CN113790046A

CN113790046A - Heterogeneous system evaluation method and device, electronic device and storage medium

Info

Publication number: CN113790046A
Application number: CN202110972606.1A
Authority: CN
Inventors: 李宜强; 陈鑫; 刘哲宇; 隋铭月; 张含; 高文彬; 汤翔; 曹涵; 刘涛
Original assignee: China University of Petroleum Beijing
Current assignee: China University of Petroleum Beijing
Priority date: 2021-08-24
Filing date: 2021-08-24
Publication date: 2021-12-14
Anticipated expiration: 2041-08-24
Also published as: CN113790046B

Abstract

The application provides an evaluation method, an evaluation device, electronic equipment and a storage medium for a heterogeneous system, wherein the method comprises the following steps: acquiring a median particle size of a heterogeneous system, and determining the type of an oil displacement experiment model according to the median particle size; determining seepage parameters of an oil displacement experimental model; constructing an oil displacement experiment model according to the seepage parameters, injecting water into the oil displacement experiment model after the oil displacement experiment model is saturated with oil to perform an oil displacement experiment until the oil production at the output end of the oil displacement experiment model is reduced to a first value, and determining a first recovery ratio; continuing to inject a heterogeneous system into the oil displacement experiment model and then performing an oil displacement experiment until the oil yield at the output end of the oil displacement experiment model is reduced to a second value, and obtaining a second recovery ratio of the oil displacement experiment; and determining the evaluation result of the heterogeneous system according to the first recovery factor and the second recovery factor. By the method, heterogeneous systems with different particle sizes can be matched with a proper oil displacement model, and the problem of inaccurate evaluation results caused by improper models is solved.

Description

Heterogeneous system evaluation method and device, electronic device and storage medium

Technical Field

The application relates to the field of petroleum logging, in particular to an evaluation method and device of a heterogeneous system, electronic equipment and a storage medium.

Background

Currently, in order to further improve the recovery ratio of an oil reservoir, a heterogeneous oil displacement system is usually selected as an oil displacement agent in the oil exploitation process in the oil reservoir exploitation. Because different heterogeneous systems have different applicability to different reservoirs and different degrees of improvement of recovery efficiency, the heterogeneous systems need to be evaluated before use to determine the reservoir suitable for the current heterogeneous system.

At present, when a heterogeneous system is evaluated, a core model is generally adopted to carry out an oil displacement experiment, and the ratio of the injected oil content to the oil content in a produced liquid before the oil displacement experiment is obtained as a recovery ratio to evaluate the adaptability of the heterogeneous system to a reservoir.

In the method, because the orders of magnitude of the dispersed phases in different heterogeneous systems are different, for the heterogeneous system with a larger order of magnitude, the heterogeneous system is easy to block the core injection port, so that the finally measured recovery ratio is inaccurate, and the final evaluation result is inaccurate.

Disclosure of Invention

The evaluation method and device for the heterogeneous system, the electronic device and the storage medium are used for solving the problem that the evaluation result of the heterogeneous system is inaccurate in the prior art.

In a first aspect, the present application provides a method for evaluating a heterogeneous system, the method comprising:

obtaining a median particle size of a heterogeneous system, and determining a type of an oil displacement experiment model according to the median particle size, wherein the type of the oil displacement experiment model comprises the following steps: parallel sand-filled pipe models and parallel core models;

determining seepage parameters of the oil displacement experimental model, wherein the seepage parameters comprise: maximum permeability, permeability grade difference;

constructing an oil displacement experiment model according to the seepage parameters, injecting water into the oil displacement experiment model after the oil displacement experiment model is saturated with oil, performing an oil displacement experiment until the oil production at the output end of the oil displacement experiment model is reduced to a first value, and determining a first recovery ratio; continuing to inject a heterogeneous system into the oil displacement experiment model and then performing an oil displacement experiment until the oil yield at the output end of the oil displacement experiment model is reduced to a second value, and acquiring a second recovery ratio of the oil displacement experiment;

determining the evaluation result of the heterogeneous system according to the first recovery factor and the second recovery factor

In one possible implementation manner, the determining a flooding experimental model according to the median particle size includes:

if the median particle size of the heterogeneous system is in a millimeter interval, the oil displacement experimental model is a parallel sand filling pipe model;

if the median particle size of the heterogeneous system is in a micron interval, the oil displacement experimental model is a parallel core model;

and if the median particle size of the heterogeneous system is in a nanometer interval, the oil displacement experimental model is a parallel core model.

In a possible implementation manner, if the median particle size of the heterogeneous system is located in a millimeter interval, the determining the seepage parameter of the oil displacement experimental model includes:

determining a second diameter value according to the median of the particle sizes of the heterogeneous system and a preset first matching coefficient, wherein the preset first matching coefficient is the ratio of the median of the particle sizes of the heterogeneous system injected in the microtube experiment to the particle sizes of the microtubes;

determining the maximum permeability corresponding to the second pipe diameter value according to the second pipe diameter value;

constructing a plurality of parallel microtube models, wherein each parallel microtube model is formed by connecting a first microtube and a second microtube in parallel, the diameter of the first microtube is smaller than that of the second microtube, the diameters of the first microtube in different parallel microtube models are different, and the diameter value of the second microtube in each parallel microtube model is the second diameter value;

injecting a heterogeneous system and water in sequence for a displacement experiment aiming at each parallel microtube model to obtain the section improvement rate of each parallel microtube model after the experiment;

and taking the ratio of the second pipe diameter value to the pipe diameter value of the first microtube in the parallel microtube model corresponding to the maximum profile improvement rate as the permeability grade difference of the oil displacement experimental model.

In one possible implementation manner, if the median particle size of the heterogeneous system is located in a micron interval, the determining the seepage parameter of the oil displacement experimental model includes:

determining a second pore throat radius according to the median particle size of the heterogeneous system and a preset second matching coefficient, wherein the preset second matching coefficient is the ratio of the median particle size of the heterogeneous system injected in the core experiment to the pore throat radius of the core;

determining the maximum permeability corresponding to the second pore throat radius according to the second pore throat radius;

establishing a plurality of parallel core models, wherein each parallel core model is formed by connecting a first core and a second core in parallel, the pore throat radius of the first core is smaller than that of the second core, the pore throat radii of the first core models in different parallel core models are different, and the pore throat radius of the second core model in each parallel core model is the second pore throat radius;

injecting a heterogeneous system and water into each parallel core model in sequence for a displacement experiment, and obtaining the section improvement rate of each parallel core model after the experiment;

and taking the ratio of the second pore throat radius to the pore throat radius of the first core in the parallel core model corresponding to the maximum profile improvement rate as the permeability level difference of the oil displacement experiment model.

In a possible implementation manner, if the median particle size of the heterogeneous system is located in a nanometer interval, the determining the seepage parameter of the oil displacement experimental model includes:

constructing a plurality of core models with different permeabilities, injecting water and a heterogeneous system for displacement experiment aiming at each core model, and obtaining a resistance coefficient in the experiment process of each core model;

taking the permeability of the core model with the resistance coefficient meeting the preset condition as the maximum permeability of the heterogeneous system;

determining a fourth pore throat radius of the core model according to the maximum permeability;

establishing a plurality of parallel core models, wherein each parallel core model is formed by connecting a third core and a fourth core in parallel, the pore throat radius of the third core is smaller than that of the fourth core, the pore throat radii of the third cores in different parallel core models are different, and the pore throat radius of the fourth core in each parallel core model is the fourth pore throat radius;

and taking the ratio of the fourth pore throat radius to the pore throat radius of the fourth core in the parallel core model corresponding to the maximum profile improvement rate as the permeability level difference of the oil displacement experiment model.

In one possible implementation, the obtaining the median particle size of the heterogeneous system includes:

measuring a first particle size distribution frequency curve of the heterogeneous system by using a laser particle sizer;

acquiring image information of a dispersed phase in the heterogeneous system, and determining a second particle size distribution frequency distribution curve according to the image information;

and taking the average value of the first particle size distribution frequency curve and the second particle size distribution frequency curve to obtain the particle size median of the heterogeneous system.

In one possible implementation, before the determining the seepage parameters of the flooding experimental model, the method further includes:

obtaining a dispersant solution and a dispersed phase solution of the heterogeneous system;

if the median particle size of the heterogeneous system is located in a millimeter interval, sequentially testing the dispersion stability, the micro morphology and the volume expansion of a dispersed phase solution of the heterogeneous system, and sequentially testing the viscosity increasing property, the interface performance, the rheological property, the temperature resistance and the salt tolerance of a dispersing agent solution of the heterogeneous system;

if the median particle size of the heterogeneous system is located in the nanometer interval, sequentially testing the dispersion stability and the micro morphology of a dispersed phase solution of the heterogeneous system, and sequentially testing the viscosity increasing property, the interface property, the rheological property, the temperature resistance and the salt tolerance of a dispersant solution of the heterogeneous system;

and if the median particle size of the heterogeneous system is positioned in a micron interval, sequentially testing the dispersion stability, the micro morphology and the volume swelling property of the dispersed phase solution of the heterogeneous system, and sequentially testing the viscosity increasing property, the interface performance, the rheological property, the temperature resistance and the salt tolerance of the dispersing agent solution of the heterogeneous system.

In a second aspect, the present application provides an apparatus for evaluating a heterogeneous system, the apparatus comprising:

the first acquisition unit is used for acquiring a median particle size of a heterogeneous system and determining a flooding experimental model type according to the median particle size, wherein the flooding experimental model type comprises the following components: parallel sand-filled pipe models and parallel core models;

a first determining unit, configured to determine a seepage parameter of the reservoir oil displacement experimental model, where the seepage parameter includes: maximum permeability, permeability grade difference;

the second acquisition unit is used for constructing an oil displacement experiment model according to the seepage parameters, injecting water into the oil displacement experiment model after the oil displacement experiment model is saturated with oil to carry out an oil displacement experiment until the oil yield of the output end of the oil displacement experiment model is reduced to a first value, and determining a first recovery ratio; continuing to inject a heterogeneous system into the oil displacement experiment model and then performing an oil displacement experiment until the oil yield at the output end of the oil displacement experiment model is reduced to a second value, and acquiring a second recovery ratio of the oil displacement experiment;

and the second determination unit is used for determining the evaluation result of the heterogeneous system according to the first recovery factor and the second recovery factor.

In a possible implementation manner, the first obtaining unit is specifically configured to:

In a possible implementation, if the median particle size of the heterogeneous system lies in the millimeter interval, the first determining unit comprises:

the first determining module is used for determining a second diameter value according to a median diameter value of a heterogeneous system and a preset first matching coefficient, wherein the preset first matching coefficient is a ratio of the median diameter value of the heterogeneous system injected in a microtube experiment to the particle diameter of the microtube;

the second determining module is used for determining the maximum permeability corresponding to the second pipe diameter value according to the second pipe diameter value;

the first building module is used for building a plurality of parallel microtubes models, wherein each parallel microtube model is formed by connecting a first microtube and a second microtube in parallel, the diameter of the first microtube is smaller than that of the second microtube, the diameters of the first microtube in different parallel microtube models are different, and the diameter value of the second microtube in each parallel microtube model is the second diameter value;

the first acquisition module is used for sequentially injecting a heterogeneous system and water into each parallel microtube model to perform a displacement experiment so as to acquire the section improvement rate of each parallel microtube model after the experiment;

and the third determining module is used for taking the ratio of the second pipe diameter value to the pipe diameter value of the first microtube in the parallel microtube model corresponding to the maximum profile improvement rate as the permeability grade difference of the oil displacement experimental model.

In a possible implementation, if the median particle size of the heterogeneous system lies in the micron interval, the first determining unit comprises:

the fourth determining module is used for determining a second pore throat radius according to the particle size median of the heterogeneous system and a preset second matching coefficient, wherein the preset second matching coefficient is the ratio of the particle size median of the heterogeneous system injected in the core experiment to the core pore throat radius;

a fifth determining module, configured to determine, according to the second throat radius, a maximum permeability corresponding to the second throat radius;

the second building module is used for building a plurality of parallel core models, wherein each parallel core model is formed by connecting a first core and a second core in parallel, the pore throat radius of the first core is smaller than that of the second core, the pore throat radii of the first core models in different parallel core models are different, and the pore throat radius of the second core model in each parallel core model is the second pore throat radius;

the second acquisition module is used for sequentially injecting a heterogeneous system and water into each parallel core model to perform a displacement experiment so as to acquire the section improvement rate of each parallel core model after the experiment;

and the sixth determining module is used for taking the ratio of the second pore throat radius to the pore throat radius of the first core in the parallel core model corresponding to the maximum profile improvement rate as the permeability level difference of the oil displacement experiment model.

In a possible implementation, if the median particle size of the heterogeneous system is in the nanometer interval, the first determining unit includes:

the third acquisition module is used for constructing a plurality of core models with different permeabilities, injecting water and a heterogeneous system in sequence for a displacement experiment aiming at each core model, and acquiring a resistance coefficient in the experiment process of each core model;

the seventh determining module is used for taking the permeability of the core model with the resistance coefficient meeting the preset condition as the maximum permeability of the heterogeneous system;

an eighth determining module, configured to determine a fourth pore throat radius of the core model according to the maximum permeability;

the third building module is used for building a plurality of parallel core models, each parallel core model is formed by connecting a third core and a fourth core in parallel, the pore throat radius of the third core is smaller than that of the fourth core, the pore throat radii of the third cores in different parallel core models are different, and the pore throat radius of the fourth core in each parallel core model is the fourth pore throat radius;

the third acquisition module is used for sequentially injecting a heterogeneous system and water into each parallel core model to perform a displacement experiment so as to acquire the section improvement rate of each parallel core model after the experiment;

and the ninth determining module is used for taking the ratio of the fourth pore throat radius to the pore throat radius of the fourth core in the parallel core model corresponding to the maximum profile improvement rate as the permeability level difference of the oil displacement experiment model.

In a possible implementation manner, the first obtaining unit includes:

the first measurement module is used for measuring a first particle size distribution frequency curve of the heterogeneous system by using a laser particle sizer;

the second measurement module is used for acquiring image information of a dispersed phase in the heterogeneous system and determining a second particle size distribution frequency distribution curve according to the image information;

and the tenth determining module is used for obtaining the average value of the first particle size distribution frequency curve and the second particle size distribution frequency curve to obtain the particle size median of the heterogeneous system.

In one possible implementation, the apparatus further includes:

the third obtaining unit is used for determining seepage parameters of the oil displacement experiment model in the first determining unit to obtain a dispersing agent solution and a dispersed phase solution of the heterogeneous system;

the first testing unit is used for sequentially testing the dispersion stability, the micro morphology and the volume swelling property of a dispersed phase solution of the heterogeneous system and sequentially testing the viscosity increasing property, the interface property, the rheological property, the temperature resistance and the salt tolerance of a dispersing agent solution of the heterogeneous system if the median of the particle size of the heterogeneous system is positioned in a millimeter interval;

the second testing unit is used for sequentially testing the dispersion stability and the micro morphology of the dispersed phase solution of the heterogeneous system and the viscosity increasing property, the interface property, the rheological property, the temperature resistance and the salt tolerance of the dispersing agent solution of the heterogeneous system if the median of the particle size of the heterogeneous system is positioned in a nanometer interval;

and the third testing unit is used for sequentially testing the dispersion stability, the micro morphology and the volume swelling property of the dispersed phase solution of the heterogeneous system and sequentially testing the viscosity increasing property, the interface property, the rheological property, the temperature resistance and the salt tolerance of the dispersing agent solution of the heterogeneous system if the median of the particle size of the heterogeneous system is positioned in a micron interval.

In a third aspect, the present application provides an electronic device, comprising: a memory, a processor.

A memory for storing the processor-executable instructions;

wherein the processor is configured to perform the method according to any one of the first aspect according to the executable instructions.

In a fourth aspect, the present application provides a computer-readable storage medium having stored thereon computer-executable instructions for implementing the method according to any one of the first aspect when executed by a processor.

In a fifth aspect, the present application provides a computer program product comprising a computer program that, when executed by a processor, implements the method according to any one of the first aspect.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and together with the description, serve to explain the principles of the application.

FIG. 1 is a flow chart of a method for evaluating a heterogeneous system according to an embodiment of the present disclosure;

FIG. 2 is a schematic flow chart illustrating a method for determining seepage parameters according to the present disclosure;

FIG. 3 is a schematic diagram illustrating a micro-pipe model according to an embodiment of the present disclosure;

FIG. 4 is a schematic flow chart illustrating another method for determining seepage parameters provided herein;

FIG. 5 is a schematic flow chart illustrating another method for determining seepage parameters provided herein;

fig. 6 is a schematic flow chart of a method for determining a median particle size of a heterogeneous system according to an embodiment of the present disclosure;

FIG. 7 is a schematic view of a zeta potential curve provided by an embodiment of the present application;

FIG. 8 is a schematic illustration of a particle size distribution curve provided in an embodiment of the present application;

FIG. 9 is a particle size distribution curve of an emulsion polymer provided in an example of the present application;

FIG. 10 is a graph showing the particle size distribution of a polymer microsphere and PPG provided in the examples herein;

FIG. 11 is a plot of the particle size distribution of another polymeric microsphere provided in the examples herein;

FIG. 12 is a schematic diagram of a variation of the expansion factor provided by an embodiment of the present application;

FIG. 13 is a schematic view of a viscosity-concentration curve provided by an embodiment of the present application;

FIG. 14 is a graph showing the viscosity change at different temperatures according to the examples of the present application;

FIG. 15 is a graph showing the variation of interfacial tension with concentration according to an embodiment of the present disclosure;

FIG. 16 is a schematic view of a viscoelastic curve provided by an embodiment of the present application;

FIG. 17 is a schematic structural diagram of an evaluation apparatus for a heterogeneous system according to an embodiment of the present application;

FIG. 18 is a schematic structural diagram of an evaluation apparatus of still another heterogeneous system according to an embodiment of the present application;

fig. 19 is a schematic structural diagram of an electronic device provided in an embodiment of the present application.

With the above figures, there are shown specific embodiments of the present application, which will be described in more detail below. These drawings and written description are not intended to limit the scope of the inventive concepts in any manner, but rather to illustrate the inventive concepts to those skilled in the art by reference to specific embodiments.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

In the process of developing oil reservoirs, the water-drive oil reservoir has the characteristic of low recovery ratio due to the difference of oil-water viscosity. In order to improve the recovery ratio in the oil reservoir development process, an oil displacement technology of a heterogeneous oil displacement system can be adopted, in the oil displacement process, an oil displacement channel for regulating the migration of an oil displacement agent in a heterogeneous stratum can be realized by adopting the heterogeneous system, the heterogeneous system can block a large pore channel by staying in pores, so that a subsequent oil displacement agent enters the channel in the previous heterogeneous stratum which is not affected during oil displacement, oil production is continued through the channel which is not affected, and the recovery ratio is greatly improved.

Because different heterogeneous systems have different applicability to different reservoirs and different degrees of improvement of recovery efficiency, the heterogeneous systems need to be evaluated before use to determine the reservoir suitable for the current heterogeneous system.

In the evaluation process of a traditional heterogeneous system, a core model is usually selected for carrying out an oil displacement experiment, and a reservoir suitable for the heterogeneous system is determined through a recovery ratio obtained in the oil displacement experiment process. However, the magnitude of the dispersed phase in different heterogeneous systems is different, and for a heterogeneous system with a larger magnitude, the heterogeneous system is easily blocked at a core injection port, so that the finally measured recovery ratio is inaccurate, and the final evaluation result is inaccurate.

The application provides an evaluation method and device for a heterogeneous system, electronic equipment and a storage medium, and aims to solve the technical problems in the prior art.

The following describes the technical solutions of the present application and how to solve the above technical problems with specific embodiments. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments. Embodiments of the present application will be described below with reference to the accompanying drawings.

Fig. 1 is a flowchart of an evaluation method of a heterogeneous system according to an embodiment of the present application, the method including the following steps:

s101, obtaining a particle size median of a heterogeneous system, and determining a flooding experiment model type according to the particle size median, wherein the flooding experiment model type comprises the following steps: parallel sand-filled pipe models and parallel core models.

For example, in the embodiment, when a heterogeneous system is evaluated, a median particle size of the heterogeneous system is obtained first, and whether a parallel sand-packed pipe model or a parallel core model is used for a subsequent oil displacement experiment model is further determined according to the measured median particle size. When the median of the particle size of the heterogeneous system is larger, the parallel sand filling pipe model is selected, so that the phenomenon that the injection end face of the model is blocked when the system is injected into the model can be effectively avoided.

In one example, when the selected oil displacement experiment model is determined according to the median particle size, the model can be divided into three intervals according to the median particle size order of a heterogeneous system: millimeter interval, micrometer interval, nanometer interval. Specifically, if the median of the particle size of the heterogeneous system is in the millimeter interval, the oil displacement experimental model is a parallel sand-packed pipe model; if the median of the grain size of the heterogeneous system is in the micron interval, the oil displacement experimental model is a parallel core model; and if the median of the particle size of the heterogeneous system is in the nanometer interval, the oil displacement experimental model is a parallel core model.

S102, determining seepage parameters of the oil displacement experiment model, wherein the seepage parameters comprise: maximum permeability, grade difference in permeability.

Exemplarily, after determining the oil displacement experimental model according to the heterogeneous median particle size, determining a seepage parameter of the oil displacement experimental model suitable for the heterogeneous system, where the seepage parameter includes: maximum permeability and permeability grade difference of the oil displacement model. The seepage parameters of the oil displacement experimental model are related to the particle size of a heterogeneous system, if the maximum seepage parameter of the oil displacement experimental model is selected to be too large, the heterogeneous system cannot play a role in plugging the oil displacement model, and when the maximum permeability of the oil displacement experimental model is selected to be small, the heterogeneous system cannot be injected into the oil displacement model. When the maximum permeability is determined, a displacement experiment can be performed under displacement models with different permeabilities, the particle size difference of an injected heterogeneous system and an output heterogeneous system and the pressure change value of a model along a process pressure measuring point in the experiment process are observed, and the maximum permeability of a final oil displacement experiment model is further determined, wherein the displacement model is a serial core model or a serial microtube model and the like. And then, respectively connecting the model determined according to the maximum permeability in parallel with models with different low permeability, carrying out displacement experiments, and determining the permeability grade difference according to the profile improvement rate obtained by each displacement experiment, wherein the permeability grade difference refers to the ratio of the permeability of a channel in the heterogeneous stratum which can be reached after the heterogeneous system is injected to the maximum permeability in the oil displacement experiment, namely determining the heterogeneous range of the reservoir applicable to the heterogeneous system.

S103, constructing an oil displacement experiment model according to the seepage parameters, injecting water into the oil displacement experiment model after the oil displacement experiment model is saturated with oil, performing an oil displacement experiment until the oil production at the output end of the oil displacement experiment model is reduced to a first value, and determining a first recovery ratio; and continuing to inject a heterogeneous system into the oil displacement experiment model and then performing an oil displacement experiment until the oil yield at the output end of the oil displacement experiment model is reduced to a second value, and obtaining a second recovery ratio of the oil displacement experiment.

Illustratively, after determining the seepage parameters of the oil displacement experimental model, the oil displacement experimental model is constructed according to the seepage parameters of the oil displacement experimental model. For example, when the selected oil displacement model is a parallel core model, the porosity, the core size and the like of the core model can be determined according to seepage parameters. When the selected oil displacement model is a parallel sand filling pipe model, the sand grain proportion of the sand filling pipe model and the like can be determined according to seepage parameters. And determining the pipe diameter values of the sand filling pipes connected in parallel or the pore throat radii of the rock cores connected in parallel in the oil displacement experimental model according to the seepage parameters.

And then, vacuumizing the oil displacement experimental model, injecting crude oil after saturated water is pumped, and enabling the oil displacement experimental model to be in a saturated oil state. And then, injecting water into the oil displacement experimental model to perform an oil displacement process, wherein after water is injected, the water preferentially passes through the core or the sand filling pipe with higher permeability until the oil production is stopped, namely the oil production is reduced to a first value (for example, the first value can be 2%), and calculating the ratio of the oil production in the stage to the injected crude oil quantity during saturated oil, namely the first recovery ratio, because the sizes and the permeabilities of the core or the sand filling pipe connected in parallel are different. And then, injecting a heterogeneous system to plug the sand filling pipe or the core model with higher original permeability in the oil displacement model, and then continuing to inject water or other polymer oil displacement agents to perform an oil displacement experiment until oil is not produced any more, namely the oil production is reduced to a second value (for example, the second value can be 2%), and finishing the oil displacement experiment. And calculating the ratio of the oil yield in the whole oil displacement experiment to the injected crude oil amount in the saturated oil process, namely the second recovery ratio.

And S104, determining an evaluation result of the heterogeneous system according to the first recovery factor and the second recovery factor.

Illustratively, after the first recovery factor and the second recovery factor are obtained, whether the heterogeneous system can effectively improve the oil recovery rate is determined by comparing the first recovery factor and the second recovery factor.

For example, if the second recovery factor is greater than the first recovery factor, this indicates that the heterogeneous system can effectively enhance the recovery factor, and the greater the difference between the second recovery factor and the first recovery factor, the better the heterogeneous system will perform.

In this embodiment, in order to avoid selecting an inaccurate oil displacement model and consequently inaccurate the final evaluation result to heterogeneous system, this embodiment selects different oil displacement models for the heterogeneous system of different particle sizes, and further because the particle size of millimeter-scale heterogeneous system is big, needs to select loose porous medium system for use, needs to select for use promptly and connects in parallel to fill in the sand pipe model, and the phenomenon of jam takes place at the model injection terminal surface when the effectual system of avoiding pours into the model into. The nano-scale and micron-scale particles can meet the requirements of injection of the end face of the rock core and internal migration, the rock core model which is a model closer to a real reservoir can be connected in parallel to evaluate a heterogeneous system, namely, the evaluation method of the heterogeneous system provided by the embodiment is suitable for evaluation of the heterogeneous system with full size (nano, micron and millimeter), the application range is wide, through the method, the heterogeneous systems with different particle sizes can be matched with a proper oil displacement model, and the problem of inaccurate evaluation result caused by improper model and parameter selection is avoided.

When the seepage parameter is actually determined, for heterogeneous systems with different particle sizes, different index parameters can be selected to determine the maximum permeability of the heterogeneous system, for example, for the heterogeneous system in a nanometer interval, the index parameter can be selected to be a matching coefficient (i.e., the ratio of the particle size of the heterogeneous system to the pore throat radius of the core). For heterogeneous systems in the micron range, the index parameter may be the drag coefficient (i.e., the ratio of the injection pressure of the heterogeneous system to the injection pressure of the water drive). For heterogeneous systems within millimeter intervals, the index parameter may be a matching coefficient (i.e., the ratio of the particle size of the heterogeneous system to the diameter of the microtube).

Specifically, when the median particle size of the heterogeneous system is located in the millimeter interval, the steps shown in fig. 2 may be adopted when determining the seepage parameters of the oil displacement experimental model. Fig. 2 is a schematic flow chart of a method for determining a seepage parameter according to the present application, where the method includes:

s201, determining a second pipe diameter value according to the median of the particle diameters of the heterogeneous system and a preset first matching coefficient, wherein the preset first matching coefficient is the ratio of the median of the particle diameters of the heterogeneous system injected in the microtube experiment to the pipe diameters of the microtubes.

Illustratively, since heterogeneous systems on the millimeter scale are suitable for microtube models, the matching coefficient determined herein is the ratio of the median particle size to the radius of the microtube for heterogeneous systems. In order to determine the permeability range of the reservoir which can be injected and plugged by the heterogeneous system, namely when determining the seepage parameter of the heterogeneous system in a millimeter interval, a second pipe diameter value can be determined according to the median value of the particle diameter of the system and a predetermined first matching coefficient. In the practical application process, the first matching coefficient is obtained through a plurality of microtube displacement experiments, and is the optimal matching coefficient suitable for a heterogeneous system in a millimeter interval, and the value of the optimal matching coefficient is 1.1 (namely, the value of the first matching coefficient is 1.1). Subsequently, when the maximum permeability is determined for a heterogeneous system at millimeter level, the permeability corresponding to the ratio (i.e., the second pipe diameter value) of the median diameter of the heterogeneous system to the first matching coefficient (1.1) may be directly taken as the maximum permeability, and the microtube displacement experiment here is a displacement experiment performed on a microtube model formed by serially connecting a plurality of microtubes with equal pipe diameters.

Specifically, when a first matching coefficient is determined, a plurality of microtube models with different pipe diameters can be respectively constructed, a displacement experiment is carried out in each microtube model, an injection pressure curve and a path pressure curve of a heterogeneous system of the microtube model and a particle size difference value of the heterogeneous system in an injection and production liquid are obtained, if the value range of the injection pressure curve is in a preset range, the path pressure change curve is not equal to 0, and the particle size difference value of the heterogeneous system in the injection and production liquid is smaller than a preset value, the ratio of the pipe diameter value of the microtube model of the displacement experiment and the particle size median value of the heterogeneous system is used as the first matching coefficient.

For example, fig. 3 is a schematic structural diagram of a microtube model according to an embodiment of the present disclosure. In the practical experiment process, two microtubes with the same inner diameter, the length of 1 meter and smooth inner diameter can be connected in series through a valve, and a pressure sensor is connected to the valve; utilizing a constant-speed pump to inject water (namely, saline water in the figure) and heterogeneous solution (namely, microspheres in the figure) in sequence, respectively recording the middle pressure and the injection pressure of each micro-pipe, and stopping injecting after each pressure is stable; collecting the produced fluid of each microtube in each group of displacement experiments, measuring the median particle size by using a laser particle sizer, and researching the matching relation of the inner diameter of each microtube and the median particle size of a heterogeneous system. In addition, multiple groups of parallel experiments can be performed in the experiment process, namely, a flow distribution plate is adopted, and water and heterogeneous solution are injected into multiple groups of micro-tubes connected in series.

S202, determining the maximum permeability corresponding to the second pipe diameter value according to the second pipe diameter value.

For example, after the second pipe diameter value is obtained, the maximum permeability corresponding to the pipe diameter value can be calculated according to the poisson equation.

S203, constructing a plurality of parallel microtubes models, wherein each parallel microtube model is formed by connecting a first microtube and a second microtube in parallel, the diameter of the first microtube is smaller than that of the second microtube, the diameters of the first microtube in different parallel microtubes are different, and the diameter value of the second microtube in each parallel microtube model is the second diameter value.

Illustratively, after the maximum permeability is determined, a further determination of the permeability range of the heterogeneous reservoir for which the heterogeneous system is suitable is made. Firstly, permeability level difference (i.e. the ratio of the permeability of a high permeability layer to the permeability of a low permeability layer in a heterogeneous reservoir) needs to be determined, at this time, a plurality of parallel microtube models need to be constructed, that is, the second tube diameter value determined in step S201 is used as a larger tube diameter value in each parallel microtube model, i.e. the tube diameter value of the second microtube, each parallel microtube model also comprises another microtube (i.e. a first microtube), the tube diameter value of the first microtube is smaller than that of the second microtube, and the tube diameter values of the first microtubes in different parallel microtube models are different.

S204, aiming at each parallel micro-pipe model, a heterogeneous system and water are injected in sequence to carry out a displacement experiment, and the section improvement rate after each parallel micro-pipe model experiment is obtained.

Illustratively, for each parallel micro-tube model, after vacuumizing and saturated water, a heterogeneous system and water are sequentially injected for a displacement experiment, the flow dividing rate of the first micro-tube and the second micro-tube in the heterogeneous system displacement process and the flow dividing rate of the first micro-tube and the second micro-tube in the water displacement process are respectively recorded, and then the section improvement rate of the heterogeneous system for each parallel micro-tube model is calculated.

S205, taking the ratio of the second pipe diameter value to the pipe diameter value of the first microtube in the parallel microtube model corresponding to the maximum profile improvement rate as the permeability grade difference of the oil displacement experiment model.

Illustratively, the maximum profile improvement rate is selected from the plurality of profile improvement rates, and the permeability level difference is determined as the ratio of the second diameter value to the first diameter value in the parallel microtube model corresponding to the maximum profile improvement rate.

In this embodiment, when determining the seepage parameters corresponding to the heterogeneous system in the millimeter interval, the diameter value may be determined according to a predetermined first matching coefficient, and then the microtubes of different sizes construct a parallel microtube model, perform a displacement experiment, and determine the permeability level difference. When a heterogeneous system is evaluated, firstly, a median particle size of the system is obtained, an optimal oil displacement physical model is determined according to the size grade of the median particle size, and then a matching interval of the heterogeneous system and a model permeability parameter is determined according to the strength of a blocking physical model of the heterogeneous system; and determining the adaptability of the heterogeneous system to the permeability heterogeneous degree according to the heterogeneous model (namely the parallel microtube model under the different permeability level differences), namely determining the permeability range of the movable low-permeability layer on the basis that the heterogeneous system can effectively block the high-permeability layer.

Fig. 4 is a schematic flow chart of another method for determining a seepage parameter provided in the present application, where if the median particle size of the heterogeneous system is in the micrometer range, the method for determining a seepage parameter of the flooding experimental model includes:

s301, determining a second pore throat radius according to the particle size median of the heterogeneous system and a preset second matching coefficient, wherein the preset second matching coefficient is the ratio of the particle size median of the heterogeneous system injected in the core experiment to the core pore throat radius.

Illustratively, since heterogeneous systems on the micron scale may be suitable for core models, the matching coefficient determined here is the ratio of the median particle size to the core pore throat radius of the heterogeneous system. When determining the seepage parameters of the heterogeneous system in the micron interval, the second pore throat radius can be determined according to the median particle size of the system and a predetermined second matching coefficient. In the practical application process, the second matching coefficient is obtained through multiple core displacement experiments, and is the optimal matching coefficient suitable for the heterogeneous system in the micron interval, and the value of the optimal matching coefficient is 1.3 (namely, the value of the second matching coefficient is 1.3, and the value is the ratio of the particle size median of the heterogeneous system injected in the core experiment to the pore throat radius of the core). Subsequently, when the maximum permeability is determined for a micron-level heterogeneous system, the permeability corresponding to the ratio (namely, the second pore throat radius) of the particle size median of the heterogeneous system to the second matching coefficient (1.3) can be directly taken as the maximum permeability, and the core displacement experiment is a displacement experiment performed by a core model formed by serially connecting a plurality of cores with equal pore throat radii.

Specifically, when the second matching coefficient is determined, a plurality of core models with different pore throat radiuses can be respectively constructed, a displacement experiment is performed in each core model, an injection pressure curve and a process pressure curve of a heterogeneous system of the core model and a particle size difference value of the heterogeneous system in an injection liquid and a produced liquid are obtained, if the value range of the injection pressure curve is in a preset range, the process pressure change curve is not equal to 0, and the particle size difference value of the heterogeneous system in the injection liquid and the produced liquid is smaller than a preset value, the ratio of the pore throat radius value of the core model of the displacement experiment and the particle size median value of the heterogeneous system is used as the second matching coefficient.

S302, determining the maximum permeability corresponding to the second pore throat radius according to the second pore throat radius.

After the second pore throat radius is obtained, the maximum permeability corresponding to the pore throat radius may be calculated according to the poisson equation.

S303, constructing a plurality of parallel core models, wherein each parallel core model is formed by connecting a first core and a second core in parallel, the pore throat radius of the first core is smaller than that of the second core, the pore throat radii of the first core models in different parallel core models are different, and the pore throat radius of the second core model in each parallel core model is the second pore throat radius.

Illustratively, after the maximum permeability is determined, a further determination of the permeability range of the heterogeneous reservoir for which the heterogeneous system is suitable is made. Firstly, the permeability level difference (i.e., the ratio of the permeability of a high-permeability layer to the permeability of a low-permeability layer in the heterogeneous reservoir) needs to be determined, at this time, a plurality of parallel core models need to be constructed, that is, the second pore throat radius determined in step S301 is used as a larger pore throat size value in each parallel core model, that is, the pore throat radius of the second core, each parallel core model also includes another core (i.e., a first core), the pore throat radius of the first core is smaller than that of the second core, and the pore throat radii of the first cores in different parallel core models are different.

S304, aiming at each parallel core model, a heterogeneous system and water are injected in sequence to carry out a displacement experiment, and the section improvement rate after each parallel core model experiment is obtained.

Illustratively, for each parallel core model, after vacuumizing and saturated water, a heterogeneous system and water are sequentially injected for a displacement experiment, the flow splitting rate of a first core and a second core in the heterogeneous system displacement process and the flow splitting rate of the first core and the second core in the water displacement process are respectively recorded, and then the section improvement rate of the heterogeneous system for each parallel core model is calculated.

S305, taking the ratio of the second pore throat radius to the pore throat radius of the first core in the parallel core model corresponding to the maximum profile improvement rate as the permeability level difference of the oil displacement experiment model.

Illustratively, the maximum profile improvement rate is selected from the plurality of profile improvement rates, and the permeability level difference is determined as the ratio of the second pore throat radius to the pore throat radius of the first core in the parallel core model corresponding to the maximum profile improvement rate.

For example, in the actual experiment process, the rock core corresponding to the optimal matching coefficient obtained in steps S301 to S303 is used as the reference permeability rock core, the permeability level differences are set to be 3, 5, 8 and 10 respectively, and rock cores with corresponding permeabilities are manufactured to form a parallel experiment. Respectively vacuumizing the rock core for 2h and saturating the rock core with water for 2h, injecting a heterogeneous solution with 4 times of pore volume (namely PV) at an injection speed of 0.6mL/min after measuring the permeability with water, and finally performing subsequent water displacement until the pressure is stable. Recording the high-low permeability layer flow rate in the heterogeneous system displacement process and the high-low permeability layer flow rate in the subsequent water displacement process, calculating the profile improvement effect of the heterogeneous system, evaluating the applicability of the heterogeneous system to reservoir heterogeneity, and selecting the permeability grade difference corresponding to the displacement experiment with the maximum profile improvement rate as the permeability grade difference corresponding to the heterogeneous system.

In this embodiment, when determining the seepage parameter of the heterogeneous system in the micrometer interval, the core pore throat radius corresponding to the heterogeneous system under the matching coefficient may be determined according to a preset second matching coefficient, and then the core pore throat radius is used as the core size with a larger radius in the parallel core models, and the permeability level difference is obtained after performing a plurality of displacement experiments on the plurality of parallel core models.

Fig. 5 is a schematic flow chart of another method for determining a seepage parameter provided in the present application, where if the median particle size of the heterogeneous system is in the nanometer range, the method for determining a seepage parameter of the oil displacement experimental model includes:

s401, constructing a plurality of core models with different permeabilities, injecting water and a heterogeneous system in sequence for a displacement experiment aiming at each core model, and obtaining a resistance coefficient in the experiment process of each core model.

For example, for a heterogeneous system in the nanometer interval, the heterogeneous system in the interval can be injected for a general reservoir because of the small particle size of the system in the interval. Therefore, in this case, when the characteristics of the heterogeneous system are analyzed, the migration resistance-increasing effect of the heterogeneous system is mainly evaluated. At the moment, the seepage parameters corresponding to the heterogeneous system are mainly determined according to the resistance coefficient in the core experiment.

Specifically, a plurality of core models are constructed, each core model comprises a core, and the permeability of each core model is different. And for each core model, sequentially injecting water and a heterogeneous system into the core model of saturated water to perform a water drive experiment and a heterogeneous system displacement experiment, and taking the ratio of the injection pressure value of the heterogeneous system to the injection pressure value in the water drive experiment as a resistance coefficient corresponding to the core model experiment.

S402, taking the permeability of the core model with the resistance coefficient meeting the preset condition as the maximum permeability of the heterogeneous system.

Exemplarily, if the resistance coefficient corresponding to the core model experiment meets the preset condition, the permeability of the core model corresponding to the experiment is taken as the maximum permeability. In one example, the resistance coefficient is usually in the interval of 40-100 during the actual exploitation of the oil reservoir, so the preset condition here may be the value interval of 40-100 of the resistance coefficient.

And S403, determining the fourth pore throat radius of the rock core model according to the maximum permeability.

Illustratively, according to the Poiseuille equation and the maximum permeability, the determined pore throat radius is used as a pore throat radius parameter of a core with a larger size in the parallel core model when the permeability level difference is subsequently determined, namely, the fourth pore throat radius of the core model.

S404, constructing a plurality of parallel core models, wherein each parallel core model is formed by connecting a third core and a fourth core in parallel, the pore throat radius of the third core is smaller than that of the fourth core, the pore throat radii of the third cores in different parallel core models are different, and the pore throat radius of the fourth core in each parallel core model is the fourth pore throat radius.

For example, to determine the permeability level difference, at this time, parallel core models are selected, and a plurality of parallel core models are constructed to perform a displacement experiment, where each parallel core model includes two cores connected in parallel, a third core and a fourth core, and the throat radius of the fourth core in each parallel core model is the fourth throat radius obtained in step S403. And the pore throat radius of the third core in each parallel core model is smaller than that of the fourth core, and the pore throat radii of the third cores in different parallel core models are different.

S405, aiming at each parallel core model, a heterogeneous system and water are injected in sequence to carry out a displacement experiment, and the section improvement rate after each parallel core model experiment is obtained.

Illustratively, for each parallel core model, after vacuumizing and saturated water, a heterogeneous system and water are sequentially injected for a displacement experiment, the flow rate of the third core and the fourth core in the heterogeneous system displacement process and the flow rate of the third core and the fourth core in the water displacement process are respectively recorded, and then the section improvement rate of the heterogeneous system for each parallel core model is calculated.

S406, taking the ratio of the fourth pore throat radius to the pore throat radius of the fourth core in the parallel core model corresponding to the maximum profile improvement rate as the permeability level difference of the oil displacement experiment model.

Illustratively, the maximum profile improvement rate is selected from the plurality of profile improvement rates, and the permeability level difference is determined as the ratio of the fourth pore throat radius to the pore throat radius of the third core in the parallel core model corresponding to the maximum profile improvement rate.

In this embodiment, when determining the seepage parameters of the heterogeneous system in the nanometer interval, the pore throat radius of the rock core corresponding to the heterogeneous system under the matching coefficient may be determined according to the magnitude of the resistance coefficient in the displacement process under the rock core models with different permeabilities, and then the pore throat radius is used as the core size with a larger radius in the parallel rock core models, so that the permeability level difference is obtained after performing a plurality of displacement experiments on the plurality of parallel rock core models.

Fig. 6 is a schematic flow chart of a method for determining a median particle diameter of a heterogeneous system according to an embodiment of the present application, where the method includes the following steps:

s501, measuring a first particle size distribution frequency curve of the heterogeneous system by using a laser particle sizer.

S502, acquiring image information of a dispersed phase in a heterogeneous system, and determining a second particle size distribution frequency distribution curve according to the image information.

S503, taking the average value of the first particle size distribution frequency curve and the second particle size distribution frequency curve to obtain the particle size median of the heterogeneous system.

For example, in the present embodiment, in order to determine the median particle size of the heterogeneous system, a laser particle sizer measurement is used in combination with image recognition to determine the median particle size of the heterogeneous system. Firstly, the dynamic rotation diameter of each particle in a dispersed phase in a heterogeneous system is measured according to a laser particle sizer, and a first particle size distribution frequency curve of the system is obtained. Shooting a microscopic image of dispersed phase ions by using a body type microscope, determining the number of particles in the image by using an image identification method, counting according to the equal particle size to obtain a number distribution curve of the particle size of each particle, and converting the curve into a second particle size distribution frequency curve according to the median particle size of each segment of particle size range; and taking the average value of the first particle size distribution frequency curve and the second particle size distribution frequency curve to obtain the optimal particle size distribution curve, and then taking the median value in the curve as the particle size median value of the heterogeneous system.

In this embodiment, the dynamic rotation diameter of the particles in the solution is obtained by using the laser particle sizer, so that the test result is larger, and the particle size median determined by using only the image recognition method is smaller because of the smaller impurity particles in the solution, so that when the particle size median is determined, the particle size obtained by averaging the particle size distribution curves obtained by the two methods and then taking the median is considered to be more accurate.

In some embodiments, before determining the seepage parameters of the flooding experimental model, the evaluation method further comprises:

the method comprises the following steps of firstly, obtaining a dispersant solution and a dispersed phase solution of a heterogeneous system.

For example, in this embodiment, for a heterogeneous system, a dispersant solution and a dispersed phase solution in the heterogeneous system are first configured, and then static parameters of the dispersant solution and dynamic parameters of the dispersed phase solution are analyzed, respectively, where the dynamic parameters and the static parameters selected in the heterogeneous systems with different particle sizes are different. Any one of the following second to fourth steps is selectively performed according to the different particle size.

And secondly, if the median of the particle size of the heterogeneous system is positioned in a millimeter interval, sequentially testing the dispersion stability, the micro morphology and the volume swelling property of the dispersed phase solution of the heterogeneous system and sequentially testing the viscosity increasing property, the interface property, the rheological property, the temperature resistance and the salt tolerance of the dispersing agent solution of the heterogeneous system.

For example, for a heterogeneous system in a millimeter interval, although the dispersion stability of particles in the millimeter range is poor and coagulation is easy to occur, the coagulation time and degree can also be used for judging the injectability.

For example, the dispersion phase to be measured can be dissolved in deionized water in proportion to prepare dispersion phase solution mother liquor with the concentration of 5000 mg/L; preparing dispersed phase solutions with the concentrations of 500mg/L, 1000mg/L, 1500mg/L, 2000mg/L and 3000mg/L respectively, testing the zeta potential of the solution by a zeta potential instrument, drawing a change curve of the potential of the solution along with the concentration, and if the absolute value of the zeta potential is more than 30, indicating that the dispersed phase solution is stable; and then placing the dispersed phase solution with the concentration of 2000mg/L into a thermostat, aging the target oil deposit at the temperature for 1 day, 3 days, 5 days, 7 days and 10 days, respectively sucking 60mL of samples at the same position of the dispersed phase solution to divide the samples into two parts, directly testing the particle size of one part by using a laser particle sizer, firstly dispersing the other part by using ultrasonic waves, then testing the particle size of the laser particle sizer, and comparing the particle size distribution of the two parts to evaluate the dispersion stability of the dispersed phase. After the dispersed phase solution is stood still, the particles in the dispersed phase solution are coagulated, so that the tested particle size result is small, the influence of coagulation on the particle size value is eliminated after the other part of the dispersed phase solution is re-dispersed by ultrasonic waves, and the larger the difference of the particle size results, the more unstable the dispersed phase is, and the dispersion stability is poor.

For millimeter-sized particles, the microscopic morphology of the particles can be observed by a microscope, and the more irregular the particle shape, the poorer the injectability of the particles.

The bulk of particles in the millimeter range can be determined by the increase in median particle size after absorption of water. Bulk expansion, which mainly affects the deformability of the particles, which need to pass through the pore throats by deformation, is well matched when the particles can pass through by deformation, and cannot pass through by deformation or need not be deformed, which is not good.

The viscosification of the dispersant solution can be tested using a brookfield viscometer for dispersant solutions in heterogeneous systems in the millimeter interval. For example: measuring apparent viscosities of the dispersing agent solutions with concentrations of 200mg/L, 500mg/L, 800mg/L, 1000mg/L, 1500mg/L, 1750mg/L and 2000mg/L respectively at a speed of 6r/min, injecting 18-20 mL of a sample to be measured into a sleeve, keeping the temperature for 15min, starting a viscometer to measure, recording the viscosity value after stabilization, and drawing a viscosity-concentration curve.

The rheology of the dispersant solution can be tested using a haake rheometer for dispersant solutions in heterogeneous systems in the millimeter range. For example: preparing the dispersant solution to a target concentration, placing the dispersant solution into a sample cell of a Haake rheometer, and measuring the shear rate from 0.01s in a shear rate control mode^-1Increased to 1000s^-1The apparent viscosity of the solution during the process; under the control stress mode, the fixed vibration frequency is not changed at 1Hz, and the elastic model and the viscous modulus of the solution with the vibration frequency from 0.01Hz to 10Hz are tested.

The temperature and salt tolerance of the dispersant solution at different temperatures or in different reservoirs can be tested for the dispersant solution in heterogeneous systems in the millimeter interval using a viscometer.

The oil-water interface performance of the dispersant can be tested by using a rotary interfacial tensiometer for the dispersant solution in a heterogeneous system in a millimeter interval. For example: the mother liquid of the dispersing agent is prepared to the target concentration and is injected into a glass tubule through a specific needle tube, and then a drop of crude oil is dripped into the activated water solution through another specific needle tube. And (3) putting the thin tube into an instrument, fully rotating for 2h, and finding out the slender oil drops to perform image processing to obtain an interfacial tension value.

And thirdly, if the median of the particle size of the heterogeneous system is positioned in the nanometer interval, sequentially testing the dispersion stability and the micro morphology of the dispersed phase solution of the heterogeneous system and sequentially testing the viscosity increasing property, the interface property, the rheological property, the temperature resistance and the salt tolerance of the dispersing agent solution of the heterogeneous system.

For example, for a heterogeneous system located in the nanometer range, due to the small particle size itself, only dispersion stability, micro-morphology, and in turn, viscosifying, interfacial properties, rheology, temperature and salt tolerance of the dispersant solution of the heterogeneous system need to be tested.

And fourthly, if the median of the particle size of the heterogeneous system is positioned in a micron interval, sequentially testing the dispersion stability, the micro morphology and the volume swelling property of the dispersed phase solution of the heterogeneous system and sequentially testing the viscosity increasing property, the interface property, the rheological property, the temperature resistance and the salt tolerance of the dispersing agent solution of the heterogeneous system.

For example, for heterogeneous systems in the micrometer range, the test performance is similar to the millimeter range, and is not described here.

For example, three types of micro-heterogeneous systems were evaluated for their performance using the above methods, including emulsion polymers, polymeric microspheres, and PPG (pre-crosslinked gel particles).

Firstly, the particle size interval of a heterogeneous system is determined, and performance parameters to be evaluated are selected. The emulsion polymer is obtained by a laser particle size analyzer and an image recognition method to be in a nano-scale interval, the polymer microsphere is in a micron-scale interval, and the PPG is in a millimeter-scale interval.

The performance parameters of the emulsion polymer are then: dispersion stability, micro-morphology, viscosity increasing property, interface property, rheological property, temperature resistance and salt tolerance; the performance parameters of the polymer microspheres are as follows: dispersion stability, micro-morphology, bulk expansion, viscosity increasing, interface performance, rheological property, temperature resistance and salt tolerance; the performance parameters of PPG were: dispersion stability, micro-morphology, bulk expansion property, viscosity increasing property, interface property, rheological property, temperature resistance and salt tolerance.

(1) Dispersion stability testing of heterogeneous systems

Zeta potential is adopted to test the dispersion stability of the standard dispersion system for the emulsion polymer and the PPG, and the dispersion stability of the polymer microspheres is determined by comparing particle size distribution curves before and after zeta potential + ultrasonic dispersion, and the result is shown in FIG. 7. Fig. 7 is a schematic view of zeta potential curves provided in the embodiments of the present application, where the zeta potential curves respectively include potential curves of three different heterogeneous dispersion systems, and it can be seen from the graph that emulsion polymer and polymer microspheres have good dispersion stability, PPG has poor dispersion stability, and precipitation may occur. Fig. 7 is a schematic diagram of a particle size distribution curve according to an embodiment of the present application. FIG. 8 shows the particle size distribution curve of PPG before and after ultrasonic dispersion, and it can be seen that the two curves before and after ultrasonic dispersion are substantially coincident, indicating that the system has good stability.

(2) Dispersion stability testing of heterogeneous systems

The emulsion polymer is tested by adopting a nano-scale laser particle analyzer, the polymer microsphere and the PPG are tested by adopting a method of combining a micro-scale laser particle analyzer and a body type microscope, and the initial particle size of the polymer microsphere is tested by adopting a scanning electron microscope under the condition of completely isolating a water phase. The results are shown in FIGS. 9 to 11. The median particle size of the emulsion polymer is 59.5nm, the mean value of the median particle sizes of the polymer microspheres is 18.5 mu m, and the median particle size of the PPG is 500 mu m. FIG. 9 is a particle size distribution curve of an emulsion polymer according to the examples provided herein. Fig. 10 is a particle size distribution curve of a polymer microsphere and PPG provided in this application. Both curves in fig. 10 were measured using a laser particle sizer. Fig. 11 is a particle size distribution curve of another polymer microsphere provided in the examples of the present application, wherein the curve is a particle size distribution curve of the polymer microsphere identified by a stereomicroscope image.

(3) Bulk swelling test of polymeric microspheres and PPG

The volume expansion of the polymer microsphere and the PPG is characterized by water absorption expansion times, namely the median particle size after water absorption is multiplied by, and the particle sizes before and after water absorption are tested by adopting laser particle size. Fig. 12 is a schematic diagram of a variation of the expansion factor provided in the embodiments of the present application. As shown, the water absorption expansion factor of the polymer microspheres stabilized to 4 times with aging time, and the water absorption expansion factor of the PPG stabilized to 10 times with aging time.

(4) Flow properties

The fluidity of the emulsion polymer is mainly characterized by resistance coefficients, and resistance increasing capability is tested by testing residual resistance coefficients of the core after the core is aged for different times according to the slow-release tackifying function of the emulsion polymer; the polymer microspheres are mainly evaluated by using artificial rock cores, and the optimal matching relation of the microspheres to a reservoir is determined through matching coefficients and plugging strength; the PPG evaluates the migration rule in the pore throat through a micro-tube experimental model. The experimental result shows that the residual resistance coefficient of the emulsion polymer continuously increases along with the increase of the aging time; the optimal matching coefficient of the polymer microspheres and the reservoir is 1-1.2; PPG tends to block large channels with similar particle sizes.

(5) Reservoir adaptability

The heterogeneous system reservoir adaptability is mainly performed through parallel displacement, wherein emulsion polymers and polymer microspheres are performed through parallel artificial core displacement experiments, the permeability grade differences are set to be 4, 6, 8 and 10 respectively, and the heterogeneous adaptability range of the system is comprehensively judged through the flow splitting rate, the water content and the enhanced recovery ratio. Because of the large particles, the PPG is definitely suitable for a large-advantage channel or a fractured reservoir through an injection experiment. Table 1 shows experimental data of profile improvement and enhanced oil recovery for emulsion polymers at different permeability level differences, as shown in the following table. Table 2 shows the profile improvement and enhanced oil recovery of the polymer microspheres at different permeability level differences.

TABLE 1

Difference in permeability grade	Rate of profile improvement	Enhanced recovery ratio
			2	71.3	31.9
4	73.2	28.3
			6	78.4	26.8
8	83.5	19.1
			10	67.2	15.9

TABLE 2

Difference in permeability grade	Rate of profile improvement	Enhanced recovery ratio
			4	83.3	12.5
6	84.5	14.6
			8	89.9	18.4
10	78.6	16.9

From the above table, it can be concluded that the profile improvement and enhanced recovery of the emulsion polymer increase first and then decrease with increasing permeability step, with the highest values appearing at

steps

8 and 6, respectively; the profile improvement rate and the enhanced recovery rate of the polymer microspheres are increased and then reduced along with the increase of the permeability grade difference, and the highest value is 8. On the premise of ensuring that the enhanced recovery ratio is higher, the emulsion polymer is definitely suitable for a reservoir stratum with the permeability grade difference of less than 6, and the polymer microspheres are suitable for a reservoir stratum with the permeability grade difference of less than 10.

(6) Other properties

Viscosity increasing property of emulsion polymer viscosity of emulsion polymer of different concentration was measured using brookfield viscometer to plot viscosity concentration curve, as shown in fig. 13, fig. 13 is a schematic view of viscosity concentration curve provided in the examples of the present application; temperature resistance and salt tolerance are characterized by viscosity, and a viscosity change curve of the emulsion polymer solution aged at different temperatures for different times and a viscosity change curve aged at different mineralization degrees for different times are tested, as shown in fig. 14, fig. 14 is a viscosity change curve at different temperatures provided by the embodiment of the present application; the interfacial activity is characterized by interfacial tension, and is tested by using rotary interfacial tension, and a change curve of interfacial tension along with concentration is drawn, as shown in fig. 15, fig. 15 is a schematic view of a change curve of interfacial tension along with concentration provided by an embodiment of the present application; the rheological property and the viscoelasticity are tested by a haake rheometer to obtain the flow characteristics, as shown in fig. 16, fig. 16 is a schematic diagram of a viscoelastic curve provided by an embodiment of the present application; in the figure, 0d represents day 0.

Fig. 17 is a schematic structural diagram of an evaluation apparatus for a heterogeneous system according to an embodiment of the present application, where the apparatus includes:

the first obtaining unit 41 is configured to obtain a median particle size of the heterogeneous system, and determine a type of a flooding experiment model according to the median particle size, where the type of the flooding experiment model includes: parallel sand-filled pipe models and parallel core models.

A first determining unit 42, configured to determine a seepage parameter of the reservoir oil displacement experimental model, where the seepage parameter includes: maximum permeability, grade difference in permeability.

The second obtaining unit 43 is configured to construct an oil displacement experiment model according to the seepage parameters, inject water into the oil displacement experiment model after the oil displacement experiment model is saturated with oil, perform an oil displacement experiment until the oil yield at the output end of the oil displacement experiment model is reduced to a first value, and determine a first recovery ratio; and continuing to inject a heterogeneous system into the oil displacement experiment model and then performing an oil displacement experiment until the oil yield at the output end of the oil displacement experiment model is reduced to a second value, and obtaining a second recovery ratio of the oil displacement experiment.

In a possible implementation manner, the first obtaining unit 41 is specifically configured to:

if the median of the particle size of the heterogeneous system is in the millimeter interval, the oil displacement experimental model is a parallel sand-packed pipe model;

if the median of the grain size of the heterogeneous system is in the micron interval, the oil displacement experimental model is a parallel core model;

and if the median of the particle size of the heterogeneous system is in the nanometer interval, the oil displacement experimental model is a parallel core model.

The apparatus provided in this embodiment is used to implement the technical solution provided by the above method, and the implementation principle and the technical effect are similar and will not be described again.

Fig. 18 is a schematic structural diagram of an evaluation apparatus of another heterogeneous system according to an embodiment of the present application, and on the basis of fig. 17,

if the median particle size of the heterogeneous system lies in the millimetre interval, the first determining unit 42 includes:

the first determining module 4201 is configured to determine the second diameter value according to a median diameter of the heterogeneous system and a preset first matching coefficient, where the preset first matching coefficient is a ratio of the median diameter of the heterogeneous system injected in the microtube experiment to the particle diameter of the microtube.

The second determining module 4202 is configured to determine the maximum permeability corresponding to the second pipe diameter value according to the second pipe diameter value.

The first modeling module 4203 is configured to construct a plurality of parallel-connected microtubes models, where each parallel-connected microtube model is formed by connecting a first microtube and a second microtube in parallel, a diameter of the first microtube is smaller than a diameter of the second microtube, diameters of the first microtube in different parallel-connected microtubes are different, and a diameter value of the second microtube in each parallel-connected microtube model is a second diameter value.

The first obtaining module 4204 is configured to, for each parallel microtube model, sequentially inject a heterogeneous system and water for a displacement experiment, and obtain a profile improvement rate after the experiment of each parallel microtube model.

A third determining module 4205, configured to use a ratio of the second pipe diameter value to the pipe diameter value of the first microtube in the parallel microtube model corresponding to the maximum profile improvement rate as a permeability level difference of the oil displacement experiment model.

In a possible implementation, if the median particle size of the heterogeneous system lies in the micron interval, the first determining unit 42 includes:

a fourth determining module 4206, configured to determine a second pore throat radius according to the median particle size of the heterogeneous system and a preset second matching coefficient, where the preset second matching coefficient is a ratio of the median particle size of the heterogeneous system injected in the core experiment to the core pore throat radius.

A fifth determining module 4207, configured to determine a maximum permeability corresponding to the second throat radius according to the second throat radius.

The second modeling block 4208 is configured to construct a plurality of parallel core models, where each parallel core model is formed by connecting a first core and a second core in parallel, a pore throat radius of the first core is smaller than a pore throat radius of the second core, pore throat radii of the first core models in different parallel core models are different, and a pore throat radius of the second core model in each parallel core model is the second pore throat radius.

And a second obtaining module 4209, configured to sequentially inject a heterogeneous system and water into each parallel core model to perform a displacement experiment, and obtain a profile improvement rate after each parallel core model experiment.

A sixth determining module 4210, configured to use a ratio of the second pore throat radius to the pore throat radius of the first core in the parallel core model corresponding to the maximum profile improvement rate as a permeability level difference of the oil displacement experiment model.

In a possible implementation manner, if the median particle size of the heterogeneous system is located in the nanometer interval, the first determining unit includes:

the third obtaining module 4211 is configured to construct a plurality of core models with different permeabilities, inject water and a heterogeneous system in sequence for a displacement experiment for each core model, and obtain a resistance coefficient in the experiment process of each core model.

A seventh determining module 4212 for determining the permeability of the core model with a drag coefficient satisfying a predetermined condition as the maximum permeability of the heterogeneous system.

An eighth determining module 4213 is configured to determine a fourth pore throat radius of the core model according to the maximum permeability.

The third group of modeling blocks 4214 are used for constructing a plurality of parallel core models, each parallel core model is formed by connecting a third core and a fourth core in parallel, the pore throat radius of the third core is smaller than that of the fourth core, the pore throat radii of the third cores in different parallel core models are different, and the pore throat radius of the fourth core in each parallel core model is the fourth pore throat radius.

And a third obtaining module 4215, configured to sequentially inject a heterogeneous system and water into each parallel core model to perform a displacement experiment, so as to obtain a profile improvement rate after each parallel core model experiment.

A ninth determining module 4216, configured to use a ratio of the fourth pore throat radius and the pore throat radius of the fourth core in the parallel core model corresponding to the maximum profile improvement rate as a permeability level difference of the oil displacement experiment model.

In a possible implementation manner, the first obtaining unit 41 includes:

the first measurement module 411 is configured to measure a first particle size distribution frequency curve of the heterogeneous system by using a laser particle sizer.

The second measurement module 412 is configured to obtain image information of a dispersed phase in a heterogeneous system, and determine a second particle size distribution frequency distribution curve according to the image information.

And a tenth determining module 413, configured to obtain an average value of the first particle size distribution frequency curve and the second particle size distribution frequency curve, and obtain a median particle size of the heterogeneous system.

In one possible implementation, the apparatus further includes:

the third obtaining unit 44 is configured to determine a seepage parameter of the oil displacement experiment model at the first determining unit 42 to obtain a dispersant solution and a dispersed phase solution of the heterogeneous system; obtaining a dispersant solution and a dispersed phase solution of a heterogeneous system.

The first testing unit 45 is used for sequentially testing the dispersion stability, the micro morphology and the volume swelling property of the dispersed phase solution of the heterogeneous system and sequentially testing the viscosity increasing property, the interface property, the rheological property, the temperature resistance and the salt tolerance of the dispersing agent solution of the heterogeneous system if the median of the particle size of the heterogeneous system is located in a millimeter interval.

And a second testing unit 46, configured to sequentially test dispersion stability and micro morphology of the dispersed phase solution of the heterogeneous system, and sequentially test viscosity increasing property, interface performance, rheological property, temperature resistance, and salt tolerance of the dispersant solution of the heterogeneous system, if the median of the particle size of the heterogeneous system is located in the nanometer interval.

And the third testing unit 47 is used for sequentially testing the dispersion stability, the micro morphology and the volume swelling property of the dispersed phase solution of the heterogeneous system and sequentially testing the viscosity increasing property, the interface property, the rheological property, the temperature resistance and the salt tolerance of the dispersing agent solution of the heterogeneous system if the median of the particle size of the heterogeneous system is located in the micrometer range.

Fig. 19 is a schematic structural diagram of an electronic device provided in an embodiment of the present application, and as shown in fig. 19, the electronic device includes:

a processor (processor)291, the electronic device further including a memory (memory) 292; a Communication Interface 293 and bus 294 may also be included. The processor 291, the memory 292, and the communication interface 293 may communicate with each other via the bus 294. Communication interface 293 may be used for the transmission of information. Processor 291 may call logic instructions in memory 294 to perform the methods of the embodiments described above.

Further, the logic instructions in the memory 292 may be implemented in software functional units and stored in a computer readable storage medium when sold or used as a stand-alone product.

The memory 292 is a computer-readable storage medium for storing software programs, computer-executable programs, such as program instructions/modules corresponding to the methods in the embodiments of the present application. The processor 291 executes the functional application and data processing by executing the software program, instructions and modules stored in the memory 292, so as to implement the method in the above method embodiments.

The memory 292 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application program required for at least one function; the storage data area may store data created according to the use of the terminal device, and the like. Further, the memory 292 may include a high speed random access memory and may also include a non-volatile memory.

The embodiment of the application provides a computer-readable storage medium, in which computer-executable instructions are stored, and the computer-executable instructions are executed by a processor to implement the method provided by the above embodiment.

The embodiment of the present application provides a computer program product, which includes a computer program, and the computer program is executed by a processor to implement the method provided by the above embodiment.

Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.

It will be understood that the present application is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims

1. A method for evaluating a heterogeneous system, the method comprising:

and determining the evaluation result of the heterogeneous system according to the first recovery factor and the second recovery factor.

2. The method of claim 1, wherein the determining a flooding experimental model from the median particle size comprises:

3. The method of claim 2, wherein the determining the seepage parameters of the flooding experimental model if the median particle size of the heterogeneous system is in the millimeter interval comprises:

4. The method of claim 2, wherein the determining the seepage parameters of the flooding experimental model if the median particle size of the heterogeneous system is in the micron interval comprises:

5. The method of claim 2, wherein determining the seepage parameters of the flooding experimental model if the median particle size of the heterogeneous system is in the nanometer interval comprises:

6. The method of claim 1, wherein obtaining the median particle size of the heterogeneous system comprises:

7. The method of claim 1, wherein prior to the determining the seepage parameters of the flooding experimental model, the method further comprises:

if the median particle size of the heterogeneous system is located in the nanometer interval, sequentially testing the dispersion stability and the micro morphology of a dispersed phase solution of the heterogeneous system, and sequentially testing the viscosity increasing property, the interface property, the rheological property, the temperature resistance and the salt tolerance of a dispersing agent solution of the heterogeneous system;

8. An apparatus for evaluating a heterogeneous system, the apparatus comprising:

9. An electronic device, comprising: a memory, a processor;

a memory; a memory for storing the processor-executable instructions;

wherein the processor is configured to perform the method according to the executable instructions of any one of claims 1-7.

10. A computer-readable storage medium having computer-executable instructions stored thereon, which when executed by a processor, perform the method of any one of claims 1-7.