Wellbore stability evaluation method, electronic device and medium

Abstract

This invention belongs to the field of drilling stability analysis technology, specifically a wellbore stability evaluation method, electronic equipment, and media. This method establishes a wellbore stability index for the first time, using the average of the wellbore stability indices from multiple wellbore stability sample wells as a threshold. The closer the target well's wellbore stability index is to the threshold, the better the wellbore stability; conversely, the further away, the worse the wellbore stability. This invention's method can evaluate wellbore stability while drilling with high accuracy. The electronic equipment and media based on this invention broaden its application scenarios, making it suitable for evaluating the wellbore stability of horizontal wells in sandstone and mudstone formations.

Description

Technical Field

[0001] This invention belongs to the field of drilling stability analysis technology, specifically a wellbore stability evaluation method, electronic equipment, and medium. Background Technology

[0002] Wellbore stability is a key factor affecting drilling safety. During drilling operations, due to friction and the complexity of the actual geological structure, the drilled wellbore diameter is not always consistent with the drill bit size. This variation in diameter leads to irregular wellbore geometry, resulting in poor wellbore stability. When encountering geological conditions such as brittle mudstone, poor wellbore stability can not only cause safety accidents such as rock cuttings and wellbore collapse, but also, due to increased friction between rock cuttings and the irregular wellbore, prevent effective upward movement of cuttings from the bottom of the well, leading to a "cuttings bed" phenomenon, further causing complex accidents such as stuck drill bit and obstruction during tripping. Therefore, during drilling operations, it is necessary to continuously assess wellbore stability as the drill bit advances, identifying potential instability risks as early as possible for timely warnings.

[0003] Currently, various methods for evaluating wellbore stability have their shortcomings. For example, methods that judge the degree of wellbore collapse based on the amount of cuttings returned are problematic because the returned cuttings are greatly affected by the properties of the drilling fluid. For instance, oil-based drilling fluids can distort the weight of the cuttings, and changes in the density and viscosity of the drilling fluid during drilling can affect the amount of cuttings returned. These factors make it impossible to accurately quantify changes in cuttings weight, thus reducing the effectiveness of using cuttings weighing to evaluate wellbore stability. Furthermore, some methods only consider elemental variations at a single layer and point, neglecting the comprehensive impact of the entire formation and sedimentary assemblage on wellbore stability. Therefore, these methods are cumbersome, inefficient, and yield inaccurate evaluation results. Additionally, while Chinese invention patent application CN103541720A discloses a rapid wellbore stability evaluation technology, it is based on a gas drilling model and is applicable to gas drilling technology, thus limiting its scope of application. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention utilizes the elemental mass percentages obtained from previous X-ray fluorescence elemental logging techniques to select aluminum and silicon as representative sensitive elements in mudstone and sandstone. Through analysis, reasoning, and verification, a new wellbore stability evaluation parameter I is established. d Based on this parameter, a wellbore stability evaluation method is developed for real-time evaluation of wellbore stability during drilling, thereby improving the early warning capability for formation collapse.

[0005] Another objective of this invention is to provide an electronic device and a computer-readable storage medium based on the above-described wellbore stability evaluation method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A wellbore stability evaluation method uses the average wellbore stability index of multiple wellbore stability sample wells as a threshold. The closer the wellbore stability index of the target well is to the threshold, the better the wellbore stability is; conversely, the worse the wellbore stability is.

[0008] Among them, the wellbore stability index I d The calculation formula is as follows:

[0009]

[0010] In the formula, i represents the depth per meter of well; n represents the total well depth;

[0011] Al i It is the mass percentage of aluminum at a well depth of i;

[0012] Al i+1 It is the mass percentage of aluminum at a well depth of (i+1);

[0013] Si i It is the mass percentage of silicon at a well depth of i;

[0014] Si i+1 It is the mass percentage of silicon at a well depth of (i+1);

[0015] This is the average of the differences between the mass percentage of aluminum and the mass percentage of silicon per meter of well depth.

[0016] Among them, X-ray fluorescence elemental logging technology is an existing technology that can detect the mass percentage of 36 elements from sodium to uranium in cores and cuttings.

[0017] As a limitation of the present invention, it includes the following steps performed sequentially:

[0018] S1. Extract the mass percentage of aluminum and silicon per meter of well depth to obtain...

[0019] Using wellbore stability index I d The calculation formula is used to obtain the average value of the wellbore stability index of multiple wellbore stability sample wells, which is the threshold.

[0020] S2. Calculate the wellbore stability index of the target well, plot the curve of the wellbore stability index change, and compare it with the threshold. If the curve of the target well's wellbore stability index change coincides more with the curve of the threshold, the wellbore stability is better; conversely, the wellbore stability is worse.

[0021] As a further limitation of the present invention, the mass percentage of the elements is obtained by X-ray fluorescence elemental logging technology.

[0022] As a further limitation of the present invention, both the sample well and the target well are horizontal wells in the same area of ​​sandstone and mudstone formations.

[0023] The present invention also provides an electronic device based on a wellbore stability evaluation method, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the aforementioned wellbore stability evaluation method.

[0024] The present invention also provides a computer-readable storage medium storing a computer program that performs the above-described wellbore stability evaluation method.

[0025] By adopting the above-described technical solution, the beneficial effects achieved by this invention compared to the prior art are as follows:

[0026] In clastic rock formations, Si and Al are representative elements of sandstone and mudstone, respectively. However, in actual drilling, the Si and Al content and reservoir thickness in the sandstone and mudstone formations encountered are unpredictable. This invention uses the mass percentage of Si and Al from the X-ray fluorescence elemental data analysis results during the drilling process of the target well to calculate the wellbore stability index. This can effectively determine the wellbore expansion during the drilling process, promptly alert the drilling team to risks in easily expandable sections, avoid the accumulation of cuttings to form cuttings beds, thereby reducing the risk of stuck tripping during tripping, saving construction time, and reducing construction costs.

[0027] This invention screens aluminum and silicon, sensitive elements reflecting the diameter enlargement of sandstone and mudstone formations, from X-ray fluorescence elemental data analysis results. Through analysis, reasoning, and verification, a wellbore stability index I is established. d The calculation formula is used for wellbore stability evaluation of horizontal wells in sandstone and mudstone formations. It can quickly and instantly analyze changes in well diameter size, provide early warning while drilling, and promptly reflect wellbore instability.

[0028] The electronic equipment and media based on the wellbore stability evaluation method of the present invention can be implemented efficiently to make timely evaluations of wellbore stability. Attached Figure Description

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0030] Figure 1 This is a graph showing the integrated logging and wellbore stability index of well HT4 in Embodiment 1 of the present invention. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the described embodiments are only used to explain the present invention and do not limit the present invention.

[0032] Example 1: A method for evaluating wellbore stability

[0033] This embodiment evaluates the wellbore stability of well HT4 in an oilfield during drilling. The total well depth n is 4413 meters, as detailed below:

[0034] S1. Extract the mass percentage of aluminum and silicon per meter of well depth in well HT4, and calculate the average of the differences between the two per meter of well depth.

[0035] Taking a well depth of 3915 meters as an example, calculate the wellbore stability index of well HT4.

[0036] For well sections with depths ranging from 3916 meters to 4413 meters, the wellbore stability index I per meter of well depth was calculated. d The results are shown in Table 1.

[0037] Using the formula for calculating the wellbore stability index, the wellbore stability index of wellbore stability sample 1 was calculated to be 26.78, the wellbore stability index of wellbore stability sample 2 was calculated to be 23.57, and the wellbore stability index of wellbore stability sample 3 was calculated to be 25.34. The average value of the wellbore stability index of the three sample wells was obtained, which is the threshold value of 25.23.

[0038] S2. Calculate the wellbore stability index per meter depth for well HT4, and plot the curve of wellbore stability index variation, as follows: Figure 1 The wellbore stability index curve in well HT4 is compared with the curve containing the threshold value. The smaller the area enclosed by the two curves, the higher the overlap between the wellbore stability index curve and the threshold curve, indicating better wellbore stability. For example... Figure 1 In the well section with a depth of 4000 to 4030 meters, the wellbore stability index curve almost coincides with the threshold curve, indicating good wellbore stability in this section. Conversely, the wellbore stability is poor in the well sections with a depth of 4060 to 4070 meters and 4120 to 4140 meters. If the wellbore stability remains poor, an early warning should be issued and the drilling team should be notified.

[0039] Table 1. Analysis results of X-ray fluorescence elemental data and wellbore stability index of Well HT4

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[0060] Wellbore stability evaluation effect verification:

[0061] By comparing with the actual well diameter measured after the drilling operation, such as Figure 1 As shown, the curve formed by the wellbore stability index calculated by this invention has a high degree of correspondence with the measured well diameter change curve. In the range where the wellbore stability index is relatively stable, for example, in the section with a well depth of 4000 to 4030 meters, the wellbore stability index curve is almost a straight line. The evaluation result indicates that the wellbore stability in this section is relatively good. Figure 1The measured well diameter also showed little variation, consistent with the evaluation results. The evaluation results showed that the wellbore stability was poor in the section with a depth of 4120 to 4140 meters, and the corresponding measured well diameter also varied significantly. This verifies that the wellbore stability evaluation method of this invention is accurate and has good application results.

[0062] Example 2: A computer device

[0063] This embodiment provides a computer device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, to implement a wellbore stability evaluation method of Embodiment 1.

[0064] This memory is used to store non-transitory computer-readable instructions. Specifically, the memory may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM) and / or cache memory. The non-volatile memory may, for example, include read-only memory (ROM), hard disk, flash memory, etc.

[0065] The processor may be a central processing unit (CPU) or other form of processing unit with data processing and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions. The processor is used to execute computer-readable instructions stored in the memory.

[0066] Those skilled in the art will understand that, in order to solve the technical problem of how to achieve a good user experience, this embodiment may also include well-known structures such as communication buses and interfaces, and these well-known structures should also be included within the protection scope of this disclosure.

[0067] For a detailed description of this embodiment, please refer to the corresponding descriptions in the foregoing embodiments, which will not be repeated here.

[0068] Example 3: A computer-readable storage medium

[0069] This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements a wellbore stability evaluation method of Embodiment 1.

[0070] The computer-readable storage medium stores non-transitory computer-readable instructions thereon. When the non-transitory computer-readable instructions are executed by a processor, all or part of the steps of the methods of the foregoing embodiments are performed.

[0071] The aforementioned computer-readable storage media include, but are not limited to: optical storage media (e.g., CD-ROM and DVD), magneto-optical storage media (e.g., MO), magnetic storage media (e.g., magnetic tape or portable hard drive), media with built-in rewritable non-volatile memory (e.g., memory card), and media with built-in ROM (e.g., ROM cartridge).

[0072] It should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method of evaluating borehole stability, characterized by, It uses the average wellbore stability index of multiple wellbore stability sample wells as the threshold. The closer the wellbore stability index of the target well is to the threshold, the better the wellbore stability is, and vice versa. The well wall stability index I d The calculation formula of the well wall stability index I is as follows: In the formula, i represents the depth per meter of well; n represents the total well depth; Al i is the mass percentage content of aluminum element when the well depth is i; Al i+1 is the mass percentage of aluminum element when the well depth is (i+1); Si i is the mass percent content of the silicon element when the well depth is i; Si i+1 is the mass percent content of the silicon element at a well depth of (i+1); The average of the difference between the mass percent of aluminum and the mass percent of silicon per meter of well depth for the well.

2. The method of evaluating the borehole stability according to claim 1, wherein, The mass percentages of the elements were obtained using X-ray fluorescence elemental logging technology.

3. A method of evaluating the stability of a borehole wall according to claim 1 or 2, characterized in that, Both the sample well and the target well are horizontal wells in the same area of ​​sandstone and mudstone formations.

4. The wellbore stability evaluation method according to claim 3, characterized in that, This includes the following steps performed sequentially: S1. Extract the mass percentage of aluminum and silicon per meter of well depth to obtain... The average value of the wellbore stability indexes of the multiple wellbore stability sample wells is calculated by using a calculation formula of a wellbore stability index I d , and the average value is the threshold value. S2. Calculate the wellbore stability index of the target well, plot the curve of the wellbore stability index change, and compare it with the threshold. If the curve of the target well's wellbore stability index change coincides more with the curve of the threshold, the wellbore stability is better; conversely, the wellbore stability is worse.

5. An electronic device based on a wellbore stability evaluation method, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements a wellbore stability evaluation method according to any one of claims 1-4.

6. A computer readable storage medium characterized by The computer-readable storage medium stores a computer program that performs a wellbore stability evaluation method according to any one of claims 1-4.

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