Method and system for judging carbonate cement enrichment section of clastic rock reservoir and storage medium
By calculating the relative content indicator curve of carbonate cement and identifying the carbonate cement enrichment section, the problem of inaccurate identification of carbonate cement enrichment sections in clastic reservoirs in the prior art is solved, and the accuracy of reservoir evaluation is improved.
Patent Information
- Application Number
- CN202510290813.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-12
- Publication Date
- 2025-06-24
AI Technical Summary
The prior art is difficult to accurately identify the carbonate cement-enriched sections in clastic rock reservoirs, resulting in errors in reservoir evaluation and high-quality reservoir identification.
By obtaining the resistivity value, density value and acoustic time difference of sandstone in the clastic rock formation, the carbonate cement relative content indicator curve was calculated, and the straight section in the curve was used as the baseline to identify the carbonate cement enrichment section.
It improves the identification accuracy of oil (gas) layers and carbonate cement enrichment sections, and enhances the accuracy of reservoir evaluation and high-quality reservoir identification.
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Figure CN120195767A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical fields of oil logging and reservoir evaluation, and more particularly to a method, system and storage medium for judging the enrichment section of carbonate cements in clastic rock reservoirs. Background Art
[0002] Carbonate cements are one of the main cement types in clastic rock reservoirs and are one of the important reasons for the deterioration of reservoir quality and even the formation of tight reservoirs. Judging the development characteristics of carbonate cements in reservoirs is of great significance for the identification of high-quality reservoirs and reservoir evaluation.
[0003] Through testing means such as rock thin section identification and X-ray diffraction whole rock mineral analysis, the content of carbonate cements can be determined quantitatively or semi-quantitatively. However, due to the limited number of rock samples and the fact that drilling cores are mainly concentrated in the oil and gas layers, relying solely on experimental data is not sufficient to fully grasp the vertical development characteristics of carbonate cements in reservoirs.
[0004] Well logging data is a comprehensive response of mineral content, pores, fractures, fluids (oil, gas, water), organic matter, pressure, etc. in the formation. Therefore, the abnormal response of well logging also has multiple solutions. For example, oil layers, gas layers, organic-rich mudstones, coal seams, and carbonate cement enrichment sections all show high resistivity characteristics, while oil layers, gas layers, organic-rich mudstones, and coal seams show low density characteristics. Identifying carbonate cement enrichment sections only using resistivity logging may lead to incorrect interpretation of oil (gas) layers; there are differences in the calibration ranges of different well logging series or well logging data from different sources, and there is also a risk of error when using the threshold values of combined well logging curves to judge carbonate cement enrichment layers.
[0005] Reservoirs with different lithologies or fluid types all have problems of high resistivity or inconsistent well logging curve calibration ranges, which may cause incorrect identification of carbonate cement enrichment sections, resulting in misidentifying oil (gas) layers as carbonate cement enrichment sections or misidentifying carbonate cement enrichment sections as oil (gas) layers. The above results will all have an adverse impact on reservoir evaluation or the identification of high-quality reservoirs. Summary of the Invention
[0006] In view of the above problems, the present invention provides a method, system and storage medium for judging the enrichment section of carbonate cements in clastic rock reservoirs. The judging method of the present invention can accurately identify the enrichment section of carbonate cements.
[0007] The first object of the present invention is to provide a method for judging the enrichment section of carbonate cements in clastic rock reservoirs, including the following steps:
[0008] Obtain the resistivity value, density value, and acoustic travel time difference of sandstone in the clastic rock formation within the target interval; obtain the relative content of carbonate cement in the sandstone within the target interval based on the resistivity value, density value, and acoustic travel time difference of the sandstone; draw the relative content indication curve of carbonate cement within the target interval according to the relative content of carbonate cement.
[0009] Take the straight section in the relative content indication curve of carbonate cement as the baseline. When the relative content of carbonate cement in the relative content indication curve of carbonate cement is greater than the baseline value, and the interval with the largest offset amplitude is the carbonate cement enrichment section.
[0010] In a preferred embodiment of the present invention, the relative content Log of carbonate cement carbonate The calculation formula is:
[0011]
[0012] Wherein, R is the resistivity value; DEN is the density value; Δt is the acoustic travel time difference.
[0013] In a preferred embodiment of the present invention, compared with the baseline, if the relative content of carbonate cement in the relative content indication curve of carbonate cement is less than or close to the baseline value, it is the low carbonate cement content section, and the actual measured content of carbonate cement in the low carbonate cement content section accounts for less than 5% of the rock volume percentage. It should be noted that 5% is an empirical value obtained based on the statistical results of the measured carbonate cement content, and this empirical value may vary in different regions.
[0014] In a preferred embodiment of the present invention, the calculation method is to perform calculations using the calculation functions of Excel software, Gxplore software, Forward software, or Petrel software.
[0015] In a preferred embodiment of the present invention, the resistivity value is the true formation resistivity value. Specifically, the deep induction resistivity value or deep lateral resistivity value is used.
[0016] In a preferred embodiment of the present invention, the depth range of the target interval is 1777m to 1847m.
[0017] In a preferred embodiment of the present invention, the depth range of the target interval is 3227m to 3519m.
[0018] The second object of the present invention is to provide a system for judging the carbonate cement enrichment section of a clastic rock reservoir, which is used to execute the steps of the method for judging the carbonate cement enrichment section of a clastic rock reservoir, including a data acquisition module, a data processing module, a data calculation module, and an evaluation module.
[0019] A data acquisition module is used to acquire the resistivity value, density value, and acoustic time difference value of sandstone in the clastic rock formation within the target interval.
[0020] A data processing module is used to calculate the relative content of carbonate cement in the sandstone within the target interval based on the acquired resistivity value, density value, and acoustic time difference value, and obtain an indicator curve of the relative content of carbonate cement.
[0021] An evaluation module is used to determine the position of the carbonate cement enrichment section by taking the indicator curve of the relative content of carbonate cement as a judgment index.
[0022] The third object of the present invention is to provide a storage medium storing one or more programs, which can be executed by one or more processors to implement the steps in the method for determining the carbonate cement enrichment section of the clastic rock reservoir as described above.
[0023] Compared with the prior art, the present invention has the following beneficial effects:
[0024] The present invention utilizes the high resistivity, high density, and low acoustic time difference characteristics of the carbonate cement enrichment section, and the high resistivity, high acoustic time difference, and low density characteristics of the oil (gas) layer, and calculates the indicator curve of the relative content of carbonate cement. The value of the relative content indicator curve corresponding to the oil (gas) layer is less than or close to the baseline value, and the value of the relative content indicator curve corresponding to the carbonate cement enrichment section is greater than the baseline value and far from the baseline, improving the accuracy of identifying the oil (gas) layer and the carbonate cement enrichment section, which is of great significance for reservoir evaluation and identification of high-quality reservoirs. Description of the Drawings
[0025] Figure 1 It is a crossplot of carbonate cement content, resistivity, acoustic time difference, and density, where a is the relationship diagram between carbonate cement content and resistivity, b is the relationship diagram between carbonate cement content and density, and c is the relationship diagram between carbonate cement content and acoustic time difference.
[0026] Figure 2 It is a comprehensive histogram of resistivity, density, acoustic time difference, carbonate cement content, and the indicator curve of the relative content of carbonate cement in Example 2.
[0027] Figure 3 It is a comprehensive histogram of resistivity, density, acoustic time difference, carbonate cement content, and the indicator curve of the relative content of carbonate cement in Example 3. Detailed Embodiments
[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.
[0029] Embodiment 1
[0030] (1) Obtain the resistivity log curve, density log curve, and acoustic travel time log curve of the target layer. The resistivity value is the true resistivity value (Rt) of the formation. It should be noted that the resistivity log curve can be a resistivity log curve such as the deep induction resistivity value (RILD) or the deep lateral resistivity value (RLLD), and the acoustic travel time log curve can be an AC or DT acoustic travel time log curve.
[0031] Obtain the relative content indication curve of carbonate cement based on the resistivity log curve, density log curve, and acoustic travel time log curve.
[0032] The carbonate cement enrichment section mainly appears at the bottom and top of the sandstone, especially at the bottom of the sandstone section. As the content of carbonate cement increases, the resistivity value and density value tend to increase, and the acoustic travel time value tends to decrease, that is, the logging response of the carbonate cement enrichment section has the characteristics of high resistivity value, high density value, and low acoustic travel time, as shown in Figure 1 a, b, and c in the figure. Using the above characteristics, a new logging curve, that is, the relative content indication curve of carbonate cement Log carbonate .
[0033] The relative content of carbonate cement is calculated by the following formula:
[0034]
[0035] where Log carbonate is the relative content of carbonate cement, dimensionless; R is the resistivity, Ω·m; DEN is the density, g / cm 3 ; Δt is the acoustic travel time, μs / m or μs / ft.
[0036] Using the above formula, the relative content of carbonate cement can be obtained through the calculation function of Excel, or the relative content indication curve of carbonate cement can be obtained using the built-in calculation function in professional software such as Gxplore, Forward, and Petrel.
[0037] Taking the low-value flat section of the relative content indication curve of carbonate cements as the baseline, compared with the baseline, if the relative content of carbonate cements in the relative content indication curve of carbonate cements is less than or close to the baseline value (the indication curve is left-biased or close to the baseline relative to the baseline), it is the low carbonate cement content section; compared with the baseline, if the relative content of carbonate cements in the relative content indication curve of carbonate cements is much greater than the baseline value (the indication curve is right-biased and has the largest amplitude relative to the baseline), it is the carbonate cement enrichment section.
[0038] It should be noted that for clastic rock formations, the resistivity logging curve, density logging curve, and acoustic time difference logging curve in the present invention can be obtained from logging data.
[0039] Example 2
[0040] (1) For a well drilled in an oilfield in eastern China, the RILD logging curve, density logging curve, and AC acoustic time difference logging curve of the target layer of this well were obtained.
[0041] The relative content indication curve of carbonate cements was obtained based on the resistivity logging curve, density logging curve, and acoustic time difference logging curve, as Figure 2 .
[0042] The relative content of carbonate cements was calculated by the following formula:
[0043]
[0044] where Log carbonate is the relative content of carbonate cements, dimensionless; R is the resistivity, with the unit of Ω·m; the resistivity used in this example is the deep induction resistivity (RILD); DEN is the density, with the unit of g / cm 3 ; Δt is the acoustic time difference, and the acoustic time difference used in this example is DT, with the unit of μs / ft.
[0045] Taking the low-value flat section of the relative content indication curve of carbonate cements as the baseline, compared with the baseline, if the relative content of carbonate cements in the relative content indication curve of carbonate cements is less than or close to the baseline value, that is, Figure 2 the relative content indication curve of carbonate cements in
[0046] is left-biased or close to the baseline relative to the baseline, it is the low carbonate cement content section. Figure 2 Compared with the baseline, the layer section where the relative content of carbonate cements in the relative content indication curve of carbonate cements is greater than the baseline value and has the largest deviation amplitude, that is,
[0047] According to this result, the relative content indication curve of carbonate cements in the depth interval of 3227 - 3233 m is deflected to the right relative to the baseline and the deflection amplitude is large. It is predicted that the above depth interval is an enrichment section of carbonate cements. According to Figure 2 the measured results of carbonate cements in
[0048] it is known that the measured content of carbonate cements at 3231 m is 6%, which is higher than other measured data points in its upper and lower ranges (within 3188 - 3272 m). The predicted enrichment section is basically consistent with the measured data. Figure 2 the measured results of carbonate cements in
[0049] In the depth interval of 3448 - 3453 m, the relative content indication curve of carbonate cements is deflected to the right relative to the baseline and the deflection amplitude is large. It is predicted that the above depth interval is an enrichment section of carbonate cements. According to
[0050] Example 3
[0051] (1) For a well drilled in a gas field in western China, the RILD logging curve, density logging curve, and AC acoustic travel time logging curve of the target layer of this well are obtained.
[0052] The relative content indication curve of carbonate cements is obtained based on the resistivity logging curve, density logging curve, and acoustic travel time logging curve, as shown in Figure 3 .
[0053] The relative content of carbonate cements is calculated by the following formula:
[0054]
[0055] where Log carbonate is the relative content of carbonate cements, dimensionless; R is the resistivity, in units of Ω·m; the resistivity used in this example is the deep induction resistivity (RILD); DEN is the density, in units of g / cm 3 ; Δt is the acoustic travel time, and the acoustic travel time used in this example is AC, in units of μs / m.
[0056] Taking the low - value flat section of the relative content indication curve of carbonate cements as the baseline, compared with the baseline, the relative content of carbonate cements in the relative content indication curve of carbonate cements is less than or close to the baseline value, that is Figure 3If the relative content indication curve of carbonate cements is left - skewed relative to the baseline or close to the baseline, it is a low - carbonate - cement - content section.
[0057] Compared with the baseline, the relative content of carbonate cements in the relative content indication curve of carbonate cements is much greater than the baseline value, and the section with the largest deviation amplitude, that is Figure 3 If the relative content indication curve of carbonate cements is right - skewed relative to the baseline and has the largest right - skewed amplitude, it is a carbonate - cement - enrichment section.
[0058] According to this result, in the depth range of 1777.8 - 1781.3m, the relative content indication curve of carbonate cements is right - skewed relative to the baseline and has a large right - skewed amplitude. It is predicted that the above - mentioned depth section is a carbonate - cement - enrichment section. According to Figure 3 the measured results of carbonate cements in [], it can be known that the measured carbonate - cement content at 1780.95m is 20%, which is higher than the measured data points in its lower part (in the range of 1777.48 - 1785.38m). The prediction result is basically consistent with the measured data.
[0059] In the depth ranges of 1798.5 - 1799.7m and 1800.6 - 1801.5m, the relative content indication curve of carbonate cements is right - skewed relative to the baseline and has a large right - skewed amplitude. It is speculated that the above - mentioned depth sections are carbonate - cement - enrichment sections.
[0060] In the depth range of 1812.15 - 1813.31m, the relative content indication curve of carbonate cements is right - skewed relative to the baseline and has a large right - skewed amplitude. It is speculated that the above - mentioned depth section is a carbonate - cement - enrichment section. According to Figure 3 the measured results of carbonate cements in [], it can be known that the measured carbonate - cement content at 1812.5m is 10%, which is the highest value of the measured data in this section. The depth range of the curve peak basically corresponds to 1812.5m.
[0061] In the depth range of 1817.61 - 1819.14m, the relative content indication curve of carbonate cements is right - skewed relative to the baseline and has a large amplitude. It is speculated that the above - mentioned depth section is a carbonate - cement - enrichment section.
[0062] In the depth range of 1839.5 - 1847.1m, the relative content indication curve of carbonate cements is right - skewed relative to the baseline and has a large amplitude. The right - skewed amplitude is the largest within 1845.4 - 1847m. It is speculated that this depth section is a carbonate - cement - enrichment section.
[0063] Example 4
[0064] This example provides a system for judging the carbonate - cement - enrichment section of clastic rock reservoirs. The system includes a data acquisition module, a data processing module, a data calculation module, and an evaluation module.
[0065] The data acquisition module, the data processing module, the data calculation module, and the evaluation module are connected in sequence.
[0066] The data acquisition module is used to acquire the resistivity value, density value, and acoustic travel time difference of sandstone in the clastic rock formation within the target interval.
[0067] The data processing module is used to calculate the relative content of carbonate cement in the sandstone within the target interval based on the acquired resistivity value, density value, and acoustic travel time difference, and obtain the relative content indication curve of carbonate cement. For example, the calculation function of software such as Excel, Gxplore, Forward, and Petrel is used to calculate the relative content of carbonate cement, and the relative content indication curve of carbonate cement is plotted.
[0068] The evaluation module is used to judge the position of the carbonate cement enrichment section with the relative content indication curve of carbonate cement as the judgment index.
[0069] Embodiment 5
[0070] This embodiment provides a storage medium. The storage medium can be a common storage device, such as a hard disk, a solid-state drive, a USB flash drive, or an optical disc. The storage medium stores a computer program, and the computer program can be executed by a processor to implement the steps in the method for judging the carbonate cement enrichment section in the clastic rock reservoir in Embodiment 1.
[0071] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.
[0072] Obviously, those skilled in the art can make various changes and deformations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and deformations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and deformations.
Claims
1. A method for determining carbonate cement-rich sections in clastic reservoirs, characterized in that: The following steps are involved: Obtain the resistivity value, density value and acoustic wave time difference value of the sandstone of the clastic rock formation in the target layer; obtain the relative content of carbonate cement in the sandstone in the target layer through the resistivity value, density value and acoustic wave time difference value of the sandstone of the clastic rock formation in the target layer; and draw an indicator curve of the relative content of carbonate cement in the target layer according to the relative content of carbonate cement; The straight section in the carbonate cement relative content indicator curve is used as the baseline. When the carbonate cement relative content in the carbonate cement relative content indicator curve is greater than the baseline value and the layer with the largest deviation amplitude is the carbonate cement-rich section.
2. A method for determining carbonate cement-rich sections in clastic reservoirs according to claim 1, characterized in that: Relative content of carbonate cement Log carbonate The calculation formula is: Where R is the resistivity value; DEN is the density value; Δt is the acoustic time difference.
3. The method for determining the carbonate cement-rich section of a clastic reservoir according to claim 1, characterized in that: Compared with the baseline, if the relative content of carbonate cement in the carbonate cement relative content indicator curve is less than or close to the baseline value, it is a low carbonate cement content section, and the actual tested content of carbonate cement in the low carbonate cement content section accounts for less than 5% of the rock volume.
4. The method for determining the carbonate cement-rich section of a clastic reservoir according to claim 1, characterized in that: The calculation method is to use the calculation function of Excel software, Gxplore software, Forward software or Petrel software.
5. The method for determining the carbonate cement-rich section of a clastic reservoir according to claim 1, characterized in that: The resistivity value is the true resistivity value of the formation.
6. The method for determining the carbonate cement-rich section of a clastic reservoir according to claim 1, characterized in that: The depth range of the target layer is 1777m to 1847m.
7. The method for determining the carbonate cement-rich section of a clastic reservoir according to claim 1, characterized in that: The depth range of the target layer is 3227m~3519m.
8. A system for determining carbonate cement-rich sections in clastic reservoirs, used to execute the steps of the method for determining carbonate cement-rich sections in clastic reservoirs as claimed in any one of claims 1 to 7, characterized in that: It includes data acquisition module, data processing module, data calculation module and evaluation module; The data acquisition module is used to collect the resistivity value, density value and acoustic wave time difference value of the clastic rock formation sandstone in the target layer; A data processing module is used to calculate the relative content of carbonate cement in the sandstone in the target layer according to the collected resistivity value, density value and acoustic wave time difference value, and obtain a relative content indicator curve of carbonate cement; The evaluation module is used to determine the location of the carbonate cement enrichment section by taking the carbonate cement relative content indicator curve as a judgment index.
9. A storage medium, characterized in that: The storage medium stores a computer program, which is executed by a processor to implement the steps of the method for determining a carbonate cement-rich section in a clastic reservoir according to any one of claims 1 to 7.