CN118642190B - Method and system for obtaining rock induced polarization parameters of isotropic tight sandstone reservoir - Google Patents

Abstract

The present application provides a method and system for acquiring rock induced polarization parameters of isotropic tight sandstone reservoirs, which belongs to the field of oil and natural gas exploration and development. The method for acquiring the theoretical induced polarization model corresponding to the target area to be tested is as follows: the composition of the reservoir rock minerals is analyzed to obtain the reservoir rock mineral content, and the connectivity of the reservoir rock mineral components and the correlation with the pores are analyzed by scanning electron microscope images; based on the equivalent medium model of the underground reservoir rock, a theoretical induced polarization model based on the MGEMTIP model is constructed; rock induced polarization parameters are obtained by testing; the rock induced polarization parameters of different rock samples are simultaneously combined with different reservoir physical property parameters and input into the theoretical induced polarization model to obtain model parameters, and then the theoretical induced polarization model corresponding to the target area to be tested is obtained. The present application effectively establishes a quantitative relationship between reservoir physical properties and induced polarization parameters, and provides a theoretical and experimental basis for accurately establishing a complex resistivity geoelectric model of the target area.

Description

Method and system for obtaining rock induced polarization parameters of isotropic tight sandstone reservoir

Technical Field

The present application belongs to the field of oil and gas exploration and development, and more specifically, to a method and system for acquiring rock induced polarization parameters of an isotropic dense sandstone reservoir.

Background Art

Complex resistivity (true resistivity and polarizability, etc.) is an important parameter that describes the induced polarization (induced polarization) characteristics of underground media. As the depth of the formation increases, the reservoir rock is more likely to meet the characteristics of low porosity and low permeability, and the induced polarization characteristics (polarizability of complex resistivity) will gradually increase.

At present, the resistivity rock physics research based on electromagnetic exploration is mainly based on real resistivity, which is difficult to meet the growing exploration depth and accuracy requirements. The research on complex resistivity is mainly based on logging technology, mainly focusing on high-frequency dielectric polarization greater than 1kHz. The low-frequency induced polarization rock physics research for exploration problems is in its infancy, mainly studying the low-frequency polarization mechanism and the corresponding influencing factors. The induced polarization research on oil and gas reservoirs is also mainly based on conventional high-porosity sandstone reservoirs. Complex resistivity analysis is mainly based on qualitative conclusions, and has failed to effectively achieve quantitative analysis. It is impossible to effectively establish a model of the relationship between reservoir physical properties and induced polarization in the research target area. It is difficult to provide an accurate and effective complex resistivity geoelectric model for time-frequency exploration technology, and it is also difficult to achieve quantitative evaluation of unconventional reservoirs based on electromagnetic exploration technology.

Summary of the invention

In view of the defects of the prior art, the purpose of this application is to provide a method and system for obtaining rock induced polarization parameters of isotropic tight sandstone reservoirs, aiming to solve the problems that the existing complex resistivity analysis fails to effectively realize quantitative analysis, cannot effectively establish a reservoir property and induced polarization relationship model for the research target area, is difficult to provide an accurate and effective complex resistivity geoelectric model for time-frequency exploration technology, and is difficult to realize quantitative evaluation of unconventional reservoirs based on electromagnetic exploration technology.

To achieve the above objectives, in a first aspect, the present application provides a method for obtaining rock induced polarization parameters of an isotropic tight sandstone reservoir, comprising the following steps:

Inputting different reservoir physical property parameters of the target area to be tested into the theoretical induced polarization model corresponding to the target area to be tested, and obtaining the rock induced polarization parameters of the target area to be tested;

The method for obtaining the theoretical induced polarization model corresponding to the target area to be measured includes the following steps:

S1: Obtain the mineral content of the reservoir rock by analyzing the composition of the reservoir rock minerals in the target area to be tested, and obtain the connectivity of the reservoir rock mineral components and their correlation with the pores by analyzing the scanning electron microscope images of the target area to be tested;

S2: Under the assumption of isotropy of one-dimensional spherical reservoir rock minerals, based on the equivalent medium model of underground reservoir rock, combined with the reservoir rock mineral content, the connectivity of reservoir rock mineral components and the correlation with pores, the theoretical induced polarization model expression based on the MGEMTIP model is constructed;

S3: Based on the complex resistivity experiment under the formation conditions of the target area to be tested, the rock induced polarization parameters of different rock samples in the target area to be tested are obtained;

S4: The rock induced polarization parameters of different rock samples are combined with the different reservoir physical property parameters corresponding to the rock samples and input into the theoretical induced polarization model expression based on the MGEMTIP model to obtain the model parameters, and then obtain the theoretical induced polarization model corresponding to the target area to be tested.

Further preferably, the method for obtaining the expression of the theoretical induced polarization model based on the MGEMTIP model in S2 is:

S2.1: Construct the MGEMTIP model based on the equivalent medium model of underground reservoir rock; the MGEMTIP model is a complex resistivity model established based on the equivalent medium theory and the QL approximation theory, which replaces the multiphase medium with an equivalent uniform medium containing boundary polarization;

S2.2: The conductivity model in the MGEMTIP model is represented as a Cole-Cole model;

S2.3: Based on S2.2, the conductive medium and polarization medium of the rock induced polarization model are determined according to the equivalent medium model, the equivalent medium relationship is constructed, and the theoretical induced polarization model expression based on the MGEMTIP model is obtained.

Further preferably, under the isotropic condition of the one-dimensional spherical reservoir rock minerals in step S2.1, the resistivity model in the MGEMTIP model is:

in, is the equivalent conductivity of tight sandstone in the MGEMTIP model; is the background rock conductivity; They correspond to the volume composition, conductivity, surface polarization factor and equivalent spherical radius of the i- th rock mineral relative to the background mineral;

The conductivity model in the form of the Cole-Cole model in step S2.2 is:

in, Characterize the effective space proportion of the background medium; Characterize the relaxation time corresponding to the i- th rock mineral; is the polarizability corresponding to rock minerals; is the complex imaginary part, The circular frequency ;

In step S2.3, the theoretical IP model expression based on the MGEMTIP model is:

in, is the rock conductivity under unsaturated conditions; and are the pore fluid conductivity and fluid porosity, respectively. is the clay content, and are the cementation indexes of rock pores and clay, respectively; is the saturation of pore fluid, is the saturation index of pore fluid; is the high frequency additional equivalent conductivity, satisfying , is the electrical conductivity of clay; is the total number of discretized clay scales within the research scale, ; is the effective proportion of clay minerals of the i -th scale; To measure the angular frequency.

Further preferably, the rock induced polarization parameters include rock resistivity and polarizability.

Further preferably, the reservoir physical property parameters include porosity, saturation and clay content of the target area to be measured.

Further preferably, the model parameters include the cementation index of rock pores and clay, the saturation index of pore fluid and the electrical conductivity of clay.

Further preferably, the rock induced polarization parameter in step S3 is the true resistivity and polarizability ;

in, is the formation fluid resistivity; Corresponding pore fluid resistivity index; is the rock stratigraphic factor; is the high frequency additional equivalent conductivity; is the relative proportion of clay components; is the pore fluid conductivity.

In a second aspect, the present application provides a rock induced polarization parameter acquisition system for an isotropic tight sandstone reservoir, comprising:

A component analyzer is used to obtain the mineral content of the reservoir rock by analyzing the components of the reservoir rock minerals in the target area to be tested;

A scanning electron microscope is used to scan and image the target area to be measured and obtain a scanning electron microscope image; wherein the scanning electron microscope image is used to analyze the connectivity of the mineral components of the reservoir rock and its correlation with the pores;

Theoretical IP model construction module is used to construct the theoretical IP model expression based on the MGEMTIP model, based on the equivalent medium model of underground reservoir rocks, under the assumption of isotropy of one-dimensional spherical reservoir rock minerals, combined with the reservoir rock mineral content, the connectivity of the reservoir rock mineral composition and the correlation with pores;

IP parameter test module, used to test and obtain rock IP parameters of different rock samples in the target area based on complex resistivity experiments under formation conditions in the target area to be tested;

The theoretical induced polarization model acquisition module is used to input the rock induced polarization parameters of different rock samples combined with the different reservoir physical property parameters corresponding to the rock samples into the theoretical induced polarization model expression based on the MGEMTIP model to obtain model parameters, and then obtain the theoretical induced polarization model corresponding to the target area to be tested.

Further preferably, the theoretical induced polarization model construction module includes: an MGEMTIP model construction unit, a model characterization unit and an induced polarization model acquisition unit;

The MGEMTIP model building unit is used to build the MGEMTIP model based on the equivalent medium model of the underground reservoir rock; wherein the MGEMTIP model is a complex resistivity model established according to the equivalent medium theory and the QL approximation theory, and the multiphase medium is replaced by an equivalent uniform medium containing boundary polarization;

The model characterization unit is used to characterize the conductivity model in the MGEMTIP model as a Cole-Cole model;

The IP model acquisition unit is used to determine the conductive medium and polarizable medium of the rock IP model based on the conductivity model in the form of the Cole-Cole model obtained by the model characterization unit according to the equivalent medium model, construct the equivalent medium relationship, and obtain the theoretical IP model expression based on the MGEMTIP model.

Further preferably, in the MGEMTIP model construction unit, under the isotropic condition of one-dimensional spherical reservoir rock minerals, the resistivity model in the MGEMTIP model is:

in, is the equivalent conductivity of tight sandstone in the MGEMTIP model; is the background rock conductivity; They correspond to the volume composition, conductivity, surface polarization factor and equivalent spherical radius of the i- th rock mineral relative to the background mineral;

The conductivity model in the MGEMTIP model in the form of the Cole-Cole model in the model characterization unit is:

in, Characterize the effective space proportion of the background medium; Characterize the relaxation time corresponding to the i- th rock mineral; is the polarizability corresponding to rock minerals; is the complex imaginary part, The circular frequency ;

The theoretical IP model expression based on the MGEMTIP model in the IP model acquisition unit is:

in, is the rock conductivity under unsaturated conditions; and are the pore fluid conductivity and fluid porosity, respectively. is the clay content, and are the cementation indexes of rock pores and clay, respectively; is the saturation of pore fluid, is the saturation index of pore fluid; is the high frequency additional equivalent conductivity, satisfying , is the electrical conductivity of clay; is the total number of discretized clay scales within the research scale, ; is the effective proportion of clay minerals of the i -th scale; To measure the angular frequency.

Further preferably, the rock induced polarization parameters include rock resistivity and polarizability; the reservoir physical property parameters include porosity, saturation and clay content of the target area to be measured; and the model parameters include the cementation index of rock pores and clay, the saturation index of pore fluid and the conductivity of clay.

Further preferably, the rock induced polarization parameter in the induced polarization parameter test module is the true resistivity and polarizability ;

in, is the formation fluid resistivity; Corresponding pore fluid resistivity index; is the rock stratigraphic factor; is the high frequency additional equivalent conductivity; is the relative proportion of clay components; is the pore fluid conductivity.

In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:

At present, the resistivity rock physics research based on electromagnetic exploration is mainly based on real resistivity, which is difficult to meet the growing exploration depth and accuracy requirements. The exploration technology based on complex resistivity can more accurately describe the electrical characteristics of underground rocks than conventional real resistivity exploration technology. The research on complex resistivity is mainly based on logging technology, mainly focusing on high-frequency dielectric polarization greater than 1kHz. Due to the existence of low-frequency induced polarization phenomenon, there is a certain difference in the effective value of high-frequency and low-frequency resistivity. When the rock contains low-resistance minerals, the resistivity difference may span an order of magnitude. Therefore, high-frequency complex resistivity cannot be directly applied to low-frequency exploration problems. The geoelectric model constructed only using logging resistivity is prone to large model errors. The low-frequency induced polarization rock physics research for exploration problems is in its infancy, mainly studying the low-frequency polarization mechanism and the corresponding influencing factors. The induced polarization research on oil and gas reservoirs is also mainly based on conventional high-porosity and permeability sandstone reservoirs. Complex resistivity analysis is mainly based on qualitative conclusions, and quantitative analysis has not been effectively achieved, and it is impossible to effectively establish a model of the relationship between reservoir physical properties and induced polarization in the research target area.

Based on the above problems, the present application provides a method for obtaining rock induced polarization parameters of isotropic tight sandstone reservoirs, wherein the complex resistivity amplitude and phase of the reservoir core or outcrop are obtained by means of a high temperature and high pressure rock physics experimental system (AUTOLAB1000), and the generalized equivalent medium induced polarization (MGEMTIP) model is combined to obtain the rock induced polarization parameter expression of the tight sandstone reservoir. Combined with rock physical mineral component analysis and electron microscope scanning, a theoretical induced polarization model of rocks under corresponding depth conditions with porosity, saturation and clay content is constructed, and the quantitative relationship between reservoir physical properties and induced polarization parameters is effectively established, which provides a theoretical and experimental basis for accurately establishing a complex resistivity geoelectric model of the target area, and at the same time provides a relationship model for the quantitative analysis of reservoir physical properties and induced polarization parameters, providing an important basis for the formation of electromagnetic exploration technology and unconventional reservoir evaluation technology.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flow chart of a method for obtaining rock induced polarization parameters of an isotropic tight sandstone reservoir provided in an embodiment of the present application;

FIG2 is a schematic diagram of a conductive mode of fluid conduction and viscosity polarization provided in an embodiment of the present application;

FIG3 is a comparison diagram of a complex resistivity test curve of a dense sandstone sample provided in an embodiment of the present application and suppressed low-frequency inversion data;

FIG4 is a diagram of test results in different directions according to a square sample test of a reservoir outcrop in a target area provided in an embodiment of the present application;

5 is a schematic diagram of a family of curves of complex resistivity and polarizability varying with saturation when the porosity ranges from 6% to 14% for an induced polarization model established for a target area provided in an embodiment of the present application;

6 is a schematic diagram of the resistivity and polarizability fitting results of the target area induced polarization model established based on Table 1 and the target area logging data and rock physics data provided in an embodiment of the present application.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

In the description of the embodiments of the present application, unless otherwise specified, “plurality” means two or more than two.

This application obtains the complex resistivity amplitude and phase of the reservoir core or outcrop through means such as the high-temperature and high-pressure rock physics experimental system (AUTOLAB1000), and obtains the expression of the rock induced polarization parameters of the tight sandstone reservoir by combining the generalized equivalent medium induced polarization (MGEMTIP) model. Combined with rock physical mineral component analysis and electron microscope scanning, a theoretical induced polarization model of rocks under corresponding depth conditions with changes in porosity, saturation and clay content is constructed, and the quantitative relationship between reservoir physical properties and induced polarization parameters is effectively established, which provides a theoretical and experimental basis for accurately establishing the complex resistivity geoelectric model of the target area, and at the same time provides a relationship model for the quantitative analysis of reservoir physical properties and induced polarization parameters, providing an important basis for the formation of electromagnetic exploration technology and unconventional reservoir evaluation technology.

As shown in FIG1 , the method for obtaining rock induced polarization parameters of an isotropic tight sandstone reservoir provided in the present application specifically comprises the following steps:

S1: Reservoir rock mineral composition analysis and scanning electron microscopy analysis

The mineral content of reservoir rocks can be obtained by analyzing the composition of reservoir rock minerals. Taking tight sandstone reservoirs as an example, the rock is usually rich in clay minerals and contains a small amount of metal minerals. The connectivity of reservoir rock mineral components and their correlation with pores can be accurately analyzed by scanning electron microscopy, which is used to construct an equivalent medium model, as shown in Figure 2.

S2: Construction of theoretical IP model based on MGEMTIP model

The MGEMTIP model is constructed based on the equivalent medium model of underground reservoir rocks. The MGEMTIP model is a complex resistivity model established based on the equivalent medium theory and the Quasi-Linear (QL) approximation theory. The complex multiphase medium is replaced by an equivalent uniform medium containing boundary polarization. The MGEMTIP model modifies the definition of equivalent conductivity in the GEMTIP model. Under the isotropic assumption of a one-dimensional spherical perturbation body, the conductivity model of the re-derived MGEMTIP model is:

(1)

in, is the equivalent conductivity of rock in the MGEMTIP model; is the background rock conductivity; N is the total number of different low-resistance minerals at different scales, , They correspond to the volume composition, conductivity, surface polarization factor and equivalent spherical radius of the i- th low-resistance mineral relative to the background mineral; the conductivity model in the MGEMTIP model can be characterized as a relationship similar to the Cole-Cole model:

(2)

in, Characterize the effective space proportion of the background medium; Characterize the relaxation time corresponding to the i- th rock mineral; is the polarizability corresponding to rock minerals; is the complex imaginary part, The circular frequency ;

According to the equivalent medium model, the conductive medium and polarized medium of the rock induced polarization model are determined, and the equivalent medium relationship is constructed to obtain the rock conductivity dispersion model under unsaturated conditions, that is, the theoretical induced polarization model expression based on the MGEMTIP model:

(3)

in, is the rock conductivity under unsaturated conditions; and are the pore fluid conductivity and fluid porosity, respectively. is the clay content, and are the cementation indexes of rock pores and clay, respectively; is the saturation of pore fluid, is the saturation index of pore fluid; is the high frequency additional equivalent conductivity, satisfying , is the electrical conductivity of clay; is the total number of discretized clay scales within the research scale, ; is the effective proportion of clay minerals of the i -th scale; is the time constant of clay mineral of the ith scale; To measure the angular frequency; the model needs to be calibrated with the complex resistivity data of the target area , , and Equivalent medium model is used to describe the spatial relationship between rock minerals and pores, and to determine some parameters of the electromechanical model;

S3: Obtain IP parameters by combining complex resistivity experiments under formation conditions

Based on the theoretical induced polarization model, the model parameters are estimated. Under the low-frequency electrode polarization condition of the pressed electrode material, the true resistivity, polarizability and other induced polarization parameters of each rock sample are obtained. The estimated curve of the pressed electrode polarization is shown in Figure 3. According to formula (3), the true resistivity and polarizability obtained under different conditions correspond to （ is the formation fluid resistivity) and ;

S4: Combining experimental data to implement MEGMTIP model characterization

For tight reservoir sandstone, the theoretical IP model characterization under isotropic conditions can be realized. Combined with the different test conditions of each sample (different porosity, saturation and clay content), the theoretical IP model is substituted to obtain the L2 norm (least square method) , , and The theoretical induced polarization model under the conditions of changing porosity, saturation and clay content in the target area is obtained by using the model parameters.

Example 1

Modeling tests were conducted on core and outcrop samples in a certain area. The rocks in the area do not meet the isotropic assumption as shown in Figure 4. The theoretical model with porosity, saturation and clay content was obtained. The corresponding parameters of the model formula (3) are shown in Table 1;

Table 1

Combined with the model, some logging data and rock physics experimental data were fitted and analyzed. According to the regional porosity range of 6% to 14%, the induced polarization model corresponding to Table 1 is shown in Figure 5, and the model prediction results are shown in Figure 6. The average relative errors of true resistivity and polarizability prediction are as low as 9.79% and 18.34%, respectively. It can effectively characterize the exciting point characteristics of the formation with the change of porosity, water saturation and clay content, and can be effectively used for geoelectric modeling in the region to improve the inversion stability and reduce the non-uniqueness of the inversion.

Example 2

The present application provides a rock induced polarization parameter acquisition system for an isotropic tight sandstone reservoir, comprising:

A component analyzer is used to obtain the mineral content of the reservoir rock by analyzing the components of the reservoir rock minerals in the target area to be tested;

A scanning electron microscope is used to scan and image the target area to be measured and obtain a scanning electron microscope image, wherein the scanning electron microscope image is used to analyze the connectivity of the mineral components of the reservoir rock and its correlation with the pores;

Theoretical IP model construction module is used to construct the theoretical IP model expression based on the MGEMTIP model, based on the equivalent medium model of underground reservoir rocks, under the assumption of isotropy of one-dimensional spherical reservoir rock minerals, combined with the reservoir rock mineral content, the connectivity of the reservoir rock mineral composition and the correlation with pores;

The IP parameter test module is used to test and obtain the rock IP parameters of different rock samples in the target area based on the formation conditions of the target area to be tested;

The theoretical induced polarization model acquisition module is used to input the rock induced polarization parameters of different rock samples combined with the different reservoir physical property parameters corresponding to the rock samples into the theoretical induced polarization model expression of the MGEMTIP model to obtain the model parameters, and then obtain the theoretical induced polarization model corresponding to the target area to be tested.

Further preferably, the theoretical induced polarization model construction module includes: an MGEMTIP model construction unit, a model characterization unit and an induced polarization model acquisition unit;

The MGEMTIP model building unit is used to build the MGEMTIP model based on the equivalent medium model of the underground reservoir rock; wherein the MGEMTIP model is a complex resistivity model established according to the equivalent medium theory and the QL approximation theory, and the multiphase medium is replaced by an equivalent uniform medium containing boundary polarization;

The model characterization unit is used to characterize the conductivity model in the MGEMTIP model as a Cole-Cole model;

The IP model acquisition unit is used to determine the conductive medium and polarizable medium of the rock IP model based on the conductivity model in the MGEMTIP model in the form of the Cole-Cole model obtained by the model characterization unit, according to the equivalent medium model, to construct the equivalent medium relationship, and to obtain the theoretical IP model expression based on the MGEMTIP model.

Further preferably, in the MGEMTIP model construction unit, under the isotropic condition of one-dimensional spherical reservoir rock minerals, the resistivity model in the MGEMTIP model is:

in, is the equivalent conductivity of tight sandstone in the MGEMTIP model; is the background rock conductivity; They correspond to the volume composition, conductivity, surface polarization factor and equivalent spherical radius of the i- th rock mineral relative to the background mineral;

The conductivity model in the MGEMTIP model in the form of the Cole-Cole model in the model characterization unit is:

in, Characterize the effective space proportion of the background medium; Characterize the relaxation time corresponding to the i- th rock mineral; is the polarizability corresponding to rock minerals; is the complex imaginary part, The circular frequency ;

The theoretical IP model expression based on the MGEMTIP model in the IP model acquisition unit is:

in, is the rock conductivity under unsaturated conditions; and are the pore fluid conductivity and fluid porosity, respectively. is the clay content, and are the cementation indexes of rock pores and clay, respectively; is the saturation of pore fluid, is the saturation index of pore fluid; is the high frequency additional equivalent conductivity, satisfying , is the electrical conductivity of clay; is the total number of discretized clay scales within the research scale, ; is the effective proportion of clay minerals of the i -th scale; To measure the angular frequency.

Further preferably, the rock induced polarization parameters include rock resistivity and polarizability; the reservoir physical property parameters include porosity, saturation and clay content of the target area to be measured; and the model parameters include the cementation index of rock pores and clay, the saturation index of pore fluid and the conductivity of clay.

Further preferably, the rock induced polarization parameter in the induced polarization parameter test module is the true resistivity and polarizability ;

in, is the formation fluid resistivity; is the pore fluid resistivity index; ; is the rock stratigraphic factor; is the high frequency additional equivalent conductivity; is the relative proportion of clay components; is the pore fluid conductivity.

In summary, compared with the prior art, the present application has the following advantages:

The present application provides a method for obtaining rock induced polarization parameters of an isotropic tight sandstone reservoir, and proposes an induced polarization modeling method for an isotropic tight sandstone reservoir based on the MGEMTIP model. An induced polarization model of reservoir sandstone under clay mineral conditions that changes with porosity, water saturation and clay content is established. The method can effectively characterize the true resistivity and polarizability of the target reservoir under different porosity, water saturation and clay content conditions. The prediction results for the reservoir are accurate, and the average relative errors of the true resistivity and polarizability can be as low as 10% and 20%, respectively. This makes up for the problem that conventional logging tests cannot observe induced polarization characteristics (true resistivity and polarizability). The method can provide a geoelectric model for inversion based on time-frequency electromagnetic exploration, improve the inversion stability, reduce the non-uniqueness of the inversion, and provide a theoretical basis and experimental foundation for reservoir interpretation.

It should be understood that the above-mentioned device is used to execute the method in the above-mentioned embodiment. The implementation principle and technical effect of the corresponding program module in the system are similar to those described in the above-mentioned method. The working process of the system can refer to the corresponding process in the above-mentioned method and will not be repeated here.

It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims (6)

1. A method for obtaining rock induced polarization parameters of an isotropic tight sandstone reservoir, characterized in that it comprises the following steps: Inputting different reservoir physical property parameters of the target area to be tested into the theoretical induced polarization model corresponding to the target area to be tested, and obtaining the rock induced polarization parameters of the target area to be tested; The method for obtaining the theoretical induced polarization model corresponding to the target area to be measured includes the following steps: S1: Obtain the mineral content of the reservoir rock by analyzing the composition of the reservoir rock minerals in the target area to be tested, and obtain the connectivity of the reservoir rock mineral components and their correlation with the pores by analyzing the scanning electron microscope images of the target area to be tested; S2: Under the assumption of isotropy of one-dimensional spherical reservoir rock minerals, based on the equivalent medium model of underground reservoir rock, combined with the reservoir rock mineral content, the connectivity of reservoir rock mineral components and the correlation with pores, the theoretical induced polarization model expression based on the MGEMTIP model is constructed; S3: Based on the complex resistivity experiment under the formation conditions of the target area to be tested, the rock induced polarization parameters of different rock samples in the target area to be tested are obtained; S4: inputting the rock induced polarization parameters of different rock samples into the theoretical induced polarization model expression based on the MGEMTIP model in combination with the different reservoir physical property parameters corresponding to the rock samples to obtain the model parameters, and then obtaining the theoretical induced polarization model corresponding to the target area to be tested; The method for obtaining the expression of the theoretical IP model based on the MGEMTIP model in S2 is: S2.1: Construct the MGEMTIP model based on the equivalent medium model of underground reservoir rock; the MGEMTIP model is a complex resistivity model established based on the equivalent medium theory and the QL approximation theory, which replaces the multiphase medium with an equivalent uniform medium containing boundary polarization; S2.2: The conductivity model in the MGEMTIP model is represented as a Cole-Cole model; S2.3: Based on S2.2, the conductive medium and polarization medium of the rock induced polarization model are determined according to the equivalent medium model, the equivalent medium relationship is constructed, and the theoretical induced polarization model expression based on the MGEMTIP model is obtained; Under the isotropic condition of one-dimensional spherical reservoir rock minerals in step S2.1, the resistivity model in the MGEMTIP model is: in, is the equivalent conductivity of tight sandstone in the MGEMTIP model; is the background rock conductivity; They correspond to the volume composition, conductivity, surface polarization factor and equivalent spherical radius of the i- th rock mineral relative to the background mineral; The conductivity model in the form of the Cole-Cole model in step S2.2 is: in, Characterize the effective space proportion of the background medium; Characterize the relaxation time corresponding to the i- th rock mineral; is the polarizability corresponding to rock minerals; is the complex imaginary part, is the circular frequency, ; In step S2.3, the theoretical IP model expression based on the MGEMTIP model is: in, is the rock conductivity under unsaturated conditions; and are the pore fluid conductivity and fluid porosity, respectively. is the clay content, and are the cementation indexes of rock pores and clay, respectively; is the saturation of pore fluid, is the saturation index of pore fluid; is the high frequency additional equivalent conductivity, satisfying , is the electrical conductivity of clay; is the total number of discretized clay scales within the research scale, ; is the effective proportion of clay minerals of the i -th scale; To measure the angular frequency. 2. The rock induced polarization parameter acquisition method according to claim 1 is characterized in that the rock induced polarization parameters include rock resistivity and polarizability; reservoir physical property parameters include porosity, saturation and clay content of the target area to be measured; model parameters include cementation index of rock pores and clay, saturation index of pore fluid and conductivity of clay. 3. The rock induced polarization parameter acquisition method according to claim 1, characterized in that the rock induced polarization parameter in S3 is the true resistivity and polarizability ; in, is the formation fluid resistivity; is the pore fluid resistivity index; is the rock stratigraphic factor; is the high frequency additional equivalent conductivity; is the relative proportion of clay components; is the pore fluid conductivity. 4. A rock induced polarization parameter acquisition system for isotropic tight sandstone reservoir, characterized by comprising: A component analyzer is used to obtain the mineral content of the reservoir rock by analyzing the components of the reservoir rock minerals in the target area to be tested; Scanning electron microscope, used to scan and image the target area to be tested and obtain scanning electron microscope images; wherein the scanning electron microscope images are used to analyze the connectivity of the mineral components of the reservoir rock and their correlation with the pores; Theoretical IP model construction module is used to construct the theoretical IP model expression based on the MGEMTIP model, based on the equivalent medium model of underground reservoir rocks, under the assumption of isotropy of one-dimensional spherical reservoir rock minerals, combined with the reservoir rock mineral content, the connectivity of the reservoir rock mineral composition and the correlation with pores; IP parameter test module, used to test and obtain rock IP parameters of different rock samples in the target area based on complex resistivity experiments under formation conditions in the target area to be tested; Theoretical IP model acquisition module is used to input the rock IP parameters of different rock samples into the theoretical IP model expression based on the MGEMTIP model in combination with the different reservoir physical property parameters corresponding to the rock samples to obtain the model parameters, and then obtain the theoretical IP model corresponding to the target area to be tested; Theoretical IP model building module includes: MGEMTIP model building unit, model characterization unit and IP model acquisition unit; The MGEMTIP model building unit is used to build the MGEMTIP model based on the equivalent medium model of the underground reservoir rock; wherein the MGEMTIP model is a complex resistivity model established according to the equivalent medium theory and the QL approximation theory, and the multiphase medium is replaced by an equivalent uniform medium containing boundary polarization; The model characterization unit is used to characterize the conductivity model in the MGEMTIP model as a Cole-Cole model; The IP model acquisition unit is used to determine the conductive medium and polarization medium of the rock IP model based on the conductivity model in the form of the Cole-Cole model obtained by the model characterization unit according to the equivalent medium model, build an equivalent medium relationship, and obtain the theoretical IP model expression based on the MGEMTIP model; In the MGEMTIP model construction unit, under the isotropic condition of one-dimensional spherical reservoir rock minerals, the resistivity model in the MGEMTIP model is: in, is the equivalent conductivity of tight sandstone in the MGEMTIP model; is the background rock conductivity; They correspond to the volume composition, conductivity, surface polarization factor and equivalent spherical radius of the i- th rock mineral relative to the background mineral; The conductivity model in the MGEMTIP model in the form of the Cole-Cole model in the model characterization unit is: in, Characterize the effective space proportion of the background medium; Characterize the relaxation time corresponding to the i- th rock mineral; is the polarizability corresponding to rock minerals; is the complex imaginary part, is the circular frequency, ; The theoretical IP model expression based on the MGEMTIP model in the IP model acquisition unit is: in, is the rock conductivity under unsaturated conditions; and are the pore fluid conductivity and fluid porosity, respectively. is the clay content, and are the cementation indexes of rock pores and clay, respectively; is the saturation of pore fluid, is the saturation index of pore fluid; is the high frequency additional equivalent conductivity, satisfying , is the electrical conductivity of clay; is the total number of discretized clay scales within the research scale, ; is the effective proportion of clay minerals of the i -th scale; To measure the angular frequency. 5. The rock induced polarization parameter acquisition system according to claim 4 is characterized in that the rock induced polarization parameters include rock resistivity and polarizability; the reservoir physical property parameters include porosity, saturation and clay content of the target area to be measured; and the model parameters include the cementation index of rock pores and clay, the saturation index of pore fluid and the electrical conductivity of clay. 6. The rock induced polarization parameter acquisition system according to claim 4 is characterized in that the rock induced polarization parameter in the induced polarization parameter test module is the true resistivity and polarizability ; in, is the formation fluid resistivity; Corresponding pore fluid resistivity index; is the rock stratigraphic factor; is the high frequency additional equivalent conductivity; is the relative proportion of clay components; is the pore fluid conductivity.