Shale oil reservoir rock pyrolysis geochemical correction method and device based on stratum element data

Abstract

The invention provides a shale oil reservoir rock pyrolysis geochemical correction method and device based on stratum element data. The correction method comprises the steps that geological element data and rock pyrolysis geochemical data of a drilled well and a well to be corrected in a target area are acquired; calculating corresponding paleoenvironment data through the geological element data, and determining a sedimentary environment corresponding to the drilled well and the well to be corrected; a drilled well with the same sedimentary environment as the well to be corrected is selected, and the mapping relation between the organic matter contents at different temperatures in rock pyrolysis geochemistry of the drilled well is calculated; and calculating the organic matter content data of the to-be-corrected well according to the determined mapping relation and the rock pyrolysis geochemical organic matter content data of the to-be-corrected well, thereby completing data correction. According to the method, the adverse effect of the oil-based / synthetic-based drilling fluid on the rock pyrolysis geochemical data is eliminated, the precision and reliability of the data in the shale oil reservoir evaluation process are improved, and the method is of great significance to optimization of exploration and development of shale oil resources.

Description

Technical Field

[0001] The present invention relates to the technical field of petroleum engineering, and particularly relates to a method and device for shale oil reservoir rock pyrolysis geochemical correction based on formation element data. Background Art

[0002] Shale oil reservoirs are currently the key areas for oil exploration and development. Due to the particularity of shale oil reservoirs, traditional water-based drilling fluids cannot effectively meet the requirements of drilling operations, and oil-based / synthetic-based drilling fluids must be used. However, due to their special physical and chemical properties, these drilling fluids will have a greater adverse impact on rock pyrolysis geochemical data.

[0003] In the evaluation of hydrocarbon-bearing properties of shale oil reservoirs, rock pyrolysis geochemical data is a very important evaluation basis. Through rock pyrolysis data, geologists and engineers can understand the quantity, type, and maturity of organic matter in the reservoir, so as to evaluate its potential hydrocarbon resources and recoverability. However, due to the influence of oil-based / synthetic-based drilling fluids, the obtained rock pyrolysis data is biased. Therefore, there is an urgent need for a more accurate correction method to reduce or even eliminate the adverse effects brought by oil-based / synthetic-based drilling fluids. Summary of the Invention

[0004] To solve the above technical problems, the main object of the present invention is a method for shale oil reservoir rock pyrolysis geochemical correction based on formation element data. The correction method of the present invention eliminates the adverse effects of oil-based / synthetic-based drilling fluids on rock pyrolysis geochemical data, and the accuracy and reliability of the calculated data meet the requirements of formation evaluation, providing a scientific basis for oil and gas exploration and development.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows: A method for shale oil reservoir rock pyrolysis geochemical correction based on formation element data, comprising the following steps: Step 1: Obtain the formation element data and rock pyrolysis geochemical data of the drilled wells and wells to be corrected in the target area; Step 2: Calculate the corresponding paleoenvironmental data according to the formation element data, and determine the sedimentary environment corresponding to the drilled wells and wells to be corrected; Step 3: According to the determined sedimentary environment, select the drilled wells with the same sedimentary environment as the well to be corrected, and determine the mapping relationship between the S4 data and the S1 and S2 data in the rock pyrolysis geochemistry of the drilled wells; Step 4: According to the determined mapping relationship, use the S4 data of the rock pyrolysis geochemistry of the well to be corrected to calculate the S1 and S2 data of the rock pyrolysis geochemistry of the well to be corrected, and complete the data correction; Among them, S1 is the content of organic matter volatilized and cracked at a temperature of 90°C to 300°C, S2 is the content of organic matter cracked at a temperature of 300°C to 550°C, and S4 is the content of residual organic matter after cracking.

[0006] According to an embodiment of the present invention, in the first step, the paleoenvironmental data usually includes: paleoclimate index, paleo-redox index, and water salinity index.

[0007] According to an embodiment of the present invention, in the third step, the mapping relationship between the S4 data and the S1 data in rock pyrolysis geochemistry is: , Among them, S1 corresponds to the content of organic matter volatilized and cracked at a temperature of 90°C to 300°C, S4 corresponds to the content of residual organic matter after cracking, and A1, A2, and A3 are region-based constants.

[0008] According to an embodiment of the present invention, in the third step, the mapping relationship between the S4 data and the S2 data in rock pyrolysis geochemistry is: , Among them, S2 corresponds to the content of organic matter cracked at a temperature of 300°C to 550°C, S4 corresponds to the content of residual organic matter after cracking, and B1, B2, and B3 are region-based constants.

[0009] According to an embodiment of the present invention, the present invention also provides a shale oil reservoir rock pyrolysis geochemistry correction device based on formation element data, including: Data acquisition module: used to acquire the formation element data and rock pyrolysis geochemistry data of the drilled wells and wells to be corrected in the target area; Sedimentary environment determination module: used to calculate the corresponding paleoenvironmental data according to the acquired formation element data, and determine the sedimentary environment corresponding to the drilled wells and wells to be corrected; Correction model module: used to select the drilled wells with the same sedimentary environment as the well to be corrected according to the determined sedimentary environment, and determine the mapping relationship between the S4 data and the S1 and S2 data in the rock pyrolysis geochemistry of the drilled wells; Correction module: used to calculate the rock pyrolysis geochemistry S1 and S2 data of the well to be corrected according to the determined mapping relationship, using the rock pyrolysis geochemistry S4 data of the well to be corrected, and complete the data correction; Among them, S1 corresponds to the content of organic matter volatilized and cracked at a temperature of 90°C to 300°C, S2 corresponds to the content of organic matter cracked at a temperature of 300°C to 550°C, and S4 corresponds to the content of residual organic matter after cracking.

[0010] According to an embodiment of the present invention, the present invention further provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the correction method when executing the computer program.

[0011] According to an embodiment of the present invention, the present invention further provides a computer-readable storage medium storing a computer program, and the computer program implements the correction method as claimed when executed by a processor.

[0012] The present invention has the following beneficial effects: The present invention uses formation elements to calculate paleoenvironmental data such as paleoclimate index, paleo-redox index, and water salinity index, and determines the sedimentary environment of the corresponding formations of the drilled wells and the wells to be corrected; according to the principle that for rocks formed in the same age, the same area, and the same sedimentary environment, the provenance and evolution process contained therein are similar, so the types and properties of the organic matter therein are also similar, and the characteristic that the S4 data in the rock pyrolysis geochemical data is not affected by the adverse effects of oil-based / synthetic-based drilling fluids, select the drilled wells with the same sedimentary environment as the wells to be corrected, obtain the mapping relationship between the S1, S2 data and the S4 data of the rock pyrolysis geochemistry of the drilled wells, and substitute the S4 data of the rock pyrolysis geochemistry of the wells to be corrected into the obtained mapping relationship to calculate the corresponding rock pyrolysis geochemical data, so as to realize data correction. Through the above correction method in the embodiments of the present invention, the adverse effects of oil-based / synthetic-based drilling fluids on the rock pyrolysis geochemical data are eliminated, and the accuracy and reliability of the calculated data meet the requirements of formation evaluation. Description of the Drawings

[0013] The present invention will be further described below with reference to the accompanying drawings: Figure 1 is a schematic flow chart of a method for correcting rock pyrolysis geochemistry of a shale oil reservoir based on formation element data according to the present invention; Figure 2 is a schematic diagram of a device for correcting rock pyrolysis geochemistry of a shale oil reservoir based on formation element data according to the present invention. Detailed Embodiments

[0014] As Figure 1 shown, a method for correcting rock pyrolysis geochemistry of a shale oil reservoir based on formation element data includes the following steps: Step 1: Obtain the formation element data and rock pyrolysis geochemical data of the drilled wells and the wells to be corrected in the target area; specifically: S101. Obtain the rock pyrolysis geochemistry and formation element data of the target well section of the drilled wells in the target area.

[0015] The target drilled well to be evaluated shall meet the following requirements: the source rock or shale reservoir in the target well section shall be well-developed, and the rock pyrolysis geochemistry shall be based on the data measured by using sidewall cores or cores, or the data measured from cuttings in the well section where synthetic-based drilling fluids are not used.

[0016] S102. Obtain the rock pyrolysis geochemistry and formation element data of the target well section of the well to be calibrated.

[0017] The organic matter in rocks is the transformation product of the biological remains in sediments through complex physical and chemical changes. In the same era and the same region, for rocks formed under the same sedimentary environment, the organic matter contained therein will have similar properties, while for rocks formed under different sedimentary environments, the properties of the organic matter contained therein will also be different.

[0018] Rock pyrolysis geochemistry is a method of heating a rock sample to a preset temperature, measuring the hydrocarbon gases volatilized and cracked at high temperatures, and thereby judging the type and maturity of organic matter in the rock. In the evaluation of the oil-bearing property of shale oil reservoirs, the parameters directly measured by rock pyrolysis geochemistry include S0, S1, S2, and S4.

[0019] Among the above parameters, S0 is the content of organic matter volatilized and cracked below 90°C, S1 is the content of organic matter volatilized and cracked at 90°C - 300°C, S2 is the content of organic matter cracked at 300°C - 550°C, and S4 is the content of residual organic matter after cracking.

[0020] In actual work, since the normal value of S0 is usually less than 0.01 and has a minimal impact on the data, it can be ignored. Therefore, when discussing the impact of oil-based / synthetic-based drilling fluids on rock pyrolysis geochemistry data, its impact on S0 data is not considered either.

[0021] For the currently used mainstream oil-based / synthetic-based drilling fluids, their continuous phases are usually various hydrocarbons and their derivatives, and the corresponding volatilization and cracking temperatures usually range from 200°C to 365°C. Therefore, their impact on rock pyrolysis geochemistry data is mainly concentrated on S1, the impact on S2 is relatively small, and S4 is usually not affected.

[0022] Generally speaking, for rocks formed in the same era, the same region, and the same sedimentary environment, the provenance and evolution processes contained therein are similar. Therefore, the types and properties of the organic matter are also similar, only the content varies. Thus, the ratio among S1, S2, and S4 is also similar, and vice versa. Therefore, by measuring the ratio among S1, S2, and S4 of the organic matter in uncontaminated rocks formed in the same era, the same region, and the same sedimentary environment, the S4 data that is not affected by oil-based / synthetic-based drilling pollution can be used to calculate the S1 and S2 data that are easily contaminated and affected, thereby achieving the calibration of rock pyrolysis geochemistry data for shale oil reservoirs.

[0023] Generally, the same strata in the same block can meet the conditions of the same age and the same area, while whether it is the same sedimentary environment needs to be judged by the formation element data. The sedimentary environment factors affecting the enrichment of formation elements include paleoclimate, paleo redox conditions and water salinity, and these conditions will also affect the deposition, development and preservation of formation organic matter.

[0024] Step 2: Calculate the corresponding paleoenvironment data according to the formation element data, and determine the sedimentary environment corresponding to the drilled wells and the wells to be corrected.

[0025] The process of analyzing the sedimentary environment by using formation elements is described below: S201. Determine the paleoclimate according to the terrigenous clastic input content, water productivity and paleoclimate index. The paleoclimate includes arid, semi-arid and humid.

[0026] The terrigenous clastic input content is related to the movement of ancient rivers. Under the warm and humid paleoclimate conditions, the river water carries a large amount of terrigenous clastic minerals, and the terrigenous clastic input content in the deposition area is high; in the arid and semi-arid paleoenvironment, the river water flow is low, and the proportion of terrigenous clastic input is low. The calculation formula of the terrigenous clastic input content (Terrigenous) is: , where Tisample is the content of Ti element in the sample (unit: ppm), Tishale is the content of Ti in the post-Archean Australian sedimentary rock (PASS), which is 0.5995 ppm.

[0027] Water productivity refers to the prosperity degree of organisms in water. Under the arid paleoclimate conditions, it will show a concentration effect, and the Al / Ti content shows a high value; while under the humid paleoclimate conditions, it will show a dilution effect with the injection of river water, showing a low value.

[0028] The calculation formula of the paleoclimate index is: ; Due to the influence of different paleoclimate environments, there are great differences in the activity and enrichment ability of elements. Trace elements such as iron, manganese, chromium, vanadium, cobalt and nickel have strong activity ability and high content in rocks under the warm and humid paleoclimate conditions. Elements such as calcium, magnesium, potassium, sodium, strontium and barium belong to the arid climate type elements, and they tend to concentrate under arid conditions. According to the relationship between these elements and climate, the paleoclimate index is introduced to give a quantitative analysis of paleoclimate changes. The larger the c value, the more humid the paleoclimate environment, and the smaller the more arid. When c ≤ 0.4, it is an arid climate, 0.4 < c ≤ 0.6 is a semi-arid climate, and 0.6 < c ≤ 1.0 is a humid climate.

[0029] According to the points on the terrigenous clastic and Al / Ti paleoenvironment classification plate mentioned above, the paleoclimate index is calculated. It is obtained that in the arid paleoclimate environment, the average c value is 0.27; in the semi-arid paleoclimate environment, the average value of the paleoclimate index is 0.45; and in the humid paleoenvironment, it is 0.62. There is a good consistency between the terrigenous clastic input content, the division result of the Al / Ti paleoenvironment classification plate, and the calculation result of the paleoclimate index.

[0030] S202. Analyze the paleo-oxidation-reduction conditions and water body salinity of the shale in different paleoclimate environments to determine the paleoclimate conducive to the development and preservation of shale organic matter.

[0031] The paleo-oxidation-reduction index is . Among them, <4 is a strong reduction environment, 4 ≤ <10 is a reduction environment, 10 ≤ <30 is a weak reduction to weak oxidation environment, >30 is a strong oxidation environment.

[0032] The water body salinity index is . Among them, <0.5 is fresh water deposition, 0.5 ≤ <1 is brackish water deposition, >1 is saline water deposition.

[0033] Through the above steps S201 and S202, the paleoclimate, paleo-oxidation-reduction conditions, and water body salinity characteristics of the target intervals of each well in the target area can be determined, so as to determine the corresponding sedimentary environment.

[0034] Step 3: According to the determined sedimentary environment, select the drilled wells with the same sedimentary environment as the well to be corrected, and determine the mapping relationship between the S4 data and the S1 and S2 data in the rock pyrolysis geochemistry of the drilled well; Step 4: According to the determined mapping relationship, use the S4 data of the rock pyrolysis geochemistry of the well to be corrected to calculate the S1 and S2 data of the rock pyrolysis geochemistry of the well to be corrected, and complete the data correction.

[0035] In order to make the purpose, technical solution and advantages of the present application clearer, the following further details the technical solution of the present application in combination with specific embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0036] Embodiment To verify the effectiveness of the correction method of the present invention, this embodiment collects the formation element and rock pyrolysis geochemistry data of 5 drilled wells and 1 experimental well in the Lower Permian of Block A in the Junggar Basin, Xinjiang, and determines its sedimentary environment by analyzing the formation element data. The experimental results are shown in Table 1.

[0037] Table 1 Sedimentary Environment of the Lower Permian in Block A

[0038] As can be seen from Table 1, the sedimentary environment of Well A20 to be calibrated is the same as that of Well A16. Therefore, the relative relationship formula of the S1, S2, and S4 data of Well A16 is selected as the calibration formula.

[0039] According to the pyrolysis geochemical data analysis of the Lower Permian rocks in Well A16, the mapping relationship among its S1, S2, and S4 data is as follows: , where A1 is 0.0002, A2 is -0.0084, and A3 is 0.077; B1 is -0.0008, B2 is 0.0195, and B3 is 0.1018.

[0040] Substitute the S4 data of the cuttings of Well A20 into the above mapping relationship to calculate the corresponding S1 and S2 data. Name the average value of this data as A20-cal. Name the average value of the S1 and S2 data measured by the pyrolysis geochemistry of the core of Well A20 as A20-core. Verify the accuracy of the obtained mapping relationship by comparing the two. At the same time, calculate the mapping relationship among the S1, S2, and S4 data of other wells, and determine the corresponding S1 and S2 data of the cuttings of Well A20 accordingly. Name the average value of this data as A20-(corresponding well number). The results are shown in Table 2.

[0041] Table 2 Pyrolysis Geochemical Calibration Data of the Lower Permian Rocks in Block A

[0042] As can be seen from Table 2, the S1 and S2 data of Well A20 calculated from the pyrolysis geochemical data of the Lower Permian rocks in Well A16, that is, A20-cal, have an error of less than 5% from the pyrolysis geochemical data of the core, which can better meet the requirements of shale oil and gas evaluation. At the same time, the comparison of the multi-well mapping relationships shows that there is a positive correlation between the calibration data error and the sedimentary environment difference.

[0043] In summary, the embodiments of the present invention utilize formation elements to calculate paleoenvironmental data such as paleoclimate indices, paleo-redox indices, and water salinity indices, and determine the sedimentary environments of the corresponding formations of the drilled wells and the wells to be corrected; according to the principle that rocks formed in the same age, the same region, and the same sedimentary environment have similar provenances and evolution processes, and thus the types and properties of the organic matters therein are also similar, and the characteristic that the S4 data in the rock pyrolysis geochemical data is not affected by oil-based / synthetic-based drilling fluids, a drilled well with the same sedimentary environment as the well to be corrected is selected, the mapping relationship between the rock pyrolysis geochemical S1, S2 data and the S4 data thereof is obtained, and the rock pyrolysis geochemical S4 data of the well to be corrected is substituted into the obtained mapping relationship to calculate the corresponding rock pyrolysis geochemical data, thereby realizing data correction. Through the above correction method, the present invention eliminates the adverse effects of oil-based / synthetic-based drilling fluids on rock pyrolysis geochemical data, and the accuracy and reliability of the calculated data meet the requirements of formation evaluation, which is of great significance for optimizing shale oil and gas exploration and development strategies.

[0044] Based on the same inventive concept, the embodiments of the present invention further provide a device for correcting rock pyrolysis geochemistry of shale oil reservoirs based on formation element data, as Figure 2 shown, the device includes: A data acquisition module: used to acquire the formation element data and rock pyrolysis geochemical data of the drilled wells and the wells to be corrected in the target area; A sedimentary environment determination module: used to calculate the corresponding paleoenvironmental data according to the acquired formation element data, and determine the sedimentary environments corresponding to the drilled wells and the wells to be corrected; A correction model module: used to select a drilled well with the same sedimentary environment as the well to be corrected according to the determined sedimentary environment, and determine the mapping relationship between the S4 data and the S1, S2 data in the rock pyrolysis geochemistry of the drilled well; A correction module: used to calculate the rock pyrolysis geochemical S1, S2 data of the well to be corrected according to the determined mapping relationship by using the rock pyrolysis geochemical S4 data of the well to be corrected, and complete data correction; Wherein, S1 is the content of organic matter volatilized and cracked at a temperature of 90°C to 300°C, S2 is the content of organic matter cracked at a temperature of 300°C to 550°C, and S4 is the content of residual organic matter after cracking.

[0045] In one embodiment, the present invention provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the correction method is implemented.

[0046] In one embodiment, the present invention provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the correction method is implemented.

[0047] The above embodiments are only the preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The protection scope of the present invention should be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A geochemical correction method for rock pyrolysis of shale oil reservoirs based on formation element data, characterized in that, It includes the following steps: Step 1: Obtain the formation element data and rock pyrolysis geochemical data of the drilled wells and the wells to be corrected in the target area; Step 2: Calculate the corresponding paleoenvironmental data based on the formation element data, and determine the sedimentary environment corresponding to the drilled wells and the wells to be corrected; Step 3: According to the determined sedimentary environment, select the drilled wells with the same sedimentary environment as the well to be corrected, and determine the mapping relationship between the S4 data and the S1 and S2 data in the rock pyrolysis geochemistry of the drilled well; Step 4: According to the determined mapping relationship, use the S4 data of the rock pyrolysis geochemistry of the well to be corrected to calculate the S1 and S2 data of the rock pyrolysis geochemistry of the well to be corrected, and complete the data correction; Among them, S1 is the content of organic matter volatilized and cracked at a temperature of 90°C to 300°C, S2 is the content of organic matter cracked at a temperature of 300°C to 550°C, and S4 is the content of residual organic matter after cracking.

2. The calibration method according to claim 1, characterized in that, In the said Step 1, the paleoenvironmental data includes: paleoclimate index, paleo-redox index and water salinity index.

3. The calibration method according to claim 1, characterized in that, In the said Step 3, the mapping relationship between the S4 data and the S1 data in the rock pyrolysis geochemistry is: ， Among them, S1 corresponds to the content of organic matter volatilized and cracked at a temperature of 90°C to 300°C, S4 corresponds to the content of residual organic matter after cracking, and A1, A2, and A3 are constants based on the region.

4. The calibration method according to claim 1, characterized in that In the said Step 3, the mapping relationship between the S4 data and the S2 data in the rock pyrolysis geochemistry is: ， Among them, S2 corresponds to the content of organic matter cracked at a temperature of 300°C to 550°C, S4 corresponds to the content of residual organic matter after cracking, and B1, B2, and B3 are constants based on the region.

5. A geochemical correction device for rock pyrolysis of shale oil reservoirs based on formation element data, characterized in that, It includes: Data acquisition module: used to obtain the formation element data and rock pyrolysis geochemical data of the drilled wells and the wells to be corrected in the target area; Sedimentary environment determination module: used to calculate the corresponding paleoenvironmental data according to the obtained formation element data, and determine the sedimentary environment corresponding to the drilled wells and the wells to be corrected; Calibration model module: used to select the drilled wells with the same sedimentary environment as the well to be corrected according to the determined sedimentary environment, and determine the mapping relationship between the S4 data and the S1 and S2 data in the rock pyrolysis geochemistry of the drilled well; Calibration module: used to calculate the S1 and S2 data of the rock pyrolysis geochemistry of the well to be corrected according to the determined mapping relationship, and use the S4 data of the rock pyrolysis geochemistry of the well to be corrected to complete the data correction; Among them, S1 corresponds to the content of organic matter volatilized and cracked at a temperature of 90°C to 300°C, S2 corresponds to the content of organic matter cracked at a temperature of 300°C to 550°C, and S4 corresponds to the content of residual organic matter after cracking.

6. A computer device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the said processor executes the said computer program, it implements the calibration method described in any one of claims 1-4.

7. A computer-readable storage medium, characterized in that, The said computer-readable storage medium stores a computer program, and when the computer program is executed by the processor, it implements the calibration method described in any one of claims 1 to 2.

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