Calculation method and device for porosity of sandstone containing carbon chips and electronic equipment

Abstract

The invention relates to the technical field of petroleum and natural gas resource evaluation and exploitation, and discloses a method and device for calculating the porosity of sandstone containing carbon chips and electronic equipment. The method comprises the following steps: determining logging response characteristics of a sandstone layer section containing carbon chips; establishing a rock physical volume equation set and mineral content rock physical constraint conditions of the carbon scrap-containing sandstone reservoir; selecting reasonable mineral and fluid logging skeleton parameters; and solving the rock physical volume equation set to obtain the required logging porosity curve of the carbon-chip-containing sandstone reservoir. According to the technical scheme, the response characteristics of the core on a main logging curve are defined through development calibration of the carbon chips on the core, the carbon chips are added into the logging rock physical volume model, logging skeleton parameters of various minerals and fluids are preferably determined, the porosity calculation precision is remarkably improved, and the porosity calculation accuracy is improved. And a high-precision technical process for calculating the porosity of the sandstone section containing the carbon chips is provided for reservoir evaluation personnel.

Description

Technical Field

[0001] This invention relates to the field of oil and gas resource evaluation and exploitation technology, specifically to a method, apparatus and electronic equipment for calculating the porosity of carbonaceous sandstone, belonging to the geophysical logging calculation and evaluation technology for oil and gas reservoir porosity. Background Technology

[0002] Tight sandstone is widely distributed in major oil and gas basins worldwide, possessing enormous exploration and development potential, and is one of China's most important oil and gas producing formations. Typically, sandstone minerals mainly consist of quartz, feldspar, rock fragments, and carbonate minerals. However, due to various sedimentary and diagenetic processes, the presence of carbonaceous debris in sandstone is common in many regions. In the Xujiahe Formation of the Sichuan Basin, carbonaceous aggregates or bands are frequently found in sandstone cores. The presence of carbonaceous debris in sandstone leads to a significant increase in sonic transit time and the values ​​of the compensated neutron porosity curve.

[0003] Based on existing technologies, Liu Xuan et al. (Analysis of factors affecting the reservoir performance of tight sandstone reservoirs in the Shuixigou Group of the Turpan-Hami Basin, Journal of Northwest University, 2014, 44(3)) studied and explored the dual control effect of carbonaceous debris on reservoir compaction during sedimentation and diagenesis, as well as on reservoir properties during hydrocarbon generation, gas degassing, and fracture formation. However, the authors did not study how to use well logging data to continuously and quantitatively calculate the porosity of carbonaceous sandstone. Wang Honghui et al. (Study on Porosity Logging Interpretation of Low-Porosity Tight Sandstone in Xujiahe Formation, Sichuan Basin, Journal of Chengdu University of Technology, 2009, 36(3)) selected three porosity logging curves (sonic transit time, compensated neutron, compensated density) and natural gamma logging curves to establish a quaternary regression interpretation model for porosity. This model was used to interpret the porosity of tight sandstone in Xujiahe Formation in central and southern Sichuan and achieved certain application results. However, the model has two obvious limitations: First, the model does not consider the influence of carbon debris on sonic transit time and compensated neutron curves, which will inevitably cause a large deviation between the porosity calculated by logging in carbon debris-bearing sections and the actual situation in actual calculations. Second, the multiple regression method is based entirely on statistical theory. When calculating porosity, it often performs regression correlation analysis between the core measured values ​​and logging curves, without clear logging petrophysical significance, making it difficult to promote and apply in other blocks. Summary of the Invention

[0004] This invention provides a method, apparatus, and electronic device for calculating the porosity of carbonaceous sandstone, in order to solve the aforementioned technical problem of large errors in the calculation of porosity of carbonaceous sandstone in the prior art.

[0005] According to a first aspect of the present invention, a method for calculating the porosity of carbonaceous sandstone is provided, comprising:

[0006] Identify the logging response characteristics of carbonaceous sandstone intervals;

[0007] Establish the petrophysical volume equation set and mineral content petrophysical constraints for carbonaceous sandstone reservoirs;

[0008] Select appropriate mineral and fluid logging framework parameters;

[0009] Solve the set of rock physical volume equations to obtain the required well logging porosity curves for the carbonaceous sandstone reservoir.

[0010] Preferably, in clarifying the logging response characteristics of carbonaceous sandstone intervals, based on clarifying the carbonaceous deposition and diagenetic mechanism, the development characteristics of carbonaceous debris on cores from multiple wells and their response characteristics on logging curves are studied, and the response characteristics of carbonaceous sandstone on at least one of the curves of gamma, sonic transit time, neutron, and dual lateral resistivity are summarized.

[0011] Preferably, in the rock physical volume equation set, the logging measurement values ​​of each curve are equivalent to the superposition of the contribution of each mineral and its actual volume content to the logging response.

[0012] Preferably, the rock physical constraints include:

[0013] Based on the fact that the total volume of all minerals and fluids is 100%, the calculated volume content of each mineral and fluid ranges between 0 and 100%.

[0014] Preferably, in selecting reasonable mineral and fluid logging framework parameters, the logging curve characteristics of carbonaceous sandstone and other mineral framework parameter values ​​are deduced through comprehensive analysis of the sandstone carbonaceous detritus development area.

[0015] Preferably, the rock physical volume equations are solved by combining the identification results of carbonaceous debris layers on the well logging curve with error iterative optimization.

[0016] Preferably, in solving the set of rock physical volume equations, the errors of each curve obtained by inversion calculation and the measured curve are compared. When the total error is minimized and the mineral content and porosity results meet the conditions, the result is output. If the conditions are not met, the fluid logging skeleton parameters are fine-tuned until a porosity calculation result that meets the conditions is output.

[0017] According to a second aspect of the present invention, an apparatus for calculating the porosity of carbonaceous sandstone is provided, comprising:

[0018] A specific module is defined to identify the logging response characteristics of carbonaceous sandstone formations;

[0019] A module is established to create a set of petrophysical volume equations and petrophysical constraints on mineral content for carbonaceous sandstone reservoirs.

[0020] The selection module is used to select appropriate mineral and fluid logging framework parameters; and

[0021] The solution module is used to solve the set of rock physical volume equations to obtain the required well logging porosity curves of the carbonaceous sandstone reservoir.

[0022] According to a third aspect of the present invention, an electronic device is provided, comprising:

[0023] Memory; and

[0024] processor;

[0025] The memory is used to store one or more computer instructions; the one or more computer instructions are executed by the processor to implement the method described in any of the above.

[0026] According to a fourth aspect of the present invention, a readable storage medium is provided, wherein computer instructions are stored thereon; wherein, when executed by a processor, the computer instructions implement the method described in any of the preceding claims.

[0027] The technical solution of this invention clarifies the response characteristics of carbon debris on the main logging curves by calibrating the development of carbon debris on the core, and adds carbon debris to the logging rock physical volume model, thereby optimizing and determining the logging framework parameters of various minerals and fluids, which significantly improves the accuracy of porosity calculation and provides reservoir evaluation personnel with a high-precision calculation process for the porosity of carbon debris-bearing sandstone sections. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating a method for calculating the porosity of carbonaceous sandstone in one embodiment;

[0029] Figure 2 This is a response characteristic map of a carbonaceous sandstone core and its logging curve in one embodiment;

[0030] Figure 3 This is a schematic diagram of the structure of a device for calculating the porosity of carbonaceous sandstone in one embodiment;

[0031] Figure 4 This is a comparative diagram of porosity evaluation in well DF102 of the fifth section of the Zhongfengchang Formation in Sichuan Province, as an example.

[0032] Figure 5 This is a schematic diagram illustrating the comparison of porosity evaluation in well XC12 of the second section of the Xinchang section in western Sichuan, as one embodiment. Detailed Implementation

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0035] It should be noted that the terms "first," "second," etc., used in this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate for the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0036] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element present. Moreover, in this invention, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.

[0037] Example 1

[0038] Please refer to Figure 1 , 2 This embodiment provides a method for calculating the porosity of carbonaceous sandstone, including the following steps:

[0039] S1. Determine the logging response characteristics of carbonaceous sandstone intervals;

[0040] S2. Establish the petrophysical volume equation set and mineral content petrophysical constraints for carbonaceous sandstone reservoirs;

[0041] S3. Select appropriate mineral and fluid logging framework parameters;

[0042] S4. Solve the set of rock physical volume equations to obtain the required well logging porosity curves for the carbonaceous sandstone reservoir.

[0043] In one embodiment, in step S1, in view of the current situation that existing research and evaluation methods do not consider the influence of carbon debris and its content, based on clarifying the carbon debris deposition and diagenetic mechanism, the development characteristics of carbon debris on the core of multiple wells and its response characteristics on the logging curves are studied, and the response characteristics of carbon debris-bearing sandstone on at least one of the curves of gamma, sonic transit time, neutron and dual lateral resistivity are summarized.

[0044] Specifically, in carbonaceous sandstone, layered or dispersed dark carbonaceous debris is visible in the core. Due to the weak compressive strength and easy fracturing and deformation of the carbonaceous debris itself, the core is easily broken along the carbonaceous debris development surface after core extraction. The broken surface clearly shows dark, shiny, greasy-looking carbonaceous debris. The corresponding logging characteristics are: no significant gamma change, a significant increase in sonic transit time, a tendency for neutron density to increase, and an increase in resistivity instead of a decrease (e.g., ...). Figure 2 As shown in the figure, this is mainly because the carbon chip skeleton itself has the characteristics of high porosity curve and high resistivity. Through these characteristics, carbon chip-containing segments can be effectively identified.

[0045] Figure 2 In the core, layered and dispersed carbon debris is continuously developed at a depth of 1637-1643m, and the carbon debris with a black, shiny, greasy luster is obvious on the cross-section.

[0046] In one embodiment, in the rock physical volume equation set of step S2, the logging measurement values ​​of each curve are equivalent to the superposition of the contribution of each mineral and its actual volume content to the logging response. Preferably, the rock physical constraints include: based on the cumulative sum of the volumes of all minerals and fluids being 100%, the calculated volume content values ​​of each mineral and fluid are between 0 and 100%.

[0047] In detail, core observations and laboratory analysis data indicate that the minerals in the tight sandstone of the Xujiahe Formation (example) in western Sichuan are mainly composed of clay, quartz, feldspar + rock fragments, and carbonaceous fragments. The fluids consist of formation water and natural gas, with virtually no crude oil. Based on this, the rock physics logging volume equation set (logging response equation set) shown in Formula 1 is established. The logging measurements of each curve are equivalent to the superposition of the contribution of each mineral and its actual volume content to the logging response (where the two-way lateral resistivity RD and RS responses are nonlinear, and the expression in the formula is a series equivalent illustration). In addition, in order for the volume equation set to be solved correctly, rock physics constraints need to be imposed, including requiring that the cumulative sum of the volumes of all minerals and fluids be 100% (with a value of 1), and that the calculated volume content of each mineral and fluid be between 0 and 100% (see Formula 2).

[0048] GR = GR clay ·V clay +GR quartz ·Vquartz +GR feld ·In feld +GR carbon ·In carbon +GR water ·In water +GR gas ·In gas

[0049] AC=AC clay ·In clay +AC quartz ·In quartz +AC feld ·In feld +AC carbon ·In carbon +AC water ·In water +AC gas ·In gas

[0050] DAY=DAY clay ·In clay +DAY quartz ·In quartz +DAY feld ·In feld +DAY carbon ·In carbon +DAY water ·In water +DAY gas ·In gas

[0051] CNL=CNL clay ·In clay +CNL quartz ·In quartz +CNL feld ·In feld +CNL carbon ·In carbon +CNL water ·In water +CNL gas ·In gas

[0052] RD=RD clay ·In clay +RD quartz ·In quartz +RD feld ·In feld +RD carbon ·In carbon +RD water ·In water +RD gas ·Ingas

[0053] RS = RS clay ·V clay +RS quartz ·V quartz +RS feld ·V feld +RS carbon ·V carbon +RS water ·V water +RS gas ·V gas Formula 1

[0054] V clay +V quartz +V feld +V carbon +V water +V gas =1

[0055] Min(V clay V quartz V feld V carbon V water V gas )≥0

[0056] Max(V clay V quartz V feld V carbon V water V gas )≤1 Formula 2

[0057] In both formulas, GR represents natural gamma, V represents volume content, AC represents acoustic transit time, DEN represents volume density, CNL represents compensated neutrons, RD represents deep resistivity, and RS represents shallow resistivity. Regarding subscripts, clay indicates clay content, such as GR. clay This indicates the natural gamma value corresponding to the clay skeleton; quartz indicates the quartz content, such as GR. quartz This indicates the natural gamma value corresponding to the quartz framework; the rest follow the same pattern; feld indicates the content of feldspar and rock fragments, carbon indicates the content of carbon fragments, water indicates the content of water, and gas indicates the content of natural gas. All the above contents are volume percentages, and the total volume of clay, quartz, feldspar, rock fragments, carbon fragments, water, and natural gas is 1 (i.e., 100%).

[0058] In one embodiment, in step S3, through comprehensive analysis of the carbonaceous detritus development area of ​​sandstone, the logging curve characteristics of carbonaceous sandstone and other mineral framework parameter values ​​are deduced. As an example, through comprehensive comparison of geological understanding of the carbonaceous detritus development area of ​​tight sandstone in the Sichuan Basin, the sedimentary evolution of carbonaceous detritus, and the logging response characteristics of carbonaceous mudstone, the logging curve characteristics of carbonaceous sandstone and other mineral framework parameter values ​​are deduced, as shown in Table 1.

[0059] Table 1 Selection of mineral and fluid framework parameters for carbonaceous sandstone sections

[0060]

[0061] In one embodiment, in step S4, the identification results of carbonaceous debris-bearing layers on the logging curves are used to iteratively optimize the solution of the rock physical volume equations. Further, in solving the rock physical volume equations, the errors of each curve obtained from the inversion calculation and the measured curves are compared. When the total error is minimized and the mineral content and porosity results meet the conditions, the result is output; if the conditions are not met, the fluid logging framework parameters are fine-tuned until a porosity calculation result that meets the conditions is output.

[0062] This invention provides a method for calculating the porosity of carbonaceous sandstone. Starting from the origin of carbonaceous debris and its response characteristics in core samples and well logging curves, it establishes a method for calculating reservoir porosity by selecting appropriate framework parameters and solving the well logging rock physics volume equations. When sandstone contains carbonaceous debris, it leads to a significant increase in sonic transit time and the values ​​of the compensated neutron porosity curve. If the influence of carbonaceous debris and its content is not considered during well logging evaluation of reservoir porosity, and no carbonaceous debris correction is performed, the calculated porosity will be too high. This will interfere with reservoir type classification and the selection of sweet spot zones, further affecting the selection of gas testing zones and the final fracturing and gas production effects.

[0063] Furthermore, the calculation results before and after correction were compared with the core measurement results by error analysis (as shown in Table 2). The accuracy of the porosity calculation results was significantly improved, which significantly improved the reservoir porosity calculation effect of carbonaceous sandstone.

[0064] Table 2. Porosity Error Analysis of Carbonaceous Sandstone Formations

[0065]

[0066] Example 2

[0067] Please refer to Figure 3 One embodiment provides a device for calculating the porosity of carbonaceous sandstone, the structure of which includes:

[0068] 1. Define the modules

[0069] Module 10 is used to define the logging response characteristics of carbonaceous sandstone intervals;

[0070] 2. Create modules

[0071] Module 20 is used to establish the petrophysical volume equation set and mineral content petrophysical constraints for carbonaceous sandstone reservoirs.

[0072] 3. Select Module

[0073] Module 30 is used to select appropriate mineral and fluid logging framework parameters;

[0074] 4. Solver Module

[0075] The solver module 40 is used to solve the set of rock physical volume equations to obtain the required logging porosity curves of the carbonaceous sandstone reservoir.

[0076] In one embodiment, in the rock physical volume equation set of the establishment module 20, the logging measurement values ​​of each curve are equivalent to the superposition of the contribution of each mineral and its actual volume content to the logging response. The rock physical constraints include: based on the cumulative sum of the volumes of all minerals and fluids being 100%, the calculated volume content values ​​of each mineral and fluid are between 0 and 100%.

[0077] It should be noted that the above-mentioned calculation device for the porosity of carbonaceous sandstone is used to implement the calculation method for the porosity of carbonaceous sandstone in the above embodiments, and each module in the device corresponds to each step in the method.

[0078] Example 3

[0079] Based on the same inventive concept, one embodiment of the present invention provides an electronic device, including: a memory and a processor; wherein the memory is used to store one or more computer instructions; the one or more computer instructions are executed by the processor using any of the methods described in the above embodiments.

[0080] Example 4

[0081] Based on the same inventive concept, one embodiment of the present invention provides a readable storage medium storing computer instructions; wherein, when the computer instructions are executed by a processor, they implement the method of any one of the above embodiments.

[0082] One or more of the aforementioned computer instructions can form a program.

[0083] The aforementioned program can run on a processor or be stored in memory (or computer-readable medium). Computer-readable medium includes both permanent and non-permanent, removable and non-removable media, and information storage can be achieved by any method or technology. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable medium does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0084] These computer programs may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes can be implemented using different modules, and different steps can be implemented using different modules.

[0085] Example 5

[0086] Please refer to Figure 4 , 5 This embodiment provides a method for calculating the porosity of carbonaceous sandstone. The following application case illustrates this method to further understand its technical content.

[0087] The method for calculating the porosity of carbonaceous sandstone is as follows: First, the logging response characteristics of the carbonaceous sandstone interval are clarified; second, the petrophysical volume equation set and physical constraints of mineral content for the carbonaceous sandstone reservoir are established; third, the mineral and fluid logging framework parameters are selected; finally, the petrophysical volume equation set is solved by error iteration optimization to obtain the required logging porosity curve of the carbonaceous sandstone reservoir.

[0088] This method for calculating the porosity of carbonaceous sandstone considers the influence of carbonaceous material and corrects for carbonaceous logging responses. It has been applied to the porosity evaluation of tight sandstone in the Xuwu Member of the Zhongdongfengchang Formation and the Xuer Member of the Xinchang Formation in the western Sichuan Basin. First, the target formation is identified. Based on the characteristics of carbonaceous sandstone compared to the surrounding rock—significantly increased sonic waves, increased neutron activity, increased resistivity instead of decreasing, and insignificant gamma changes—its development is determined. Then, reasonable mineral and fluid framework parameters are selected, and under rock physics constraints, the rock physics logging volume equations are optimally solved to obtain the calculated mineral content and porosity. The implementation of this technical solution shows that the method has achieved good application results in both the Xuer and Xuwu Members (e.g., ...). Figure 4 , Figure 5 (As shown in the figure). The comparison between the porosity calculation results and the measured values ​​of core physical properties shows that the calculation error is significantly reduced and the calculation accuracy is significantly improved, providing technical support for the fine quantitative evaluation of reservoirs.

[0089] The present invention provides a method for calculating the porosity of carbonaceous sandstone. Based on a clear understanding of the logging response characteristics of carbonaceous sandstone, and by selecting accurate mineral framework parameters and simultaneously solving a set of logging petrophysical volume equations, a technical process for calculating reservoir porosity by correcting for the influence of carbonaceous material and its content is established. Applying this method significantly improves the accuracy of porosity calculation results and substantially enhances the effectiveness of calculating reservoir porosity in carbonaceous sandstone.

[0090] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for calculating the porosity of carbonaceous sandstone, characterized in that, include: Identify the logging response characteristics of carbonaceous sandstone intervals; Establish the petrophysical volume equation set and mineral content petrophysical constraints for carbonaceous sandstone reservoirs; Select appropriate mineral and fluid logging framework parameters; Solve the set of rock physical volume equations to obtain the required well logging porosity curves for the carbonaceous sandstone reservoir.

2. The method for calculating the porosity of carbonaceous sandstone according to claim 1, characterized in that, The well logging response characteristics of the carbonaceous sandstone strata are defined. Based on the understanding of carbonaceous deposition and diagenesis mechanisms, the development characteristics of carbonaceous debris on core samples from multiple wells and their response characteristics on well logging curves are studied. The response characteristics of carbonaceous sandstone on at least one of the curves of gamma, sonic transit time, neutron, and dual lateral resistivity are summarized.

3. The method for calculating the porosity of carbonaceous sandstone according to claim 1, characterized in that, In the rock physical volume equation set, the logging measurements of each curve are equivalent to the superposition of the contribution of each mineral and its actual volume content to the logging response.

4. The method for calculating the porosity of carbonaceous sandstone according to claim 1 or 3, characterized in that, The rock physical constraints include: Based on the fact that the total volume of all minerals and fluids is 100%, the calculated volume content of each mineral and fluid ranges between 0 and 100%.

5. The method for calculating the porosity of carbonaceous sandstone according to claim 1, characterized in that, In selecting reasonable mineral and fluid logging framework parameters, the logging curve characteristics of carbonaceous sandstone and other mineral framework parameter values ​​are deduced through comprehensive analysis of the carbonaceous sandstone development area.

6. The method for calculating the porosity of carbonaceous sandstone according to claim 1, characterized in that, Based on the identification results of carbonaceous debris layers on the well logging curves, the rock physical volume equations are solved by error iterative optimization.

7. The method for calculating the porosity of carbonaceous sandstone according to claim 1 or 6, characterized in that, In solving the set of rock physical volume equations, the errors of each curve obtained by inversion calculation and the measured curve are compared. When the total error is minimized and the mineral content and porosity results meet the conditions, the result is output. If the conditions are not met, continue to fine-tune the fluid logging framework parameters until a porosity calculation result that meets the conditions is output.

8. A device for calculating the porosity of carbonaceous sandstone, characterized in that, include: A specific module is defined to identify the logging response characteristics of carbonaceous sandstone formations. A module was established to establish the petrophysical volume equation set and mineral content petrophysical constraints for carbonaceous sandstone reservoirs. The selection module is used to select appropriate mineral and fluid logging framework parameters; and The solution module is used to solve the set of rock physical volume equations to obtain the required well logging porosity curves of the carbonaceous sandstone reservoir.

9. An electronic device, characterized in that, include: Memory; and processor; The memory is used to store one or more computer instructions; the one or more computer instructions are executed by the processor to implement the method according to any one of claims 1 to 7.

10. A readable storage medium, characterized in that, The readable storage medium stores computer instructions; wherein, when executed by a processor, the computer instructions implement the method described in any one of claims 1 to 7.

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