A method for identifying lithology while drilling, a computer device and a readable storage medium

Abstract

This invention provides a method, computer equipment, and readable storage medium for lithology identification during drilling logging. The method includes: dividing the geological strata of a study block; preparing a standard sample library; determining the mineral proportions and actual chemical elemental composition of each rock type in each stratum; determining the possible rock types present in each stratum; calculating the elemental ranges for each rock type in each stratum; determining the element set unaffected by drilling fluid parameters; selecting measured elemental data from cuttings at a certain depth during drilling, and percentage-ratio-ratioing the elemental data belonging to the element set as measured correction data; determining the stratigraphic position of the measured data, and comparing the corresponding measured correction data with the standard reference library to determine the rock type to which the measured data belongs. The equipment includes at least one processor and a memory storing instructions for executing the above method. The storage medium stores program instructions. This invention's method can quantitatively determine lithology, avoiding the influence of human judgment and improving the accuracy of the determination.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration technology, and more specifically, to a method for identifying lithology during drilling, a computer device, and a readable storage medium. Background Technology

[0002] Lithology identification is a crucial component of geological logging operations. Accurate lithology identification is essential for stratigraphic correlation, reservoir evaluation, and assessment of reservoir fluid properties.

[0003] On-site logging personnel often rely on experience or optical instruments to determine lithology, primarily through qualitative descriptions, which are heavily influenced by human factors. For example, patent publication number CN 105888657 A discloses a method for quantitative lithological identification of sedimentary rocks using elemental logging. However, existing lithological identification technologies have several problems: ① They directly use raw elemental data for lithological identification without correcting for the influence of drilling fluid composition on rock cuttings elemental data; ② They do not consider the possibility of different mineral assemblages among rock types with the same name in different stratigraphic layers, nor do they consider the possibility of different chemical element combinations among minerals with the same name. Therefore, a new method for lithological identification is urgently needed. Summary of the Invention

[0004] In view of the shortcomings of the prior art, one of the objectives of this invention is to solve one or more problems existing in the prior art. For example, one objective of this invention is to provide a well logging-while-drilling lithology identification method with high accuracy.

[0005] This invention provides a method for lithology identification during drilling logging, which may include the following steps:

[0006] Step 1: Divide the geological strata of the study block according to sequence stratigraphy; Step 2: Prepare a standard sample library, including standard samples of rock fragments or rock blocks from different strata; Step 3: Determine the mineral types and proportions of each mineral in the standard samples of each stratum; Step 4: Determine the true chemical elemental composition of each mineral in the standard samples of each stratum; Step 5: Based on the rock nomenclature standards and the mineral types of each stratum obtained in Step 3, calculate all possible rock types in each stratum and their corresponding percentage content of each mineral through permutation and combination; Step 6: Based on the rock types of each stratum obtained in Step 5 and the true chemical elemental composition of each mineral obtained in Step 4, calculate the range of elements contained in different rock types in each stratum; Step 7: Determine the set of elements in the standard sample data that are not affected by drilling fluid parameters through drilling fluid composition; Step 8: Percentage the element data belonging to the element set in Step 4, calculate the percentage range of each element in each rock type of each stratum, and use it as a standard reference library; Step 10: Compare the measured correction data with the standard reference library to confirm the rock type to which the standard sample belongs.

[0007] Furthermore, in step 2, the preparation of the standard sample library includes: collecting rock fragments or rock block samples from different strata as standard samples to obtain the standard sample library.

[0008] Furthermore, it also includes cleaning the rock fragments to ensure that they are not contaminated by mud.

[0009] Furthermore, in step 3, the mineral type and proportion of each mineral in the standard sample of each layer are determined by measuring the standard sample; wherein, measuring the standard sample includes measuring the standard sample using X-ray diffraction.

[0010] Furthermore, in step 4, the true chemical elemental composition of each mineral in each layer of the standard sample is determined by measuring the standard sample; wherein, measuring the standard sample includes measuring the standard sample using laser ablation inductively coupled plasma technology.

[0011] Furthermore, in step 6, the range of elements contained in different rock types of each stratum is calculated using the following formula:

[0012]

[0013] Among them, X i This indicates the percentage by mass of a certain element, where i refers to the element; f j This indicates the percentage of a particular mineral among all minerals, where j refers to that mineral; n j p represents the standard number of elements i in mineral j; i Let i represent the molar mass of element i, and M represent the weighted molar mass of all minerals.

[0014] Furthermore, in step 7, determining the set of elements in the standard sample that are not affected by drilling fluid parameters includes confirming whether the actual drilling fluid composition and foreign components have a significant impact on the elements of the cuttings or rock block samples.

[0015] Further, in step 8, the percentage range of each element for each rock type in each stratum is calculated using the following formula:

[0016]

[0017] Where, k i X represents the mass percentage of a certain element. i The sum of the mass percentages of all elements in the set of elements: X1 + X2 + ... + X i The ratio of .

[0018] Furthermore, in step 10, the comparison method includes using correlation coefficients, using feature elements, or establishing element charts to determine correlation.

[0019] In another aspect, the present invention provides a computer device.

[0020] The device includes: at least one processor; and a memory storing program instructions, wherein the program instructions are configured to be executed by the at least one processor, the program instructions including instructions for performing the logging-while-drilling lithology identification method as described above.

[0021] In another aspect, the present invention provides a computer-readable storage medium.

[0022] The computer-readable storage medium stores computer program instructions, which, when executed by a processor, implement the drilling logging lithology identification method as described above.

[0023] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0024] (1) The method of the present invention can determine the lithology in a quantitative way, avoiding the influence of human judgment and improving the accuracy of the judgment.

[0025] (2) The method of the present invention eliminates the influence of drilling fluid composition on elements, and takes into account the differences in mineral assemblage ratio and mineral chemical composition in different strata of the same lithology, making quantitative judgment more accurate. Detailed Implementation

[0026] In the following, the drilling logging lithology identification method, computer device, and readable storage medium according to the present invention will be described in detail with reference to exemplary embodiments.

[0027] Exemplary Example 1

[0028] This invention provides a method for lithology identification during drilling logging, which may include the following steps:

[0029] Step 1: Divide the geological strata of the study block by sequence stratigraphy.

[0030] In this embodiment, the study area can be determined first, and standard wells and field profiles can be selected. Geological strata can then be delineated based on sequence stratigraphic characteristics. Methods for determining geological strata primarily involve classifying them based on rock assemblage type, color, grain size, and other characteristics. This classification can be performed using existing technologies within the industry.

[0031] Step 2: Prepare a standard sample library, including standard samples of rock fragments or rock blocks from different strata.

[0032] In this embodiment, rock fragments or rock blocks from different strata can be collected as standard samples.

[0033] In this embodiment, the rock sample can be a rock block selected from the surface that is the same as the stratum to be tested.

[0034] Step 3: Determine the mineral types and proportions of each mineral in the standard samples of each stratum.

[0035] In this embodiment, the mineral types and proportions of each mineral in the standard samples of each layer can be determined by measuring the standard samples.

[0036] In this embodiment, X-ray diffraction (XRD) can be used to measure the collected standard samples to determine the mineral type and proportion f of each standard sample in each layer. i , where 0≤f i ≤1, i=1,2,3,... Furthermore, X-ray fluorescence spectrometry can be used to measure the standard samples to determine the mineral types and proportions of each mineral in each stratum.

[0037] Step 4: Measure the standard samples to determine the true chemical elemental composition of each mineral in each layer of the standard samples.

[0038] In this embodiment, the true chemical elemental composition of each mineral in each layer of the standard sample can be determined by measuring the standard sample.

[0039] In this embodiment, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) can be used to measure the minerals in each standard sample collected from each layer, thereby determining the true chemical elemental composition m of each mineral in each layer. i , i = 1, 2, 3, ...

[0040] In this embodiment, X-ray fluorescence spectrometry can also be used to measure the standard samples to determine the true chemical elemental composition of each mineral in each layer of the standard samples.

[0041] For example, rock type, mineral type, mineral ratio, and actual chemical composition can be represented as follows:

[0042]

[0043] Step 5: Based on the rock naming standards and the mineral types of each stratum obtained in Step 3, calculate all possible rock types and their corresponding percentage contents of each mineral by permutation and combination.

[0044] In this embodiment, the naming criteria for rocks can be based on compositional classification and named according to existing technology. For example, generally speaking, the relative content of a certain substance "5-25%" is used as a secondary adjective in the rock name, represented by "containing XX"; the relative content of a certain substance "25-50%" is used as a primary adjective in the rock name, represented by "XX substance"; and the relative content of a certain substance ">50%" is used as the primary name of the rock, represented by "XX rock".

[0045] Step 6: Based on the rock types of each stratum obtained in Step 5 and the actual chemical element composition of each mineral obtained in Step 4, calculate the range of elements contained in different rock types of each stratum.

[0046] In this embodiment, step 6 can be calculated using the following formula to obtain the desired result:

[0047]

[0048] Among them, X i This indicates the percentage by mass of a certain element, where i refers to the element; f j This indicates the percentage of a particular mineral among all minerals, where j refers to that mineral; n j p represents the standard number of elements i in mineral j; i Let i represent the molar mass of element i, and M represent the weighted molar mass of all minerals.

[0049] Step 7: Determine the set of elements in the standard sample that are not affected by drilling fluid parameters based on the drilling fluid composition.

[0050] In this embodiment, the element set can be represented as A = (Ca, Mg, Al, Si, Na…). Determining whether the elemental data in the standard sample is unaffected by drilling fluid parameters can be confirmed by whether the actual drilling fluid composition and foreign components significantly affect the elemental data of the cuttings or rock fragments. For example, the native component S in the drilling fluid and the foreign component Fe from the drill bit can significantly affect the elemental data of the cuttings and should be excluded.

[0051] Step 8: Percentage the element data belonging to the element set in Step 4, calculate the percentage range of each element for each layer and rock type, and use it as a standard reference library.

[0052] In this embodiment, the percentage of elements can be calculated using the following formula:

[0053]

[0054] Where, k i X represents the mass percentage of a certain element. i The sum of the mass percentages of all elements in the set of elements: X1 + X2 + ... + Xi The ratio of .

[0055] Step 9: Perform actual measurements on the elements in the standard sample, and, referring to Step 8, percentage the element data belonging to the element set in the measured element data as the measured correction data.

[0056] Step 10: Compare the measured correction data with the standard reference library to confirm the rock type of the standard sample.

[0057] In this embodiment, the comparison method may include using correlation coefficients, using feature elements, or creating an element chart to determine correlation.

[0058] To better understand the present invention, specific examples are provided below to further illustrate the content of the present invention, but the content of the present invention is not limited to the examples below.

[0059] Example 1

[0060] For the Longtan Formation, it is determined that bauxite mudstone may exist, and drilling fluid parameters only affect S and Fe elements. The mineral composition of bauxite ranges from 25% to 50%, and that of mudstone ranges from 50% to 70%. Assuming that the true chemical composition of the bauxite in the Longtan Formation is determined to be Al(OH)3 through X-ray diffraction in step 3 and laser ablation inductively coupled plasma technology in step 4, and that the mineral in the mudstone is illite (Al3Si4O), then... 10 [OH]2·2H2O, Montmorillonite Na 0.33 Ca 0.33 Al2Mg2[Si4O 10 (OH)2·2H2O and kaolinite Al4[Si4O 10 ](OH)8, and each of them accounts for 1 / 3 of the mud;

[0061] Following step 6, the mass percentage of Si element in bauxite (25%) and clay content (75%) is as follows:

[0062]

[0063] Similarly, the mass percentage ranges of elements such as Si, Al, and Mg in bauxite (25%-50%) and clay content (50-70%) can be calculated. The calculated ranges are: Si 0.21-0.23, O 0.53-0.54, Al 0.18-0.20, Mg 0.029-0.033, Ca 0.008-0.009, Na 0.004-0.005, and H 0.002-0.005.

[0064] Following step 7, since drilling fluid parameters only affect S and Fe elements, the element set of the bauxite standard sample is determined to be (Si, K, Al, Na, Ca, Mg).

[0065] Following step 8, after percentage conversion, the range of Si in the bauxite standard sample is 0.49-0.54, the range of Al is 0.43-0.48, the range of Mg is 0.07-0.078, the range of Ca is 0.019-0.021, and the range of Na is 0.011-0.012.

[0066] The measured correction data were compared with the standard reference library to confirm the rock type of the standard sample.

[0067] The lithology identification method for logging while drilling according to the present invention can be programmed into a computer program and the corresponding program code or instructions can be stored in a computer-readable storage medium. When the program code or instructions are executed by a processor, the processor performs the above-described method. The processor and memory described below can be included in a computer device.

[0068] Exemplary Example 2

[0069] This exemplary embodiment provides a computer device, including:

[0070] At least one processor;

[0071] A memory storing program instructions configured to be executed by the at least one processor, the program instructions including instructions for performing the logging-while-drilling lithology identification method according to Exemplary Example 1.

[0072] Exemplary Example 3

[0073] This exemplary embodiment provides a computer-readable storage medium.

[0074] The storage medium stores a computer program, and when the computer program instructions are executed by a processor, they implement the lithology identification method for logging while drilling as described in Exemplary Example 1.

[0075] The computer-readable storage medium can be any data storage device that stores data that can be read by a computer system. Examples of computer-readable storage media include: read-only memory, random access memory, read-only optical disc, magnetic tape, floppy disk, optical data storage device, and carrier waves (such as data transmission via the Internet through wired or wireless transmission paths).

[0076] Although the invention has been described above in conjunction with exemplary embodiments, those skilled in the art will understand that various modifications and changes can be made to the exemplary embodiments of the invention without departing from the spirit and scope defined by the claims.

Claims

1. A method for identifying lithology through logging while drilling, characterized in that, Includes the following steps: Step 1: Divide the geological strata of the study block by sequence stratigraphy; Step 2: Prepare a standard sample library, including standard samples of rock fragments or rock blocks from different strata; Step 3: Determine the mineral types and proportions of each mineral in the standard samples of each stratum; Step 4: Determine the true chemical elemental composition of each mineral in the standard samples of each stratum; Step 5: Based on the rock naming standards and the mineral types of each stratum obtained in Step 3, calculate all possible rock types and their corresponding percentage contents of each mineral by permutation and combination. Step 6: Based on the rock types of each stratum obtained in Step 5 and the actual chemical element composition of each mineral obtained in Step 4, calculate the range of elements contained in different rock types of each stratum. Step 7: Determine the set of elements in the standard sample that are not affected by drilling fluid parameters based on the drilling fluid composition. Step 8: Percentage the element data belonging to the element set in Step 4, calculate the percentage range of each element for each layer and rock type, and use it as a standard reference library. Step 9: Perform actual measurements on the elements in the standard sample, and, referring to Step 8, percentage the element data belonging to the element set in the measured element data as measured correction data. Step 10: Compare the measured correction data with the standard reference library to confirm the rock type of the standard sample.

2. The lithology identification method for logging while drilling according to claim 1, characterized in that, In step 2, the preparation of the standard sample library includes: collecting rock fragments or rock block samples from different strata as standard samples to obtain the standard sample library.

3. The lithology identification method for logging while drilling according to claim 2, characterized in that, Step 2 also includes cleaning the rock fragments to ensure that the rock fragments are not contaminated by mud.

4. The lithology identification method for logging while drilling according to claim 1, characterized in that, In step 3, the mineral types and proportions of each mineral in the standard samples of each stratum are determined by measuring the standard samples. The measurement of the standard sample includes measuring the standard sample using X-ray diffraction.

5. The lithology identification method for logging while drilling according to claim 1, characterized in that, In step 4, the true chemical elemental composition of each mineral in each stratum standard sample is determined by measuring the standard sample. The measurement of the standard sample includes measuring the standard sample using laser ablation inductive coupling technology.

6. The lithology identification method for logging while drilling according to claim 1, characterized in that, In step 6, the range of elements contained in different rock types of each stratum is calculated using the following formula: Among them, X i This indicates the percentage by mass of a certain element, where i refers to the element; f j This indicates the percentage of a particular mineral among all minerals, where j refers to that mineral; n j p represents the standard number of elements i in mineral j; i Let i represent the molar mass of element i, and M represent the weighted molar mass of all minerals.

7. The lithology identification method for logging while drilling according to claim 1, characterized in that, In step 7, determining the set of elements in the standard sample that are not affected by drilling fluid parameters includes confirming whether the actual drilling fluid composition and foreign components have a significant impact on the elements of the cuttings or rock block samples.

8. The lithology identification method for logging while drilling according to claim 1, characterized in that, In step 8, the percentage range of each element for each rock type in each stratum is calculated using the following formula: Where, k i X represents the mass percentage of a certain element. i The sum of the mass percentages of all elements in the set of elements: X1 + X2 + ... + X i The ratio of .

9. The lithology identification method for logging while drilling according to claim 1, characterized in that, In step 10, the comparison method includes using correlation coefficients, feature elements, or an element chart method to determine correlation.

10. A computer device, characterized in that, include: At least one processor; A memory storing program instructions, wherein the program instructions are configured to be executed by the at least one processor, the program instructions including instructions for performing the logging-while-drilling lithology identification method according to any one of claims 1-9.

11. A computer-readable storage medium having computer program instructions stored thereon, characterized in that, When the computer program instructions are executed by the processor, they implement the logging-while-drilling lithology identification method as described in any one of claims 1-9.

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