A method and device for predicting the inflow performance of composite flooding in stages

Abstract

The present disclosure relates to a method and device for predicting the inflow performance of composite flooding in stages, including: obtaining well parameters, production performance parameters, formation parameters, and fluid parameters of target wells in the work area; establishing a basic differential equation for the seepage of viscoelastic fluids in porous media; determining the outer boundary position and outer boundary pressure value of the viscoelastic fluid in the target well formation, and determining the definite solution conditions of the seepage model of the viscoelastic fluid in porous media according to the outer boundary position and outer boundary pressure value; determining a comprehensive correction coefficient according to the formation parameters; solving the basic differential equation according to the above parameters and definite solution conditions to obtain the prediction results of the inflow performance of single wells in different development stages in the work area. To solve the problem that the existing prediction method for the inflow performance of composite flooding is solved based on the single-phase seepage model of chemical displacement agents, ignoring the important role of the oil phase in the seepage process and the stage change of formation fluids, resulting in low accuracy of prediction results.

Description

Technical Field

[0001] The present disclosure relates to the technical field of oil exploration and development, and particularly to a method and device for predicting the staged inflow performance of a composite flooding process. Background Art

[0002] In view of the serious imbalance between reservoir production and injection in current old oilfields and the deterioration of the quality of newly added reserves, improving the recovery factor of old oilfields has become an important way to maintain oilfield production. The technology of enhancing oil recovery by chemical flooding has been widely applied, and the alkaline-surfactant-polymer (ASP) flooding technology, which can significantly improve the recovery factor, was industrially promoted in Daqing Oilfield in 2014. The composition of the formation fluid in composite flooding is more complex than that in single polymer flooding, and its rheological and seepage properties are undoubtedly more complex. The system contains a certain amount of alkali and surfactant, and the interaction between them and between them and the porous medium further increases the complexity of the formation fluid flow. During the ASP flooding process, the rheology of the composite system changes from injection into the injection well to production from the production well, and the produced fluid significantly exhibits non-Newtonian fluid characteristics. Therefore, the production performance prediction method for composite flooding is different from that for water flooding development. It is necessary to optimize production parameters according to the characteristics of the formation fluid and the produced fluid and formulate a reasonable working system. The main basis for adjusting the mechanical oil production system is the study of the inflow performance of oil wells. When predicting the inflow performance of oil wells, it is necessary to clarify the seepage situation and pressure distribution of the fluid in the reservoir. The rheology of the fluid is particularly closely related to its underground seepage characteristics and plays a decisive role in the latter. Therefore, when conducting composite flooding, the study of the rheology and seepage characteristics of the formation fluid is the basis for predicting the inflow performance of oil wells.

[0003] At present, the prediction research on the inflow performance of ASP flooding is relatively limited, mostly based on the solution of a single-phase seepage model, and the differences are mainly manifested in the characterization and correction methods of fluid viscosity. Most of the existing prediction methods for the inflow performance of polymer and ASP flooding are based on the solution of a single-phase seepage model of chemical displacing agents, ignoring the important role of the oil phase in the seepage process and the staged changes in formation fluid. Taking the average formation pressure as the outer boundary and the well spacing as the seepage radius does not conform to the staged change characteristics in actual production. During the ASP flooding process, the magnitude and location of the formation pressure change regularly and significantly with the progress of the development process, and its influence cannot be ignored. Summary of the Invention

[0004] The present disclosure provides a method and device for predicting the staged inflow performance of a composite flooding process to solve the problem that the existing prediction method for the inflow performance of composite flooding is based on the solution of a single-phase seepage model of chemical displacing agents, ignoring the important role of the oil phase in the seepage process and the staged changes in formation fluid, resulting in low prediction accuracy.

[0005] According to one aspect of the present disclosure, there is provided a method for predicting the staged inflow performance of a composite flooding process, characterized by comprising:

[0006] Obtain the well parameters, production performance parameters, formation parameters, and fluid parameters of the target wells in the work area;

[0007] Establish the basic differential equation for the seepage of viscoelastic fluids in porous media;

[0008] Determine the outer boundary position and outer boundary pressure value of the viscoelastic fluid in the target well formation, and determine the definite solution conditions of the seepage model of the viscoelastic fluid in the porous media according to the outer boundary position and outer boundary pressure value;

[0009] Determine the comprehensive correction coefficient according to the formation parameters, where the comprehensive correction coefficient is the comprehensive value of the maximum residual resistance coefficient, inaccessible pore volume, and fluid viscosity change coefficient in the fluid parameters;

[0010] Solve the basic differential equation according to the well parameters, production performance parameters, formation parameters, fluid parameters, definite solution conditions, and comprehensive correction coefficient to obtain the inflow performance prediction results at different development stages of a single well in the work area.

[0011] Preferably, the method for determining the outer boundary position of the viscoelastic fluid in the target well formation includes:

[0012] Obtain the well spacing between the target well and adjacent wells in the work area;

[0013] Determine that the position at 40% - 60% of the distance from the target well to the adjacent well is the outer boundary position according to the well spacing.

[0014] Preferably, the method for determining the outer boundary pressure value of the viscoelastic fluid in the target well formation includes:

[0015] Determine the outer boundary pressure value according to the regression formula;

[0016] Among them, the regression formula includes:

[0017]

[0018] In the formula: P max is the objective function, the maximum formation pressure in the chemical flooding stage, MPa, P wf is the average bottom hole flowing pressure, MPa, P0 is the water flooding bottom hole flowing pressure in the equal flow rate water flooding stage before the conversion from water flooding to ASP flooding, MPa, k r is the average formation permeability, md, V k is the formation permeability variation coefficient, μ is the injection viscosity, mPa·s, v is the injection rate, PV / a.

[0019] Preferably, the method for determining the definite solution conditions of the seepage model of viscoelastic fluid in porous media according to the outer boundary position and the outer boundary pressure value includes:

[0020] According to the outer boundary position and the outer boundary pressure value, use the definite solution condition formula to determine the definite solution conditions;

[0021] Among them, the definite solution condition formula includes:

[0022]

[0023] In the formula: r w is the wellbore radius (m), m is the medium constant, n is the mobility index, Q is the (production rate), and B is the volume coefficient.

[0024] Preferably, the method for determining the comprehensive correction coefficient according to the formation parameters includes:

[0025] Obtain the existing actual production data in the work area;

[0026] According to the actual production data, use the comprehensive correction coefficient formula to determine the comprehensive correction coefficient corresponding to the actual production data;

[0027] Determine the relationship between the comprehensive correction coefficient corresponding to the actual production data and the permeability in the formation parameters of the actual production data;

[0028] According to the relationship and the permeability in the formation parameters of the target well, determine the comprehensive correction coefficient of the target well.

[0029] Preferably, the comprehensive correction coefficient formula includes:

[0030]

[0031] In the formula: R f is the maximum residual resistance coefficient, S h is the inaccessible pore volume, S μ is the fluid viscosity change coefficient.

[0032] Preferably, the well parameters include: skin factor, pollution radius, well completion degree, well spacing, and wellbore radius;

[0033] The production performance parameters include: initial formation pressure, initial bottom-hole flowing pressure, injection rate, and water cut;

[0034] The formation parameters include: effective thickness of the oil layer, average permeability, porosity, volume coefficient, comprehensive compressibility coefficient, heterogeneity variation coefficient, tortuosity coefficient, and medium constant;

[0035] The fluid parameters include: inaccessible pore volume, maximum residual resistance coefficient, consistency coefficient, mobility index, elastic parameter, and elastic index.

[0036] According to one aspect of the present disclosure, a device for predicting the inflow performance of a composite flooding in stages is provided, including:

[0037] An acquisition unit for acquiring well parameters, production performance parameters, formation parameters, and fluid parameters of the target well in the work area;

[0038] A basic differential equation establishment unit for establishing a basic differential equation for the seepage of viscoelastic fluid in porous media;

[0039] A definite solution condition determination unit for determining the outer boundary position and outer boundary pressure value of the viscoelastic fluid in the target well formation, and determining the definite solution conditions of the seepage model of the viscoelastic fluid in porous media according to the outer boundary position and outer boundary pressure value;

[0040] A comprehensive correction coefficient determination unit for determining a comprehensive correction coefficient according to the formation parameters, where the comprehensive correction coefficient is the comprehensive value of the maximum residual resistance coefficient, inaccessible pore volume, and fluid viscosity change coefficient in the fluid parameters;

[0041] An inflow performance prediction unit for solving the basic differential equation according to the well parameters, production performance parameters, formation parameters, fluid parameters, definite solution conditions, and comprehensive correction coefficient to obtain the inflow performance prediction results of a single well in different development stages in the work area.

[0042] The present invention has at least the following beneficial effects:

[0043] The present disclosure proposes a method and device for predicting the inflow performance of a composite flooding in stages. By using formation parameters, a comprehensive correction coefficient is determined to replace three parameters, namely the maximum residual resistance coefficient, inaccessible pore volume, and fluid viscosity change coefficient, which are difficult to determine in fluid parameters. The basic differential equation is solved according to the comprehensive correction coefficient, so as to obtain a prediction result with higher accuracy and realize reliable prediction of flowing pressure and liquid volume in different stages of composite flooding. Description of the Drawings

[0044] The drawings here are incorporated into the specification and form a part of this specification. These drawings show embodiments consistent with the present disclosure and are used together with the specification to illustrate the technical solutions of the present disclosure.

[0045] Figure 1 A flowchart showing the method for predicting the inflow performance of a composite flooding in stages according to an embodiment of the present disclosure;

[0046] Figure 2Shows the relationship diagram between the comprehensive correction coefficient and permeability at different development stages based on the existing actual production data according to the embodiments of the present disclosure;

[0047] Figure 3 Shows the final prediction result diagram of the North 2-311-E85 work area according to the embodiments of the present disclosure. Detailed implementation manners

[0048] Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the drawings denote elements having the same or similar functions. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0049] The term "exemplary" used herein means "serving as an example, embodiment, or illustration". Any embodiment described as "exemplary" herein is not necessarily to be construed as superior or better than other embodiments.

[0050] The term "and / or" in this document is merely a description of the associated relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the term "at least one" in this document means any one of a plurality or any combination of at least two of a plurality. For example, including at least one of A, B, and C can represent any one or more elements selected from the set composed of A, B, and C.

[0051] In addition, in order to better illustrate the present disclosure, numerous specific details are given in the following detailed implementation manners. Those skilled in the art should understand that the present disclosure can be implemented without some specific details. In some instances, methods, means, elements, and circuits well known to those skilled in the art are not described in detail so as to highlight the gist of the present disclosure.

[0052] Figure 1 Shows the flowchart of the composite flooding staged inflow performance prediction method according to the embodiments of the present disclosure; Figure 2 Shows the relationship diagram between the comprehensive correction coefficient and permeability at different development stages based on the existing actual production data according to the embodiments of the present disclosure; Figure 3 Shows the final prediction result diagram of the North 2-311-E85 work area according to the embodiments of the present disclosure. As Figures 1-3As shown in the figure, a method for predicting the inflow performance of composite flooding in stages includes the following steps: Step S01: Obtain the well parameters, production performance parameters, formation parameters, and fluid parameters of the target well in the work area; Step S02: Establish the basic differential equation for the seepage of viscoelastic fluid in porous media; Step S03: Determine the outer boundary position and outer boundary pressure value of the viscoelastic fluid in the target well formation, and determine the definite solution conditions of the seepage model of the viscoelastic fluid in porous media according to the outer boundary position and outer boundary pressure value; Step S04: Determine the comprehensive correction coefficient according to the formation parameters, where the comprehensive correction coefficient is the comprehensive value of the maximum residual resistance coefficient, inaccessible pore volume, and fluid viscosity change coefficient in the fluid parameters; Step S05: Solve the basic differential equation according to the well parameters, production performance parameters, formation parameters, fluid parameters, definite solution conditions, and comprehensive correction coefficient to obtain the predicted results of the inflow performance of a single well in different development stages in the work area.

[0053] The method for predicting the inflow performance of composite flooding in stages provided by the embodiment of the present invention specifically includes the following steps:

[0054] Step S01: Obtain the well parameters, production performance parameters, formation parameters, and fluid parameters of the target well in the work area.

[0055] In the present disclosure, the well parameters include: skin factor, pollution radius, well completion degree, inter-well distance, and well radius; the production performance parameters include: initial formation pressure, initial bottom-hole flowing pressure, injection rate, and water cut; the formation parameters include: effective thickness of the oil layer, average permeability, porosity, volume coefficient, comprehensive compressibility coefficient, heterogeneity variation coefficient, tortuosity coefficient, and medium constant; the fluid parameters include: inaccessible pore volume, maximum residual resistance coefficient, consistency coefficient, mobility index, elastic parameter, and elastic index.

[0056] In the embodiment of the present disclosure, the data sources of the skin factor and pollution radius are well test data / water flooding production performance analysis; the data source of the well completion degree is drilling and completion data and production performance research; the data sources of the inter-well distance, well radius, initial formation pressure, initial bottom-hole flowing pressure, injection rate, water cut, effective thickness of the oil layer, average permeability, porosity, volume coefficient, and heterogeneity variation coefficient are on-site geological data production performance; the data sources of the tortuosity coefficient, medium constant, inaccessible pore volume, maximum residual resistance coefficient, consistency coefficient, mobility index, elastic parameter, and elastic index are laboratory core experiment fluid rheology tests.

[0057] Step S02: Establish the basic differential equation for the seepage of viscoelastic fluid in porous media.

[0058] In the embodiments of the present disclosure, it is assumed that the reservoir is homogeneous, of equal thickness, and isotropic; there is a well at the center of the oil layer, and the oil well completely penetrates the formation. The fluid flows from the drainage boundary to the bottom of the well in a radial flow form, and the movement conforms to the form of Darcy's law. Gravity and the compressibility of the system are ignored, the adsorption and dilution of the fluid in the formation during ASP flooding are not considered, and the formation fluid is regarded as a viscoelastic fluid.

[0059] The establishment of the basic differential equation for the seepage of viscoelastic fluid in porous media is determined according to the continuity equation, the fluid state equation, and the motion equation.

[0060] Among them, the continuity equation is:

[0061]

[0062] The fluid state equation is:

[0063]

[0064]

[0065] The flow of the fluid in the formation porous media during ASP flooding can still be described by Darcy's formula, but the viscosity is corrected, and the corrected motion equation is:

[0066]

[0067] In the formula: k(r) is the average permeability of the formation, md, v is the injection rate, is the porosity.

[0068] In Equation (4), according to the approximate linear form between the flow rate and the seepage velocity, the shear viscosity of the power-law fluid model is obtained as:

[0069]

[0070] In the formula: k is the consistency coefficient, Pa*s n , B is the volume coefficient, h is the effective thickness of the oil layer, m, and n1 is the elastic index.

[0071] The elastic viscosity adopts the elastic viscosity model proposed by Masuda et al.:

[0072]

[0073] In the formula: C is the medium constant, A1 is the elastic parameter, N*s 2-n1 , k is the consistency coefficient, Pa*s n , is the porosity, n1 is the elastic index, n is the mobility index, B is the volume coefficient, h is the effective thickness of the oil layer, and m is the medium constant.

[0074] The effective viscosity of the ternary composite flooding formation fluid, which can be regarded as a viscoelastic fluid, flowing through a porous medium is:

[0075] μ e = Er 1-n + Fr m(n-n1)+(1-n) ; (7)

[0076] Where: m is the medium constant, n is the mobility index, and n1 is the elastic index.

[0077] Thus, the basic differential equation for the ternary composite flooding formation fluid flowing through the formation porous medium is:

[0078]

[0079] Where: k r is the average formation permeability, md, is the porosity.

[0080] After expanding Equation (8), it becomes:

[0081]

[0082] Where: m is the medium constant, n is the mobility index, n1 is the elastic index, C t is the comprehensive compressibility, MPa -1 , k r is the average formation permeability, md, is the porosity.

[0083] Step S03: Determine the outer boundary position and the outer boundary pressure value of the viscoelastic fluid in the target well formation, and determine the definite solution conditions of the seepage model of the viscoelastic fluid in the porous medium according to the outer boundary position and the outer boundary pressure value.

[0084] In the present disclosure, the method for determining the outer boundary position of the viscoelastic fluid in the target well formation includes: obtaining the well spacing between the target well and the adjacent well in the work area; according to the well spacing, determining that the position at 40% - 60% of the distance between the target well and the adjacent well is the outer boundary position.

[0085] In the embodiments of the present disclosure, the calculation basis of the inflow performance of the ASP flooding is the solution of the seepage model. In the existing solution applications, the distance between wells is used as the seepage radius to determine the outer boundary position. However, through the study of the pressure field of the ASP flooding, it is found that the position corresponding to the average formation pressure (outer boundary position) changes according to a certain law with the progress of the ASP composite development. The distance from the outer boundary position to the adjacent production well is less than the well spacing between the target well and the adjacent well, generally at about half of the well spacing (40%-60%). The reduction of the seepage area not only conforms to the actual physical phenomenon but also weakens the complexity of the fluid type and seepage space in the study area, which helps to improve the calculation accuracy.

[0086] In the present disclosure, the method for determining the outer boundary pressure value of the viscoelastic fluid in the formation of the target well includes: determining the outer boundary pressure value according to the regression formula; wherein, the regression formula includes:

[0087]

[0088] In the formula: P max is the objective function, the maximum formation pressure during the chemical flooding stage, Mpa, P wf is the average bottom-hole flowing pressure, MPa, P0 is the bottom-hole flowing pressure of the water flooding during the equal flow rate water flooding stage before the conversion from water flooding to ASP flooding, MPa, k r is the average formation permeability, md, V k is the coefficient of variation of the formation permeability, μ is the injection viscosity, mPa·s, v is the injection rate, PV / a.

[0089] In the embodiments of the present disclosure, the average formation pressure during the ASP flooding development also changes according to a certain law. By using numerical simulation orthogonal analysis for different factors, the above regression formula is obtained. According to this regression formula, the outer boundary pressure value can be determined.

[0090] In the present disclosure, the method for determining the definite solution conditions of the seepage model of the viscoelastic fluid in the porous medium according to the outer boundary position and the outer boundary pressure value includes:

[0091] Determining the definite solution conditions according to the outer boundary position and the outer boundary pressure value by using the definite solution condition formula;

[0092] Wherein the definite solution condition formula includes:

[0093]

[0094] In the formula: r w is the wellbore radius (m), m is the medium constant, n is the mobility index, Q is the production rate, and B is the volume factor.

[0095] In the embodiments of the present disclosure, the outer boundary is defined as a constant pressure according to the boundary conditions, that is:

[0096] P(r,0) = P e ; (12)

[0097] where: P e is the initial formation pressure, in MPa.

[0098] The inner boundary is defined as a constant production rate, that is:

[0099] P(r e ,t) = P e ; (13)

[0100] where: P e is the initial formation pressure, in MPa.

[0101] According to formulas (12) and (13), the definite solution condition formula is formula (11). Then, substitute the outer boundary position and the outer boundary pressure value determined in the above process into formula (11) to obtain the definite solution conditions of the seepage model of viscoelastic fluid in porous media.

[0102] Step S04: Determine the comprehensive correction coefficient according to the formation parameters, where the comprehensive correction coefficient is the comprehensive value of the maximum residual resistance coefficient, the inaccessible pore volume, and the fluid viscosity change coefficient in the fluid parameters.

[0103] In the present disclosure, the method for determining the comprehensive correction coefficient according to the formation parameters includes: obtaining the existing actual production data in the work area; according to the actual production data, using the comprehensive correction coefficient formula to determine the comprehensive correction coefficient corresponding to the actual production data; determining the relationship between the comprehensive correction coefficient corresponding to the actual production data and the permeability in the formation parameters of the actual production data; according to the relationship and the permeability in the formation parameters of the target well, determining the comprehensive correction coefficient of the target well.

[0104] In the present disclosure, the comprehensive correction coefficient formula includes:

[0105]

[0106] where: R f is the maximum residual resistance coefficient, S h is the inaccessible pore volume, S μ is the fluid viscosity change coefficient.

[0107] In the embodiments of the present disclosure, the comprehensive correction coefficient formula is determined according to the corrected Darcy formula, where the corrected Darcy formula is:

[0108]

[0109] Where: k(r) is the average formation permeability, md, v is the injection rate, PV / a, is the porosity.

[0110] In its formula (15):

[0111]

[0112] During the development of ASP flooding, the following physical property changes occur:

[0113] 1. The change in formation permeability caused by adsorption, retention, etc., that is:

[0114]

[0115] Where: k(r) is the average formation permeability, md, k is the consistency coefficient, Pa*s n , R f is the maximum residual resistance coefficient.

[0116] 2. The change in fluid viscosity caused by fluid components, slug injection and migration, etc., that is:

[0117] μ a (r, v) = S μ μ e ; (18)

[0118] Where: v is the injection rate, PV / a, S μ is the fluid viscosity change coefficient.

[0119] 3. The change in equivalent thickness caused by the matching of polymer size and pore throat size and the seepage difference formed by heterogeneity, etc., that is:

[0120]

[0121] Where: h is the effective thickness of the oil layer, m, S h is the inaccessible pore volume.

[0122] After substituting formulas (16)-(19) into formula (18), we get:

[0123]

[0124] Where: h is the effective thickness of the oil layer, m, k is the consistency coefficient, Pa*s n , R f is the maximum residual resistance coefficient, S h inaccessible pore volume, S μ is the fluid viscosity change coefficient.

[0125] According to formula (20), the formula (14) for the comprehensive correction coefficient a is finally determined.

[0126] In the embodiments of the present disclosure, through the fitting study of existing actual production data, it is shown that the comprehensive correction coefficient in different development stages shows a strong power-law correlation with permeability, so that the variation law of the comprehensive correction coefficient with the increase of permeability can be determined. According to this variation law, the relationship between the comprehensive correction coefficient and permeability in different development stages can be determined as follows:

[0127] The relationship between the comprehensive correction coefficient and permeability in the main slug stage of the ternary system is:

[0128] y = 0.267x -1.155 ; (21)

[0129] The relationship between the comprehensive correction coefficient and permeability in the secondary slug stage of the ternary system is:

[0130] y = 0.227x -0.932 ; (22)

[0131] The relationship between the comprehensive correction coefficient and permeability in the subsequent polymer slug stage is:

[0132] y = 0.1733x -1.001 ; (23)

[0133] In formulas (21), (22), and (23): y is the comprehensive correction coefficient, and x is the permeability.

[0134] As Figure 2 shown, it is a graph of the relationship between the comprehensive correction coefficient and permeability in different development stages of existing actual production data; in the figure, the points are the values of the comprehensive correction coefficient calculated according to the existing actual production data using the comprehensive correction coefficient formula (14); the dashed lines are the predicted values of the comprehensive correction coefficient calculated according to the permeability in the actual production data using the relationships (21), (22), and (23). It can be seen from Figure 2 that compared with the true comprehensive correction coefficient values determined by the actual formula (14), the predicted comprehensive correction coefficient values calculated using the relationships (21), (22), and (23) have higher accuracy, indicating that the relationships (21), (22), and (23) can be used to predict the comprehensive correction coefficient of the target well.

[0135] After the relationship is determined, according to the permeability of the target well and the relationships (21), (22), and (23), the values of the comprehensive correction coefficient corresponding to different development stages of the target well can be calculated.

[0136] Step S05: Solve the basic differential equation according to the well parameters, production dynamic parameters, formation parameters, fluid parameters, definite solution conditions, and comprehensive correction coefficient to obtain the inflow performance prediction results of individual wells in the work area at different development stages.

[0137] In the embodiments of the present disclosure, the skin factor, pollution radius, well completion degree, inter-well distance, well radius in well parameters, as well as the initial formation pressure, initial bottom-hole flowing pressure, injection rate, water cut in production dynamic parameters, and the effective thickness of the oil reservoir, average permeability, porosity, volume coefficient, comprehensive compressibility coefficient, heterogeneity variation coefficient, tortuosity coefficient, medium constant in formation parameters, and the inaccessible pore volume, maximum residual resistance coefficient, consistency coefficient, mobility index, elastic parameter, elastic index in fluid parameters are substituted into the basic differential equation.

[0138] Solve according to the definite solution conditions determined in step S03. Among them, during the solution, the values of the originally three constantly changing and difficult-to-determine parameters in fluid parameters, namely the maximum residual resistance coefficient, inaccessible pore volume, and fluid viscosity variation coefficient, are replaced by the comprehensive value of these three parameters determined in step S04, that is, the comprehensive correction coefficient.

[0139] Adopt an uneven logarithmic grid, that is, the grid near the bottom hole is taken denser, and it gradually becomes sparser along the radial direction outward, to perform spatial transformation on the basic differential equation and the inner and outer boundaries. The central difference format is used for the spatial difference, and the implicit difference format of the first-order backward difference is used for the time difference to discretize the basic differential equation. Solve the equation by the chasing method. An elimination and back-substitution process completes the calculation of one time step to obtain the pressure distribution of each point in the formation at the next moment. Repeat this process to obtain the pressure distribution of each point in the formation under different flow rates at different times and the bottom-hole flowing pressure under the corresponding flow rates, which is the prediction result of the inflow performance of a single well in the work area at different development stages.

[0140] In the embodiments of the present disclosure, the inflow performance prediction verification is carried out by applying the data of the North Third East field. Taking Bei 2-311-E85 as an example, the prediction of the inflow performance at different development stages is carried out by using the actual production and development data of a single well. Among them, the formation parameters of the Bei 2-311-E85 work area are shown in Table 1 below. The final prediction result is as Figure 3 shown, and the accuracy of the prediction result is higher than 80%.

[0141] Table 1: Formation parameters of Bei 2-311-E85

[0142]

[0143] The phased prediction is carried out for 20 typical well groups in the block by the same method, and the coincidence rate of the prediction result is higher than 80%.

[0144] It can be understood that the above-mentioned various method embodiments mentioned in the present disclosure can be combined with each other to form a combined embodiment without violating the principle logic. Due to space limitations, the present disclosure will not elaborate further.

[0145] The execution entity of the method for predicting the stage - by - stage inflow performance of polymer flooding can be a device for predicting the stage - by - stage inflow performance of polymer flooding. For example, the method for predicting the stage - by - stage inflow performance of polymer flooding can be executed by a terminal device, a server, or other processing devices. Among them, the terminal device can be a user equipment (UE), a mobile device, a user terminal, a terminal, a cellular phone, a cordless phone, a personal digital assistant (PDA), a handheld device, a computing device, a vehicle - mounted device, a wearable device, etc. In some possible implementation manners, the method for predicting the stage - by - stage inflow performance of polymer flooding can be implemented by a processor invoking computer - readable instructions stored in a memory.

[0146] Those skilled in the art can understand that in the above - mentioned method of the specific implementation manner, the writing order of each step does not mean a strict execution order that constitutes any limitation on the implementation process. The specific execution order of each step should be determined according to its function and possible internal logic.

[0147] The present disclosure also provides a device for predicting the stage - by - stage inflow performance of polymer flooding, including: an acquisition unit, configured to acquire well parameters, production performance parameters, formation parameters, and fluid parameters of target wells in the work area; a basic differential equation establishment unit, configured to establish a basic differential equation for the seepage of visco - elastic fluid in porous media; a definite - solution condition determination unit, configured to determine the outer - boundary position and outer - boundary pressure value of the visco - elastic fluid in the target - well formation, and determine the definite - solution conditions of the seepage model of the visco - elastic fluid in porous media according to the outer - boundary position and outer - boundary pressure value; a comprehensive correction coefficient determination unit, configured to determine a comprehensive correction coefficient according to the formation parameters, where the comprehensive correction coefficient is the comprehensive value of the maximum residual resistance coefficient, inaccessible pore volume, and fluid viscosity change coefficient in the fluid parameters; an inflow performance prediction unit, configured to solve the basic differential equation according to the well parameters, production performance parameters, formation parameters, fluid parameters, definite - solution conditions, and comprehensive correction coefficient, and obtain the prediction results of the inflow performance of single wells in different development stages in the work area.

[0148] In some embodiments, the functions or modules and units included in the device provided in the embodiments of the present disclosure can be used to execute the methods described in the above - mentioned method embodiments. The specific implementation can refer to the description of the above - mentioned method embodiments. For the sake of brevity, it will not be repeated here.

[0149] The present invention corrects the outer boundary position and outer boundary pressure value of the composite flooding influx performance prediction by using the results of large-scale flat physical model experiments and numerical simulation research, so as to determine the definite solution conditions; determines the comprehensive correction coefficient for the phased prediction of the composite flooding influx performance by parameter separation, and determines its variation law based on statistical regression to obtain the relationship between the comprehensive correction coefficient and permeability; on this basis, establishes a method for predicting the composite flooding influx performance. The method disclosed herein has a high prediction accuracy, can achieve reliable prediction of the flowing pressure and liquid volume at different stages of composite flooding, is easy to operate and implement, can be used for predicting the influx performance of individual wells at different development stages in industrial blocks of composite flooding, plays an important role in the tertiary oil recovery in oilfields, provides a basis for determining the working system of oil wells, and has a broad application prospect.

[0150] The various embodiments of the present disclosure have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to technologies in the market, or to enable other ordinary skill in the art in the technical field to understand the embodiments disclosed herein.

Claims

1. A method for predicting the inflow performance of a composite flooding in stages, characterized in that, Including: Obtaining well parameters, production performance parameters, formation parameters, and fluid parameters of target wells in the work area; Establishing the basic differential equation for the seepage of viscoelastic fluids in porous media; Determining the outer boundary position and outer boundary pressure value of the viscoelastic fluid in the target well formation. The method includes: obtaining the well spacing between the target well and adjacent wells in the work area; based on the well spacing, determining that the position 40% - 60% of the distance from the target well to the adjacent well is the outer boundary position; Determining the outer boundary pressure value according to the regression formula; wherein the regression formula includes: ； Wherein: P max is the objective function, the maximum formation pressure during the chemical flooding stage, MPa, P wf is the average bottom-hole flowing pressure, MPa, P 0 is the bottom-hole flowing pressure of the equal-flow-rate water flooding stage before the conversion from water flooding to ASP flooding, MPa, k r is the average formation permeability, md, V k is the coefficient of variation of the formation permeability, is the injection viscosity, mPa·s, and v is the injection rate, PV / a; Determining the definite solution conditions of the seepage model of viscoelastic fluid in porous media according to the outer boundary position and outer boundary pressure value. The method includes: using the definite solution condition formula to determine the definite solution conditions according to the outer boundary position and outer boundary pressure value; wherein the definite solution condition formula includes: ； where: r w is the well radius, m is the medium constant, n is the mobility index, Q is the production rate, and B is the volume factor; Determining the comprehensive correction coefficient according to the formation parameters. The method includes: obtaining the existing actual production data in the work area; according to the actual production data, using the comprehensive correction coefficient formula to determine the comprehensive correction coefficient corresponding to the actual production data; determining the relationship between the comprehensive correction coefficient corresponding to the actual production data and the permeability in the formation parameters of the actual production data; according to the relationship and the permeability in the formation parameters of the target well, determining the comprehensive correction coefficient of the target well. Among them, the comprehensive correction coefficient is the comprehensive value of the maximum residual resistance coefficient, inaccessible pore volume, and fluid viscosity change coefficient in the fluid parameters; Solving the basic differential equation according to the well parameters, production performance parameters, formation parameters, fluid parameters, definite solution conditions, and comprehensive correction coefficient. When solving, substituting the original maximum residual resistance coefficient, inaccessible pore volume, and fluid viscosity change coefficient parameters in the fluid parameters with the comprehensive correction coefficient to obtain the inflow performance prediction results at different development stages of a single well in the work area.

2. The staged inflow performance prediction method for composite flooding according to claim 1, characterized in that: The comprehensive correction coefficient formula includes: ； Where: R f is the maximum residual resistance coefficient, S h is the inaccessible pore volume, is the fluid viscosity change coefficient.

3. The staged inflow performance prediction method for composite flooding according to claim 1 or 2, characterized in that: The well parameters include: skin factor, pollution radius, well completion degree, well spacing, and well radius; The production performance parameters include: initial formation pressure, initial bottom-hole flowing pressure, injection rate, and water cut; The formation parameters include: effective thickness of the oil layer, average permeability, porosity, volume coefficient, comprehensive compressibility coefficient, heterogeneity variation coefficient, tortuosity coefficient, and medium constant; The fluid parameters include: inaccessible pore volume, maximum residual resistance coefficient, consistency coefficient, mobility index, elastic parameter, and elastic index.

4. A device for predicting the inflow performance of a composite flooding in stages, characterized in that, Including: An acquisition unit for obtaining well parameters, production performance parameters, formation parameters, and fluid parameters of target wells in the work area; A basic differential equation establishment unit for establishing the basic differential equation for the seepage of viscoelastic fluids in porous media; A definite solution condition determination unit is used to determine the outer boundary position and the outer boundary pressure value of the viscoelastic fluid in the formation of the target well. The method includes: obtaining the well spacing between the target well and the adjacent well in the work area; according to the well spacing, determining that the position at 40% - 60% of the distance from the target well to the adjacent well is the outer boundary position; determining the outer boundary pressure value according to the regression formula; wherein the regression formula includes: ； Where: P max is the objective function, the maximum formation pressure during the chemical flooding stage, MPa, P wf is the average bottom-hole flowing pressure, MPa, P 0 is the bottom-hole flowing pressure of the equal-velocity water flooding stage before the water flooding is converted to ASP flooding, MPa, k r is the average formation permeability, md, V k is the coefficient of variation of the formation permeability, is the injection viscosity, mPa·s, and v is the injection rate, PV / a; According to the outer boundary position and the outer boundary pressure value, determining the definite solution conditions of the seepage model of the viscoelastic fluid in the porous medium. The method includes: using the definite solution condition formula to determine the definite solution conditions according to the outer boundary position and the outer boundary pressure value; wherein the definite solution condition formula includes: ； Where: r w is the well radius, m is the medium constant, n is the mobility index, Q is the production rate, and B is the volume factor; A comprehensive correction coefficient determination unit is used to determine the comprehensive correction coefficient according to the formation parameters. The method includes: obtaining the existing actual production data in the work area; according to the actual production data, using the comprehensive correction coefficient formula to determine the comprehensive correction coefficient corresponding to the actual production data; determining the relationship between the comprehensive correction coefficient corresponding to the actual production data and the permeability in the formation parameters of the actual production data; according to the relationship and the permeability in the formation parameters of the target well, determining the comprehensive correction coefficient of the target well. Wherein, the comprehensive correction coefficient is the comprehensive value of the maximum residual resistance coefficient, the inaccessible pore volume and the fluid viscosity change coefficient in the fluid parameters; An inflow performance prediction unit is used to solve the basic differential equation according to the well parameters, production performance parameters, formation parameters, fluid parameters, definite solution conditions and comprehensive correction coefficient. When solving, the original maximum residual resistance coefficient, inaccessible pore volume and fluid viscosity change coefficient parameters in the fluid parameters are replaced by the comprehensive correction coefficient to obtain the inflow performance prediction results of single wells in different development stages in the work area.

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