Method and system for determining lithology and stratum interface in real time by using rock strength

Abstract

The invention discloses a method and a system for determining lithology and a stratum interface in real time by using rock strength, and belongs to the field of oil-gas exploration drilling geology. The method comprises the following steps: establishing a strength range value database corresponding to different underground lithology, establishing a parameter data array according to logging-while-drilling parameters, calculating rock strength of different depth points by using data in the parameter data array, and comparing the calculated rock strength with the data in the strength range value database. And determining lithology and a stratum interface according to a comparison result. The physical significance of a calculation result is clear, the numerical range of the calculation result represents different lithology, and a sudden change value is a stratum interface; the relation between the formation lithology while drilling and the formation interface is established by applying the comprehensive drilling parameters, and a reliable basis is provided for drilling safety and oil and gas discovery. The lithology is determined according to the corresponding strength characteristics by calculating the strength of the drilled stratum, the stratum interface is implemented according to the strength change quantity, the conclusion is objective, direct and reliable, and the effect in practical application is good.

Description

Technical Field

[0001] The invention belongs to the field of oil and gas exploration drilling geology, and in particular relates to a method and system for determining lithology and stratum interface in real time by utilizing rock strength. Background Art

[0002] The purpose of drilling is to understand the formation and discover oil and gas. Generally, the geological lithology identification of drilling is preliminarily determined based on the changes during drilling. The target layer section is identified by circulating the drilling fluid to identify the lithology of the returned rock cuttings; or by coring the well to identify the lithology of the core (Li Gansheng, Hu Wenmo, Liu Tiangu, et al. Drilling Geology Logging Manual, Beijing: Petroleum Industry Press, 1993. Chen Biyu, ed. Oilfield Geology, Beijing: Petroleum Industry Press, 1st edition, March 1987). The conventional identification method of the formation interface is to indirectly determine whether the lithology has changed significantly. The above methods have problems such as difficulty in identification, large errors, long time consumption, high requirements on personnel ability, large subjective influence, and poor efficiency in deep and ultra-deep well drilling.

[0003] There is also a patent with publication number CN112485841A that proposes a method and device for identifying the lithology of deep formations. This method obtains the stratigraphic interface seismic exploration data of the deep formations in the middle and shallow depression period, the middle and deep fault period, the deep unmetamorphosed and shallow metamorphosed formations, and performs forward modeling and stripping processing on the Bouguer gravity anomaly data based on the stratigraphic interface seismic exploration data. The data after the forward modeling and stripping processing can improve the accuracy of identification in subsequent lithology identification. After that, the first remaining Bouguer gravity anomaly data is subjected to three-dimensional density inversion, and finally the deep formation lithology is identified based on the three-dimensional density data and the three-dimensional magnetic susceptibility data. However, this method requires two inversion processes and one forward modeling and stripping process, and the operation is relatively complicated. Moreover, this method can only be used for rough prediction before drilling, and often has a large gap with the actual drilling results. Summary of the invention

[0004] In view of the above problems, in a first aspect, the present invention proposes a method for determining lithology and stratum interface in real time by using rock strength, comprising the following steps:

[0005] Establish a database of strength range values ​​corresponding to different lithologies underground;

[0006] Acquiring logging while drilling parameters, and establishing a parameter data array after preprocessing the logging while drilling parameters;

[0007] Calculating rock strength at different depths using the data in the parameter data array;

[0008] The calculated rock strength is compared with the data in the strength range value database, and the lithology and formation interface are determined based on the comparison result.

[0009] Furthermore, the strength range value database includes dry compressive strength ranges and saturated compressive strength ranges corresponding to different lithologies; wherein the strength range values ​​are determined by querying in public literature or by experiments.

[0010] Furthermore, obtaining logging while drilling parameters and establishing a parameter data array after preprocessing the logging while drilling parameters includes the following steps:

[0011] Using a logging instrument to record multiple logging parameter data in real time, the logging parameters include engineering parameters, drilling fluid parameters and gas logging parameters;

[0012] Preprocessing the logging parameter data to determine the parameter data to be constructed; the preprocessing is to select drilling pressure, rotary table speed, drilling speed and drill bit diameter from the logging parameters as the parameters to be constructed according to the geological design requirements of the drilling site and corresponding to the target layer section, and standardize the parameter data to be constructed;

[0013] A parameter data array is established according to the parameter data to be constructed, wherein the parameter data array includes drilling pressure data, rotary table speed data, drilling speed data and drill bit diameter data.

[0014] Furthermore, the rock strength at different depths is calculated using the data in the parameter data array using the following formula:

[0015]

[0016] Where, W is the drilling pressure, in kN; N is the rotation speed, in r / min; D is the drill bit diameter, in mm; V m Indicates drilling speed, unit: m / h; S d Indicates rock strength, unit: MPa.

[0017] Furthermore, the calculated rock strength is compared with the data in the strength range database, and the lithology and stratum interface are determined based on the comparison results:

[0018] If the calculated rock strength is consistent with the strength in the strength range value database, the lithology is the same.

[0019] Furthermore, the method also includes drawing a single well lithology column chart based on the determined lithology and formation interface.

[0020] In a second aspect, the present invention provides a system for determining lithology and stratum interface in real time using rock strength, comprising:

[0021] A strength range value database establishment unit is used to establish a strength range value database corresponding to different lithologies in the well;

[0022] A parameter data array establishing unit, used for acquiring logging while drilling parameters, and establishing a parameter data array after preprocessing the logging while drilling parameters;

[0023] A rock strength calculation unit, used to calculate the rock strength at different depths using the data in the parameter data array;

[0024] The lithology and formation interface determination unit is used to compare the calculated rock strength with the data in the strength range value database, and determine the lithology and formation interface according to the comparison result.

[0025] Furthermore, the system also includes a drawing unit for drawing a single well lithology column chart according to the determined lithology and formation interface.

[0026] In a third aspect, the present invention provides an electronic device, comprising a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus;

[0027] a memory storing a computer program;

[0028] The processor is used to implement the method of using rock strength to determine lithology and stratum interface in real time when executing the program stored in the memory.

[0029] In a fourth aspect, the present invention proposes a computer-readable storage medium storing a computer program, which, when executed, executes the method of determining lithology and stratum interface in real time using rock strength.

[0030] Beneficial effects of the present invention:

[0031] The present invention proposes a method for calculating and identifying lithology using real-time logging drilling parameters. The method includes establishing a database of strength range values ​​corresponding to different lithologies in the well, establishing a parameter data array according to logging parameters while drilling, and then using the data in the parameter data array to calculate the rock strength at different depths. The calculated rock strength is compared with the data in the strength range value database, and the lithology and formation interface are determined based on the comparison results. The calculation results of the present invention have clear physical meanings, and their numerical ranges represent different lithologies, while mutation values ​​represent formation interfaces. The relationship between formation lithology and formation interfaces while drilling is established using comprehensive drilling parameters, providing a reliable basis for drilling safety and oil and gas discovery. By calculating the strength of the drilled formation, the lithology is determined based on the corresponding strength characteristics, and the formation interface is determined based on the strength change. The conclusion is objective, direct, and reliable, and has good effects in practical applications.

[0032] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 A flow chart of a method for determining lithology and stratum interface in real time by using rock strength proposed by the present invention is shown;

[0035] Figure 2 An application example of the method for determining lithology and stratum interface in real time by using rock strength in an embodiment of the present invention and a comparison diagram of the effect with conventional methods are shown;

[0036] Figure 3 The schematic diagram of the architecture of the system for determining lithology and stratum interface in real time by using rock strength proposed by the present invention is shown;

[0037] Figure 4 A schematic diagram of the architecture of an electronic device proposed in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] In view of the problems existing in the conventional drilling lithology identification and formation interface determination process, the present invention proposes a method for lithology identification and formation interface determination while drilling, which calculates the strength of the drilled formation, determines the lithology according to the corresponding strength characteristics, and determines the formation interface according to the strength change. Figure 1 As shown, the following steps are included:

[0040] S1: Establish a database of strength range values ​​corresponding to different lithologies in the well;

[0041] Among them, the strength range values ​​corresponding to different lithologies can be queried in public literature. In an exemplary embodiment of the present invention, if special lithologies are likely to develop, a strength range value database is determined in advance through experiments; relevant parameters are obtained by performing strength tests on downhole core samples, or by performing ground breaking tests when drilling into a new formation after completion of the well.

[0042] In one embodiment of the present invention, part of the data in the intensity range value database is shown in Table 1:

[0043] Table 1

[0044] Dry compressive strength (MPa) Saturated compressive strength (MPa) granite 40～220 25～205 Limestone 13.4～-206.7 7.8～189.2 sandstone 17.5～250.8 5.7～145.5 shale 57-136 13.7～75.10 clay rock 20.7～59 2.4～31.8

[0045] S2: Obtaining logging while drilling parameters, and establishing a parameter database after preprocessing the logging while drilling parameters; specifically, establishing a parameter data array based on the whole meter well depth;

[0046] The establishment of parameter data array based on whole meter well depth includes the following steps:

[0047] The logging instrument actually records multiple logging parameter data; the logging parameters include engineering parameters, drilling fluid parameters and gas logging parameters, etc.

[0048] The logging parameter data is preprocessed to determine the parameter data to be constructed; the preprocessing is to select drilling pressure, rotary table speed, drilling speed and drill bit diameter from the logging parameters as the parameters to be constructed according to the geological design requirements of the drilling site and corresponding to the target layer section, and the parameter data to be constructed is standardized. In one embodiment of the present invention, the drill bit diameter, drilling pressure, rotary table speed and drilling speed data after standardized processing are shown in Table 2, that is, the units are standardized to the units in Table 2:

[0049] Table 2

[0050]

[0051] A parameter data array is established according to the parameter data to be constructed, wherein the parameter data array includes drilling pressure data, rotary table speed data, drilling speed data and drill bit diameter data.

[0052] S3: Calculate the rock strength at different depths using the data in the parameter data array; the calculation formula is as follows:

[0053]

[0054] Where, W is the drilling pressure, in kN; N is the rotation speed, in r / min; D is the drill bit diameter, in mm; V is the drilling speed, in r / min; m Indicates drilling speed in m / h; S d Indicates rock strength, unit is MPa.

[0055] S4: Compare the calculated rock strength of a single point with the data in the strength range value database to determine the lithology and formation interface; if the calculated rock strength is consistent with the strength in the strength range value database, the lithology is the same;

[0056] S5: Draw a single well lithology column chart based on the determined lithology and formation interface.

[0057] The following is a combination of specific embodiments and conventional identification methods to identify the lithology and strata of a certain area, and the process is as follows:

[0058] S1: Establish a database of strength range values ​​of lithologic strength through literature, information, test data or special drilling operations.

[0059] S2: Collect and organize the logging parameter data recorded by the logging instrument, select drilling pressure, rotary table speed, drilling speed and drill bit diameter from the logging parameters as the parameters to be constructed corresponding to the target layer section according to the geological design requirements of the drilling site, and standardize the parameter data to be constructed; establish a parameter data array according to the parameter data to be constructed, and the parameter data array includes drilling pressure data, rotary table speed data, drilling speed data and drill bit diameter data.

[0060] S3: Calculate the rock strength at the corresponding depth using the data in the parameter data array. The calculation formula is as follows:

[0061]

[0062] Where W is the drilling pressure, KN; N is the rotation speed, r / min; D is the drill bit diameter, mm; V m Indicates drilling speed, m / h; S d Indicates rock strength, MPa.

[0063] S4: Compare the calculated results with the strength range value database to obtain the lithology results; Figure 2 As shown, the lithologies calculated continuously from the well depth of 8610 meters to the well completion bottom are limestone, mudstone and diabase respectively.

[0064] S5: Draw the main lithology map according to conventional practices.

[0065] Figure 2The results of conventional lithology (drilling changes) and interface identification (e.g., identification based on rock cuttings) methods and a method proposed by the present invention to determine lithology and formation interface in real time using rock strength are shown in the figure. The calculation data is derived from actual field logging data. The lithology (logging) column in the figure is the identification result of the conventional method, and the lithology (lithology strength) column is the identification result obtained by the method proposed by the present invention. Through logging comparison, it can be clearly shown that the method provided by the present invention is more objective and accurate in determining lithology and formation interface.

[0066] Based on the same concept of the present invention, another exemplary embodiment of the present invention provides a system for determining lithology and stratum interface in real time using rock strength, such as Figure 3 As shown, including:

[0067] The strength range value database establishing unit 301 is used to establish a strength range value database corresponding to different lithologies in the well;

[0068] The parameter data array establishing unit 302 acquires the logging while drilling parameters and establishes the parameter data array after preprocessing the logging while drilling parameters;

[0069] A rock strength calculation unit 303, used to calculate the rock strength at different depths using the data in the parameter data array;

[0070] A lithology and stratum interface determination unit 304 is used to compare the calculated rock strength with the data in the strength range value database, and determine the lithology and stratum interface according to the comparison result;

[0071] The drawing unit 305 is used to draw a single well lithology column chart according to the determined lithology and formation interface.

[0072] Based on the same inventive concept, another exemplary embodiment of the present invention provides an electronic device. Figure 4 As shown, the electronic device includes at least one processor 401, at least one communication interface 402, at least one memory 403 and at least one communication bus 404; wherein the processor 401, the communication interface 402 and the memory 403 communicate with each other through the communication bus 404;

[0073] Memory 403, storing computer programs;

[0074] The processor 401 is used to implement the method of determining the lithology and stratum interface in real time by using rock strength when executing the program stored in the memory 403.

[0075] Optionally, the communication interface may be an interface of a communication module, such as an interface of a GSM module; the processor may be a processor CPU, or an application specific integrated circuit ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present invention. The memory may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory. The memory stores a program, and the processor calls the program stored in the memory to execute some or all of the above method embodiments.

[0076] Based on the same inventive concept, the embodiment of the present application further provides a computer-readable storage medium storing a computer program, which implements part or all of the above method embodiments when the computer program is executed. Optionally, the storage medium may be a non-temporary computer-readable storage medium, for example, the non-temporary computer-readable storage medium may be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc.

[0077] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining lithology and stratum interface in real time using rock strength, characterized in that: The following steps are involved: Establish a database of strength range values ​​corresponding to different lithologies underground; Acquiring logging while drilling parameters, and establishing a parameter data array after preprocessing the logging while drilling parameters; Calculating rock strength at different depths using the data in the parameter data array; The calculated rock strength is compared with the data in the strength range value database, and the lithology and formation interface are determined based on the comparison result.

2. The method for determining lithology and stratum interface in real time by using rock strength according to claim 1, characterized in that: The strength range value database includes dry compressive strength ranges and saturated compressive strength ranges corresponding to different lithologies; wherein the strength range values ​​are determined by searching in public literature or by experiments.

3. The method for determining lithology and stratum interface in real time by using rock strength according to claim 1, characterized in that: Acquiring logging while drilling parameters and establishing a parameter data array after preprocessing the logging while drilling parameters includes the following steps: Using a logging instrument to record multiple logging parameter data in real time, the logging parameters include engineering parameters, drilling fluid parameters and gas logging parameters; Preprocessing the logging parameter data to determine the parameter data to be constructed; the preprocessing is to select drilling pressure, rotary table speed, drilling speed and drill bit diameter from the logging parameters as the parameters to be constructed according to the geological design requirements of the drilling site and corresponding to the target layer section, and standardize the parameter data to be constructed; A parameter data array is established according to the parameter data to be constructed, wherein the parameter data array includes drilling pressure data, rotary table speed data, drilling speed data and drill bit diameter data.

4. The method for determining lithology and stratum interface in real time by using rock strength according to claim 1, characterized in that: The following formula is used to calculate the rock strength at different depths using the data in the parameter data array: Where, W is the drilling pressure, in kN; N is the rotation speed, in r / min; D is the drill bit diameter, in mm; V m Indicates drilling speed, unit: m / h; S d Indicates rock strength, unit: MPa.

5. The method for determining lithology and stratum interface in real time by using rock strength according to claim 1, characterized in that: The calculated rock strength is compared with the data in the strength range database, and the lithology and stratum interface are determined based on the comparison results: If the calculated rock strength is consistent with the strength in the strength range value database, the lithology is the same.

6. The method for determining lithology and stratum interface in real time by using rock strength according to any one of claims 1 to 5, characterized in that: The method further comprises drawing a single well lithology column diagram according to the determined lithology and formation interface.

7. A system for determining lithology and stratum interface in real time using rock strength, characterized in that: include: A strength range value database establishment unit is used to establish a strength range value database corresponding to different lithologies in the well; A parameter data array establishing unit, used for acquiring logging while drilling parameters, and establishing a parameter data array after preprocessing the logging while drilling parameters; A rock strength calculation unit, used to calculate the rock strength at different depths using the data in the parameter data array; The lithology and formation interface determination unit is used to compare the calculated rock strength with the data in the strength range value database, and determine the lithology and formation interface according to the comparison result.

8. The system for determining lithology and stratum interface in real time by using rock strength according to claim 7, characterized in that: The system also includes a drawing unit for drawing a single well lithology column diagram according to the determined lithology and formation interface.

9. An electronic device, characterized in that: It includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus; a memory storing a computer program; The processor is used to implement the method for determining lithology and stratum interface in real time by using rock strength as described in any one of claims 1 to 7 when executing the program stored in the memory.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed, the method for determining lithology and formation interface in real time by using rock strength according to any one of claims 1 to 7 is executed.

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