Method and system for acquiring permeability of porous medium carbonate reservoir

Abstract

The invention discloses a porous medium carbonate reservoir permeability obtaining method and system, and the method comprises the steps: taking a logging curve of a preset index as an input, and carrying out the logging facies analysis of a preset region; according to an analysis result, classifying logging facies reservoirs in a preset area, and establishing a corresponding permeability and core porosity relation model; based on the relation model, calculating to obtain the single-phase permeability corresponding to each classified reservoir; and performing weighted summation on each single-phase permeability to obtain the stratum permeability. The accuracy of obtaining the stratum permeability is improved, and meanwhile the accuracy of evaluating the carbonate reservoir is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of carbonate reservoir evaluation, and in particular to a method and system for acquiring the permeability of a porous medium carbonate reservoir. Background Art

[0002] Carbonate reservoirs are important oil and gas producing layers due to their wide distribution and uniform and stable thickness. The oil and gas reserves in carbonate reservoirs around the world account for about 40% of the total oil and gas reserves, and the production accounts for about 60% of the total oil and gas production. However, carbonate reservoirs have different reservoir characteristics due to the particularity and complexity of stratum deposition and diagenetic evolution, which are specifically reflected in two aspects: First, the reservoir space is manifested as pores, holes, fractures and their mutual combination. As a reservoir, carbonate rocks have the characteristics of deep burial, variable reservoir types, significant late transformation, and strong heterogeneity; second, fractures and holes are diverse in type and morphology, multi-scale in size, irregular in spatial distribution, and often developed in strata that have undergone multiple periods of geological tectonic movements. These objective reasons cause the evaluation of carbonate reservoirs, especially the key parameter affecting reservoir productivity: permeability. The calculation accuracy is low, which affects the later productivity evaluation.

[0003] For carbonate reservoir evaluation, due to its unique pore structure characteristics, that is, pores (holes) and cracks can serve as storage space and seepage channels, that is, for this porous medium reservoir, the pore space type is relatively complex, and the core porosity and permeability no longer satisfy a simple linear relationship. Therefore, a new method and system for obtaining the permeability of porous medium carbonate reservoirs is needed. Summary of the invention

[0004] The embodiments of the present invention provide a method and system for obtaining the permeability of a porous medium carbonate reservoir, which at least partially solves the technical problems of low permeability acquisition accuracy and inaccurate evaluation in the prior art, and achieves a technical effect of more accurate permeability in the case of a variety of pore structure types in carbonate reservoirs.

[0005] In the first aspect, to solve the above technical problems, the embodiments of the present invention provide the following technical solutions:

[0006] A method for obtaining the permeability of a porous carbonate reservoir, comprising:

[0007] Taking the well logging curve of preset indicators as input, the well logging phase analysis is performed on the preset area;

[0008] According to the analysis results, the logging phase reservoirs in the above preset areas are classified, and the corresponding permeability and core porosity relationship model is established;

[0009] Based on the above relationship model, the single-phase permeability corresponding to each classified reservoir is calculated; and the formation permeability is obtained by weighted summing up the above single-phase permeabilities.

[0010] Optionally, the above step of using the well logging curve with preset indicators as input further includes:

[0011] Takes gamma curve, deep resistivity curve, sonic curve, density curve and neutron curve as input.

[0012] Optionally, before performing logging phase analysis on the preset area, the method further includes:

[0013] Select gas fields with well numbers within a preset range and core description data, and perform curve standardization and environmental correction on the above-mentioned input logging curves.

[0014] Optionally, the above step of performing logging phase analysis on the preset area further includes:

[0015] The hierarchical clustering method is used to conduct logging phase analysis on the preset area.

[0016] Optionally, the above step of establishing a corresponding permeability and core porosity relationship model further includes:

[0017] The core porosity and permeability data of the same above-classified reservoirs in different regions are obtained, and the relationship equations of the different above-classified reservoirs are obtained by fitting as the relationship model.

[0018] Optionally, the step of performing weighted summation of the above-mentioned single-phase permeabilities to obtain the formation permeability further includes:

[0019] A weighting coefficient is set according to the proportion of different classified reservoirs in the stratum in the preset area;

[0020] Based on the above weighting coefficients, the above single-phase permeabilities are weighted and summed to obtain the formation permeability.

[0021] Optionally, the step of classifying the logging phase reservoirs in the above-mentioned preset area further includes:

[0022] According to the natural tests of historical data and experimental data, the parameters corresponding to different production rates, dissolution and fracture development states of logging are divided into multiple reservoirs classified as above.

[0023] In a second aspect, a porous medium carbonate reservoir permeability acquisition system is provided, comprising:

[0024] The logging phase analysis module is used to perform logging phase analysis on the preset area using the logging curve of the preset index as input.

[0025] A model building module is used to classify the logging phase reservoirs in the above-mentioned preset area according to the analysis results, and to establish a corresponding permeability and core porosity relationship model;

[0026] The permeability calculation module calculates the single-phase permeability corresponding to each classified reservoir based on the above relationship model; and obtains the formation permeability by weighted summing up each of the above single-phase permeabilities.

[0027] In a third aspect, an electronic device is provided, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps corresponding to the method of the first aspect when executing the computer program.

[0028] In a fourth aspect, a computer-readable storage medium is provided, on which a computer program is stored, and when the program is executed by a processor, the steps corresponding to the above method in the first aspect are implemented.

[0029] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0030] Taking into full consideration the diversity of carbonate reservoir pore structure types, a reservoir permeability calculation model for porous media was established. This completes the logging phase reservoir classification based on hierarchical clustering analysis, and accurately calculates the permeability of carbonate reservoirs with different reservoir space types such as fracture type, hole type, and fracture-cavity type, thereby improving the accuracy of formation permeability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 A flow chart of a method for obtaining the permeability of a porous medium carbonate reservoir provided by the present invention;

[0033] Figure 2 It is a well logging phase calculation result diagram of a certain exploration well in a preset area in the present invention;

[0034] Figure 3 is the logging phase reservoir characteristic table in the present invention;

[0035] Figure 4 It is the cross-plot of the core porosity and permeability after well logging phase classification in the present invention;

[0036] Figure 5 This is a comparison chart of various permeability calculation results of a certain exploration well in the present invention;

[0037] Figure 6 A structural schematic diagram of a method for obtaining the permeability of a porous medium carbonate reservoir provided by the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0041] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the term "disposed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solutions of the present application, rather than limitations of the technical solutions of the present application. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments may be combined with each other.

[0043] The technical solution of the embodiment of the present invention is to solve the above technical problems, and the overall idea is as follows:

[0044] Using conventional logging curves such as sonic, density and neutron as input, the number of logging phases is determined according to the lithology type, and the hierarchical clustering algorithm is used to classify the logging phase reservoirs. A classification permeability model of the main reservoir types such as pore-fracture type, fracture type, and pore type in the study area is established. In actual calculation, the total reservoir permeability is the weighted sum of the classified permeabilities, thereby improving the accuracy of the permeability.

[0045] In an embodiment of the present invention, there is provided Figure 1 A method for obtaining the permeability of a porous carbonate reservoir is shown, the method comprising steps S101 to S103:

[0046] First, the core lithology analysis is carried out to determine the number of logging phase outputs. In detail, according to the results of core lithology identification in the study area, the main lithology types of the formations in this area are psammite, bioclastic limestone, micrite and mudstone. Psammite has the most developed dissolution pores and fractures, and the best reservoir properties; bioclastic limestone has relatively developed dissolution pores and fractures, and the reservoir properties are second; the micrite matrix has dense pores, and some well sections have developed fractures, and the permeability of the fracture development section is high; the mudstone is dense as a whole, and the development of fractures and dissolution pores is the lowest. Combined with the core physical properties and test results, the first three are effective reservoirs, while the fourth is a non-reservoir. That is, the reservoir physical properties are closely related to the lithology type, and the lithology type is the key factor in determining whether the reservoir is effective, so the number of logging phase outputs is selected as 4. When determining the number of logging phase outputs in other areas, it is necessary to determine the key factors of reservoir effectiveness based on actual conditions.

[0047] Step S101, taking the well logging curve of the preset index as input, performing well logging phase analysis on the preset area;

[0048] It should be noted that the selection of logging curves is mainly based on the analysis of conventional logging data of exploration wells in the study area, and the reservoir characteristics and various logging curve measurement objects in the study area are comprehensively analyzed. The following five logging curves are selected as input: gamma curve reflects lithology; deep resistivity curve indicates gas content and is also a comprehensive reflection of lithology and physical properties; sonic curve, density curve and neutron curve can reflect reservoir physical properties and are also related to lithology. These five curves can comprehensively characterize the reservoir's lithology, physical properties and gas content, ensuring that the classification results are more representative.

[0049] Before performing logging phase analysis on the preset area, it also includes: selecting gas fields with a well number within a preset range and core description data, and performing curve standardization and environmental correction on the input logging curve. Among them, because the conventional logging data of the exploration wells in the study area are relatively complete, when performing logging phase analysis, the preset range of quantity is mainly to select gas fields with relatively more wells. In addition, there are many methods for logging phase analysis, usually including mathematical models such as factor analysis, cluster analysis, and discriminant analysis. After comparison and selection, this embodiment uses hierarchical clustering to perform logging phase analysis on the preset area. Hierarchical clustering is a kind of clustering algorithm, which creates a hierarchical nested clustering tree by calculating the similarity between data points of different categories. The smaller the distance, the higher the similarity. The entire clustering process can be obtained at one time, and it is insensitive to the input order of the samples. Therefore, for practical applications, it has the advantages of being quick to get started, and the results can also be appropriately adjusted according to actual needs.

[0050] Step S102, classifying the logging phase reservoirs in the preset area according to the analysis results, and establishing a corresponding permeability and core porosity relationship model;

[0051] It should be noted that if Figure 2 The figure shows the logging phase analysis results of a gas exploration well in the preset area. Combined with the reservoir space type and production capacity, the studied strata are divided into multiple categories. That is, according to the parameters corresponding to different logging production, dissolution and fracture development status in the natural test of historical data and experimental data, they are divided into multiple classified reservoirs. Specifically: Class I reservoirs, the conventional logging response characteristics are high acoustic time difference, low density, effective porosity greater than 4.0%, low resistivity, low GR value, dissolution pores and fractures, that is, fracture-pore type reservoirs, and their natural tests are often high-yield. For the second type of reservoir, the conventional logging response characteristics are high acoustic time difference, low density, effective porosity of 1.8%-4.0%, low resistivity, low GR, relatively developed dissolution pores, i.e. porous reservoirs, and natural tests often have low yields; for the third type of reservoir, the acoustic time difference and density values ​​are not much different from those of the surrounding rock, the effective porosity is less than 1.8%, the resistivity value is relatively high, the GR value is medium and low, and some sections of the well have cracks, i.e. fractured reservoirs; for the fourth type of reservoir, the conventional logging response characteristics are high GR and high resistivity values, and the overall density is not considered as an effective reservoir, such as Figure 3 As shown. Figure 2From left to right, the first column STRATIGRAPHY is the geological stratification; the second column Depth is the depth in m; in the third column, BS is the drill bit size in in, CAL is the borehole diameter in in, GR is the natural gamma in API; in the fourth column, RLLD is the deep resistivity in ohm.m, RLLS is the deep resistivity in ohm.m; in the fifth column, CNL is the neutron in %, DEN is the density in g / cm3, AC is the acoustic time difference in μs / ft; in the sixth column, VSH is the shale content in %, CALCITE is the limestone content in %; the seventh column is the logging interpretation conclusion; the eighth column is the logging phase calculation result.

[0052] In addition, the step of establishing the corresponding permeability and core porosity relationship model also includes: obtaining the core porosity and permeability data of the same classified reservoirs in different regions, and obtaining the relationship between the different classified reservoirs by fitting as the relationship model. In detail, based on the logging phase analysis results, the core analysis results are classified. Because the fourth category is a non-effective reservoir, it will not be studied, such as Figure 4 As shown, the ordinate is the core permeability, in mD; the abscissa is the core porosity, in %. The fitting result is:

[0053] Type I reservoir:

[0054] Perm1=10 (0.29*por-3.78) (1)

[0055] Type II reservoir:

[0056] Perm2=10 (0.54*por-3.22) (2)

[0057] Three types of reservoirs:

[0058] Perm3=10 (1.06*por-2.23) (3)

[0059] Among them, Perm1, Perm2 and Perm3 are the first, second and third type of logging phase permeabilities respectively, in mD; por is the porosity, in %.

[0060] Step S103, based on the relationship model, the single-phase permeability corresponding to each classified reservoir is calculated; and each single-phase permeability is weightedly summed to obtain the formation permeability.

[0061] It should be noted that the weighted summation of the permeabilities of each single phase is only based on the proportion of different reservoirs (phases). Figure 1It can be seen that the permeability of any depth point is generally a combination of different proportions of multiple phases, so the formation permeability is the weighted sum of the permeabilities of each phase, and the weight coefficient is the proportion of each phase. Therefore, in its specific implementation, the weight coefficient is first set according to the proportion of different classified reservoirs in the formation in the preset area; then, based on the weight coefficient, the weighted sum of each single-phase permeability is obtained to obtain the formation permeability. Thus, the final result is obtained.

[0062] In addition, the above method fully considers the diversity of carbonate reservoir pore structure types and establishes a reservoir permeability calculation model for porous media. The effect of the invention was verified in 12 core wells in the study area, with a total of 3051 cores, as shown in Table 1 below. The average coincidence rate of the logging phase permeability calculation of the invention is 71.7%, while that of the conventional method is 38.4%, that is, the new invention method is 33.3% higher than the conventional method. The conventional method in the table is a method of directly regressing the permeability using the core porosity. Figure 5 The meaning of the PERM-CG curve in the eighth column is as follows: When the calculated permeability is within an order of magnitude of the core permeability, it is considered to be consistent.

[0063]

[0064] Table 1 Classification results of core porosity-permeability of logging phases

[0065] The above method has been applied in fracture-cavity carbonate reservoirs in Turkmenistan, Uzbekistan, Iraq, etc., and has achieved good results. Among them, the permeability of an exploration well on the right bank of the Amu Darya River in Turkmenistan was calculated and compared with the permeability calculated by conventional methods, nuclear magnetic permeability, and array acoustic wave permeability. Figure 5 As shown in the figure, it can be seen that compared with other methods, the permeability calculated by the present invention is more consistent with the core permeability. Figure 5In the first column, STRATIGRAPHY is the geological stratification; in the second column, Depth is the depth in m; in the third column, BS is the drill bit size in in, CAL is the borehole diameter in in, GR is the natural gamma in API; in the fourth column, RLLD is the deep resistivity in ohm·m, RLLS is the deep resistivity in ohm·m; in the fifth column, CNL is the neutron in %, DEN is the density in g / cm3, AC is the acoustic time difference in μs / ft, in the sixth column, SW is the water saturation in %, in the seventh column, POR is the porosity in %; in the eighth column, PERM-CG is the permeability calculated by conventional methods, in mD, CPERM is the core permeability, in mD (the same as in the ninth, tenth and eleventh columns); in the ninth column, PERM-CMR is the permeability calculated by nuclear magnetic resonance logging, in mD; in the tenth column, PERM-DSI is the permeability calculated by array sonic logging, in mD; in the eleventh column, PERM is the permeability calculated by the method of this paper, in mD; in the twelfth column, VSH is the mud content, in %, CALCITE is the limestone content, in %; in the thirteenth column, the logging phase calculation results; in the fourteenth column, the logging interpretation conclusions.

[0066] Based on the same inventive concept, an embodiment of the present invention provides a porous medium carbonate reservoir permeability acquisition system, such as Figure 6 As shown, including:

[0067] The logging phase analysis module 201 is used to perform logging phase analysis on a preset area using a logging curve with preset indicators as input.

[0068] Model building module 202, for classifying the logging phase reservoirs in the preset area according to the analysis results, and establishing a corresponding permeability and core porosity relationship model;

[0069] The permeability calculation module 203 calculates the single-phase permeability corresponding to each classified reservoir based on the relationship model; and performs weighted summation of each single-phase permeability to obtain the formation permeability.

[0070] Based on the same inventive concept, an embodiment of the present invention provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, a method for acquiring the permeability of a porous carbonate reservoir is implemented.

[0071] Based on the same inventive concept, this embodiment provides a computer-readable storage medium on which a computer program is stored, characterized in that when the program is executed by a processor, a method for obtaining the permeability of a porous carbonate reservoir is implemented.

[0072] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0073] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0074] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for obtaining the permeability of a porous carbonate reservoir, characterized in that: The method comprises: Taking the well logging curve of preset indicators as input, the well logging phase analysis is performed on the preset area; According to the analysis results, the logging phase reservoirs in the preset area are classified, and a corresponding permeability and core porosity relationship model is established; Based on the relationship model, the single-phase permeability corresponding to each classified reservoir is calculated; and the formation permeability is obtained by weighted summing up each single-phase permeability.

2. The method according to claim 1, characterized in that The step of using the well logging curve of the preset index as input also includes: Takes gamma curve, deep resistivity curve, sonic curve, density curve and neutron curve as input.

3. The method according to claim 1, characterized in that Before performing logging phase analysis on the preset area, the method further includes: A gas field with a well number within a preset range and core description data is selected, and the input logging curve is normalized and environmentally corrected.

4. The method according to claim 1, characterized in that The step of performing logging phase analysis on the preset area also includes: The hierarchical clustering method is used to conduct logging phase analysis on the preset area.

5. The method according to claim 1, characterized in that The step of establishing a corresponding permeability and core porosity relationship model also includes: The core porosity and permeability data of the same classified reservoirs in different regions are obtained, and the relationship equations of the different classified reservoirs are obtained by fitting as the relationship model.

6. The method according to claim 1, characterized in that The step of performing weighted summation of the single-phase permeabilities to obtain the formation permeability also includes: Setting weighting coefficients according to the proportions of different classified reservoirs in the strata within the preset area; Based on the weighting coefficient, each single-phase permeability is weighted and summed to obtain the formation permeability.

7. The method according to claim 1, characterized in that The step of classifying the logging phase reservoirs in the preset area also includes: According to the natural test of historical data and experimental data, the parameters corresponding to different production rates, dissolution and fracture development states of logging are divided into multiple classification reservoirs.

8. A porous medium carbonate reservoir permeability acquisition system, characterized in that: The system comprises: The logging phase analysis module is used to perform logging phase analysis on the preset area using the logging curve of the preset index as input. A model building module, for classifying the logging phase reservoirs in the preset area according to the analysis results, and establishing a corresponding permeability and core porosity relationship model; The permeability calculation module calculates the single-phase permeability corresponding to each classified reservoir based on the relationship model; and performs weighted summation of each single-phase permeability to obtain the formation permeability.

9. An electronic device, characterized in that: The electronic device comprises: a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the method steps described in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps corresponding to the method according to any one of claims 1 to 7 are implemented.

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