 2 It is a schematic diagram of a reservoir grid division method according to an embodiment of the present invention.

[0081] Figure 3 It is a schematic diagram of the loss of fracture conductivity under the combined action of compaction-embedding-blocking in an embodiment of the present invention. DETAILED DESCRIPTION

[0082] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0083] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0084] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0085] The embodiments of the present invention are further described below in conjunction with the accompanying drawings:

[0086] like Figure 1 As shown, the production capacity evaluation method of reservoir particle migration damage and fracture filling layer composite damage includes the following steps:

[0087] S1: Through the evaluation method of permeability damage of particle migration under different production conditions in loose sandstone reservoirs, the degree of damage to reservoir permeability and production capacity caused by reservoir particle migration under different production conditions, especially under the condition of water saturation change, is predicted. Specifically, according to the critical velocity of particle migration obtained by testing under the initial water saturation condition, under the given current condition reservoir water saturation and production conditions, the range of reservoir particle migration area is predicted, and the permeability skin coefficient of reservoir damage at different radius positions and regions within the range of reservoir particle migration area is evaluated to obtain the total skin coefficient of reservoir damage, and the production capacity damage caused by reservoir particle migration is evaluated.

[0088] like Figure 2 As shown in the figure, the method for evaluating the permeability damage of particles migration in loose sandstone reservoirs under different production conditions includes the following steps:

[0089] S11: Initial water saturation S of the reservoir w0 Under these conditions, the critical velocity of particle migration is obtained through experiments, and the maximum radius r of the particle migration area is obtained according to the particle migration simulation results. max0 , and then divide the reservoir into 0-j grids from near the well to far the well. Specifically, this embodiment recommends 0.12m-0.15m as a grid unit. The initial permeability K of different grid units in the initial condition is obtained by the particle migration simulation method. 0j .

[0090] S12: According to Griffith's theory, the cohesive strength ratio of rock with increasing water saturation is calculated as follows:

[0091]

[0092] In the formula, β i The cohesive strength ratio of the reservoir rock is dimensionless; E0 is the elastic modulus of the rock, in MPa; a0 is the crack length of the rock, in m; E i is the elastic modulus of rock at different water saturations, in MPa; a i is the crack length at different water saturations of the rock, in meters; for medium- and high-permeability loose sandstone β i The value is 0.3-0.7.

[0093] S13: The critical velocity of reservoir particle migration is obtained as a function of water saturation. The formula is as follows:

[0094]

[0095] In the formula, v fci is the critical velocity under different water saturation conditions that change with time, in m / s; v fc0 is the critical velocity obtained by experimental test under the initial water saturation of the reservoir, in m / s; μ f0 is the experimental fluid viscosity, in Pa·s; μ f1 is the reservoir fluid viscosity, in Pa·s.

[0096] S14: Considering the influence of reservoir rock strength and porous media pore throat structure on solid phase particle spalling, the maximum particle migration radius with increasing water saturation is obtained. The formula is as follows:

[0097]

[0098] S15: At this time, the particle migration area expands, causing the reservoir permeability damage to increase. The grid is re-divided according to the maximum radius under the current water saturation. According to the empirical relationship between rock strength and reservoir permeability, the reservoir permeability after the particle migration damage intensifies in the grid from near well to far well is calculated. The formula is as follows;

[0099]

[0100] In the formula, K ij is the grid unit permeability after the particle migration damage increases with the increase of water saturation, in μm 2 .

[0101] S2: Through the conductivity damage evaluation method under the combined effects of compaction-embedding-blocking of fracturing-filled wells, the combined effects of proppant compaction, proppant embedding in the formation and formation sand blockage in the filling zone are comprehensively considered to evaluate the degree of fracture conductivity damage and production capacity damage.

[0102] like Figure 3 As shown, considering the combined conductivity damage caused by the compaction effect of fracture closure, the effect of proppant embedded in the formation, and the effect of formation sand plugging the filling layer, the capacity prediction model is modified to achieve the evaluation of fracture capacity damage. Specifically, the method for evaluating the conductivity damage of the fracturing filling well under the combined effect of compaction-embedding-plugging includes the following steps:

[0103] S21: Calculate the permeability damage caused by proppant compaction based on the actual closure pressure generated by the fracture closure stress, bottom hole flow pressure and fracture pore pressure. S21 includes the following steps:

[0104] S211: Calculate the actual closing pressure of the proppant as P c , the calculation formula is as follows,

[0105] P c =P-ΔP

[0106] Where P c is the actual closure pressure of the formation, in MPa; P is the pressure of the overlying rock formation, in MPa; △P (t) is the pore pressure, in MPa.

[0107] S212: The compaction permeability of proppants with different particle sizes under different pressures was measured experimentally. Based on the experimental results, the permeability damage coefficient caused by proppant compaction under different closure pressures was obtained as follows:

[0108]

[0109] In the formula, K Rc It is the permeability damage coefficient caused by proppant compaction of proppants with different particle sizes at different closure pressures, dimensionless.

[0110] S22: Calculate the fracture width loss caused by the embedding of the proppant into the formation according to the actual closure stress and the strength of the proppant and the reservoir rock. S22 includes the following steps:

[0111] S221: Calculate the ideal contact radius between the proppant and the fracture wall. The calculation formula is:

[0112]

[0113] In the formula, S cg is the reservoir compressive strength, in MPa; r is the proppant radius, in mm; r x It is the ideal contact radius between the proppant and the fracture wall under different closing pressure conditions, in mm.

[0114] S222: Calculate the fracture width loss caused by proppant embedment. The formula is as follows:

[0115]

[0116] In the formula, w f1 is the width of the crack where the proppant is embedded, in mm; r x0 is the actual contact radius between the proppant and the fracture wall, in mm; β is the embedded correction coefficient, when the closing pressure is large enough during the calculation process, r x It may be greater than r, so it is necessary to introduce an embedding correction coefficient β. The specific relationship is as follows:

[0117]

[0118] S223: Calculate the remaining effective seam width. The formula is as follows:

[0119] w f =w f0 -w f1

[0120] In the formula, w f is the crack width after proppant embedment, in mm; w f0 is the original crack width, in mm.

[0121] S23: According to the sand content of the reservoir fluid and the porosity parameters after the filling layer is closed and compacted, the degree of blockage of the fracture filling layer by the formation sand over the production time is calculated to evaluate the permeability damage. S23 includes the following steps:

[0122] S231: Calculate the dynamic blockage permeability damage coefficient. The calculation formula is as follows:

[0123]

[0124] In the formula, KRs(t) is the dynamic plugging permeability damage coefficient, dimensionless; K Rmin is the minimum plugging permeability ratio at plugging equilibrium, dimensionless.

[0125] S232: Calculate the quasi-blocking equilibrium time. The calculation formula is as follows:

[0126]

[0127] Where, T pei is the proposed blocking equilibrium time, in days; V f is the volume of sand control medium, in m 3 ; φ g is the fracture porosity, unit is dimensionless; Q l is the fracture inflow, in m 3 ·sky -1 ; C s is the sand content of the fluid, in %; R si It is the volume ratio of formation sand that can invade fractures to produced sand, dimensionless.

[0128] S24: Comprehensively consider the above three effects and evaluate the damage of fracture conductivity. In S24, the fracture conductivity damage coefficient formula of the hydraulic fracturing filling well under different production time and closure pressure conditions is:

[0129]

[0130] In the formula, C z(t) is the fracture conductivity and permeability damage coefficient under different production time and closure pressure conditions, dimensionless.

[0131] S3: Comprehensively consider the damage of reservoir particle migration and fracture conductivity to achieve dynamic production capacity prediction and evaluation.

[0132] The dynamic capacity prediction and evaluation method of combined damage of particle migration and fracture filling layer in fracturing filling wells of loose sandstone reservoirs mainly considers the permeability damage effect of proppant compaction, the fracture width loss effect of proppant embedding in the formation, the dynamic permeability loss effect of formation sand intrusion into the fracture filling layer, and the permeability damage effect of reservoir particle migration, so as to realize the dynamic capacity prediction of combined damage of particle migration and fracture filling layer in fracturing filling wells, evaluate the damage degree according to the prediction results, and propose treatment countermeasures.

[0133] Specifically, S3 includes the following steps:

[0134] S31: Calculate the total skin coefficient of the particle migration reservoir area. S31 includes the following steps:

[0135] S311: Under the water saturation condition at a certain production time, according to the reservoir grid division, the particle migration damage permeability is obtained according to the geometric size of each unit body and the prediction, the skin coefficient of particle migration damage of each grid unit is calculated, the total skin coefficient is obtained by superposition, and then the production capacity ratio is calculated. The additional skin coefficient of the i-th grid unit is:

[0136]

[0137] In the formula, s d(i) , k d(i) 、r d(i) are the additional skin coefficient, permeability and outer radius of the ith grid unit, respectively, and the units are dimensionless and μm 2 and m;β s is the turbulence velocity coefficient; ρ l is the reservoir fluid density, in kg / m 3 ;μ f is the reservoir fluid viscosity, in Pa.s.

[0138] S312: Calculate the total skin factor of the water saturation area at different production times. The formula is as follows:

[0139]

[0140] S32: Calculate the fracture damage skin coefficient of the fracturing filling well. Specifically, the calculation formula is as follows:

[0141]

[0142] Where C0 is the original conductivity of the fracture, in μm 2 cm; C x(t) To consider the fracture conductivity after embedding compaction and plugging damage, the unit is μm 2 ·cm.

[0143] S33: Calculate the dynamic production capacity of the oil well due to the combined damage of particle migration and fracture filling layer. Specifically, according to the total additional skin factor, calculate the oil well production capacity ratio:

[0144]

[0145] In the formula, r e is the reservoir control outer radius, in m; r w is the wellbore radius, in meters; S is the original inherent skin coefficient of the reservoir, such as the perforation skin coefficient, dimensionless; PR (t) is the capacity ratio that changes with production time, dimensionless.

[0146] The advantages and positive effects of the present invention are:

[0147] 1. The present invention provides a method for evaluating the permeability damage and capacity damage of particles migration in loose sandstone reservoirs under different production conditions. The method can be used to evaluate the damage to reservoir capacity caused by reservoir particles migration, especially to accurately evaluate the impact of different water saturations on reservoir particles migration and the corresponding capacity damage, so that the capacity evaluation of sand production and sand control wells can take into account the damage to reservoir particles migration, thereby greatly improving the accuracy of the results.

[0148] 2. The method for evaluating the conductivity and production capacity damage of a fracturing-filled well provided by the present invention can comprehensively consider the combined effects of the permeability damage caused by proppant compaction, the effective fracture width loss caused by proppant embedding into the formation, and the permeability loss caused by formation sand blockage in the filling zone for medium-to-high permeability weakly cemented reservoirs, thereby realizing the evaluation of conductivity damage and production capacity damage and improving the accuracy of the impact of fracturing-filling parameters on production capacity.

[0149] 3. The present invention provides a method for predicting and evaluating the dynamic production capacity of particles migration and composite damage to fracture filling layers in unconsolidated sandstone reservoir fracturing and filling wells. It comprehensively considers the damage to reservoir particles migration, composite conductivity of fracture filling, and production time effect, realizes dynamic prediction and evaluation of full-factor production capacity, and supports the optimization and implementation of particle migration and sand production control measures.

[0150] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for evaluating the production capacity of reservoir particle migration damage and fracture filling layer composite damage, characterized by: The following steps are included: S1: Through the particle migration permeability damage evaluation method under different production conditions of loose sandstone reservoirs, the degree of damage to reservoir permeability and production capacity caused by reservoir particle migration under different production conditions is predicted; S2: The conductivity damage evaluation method under the combined effects of compaction-embedding-blocking of fracturing and filling wells is used to comprehensively consider the combined effects of proppant compaction, proppant embedding in the formation and sand blockage in the filling zone to evaluate the degree of fracture conductivity damage and production capacity damage; S3: Comprehensively consider the damage of reservoir particle migration and fracture conductivity to achieve dynamic production capacity prediction and evaluation.

2. The method for evaluating the production capacity of reservoir particle migration damage and fracture filling layer composite damage according to claim 1, characterized in that: The method for evaluating the permeability damage of particles migration in loose sandstone reservoirs under different production conditions comprises the following steps: S11: Initial water saturation S of the reservoir w0 Under these conditions, the critical velocity of particle migration is obtained through experiments, and the maximum radius r of the particle migration area is obtained according to the particle migration simulation results. max0 Then, the reservoir is divided into 0-j grids from near the well to far from the well, and the initial permeability K of different grid units in the initial situation is obtained by the particle migration simulation method. 0j ; S12: According to Griffith's theory, the cohesive strength ratio of rock with increasing water saturation is calculated as follows: In the formula, β i The cohesive strength ratio of the reservoir rock is dimensionless; E0 is the elastic modulus of the rock, in MPa; a0 is the crack length of the rock, in m; E i is the elastic modulus of rock at different water saturations, in MPa; a i is the crack length at different water saturations of the rock, in meters; for medium- and high-permeability loose sandstone β i The value is 0.3-0.7; S13: The critical velocity of reservoir particle migration is obtained as a function of water saturation. The formula is as follows: In the formula, v fci is the critical velocity under different water saturation conditions that change with time, in m / s; v fc0 is the critical velocity obtained by experimental test under the initial water saturation of the reservoir, in m / s; μ f0 is the viscosity of the experimental fluid, in Pa·s; μ f1 is the reservoir fluid viscosity, in Pa·s; S14: Considering the influence of reservoir rock strength and porous media pore throat structure on solid phase particle spalling, the maximum particle migration radius with increasing water saturation is obtained. The formula is as follows: S15: At this time, the particle migration area expands, causing the reservoir permeability damage to increase. The grid is re-divided according to the maximum radius under the current water saturation. According to the empirical relationship between rock strength and reservoir permeability, the reservoir permeability after the particle migration damage intensifies in the grid from near well to far well is calculated. The formula is as follows; In the formula, K ij is the grid unit permeability after the particle migration damage increases with the increase of water saturation, in μm 2 .

3. The method for evaluating the productivity of reservoir particle migration damage and fracture filling layer composite damage according to claim 1 or 2, characterized in that: The method for evaluating the damage of conductivity of a fractured filling well under the combined action of compaction-embedding-plugging comprises the following steps: S21: Calculate the permeability damage caused by proppant compaction based on the actual closure pressure generated by the fracture closure stress, bottom hole flow pressure and fracture pore pressure; S22: Calculate the fracture width loss caused by the embedding of proppant into the formation based on the actual closure stress and the strength of proppant and reservoir rock; S23: Based on the sand content of the reservoir fluid and the porosity parameters after the filling layer is closed and compacted, the degree of blockage of the fracture filling layer by the formation sand over the production time is calculated to evaluate the permeability damage; S24: Comprehensively consider the above three effects and evaluate the damage to the fracture conductivity.

4. The method for evaluating the production capacity of reservoir particle migration damage and fracture filling layer composite damage according to claim 3 is characterized by: The S21 comprises the following steps: S211: Calculate the actual closing pressure of the proppant as P c , the calculation formula is as follows, P c =P-ΔP Where P c is the actual closure pressure of the formation, in MPa; P is the overlying rock pressure of the formation, in MPa; △P (t) is the pore pressure, in MPa; S212: The compaction permeability of proppants with different particle sizes under different pressures was measured experimentally. Based on the experimental results, the permeability damage coefficient caused by proppant compaction under different closure pressures was obtained as follows: In the formula, K Rc It is the permeability damage coefficient caused by proppant compaction of proppants with different particle sizes at different closure pressures, dimensionless.

5. The method for evaluating the production capacity of reservoir particle migration damage and fracture filling layer composite damage according to claim 3 is characterized by: The S22 comprises the following steps: S221: Calculate the ideal contact radius between the proppant and the fracture wall. The calculation formula is: In the formula, S cg is the reservoir compressive strength, in MPa; r is the proppant radius, in mm; r x is the ideal contact radius between the proppant and the fracture wall under different closing pressure conditions, in mm; S222: Calculate the fracture width loss caused by proppant embedment. The formula is as follows: In the formula, w f1 is the width of the crack where the proppant is embedded, in mm; r x0 is the actual contact radius between the proppant and the fracture wall, in mm; β is the embedded correction coefficient, when the closing pressure is large enough during the calculation process, r x It may be greater than r, so it is necessary to introduce an embedding correction coefficient β. The specific relationship is as follows: S223: Calculate the remaining effective seam width. The formula is as follows: In f =in f0 -In f1 In the formula, w f is the crack width after proppant embedment, in mm; w f0 is the original crack width, in mm.

6. The method for evaluating the production capacity of reservoir particle migration damage and fracture filling layer composite damage according to claim 3, characterized in that: The S23 comprises the following steps: S231: Calculate the dynamic blockage permeability damage coefficient. The calculation formula is as follows: In the formula, K Rs(t) is the dynamic plugging permeability damage coefficient, dimensionless; K Rmin is the minimum plugging permeability ratio at plugging equilibrium, dimensionless; S232: Calculate the quasi-blocking equilibrium time. The calculation formula is as follows: Where, T pei is the proposed blocking equilibrium time, in days; V f is the volume of sand control medium, in m 3 ; φ g is the fracture porosity, unit is dimensionless; Q l is the fracture inflow, in m 3 ·sky -1 ; C s is the sand content of the fluid, in %; R si It is the volume ratio of formation sand that can invade fractures to produced sand, dimensionless.

7. The method for evaluating the production capacity of reservoir particle migration damage and fracture filling layer composite damage according to claim 3, characterized in that: In S24, the fracture conductivity damage coefficient formula of the hydraulic fracturing filling well under different production time and closure pressure conditions is: In the formula, C z(t) is the fracture conductivity and permeability damage coefficient under different production time and closure pressure conditions, dimensionless.

8. The method for evaluating the productivity of reservoir particle migration damage and fracture filling layer composite damage according to claim 1 or 2, characterized in that: The S3 comprises the following steps, S31: Calculate the total skin factor of the reservoir area for particle migration; S32: Calculate the fracture damage skin coefficient of the fracturing filling well; S33: Calculate the dynamic production capacity of oil wells due to combined damage of particle migration and fracture filling layer.

9. The method for evaluating the productivity of reservoir particle migration damage and fracture filling layer combined damage according to claim 8, characterized in that: The S31 The following steps are included: S311: Under the water saturation condition at a certain production time, according to the reservoir grid division, the particle migration damage permeability is obtained according to the geometric size of each unit body and the prediction, the skin coefficient of particle migration damage of each grid unit is calculated, the total skin coefficient is obtained by superposition, and then the production capacity ratio is calculated. The additional skin coefficient of the i-th grid unit is: In the formula, s d(i) , k d(i) 、r d(i) are the additional skin coefficient, permeability and outer radius of the ith grid unit, respectively, and the units are dimensionless and μm 2 and m;β s is the turbulence velocity coefficient; ρ l is the reservoir fluid density, in kg / m 3 ;μ f is the reservoir fluid viscosity, in Pa.s; S312: Calculate the total skin factor of the water saturation area at different production times. The formula is as follows:

10. The method for evaluating the productivity of reservoir particle migration damage and fracture filling layer combined damage according to claim 8, characterized in that: In S32, the calculation formula of the fracture damage skin coefficient of the fracturing filling well is as follows: Where C0 is the original conductivity of the fracture, in μm 2 cm; C x(t) To consider the fracture conductivity after embedding compaction and plugging damage, the unit is μm 2 cm; In S33, the oil well productivity ratio is calculated according to the total additional skin factor: In the formula, r e is the reservoir control outer radius, in m; r w is the wellbore radius, in m; S is the original inherent skin coefficient of the reservoir, such as the perforation skin coefficient, dimensionless; PR (t) is the capacity ratio that changes with production time, dimensionless.

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