A method for determining rock mechanical parameters
By using point load experiments and sonic logging data fitting models, combined with drilling data, the mechanical parameters of rocks are calculated, solving the problem of parameter determination when rock cores cannot be obtained. This enables rapid and accurate acquisition of rock mechanical parameters, supporting drilling and fracturing design.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-11-29
- Publication Date
- 2026-05-29
AI Technical Summary
Existing technologies make it difficult to quickly and accurately determine the mechanical parameters of rocks when core samples are unavailable, especially in strata with well-developed natural fractures. Core sampling is costly and the experimental methods have issues with accuracy and applicability.
The static uniaxial compressive strength was measured by point load test on coreable rock, and the dynamic uniaxial compressive strength was calculated by combining sonic logging data. A fitting model for dynamic and static uniaxial compressive strength was established, and the formation Poisson's ratio was calculated using drilling mechanical specific energy value, density logging and minimum horizontal stress data to obtain the mechanical parameters of the rock.
Without conducting uniaxial or triaxial compression tests, the compressive strength, elastic modulus, and Poisson's ratio of the rock were accurately determined, providing fundamental data support for drilling and fracturing processes and reducing coring and experimental costs.
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Figure CN122108755A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of oil and gas exploration and development technology, and specifically to a method for determining rock mechanical parameters. Background Technology
[0002] Formation rock mechanics parameters are key parameters for oil and gas exploration and development. Especially during drilling and fracturing, rock mechanics parameters directly affect wellbore stability and fracture morphology, thereby influencing the design of the overall oilfield development plan and oil and gas production.
[0003] For formations with well-developed natural fractures, coring is very costly, and in some formations, it is even impossible to obtain standard samples for experimental testing, making it impossible to obtain the rock mechanical parameters of the formation through uniaxial or triaxial compression tests. Therefore, there is an urgent need for a method that can quickly obtain the rock mechanical parameters of the formation without performing uniaxial or triaxial compression tests. Currently, there are two main methods for determining rock mechanical parameters: one is to calculate the formation rock mechanical parameters based on well logging data and relevant formulas; the other is to use laboratory experiments, using a core drill bit to retrieve full-size rock cores from downhole, processing them into standard rock samples in the laboratory, and then using a uniaxial or triaxial rock mechanics testing system to obtain the rock's elastic modulus, Poisson's ratio, and strength parameters. Both methods have certain drawbacks. Well logging data method relies on empirical formulas for calculation. Without verification at actual measurement points, it is difficult to guarantee the accuracy of the calculation results. Moreover, the empirical formulas vary from block to block, resulting in poor applicability of this method. Indoor experimental testing method is the most direct way to obtain formation rock mechanical parameters. However, this method requires a large number of experiments to overcome the heterogeneity of the formation in order to obtain accurate formation rock mechanical parameters. However, a large number of experiments require a huge demand for downhole cores, resulting in excessively high core sampling and processing costs. Furthermore, in fractured formations, downhole cores obtained by core drilling are generally severely fractured, making it difficult to process them into standard experimental specimens.
[0004] Patent CN116609184A discloses a method for calculating the compressive strength of fractured formations based on upwelling rock blocks obtained during drilling. This method selects effective blocks from the irregular upwelling blocks, conducts point load tests on them to obtain their compressive strength, defines the equivalent diameter of the effective blocks, and establishes a relationship curve between the uniaxial compressive strength and the equivalent diameter of the effective blocks. Based on this, the compressive strength of the fractured formation is determined using the equivalent diameter of the effective upwelling blocks. However, this method has high requirements for the effective blocks, and rock compressive strength is an intrinsic mechanical property of the rock; predicting it solely based on rock shape is unreliable. Patent CN118050392A discloses a method for calculating rock mechanical parameters based on the mineral distribution of core or cuttings. This method uses electron microscopy and energy dispersive spectroscopy to determine the mineral composition of cores or cuttings obtained during drilling, and then determines the rock mechanical parameters of the formation containing the core or cuttings based on the mineral composition. This method relies on mineral composition analysis of the uptake rock fragments. However, since rock cuttings from different depths are not brought back sequentially during drilling, core samples from different depths may become mixed together, making it difficult to determine the corresponding depth for the calculated rock mechanical parameters. Furthermore, rock mechanical parameters are not solely determined by mineral composition; rock structure, natural fractures, and cementation types all significantly influence these parameters. Patent CN118095060A discloses a method for predicting rock mechanical parameters while drilling based on a dynamic time warping algorithm. This method uses machine learning to construct prediction models for elastic modulus, Poisson's ratio, and compressive strength to predict rock mechanical parameters during drilling. However, this method requires a large amount of accurate measured data to ensure model accuracy, which is impractical in fractured formations. Summary of the Invention
[0005] The purpose of this invention is to provide a method for determining rock mechanical parameters, which solves the problem of obtaining rock mechanical parameters without performing uniaxial or triaxial compression tests on rocks where core samples cannot be obtained.
[0006] To achieve the above objectives, embodiments of the present invention provide a method for determining rock mechanical parameters. The method includes: obtaining a core from a coreable rock and performing a point load test on the core to measure the static uniaxial compressive strength of the rock; calculating the reservoir dynamic uniaxial compressive strength of the rock using sonic logging data, and fitting the reservoir dynamic uniaxial compressive strength with the experimentally measured static uniaxial compressive strength to obtain a dynamic-static uniaxial compressive strength fitting model; calculating the reservoir dynamic uniaxial compressive strength of rocks for which cores cannot be obtained using sonic logging data, and inputting the dynamic uniaxial compressive strength into the fitting model to calculate the static uniaxial compressive strength of the rocks for which cores cannot be obtained; calculating the formation elastic modulus of the rock based on the static uniaxial compressive strength of the rock for which cores cannot be obtained; and calculating the formation Poisson's ratio of the rock based on the drilling mechanical specific energy value, density logging data, and minimum horizontal stress data of the formation in which the rock for which cores cannot be obtained.
[0007] Optionally, the step of calculating the reservoir dynamic uniaxial compressive strength of the rock using sonic logging data includes: calculating the dynamic elastic modulus of the rock based on the formation density, P-wave velocity, and S-wave velocity in the sonic logging data; calculating the clay content index based on the gamma logging value, and obtaining the clay content through the clay content index and the formation correlation empirical coefficient; and calculating the reservoir dynamic uniaxial compressive strength of the rock by combining the dynamic elastic modulus and the clay content.
[0008] Optionally, the formula for calculating the dynamic elastic modulus of the rock based on the formation density, P-wave velocity, and S-wave velocity from the sonic logging data is as follows:
[0009] in, The dynamic elastic modulus of the rock is given by [reference needed]. The shear wave velocity in acoustic logging. For the longitudinal wave velocity in acoustic logging, This represents the density of the formation.
[0010] Optionally, the formula for calculating the clay content index based on gamma logging values is as follows:
[0011] Where GR is the natural gamma logging value of the target layer. The natural gamma logging value is for a pure mudstone layer. The natural gamma logging value is for a pure sandstone layer. The mud content index; The formula for calculating the clay content by using the clay content index and the formation correlation empirical coefficient is as follows:
[0012] in, represents the clay content, and GCUR is the formation-related empirical coefficient.
[0013] Optionally, the formula for calculating the reservoir dynamic uniaxial compressive strength of the rock by combining the dynamic elastic modulus and the clay content is as follows:
[0014] Wherein, UCS is the reservoir dynamic uniaxial compressive strength of the rock. The content of clay, The dynamic elastic modulus of the rock is given.
[0015] Optionally, the dynamic and static uniaxial compressive strength fitting model is as follows:
[0016] in, UCS is the static uniaxial compressive strength of the rock, and A and B are the fitting coefficients.
[0017] Optionally, the formula for calculating the formation elastic modulus of the rock based on the static uniaxial compressive strength of the rock for which core samples cannot be obtained is as follows:
[0018] Where C and D are empirical coefficients, The static uniaxial compressive strength of the rock for which core samples could not be obtained.
[0019] Optionally, calculating the formation Poisson's ratio of the rock based on the drilling mechanical energy value, density logging data, and minimum horizontal stress data of the formation where the rock core cannot be obtained includes: calculating the overlying strata pressure on the rock based on data obtained from density logging data; calculating the formation pressure on the rock based on drilling data; calculating the confining pressure at the well depth where the rock is located, and approximating the confining pressure as the minimum horizontal stress; and calculating the formation Poisson's ratio using the overlying strata pressure, the formation pressure, and the minimum horizontal stress, according to the confining pressure formula.
[0020] Optionally, the formula for calculating the pressure exerted on the rock by the overlying strata is as follows:
[0021] in, g It is the acceleration due to gravity. This refers to the density of the formation rocks measured in density logging data. z The depth is denoted as 0-.h .
[0022] Optionally, calculating the formation pressure on the rock includes: calculating the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure based on the mechanical specific energy value; calculating the formation pressure equivalent drilling fluid density using the actual drilling fluid density and the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure; and calculating the formation pressure on the rock using the formation pressure equivalent drilling fluid density and the well depth.
[0023] Optionally, the formula for calculating the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure based on the mechanical specific energy value is as follows:
[0024] Where HMSE is the mechanical specific energy value, HMSEr is the mechanical specific energy value of the normal trend line, and n is the number of drill bit nozzles; The formula for calculating the formation pressure equivalent drilling fluid density by means of the actual drilling fluid density and the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure is as follows:
[0025] in, The drilling fluid density is the equivalent of formation pressure. This represents the actual drilling fluid density. This is the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure. h For well depth; The formula for calculating the formation pressure on the rock by using the formation pressure equivalent drilling fluid density and the well depth is as follows:
[0026] in, The formation pressure exerted on the rock. Let g be the drilling fluid density equivalent to formation pressure, and g be the acceleration due to gravity. h The depth of the well.
[0027] Optionally, the formula for calculating the confining pressure at the well depth where the rock is located is as follows:
[0028] in, The confining pressure of the formation at the depth of the well where the rock is located. The Poisson's ratio of the rock is given. The pressure exerted on the rock by the overlying strata. The formation pressure exerted on the rock is denoted as .
[0029] Optionally, the formula for calculating the Poisson's ratio of the formation is:
[0030] in, The Poisson's ratio of the rock is given. The pressure exerted on the rock by the overlying strata. The formation pressure exerted on the rock. The minimum horizontal stress is approximately determined as the confining pressure of the formation at the depth of the well where the rock is located.
[0031] Through the above technical solution, this invention conducts point load experiments on core samples of retrievable rock, and fits the measured static uniaxial compressive strength with the dynamic uniaxial compressive strength obtained from sonic logging data to obtain a dynamic-static uniaxial strength conversion model. The static uniaxial compressive strength of rock for which core samples cannot be obtained is calculated using this model, and the elastic modulus of the rock is calculated based on this static compressive strength. Furthermore, the formation Poisson's ratio of the rock is calculated using drilling mechanical energy, density logging data, and minimum horizontal stress data of the formation in which the rock is located, thereby obtaining the mechanical parameters of rock for which core samples cannot be obtained.
[0032] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description
[0033] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic flowchart of a method for determining rock mechanical parameters provided in an embodiment of this disclosure; Figure 2 The dynamic uniaxial compressive strength is calculated from the logging data provided in this embodiment, and the static uniaxial compressive strength is fitted curve obtained from the point load experiment. Figure 3 This is a schematic diagram of the process for calculating the dynamic uniaxial compressive strength of a reservoir using sonic logging data, provided in an embodiment of this disclosure. Figure 4 This is a schematic flowchart of the process for calculating the Poisson's ratio of a rock formation, provided in an embodiment of this disclosure. Figure 5 This is a schematic flowchart illustrating the calculation of formation pressure on rocks provided in an embodiment of this disclosure. Detailed Implementation
[0034] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.
[0035] It should be noted that the acquisition, transmission, storage, use, and processing of data in the technical solution of this application all comply with the relevant provisions of national laws and regulations. In the embodiments of this application, certain existing industry solutions such as software, components, and models may be mentioned. These should be considered exemplary, intended only to illustrate the feasibility of implementing the technical solution of this application, and do not imply that the applicant has already used or necessarily used such solutions.
[0036] Figure 1 This is a schematic flowchart illustrating a method for determining rock mechanical parameters provided in an embodiment of this disclosure. Figure 1 As shown, the method for determining rock mechanical parameters includes steps S101 to S106.
[0037] Step S101: Core the rock to obtain a core, and perform a point load test on the core to obtain the static uniaxial compressive strength of the rock.
[0038] This embodiment of the disclosure takes a shale formation in a certain area as the research object, and retrieves rock blocks with well-developed fractures and faults from the field to obtain rock cores. However, due to the well-developed fractures and faults, it is difficult to process them into standard specimens with a diameter of 25 mm and a radius of 50 mm, making it impossible to perform uniaxial and triaxial compression tests. Therefore, a point load test with less stringent requirements on the specimens is adopted to obtain the static uniaxial compressive strength of the rock.
[0039] Step S102: Calculate the dynamic uniaxial compressive strength of the reservoir using sonic logging data.
[0040] The embodiments of this disclosure obtained the dynamic uniaxial compressive strength and static uniaxial compressive strength of ten cored rock specimens through experimental testing and calculation. The data are shown in Table 1.
[0041] Table 1. Dynamic and static uniaxial compressive strength data
[0042] Step S103: Fit the calculated dynamic uniaxial compressive strength of the reservoir with the experimentally measured static uniaxial compressive strength to obtain a dynamic and static uniaxial compressive strength fitting model.
[0043] In this embodiment, the dynamic uniaxial compressive strength calculated from sonic logging data and the experimentally measured static uniaxial compressive strength are input into MATLAB software. The carve fit tool is then used for fitting to determine the fitting model. The resulting fitting curve is shown below. Figure 2 As shown. Those skilled in the art can determine the fitting method according to the actual application scenario and needs. The embodiments disclosed herein are merely illustrative and not intended to limit the scope.
[0044] Based on the data in Table 1, the expression for the fitted dynamic and static uniaxial compressive strength model is as follows:
[0045] Step S104: Calculate the dynamic uniaxial compressive strength of the reservoir for rocks for which core samples cannot be obtained using sonic logging data, and input it into the dynamic and static compressive strength fitting model to obtain the static uniaxial compressive strength of the rock.
[0046] Step S105: Calculate the formation elastic modulus of the rock based on its static uniaxial compressive strength.
[0047] In this embodiment of the disclosure, the formation elastic modulus is calculated based on the static uniaxial compressive strength obtained by inputting the dynamic uniaxial compressive strength of the reservoir (for which rock cores cannot be obtained) into the dynamic-static compressive strength fitting model. The results are shown in Table 2.
[0048] Table 2 Calculation results of formation elastic modulus
[0049] Step S106: Calculate the formation Poisson's ratio of the rock based on the drilling mechanical energy value, density logging data, and minimum horizontal stress data of the formation where the rock core cannot be obtained.
[0050] The Poisson's ratio data of the formation calculated based on the data provided in this embodiment are shown in Table 3.
[0051] Table 3 Calculation results of Poisson's ratio of the formation
[0052] In this embodiment, relatively intact rock specimens X2 and X6 were processed into standard rock cores using a wire cutting device and subjected to uniaxial compression tests to obtain rock mechanical parameters. These parameters were used to verify the accuracy of the mechanical parameters calculated using the fitting model and formula. The experimental results of the uniaxial compression test are compared with the calculation results of the above method, as shown in Table 4.
[0053] Table 4 Comparison of Calculation Results and Experimental Results
[0054] The mechanical parameters to be obtained by the method proposed in this invention are the compressive strength, elastic modulus, and Poisson's ratio of the rock. A comparison of the experimental results from uniaxial compression tests with the calculation results of the above method shows that the mechanical parameters calculated by the rock mechanical parameter determination method proposed in this disclosure have a small error compared to those obtained from uniaxial compression tests, verifying the effectiveness of this method. Therefore, this method enables the acquisition of formation rock mechanical parameters based on drilling data, logging data, core data, and point load experiments, even when uniaxial and triaxial compression tests cannot be conducted.
[0055] Figure 3 This is a schematic flowchart illustrating the process of calculating the dynamic uniaxial compressive strength of a reservoir using sonic logging data, as provided in an embodiment of this disclosure. Figure 3 As shown, the calculation of the reservoir dynamic uniaxial compressive strength of the rock using sonic logging data includes steps S201 to S203.
[0056] Step S201: Calculate the dynamic elastic modulus of the rock based on the formation density, P-wave velocity, and S-wave velocity in the sonic logging data.
[0057] Specifically, the formula for calculating the dynamic elastic modulus of the rock is as follows:
[0058] in, The dynamic elastic modulus of the rock is given by [reference needed]. The shear wave velocity in acoustic logging. For the longitudinal wave velocity in acoustic logging, This represents the density of the formation.
[0059] Step S202: Calculate the clay content index based on the gamma logging value, and obtain the clay content by combining the clay content index with the formation correlation empirical coefficient.
[0060] Specifically, the formula for calculating the clay content index based on gamma logging values is as follows:
[0061] Where GR is the natural gamma logging value of the target layer. The natural gamma logging value is for a pure mudstone layer. The natural gamma logging value is for a pure sandstone layer. The mud content index; The formula for calculating the clay content by using the clay content index and the formation correlation empirical coefficient is as follows:
[0062] in, represents the clay content, and GCUR is the formation-related empirical coefficient.
[0063] Step S203: Calculate the reservoir dynamic uniaxial compressive strength of the rock by combining the dynamic elastic modulus and the clay content.
[0064] Specifically, the formula for calculating the reservoir dynamic uniaxial compressive strength of the rock by combining the dynamic elastic modulus and the clay content is as follows:
[0065] Wherein, UCS is the reservoir dynamic uniaxial compressive strength of the rock. The content of clay, The dynamic elastic modulus of the rock is given.
[0066] In some embodiments, the dynamic and static uniaxial compressive strength fitting model is:
[0067] in, UCS is the static uniaxial compressive strength of the rock, and A and B are the fitting coefficients.
[0068] In some embodiments, the formula for calculating the formation elastic modulus of the rock based on the static uniaxial compressive strength of the rock for which core samples cannot be obtained is as follows:
[0069] Where C and D are empirical coefficients, The static uniaxial compressive strength of the rock for which core samples could not be obtained.
[0070] Figure 4 This is a schematic flowchart illustrating the calculation of Poisson's ratio of rock formations provided in an embodiment of this disclosure. Figure 4 As shown, the step of calculating the formation Poisson's ratio of the rock based on the drilling mechanical energy value, density logging data and minimum horizontal stress data of the formation where the rock core cannot be obtained includes steps S301 to S304.
[0071] Step S301: Calculate the pressure of the overlying strata on the rock based on the data obtained from density logging data.
[0072] Specifically, the formula for calculating the pressure exerted on the rock by the overlying strata is as follows:
[0073] in, g It is the acceleration due to gravity. This refers to the density of the formation rocks measured in density logging data.z The depth is denoted as 0-. h .
[0074] Step S302: Calculate the formation pressure on the rock based on drilling data.
[0075] Step S303: Calculate the confining pressure of the formation at the depth of the well where the rock is located, and approximate the confining pressure of the formation as the minimum horizontal stress.
[0076] Specifically, the formula for calculating the confining pressure at the well depth where the rock is located is as follows:
[0077] in, The confining pressure of the formation at the depth of the well where the rock is located. The Poisson's ratio of the rock is given. The pressure exerted on the rock by the overlying strata. The formation pressure exerted on the rock is denoted as .
[0078] Step S304: Using the overlying strata pressure, the formation pressure, and the minimum horizontal stress, calculate the formation Poisson's ratio according to the formation confining pressure formula.
[0079] Specifically, the formula for calculating the Poisson's ratio of the formation is as follows:
[0080] in, The Poisson's ratio of the rock is given. The pressure exerted on the rock by the overlying strata. The formation pressure exerted on the rock. The minimum horizontal stress is approximately determined as the confining pressure of the formation at the depth of the well where the rock is located.
[0081] Figure 5 This is a schematic flowchart illustrating the calculation of formation pressure on rocks according to an embodiment of this disclosure. Figure 5 As shown, the calculation of the formation pressure on the rock includes steps S401 to S403.
[0082] Step S401: Calculate the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure based on the mechanical specific energy value.
[0083] Specifically, the formula for calculating the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure based on the mechanical specific energy value is as follows:
[0084] Where HMSE is the mechanical specific energy value, HMSEr is the mechanical specific energy value of the normal trend line, and n is the number of drill bit nozzles; Step S402: Calculate the formation pressure equivalent drilling fluid density by using the actual drilling fluid density and the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure.
[0085] Specifically, the formula for calculating the formation pressure equivalent drilling fluid density by means of the actual drilling fluid density and the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure is as follows:
[0086] in, The drilling fluid density is the equivalent of formation pressure. This represents the actual drilling fluid density. This is the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure. h The depth of the well.
[0087] Step S403: Calculate the formation pressure on the rock using the formation pressure equivalent drilling fluid density and well depth.
[0088] Specifically, the formula for calculating the formation pressure on the rock by using the formation pressure equivalent drilling fluid density and the well depth is as follows:
[0089] in, The formation pressure exerted on the rock. Let g be the drilling fluid density equivalent to formation pressure, and g be the acceleration due to gravity. h The depth of the well.
[0090] Through the above technical solution, this embodiment utilizes point load experiments combined with relevant empirical formulas to fit the dynamic and static uniaxial compressive strength relationship, analyzes the compressive strength of rocks in fractured formations where core samples cannot be obtained, calculates the formation elastic modulus using empirical formulas, calculates formation pressure using drilling machinery specific energy values, calculates overlying strata pressure using density logging data, and calculates Poisson's ratio of the formation using minimum horizontal in-situ stress. This method can determine the rock mechanical parameters of formations in underground sections where core samples cannot be obtained, providing fundamental data support for drilling and completion, oil and gas extraction design, and construction.
[0091] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0092] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.
[0093] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.
[0094] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.
[0095] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.
[0096] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.
[0097] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.
[0098] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.
[0099] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.
Claims
1. A method for determining rock mechanical parameters, characterized in that, The method includes: Core samples were obtained from the coreable rock, and a point load test was performed on the core sample to measure the static uniaxial compressive strength of the rock. The dynamic uniaxial compressive strength of the reservoir is calculated using sonic logging data, and the dynamic uniaxial compressive strength of the reservoir is fitted with the experimentally measured static uniaxial compressive strength to obtain a dynamic and static uniaxial compressive strength fitting model. The dynamic uniaxial compressive strength of the reservoir rock for which core samples cannot be obtained is calculated using sonic logging data, and this dynamic uniaxial compressive strength is input into the fitting model to calculate the static uniaxial compressive strength of the rock for which core samples cannot be obtained. Calculate the formation elastic modulus of the rock based on the static uniaxial compressive strength of the rock for which core samples cannot be obtained; and Based on the drilling mechanical energy, density logging, and minimum horizontal stress data of the formation where the rock core could not be obtained, the formation Poisson's ratio of the rock was calculated.
2. The method for determining mechanical parameters according to claim 1, characterized in that, The calculation of the reservoir dynamic uniaxial compressive strength of the rock using sonic logging data includes: The dynamic elastic modulus of the rock is calculated based on the formation density, P-wave velocity, and S-wave velocity from the sonic logging data. The clay content index was calculated based on gamma logging values, and the clay content was obtained by correlating this index with an empirical coefficient related to the formation; and The dynamic uniaxial compressive strength of the rock reservoir is calculated by combining the dynamic elastic modulus and the clay content.
3. The method for determining mechanical parameters according to claim 2, characterized in that, The formula for calculating the dynamic elastic modulus of the rock based on the formation density, P-wave velocity, and S-wave velocity from the sonic logging data is as follows: in, The dynamic elastic modulus of the rock is given by [reference needed]. The shear wave velocity in acoustic logging. For the longitudinal wave velocity in acoustic logging, This represents the density of the formation.
4. The method for determining mechanical parameters according to claim 2, characterized in that, The formula for calculating the clay content index based on gamma logging values is as follows: Where GR is the natural gamma logging value of the target layer. The natural gamma logging value is for a pure mudstone layer. The natural gamma logging value is for pure sandstone layers. The mud content index; The formula for calculating the clay content by using the clay content index and the formation correlation empirical coefficient is as follows: in, represents the clay content, and GCUR is the formation-related empirical coefficient.
5. The method for determining mechanical parameters according to claim 2, characterized in that, The formula for calculating the reservoir dynamic uniaxial compressive strength of the rock by combining the dynamic elastic modulus and the clay content is as follows: Wherein, UCS is the reservoir dynamic uniaxial compressive strength of the rock. The content of clay, The dynamic elastic modulus of the rock is given.
6. The method for determining mechanical parameters according to claim 1, characterized in that, The dynamic and static uniaxial compressive strength fitting model is as follows: in, UCS is the static uniaxial compressive strength of the rock, and A and B are the fitting coefficients.
7. The method for determining mechanical parameters according to claim 1, characterized in that, The formula for calculating the formation elastic modulus of the rock based on the static uniaxial compressive strength of the rock for which core samples cannot be obtained is as follows: Where C and D are empirical coefficients, The static uniaxial compressive strength of the rock for which core samples could not be obtained.
8. The method for determining mechanical parameters according to claim 1, characterized in that, The calculation of the formation Poisson's ratio of the rock based on the drilling mechanical energy, density logging, and minimum horizontal stress data of the formation where core samples cannot be obtained includes: Based on data obtained from density logging, the pressure exerted on the rock by the overlying strata is calculated. Based on drilling data, the formation pressure on the rock is calculated; Calculate the confining pressure at the depth of the well where the rock is located, and approximate the confining pressure as the minimum horizontal stress. Using the overlying strata pressure, the formation pressure, and the minimum horizontal stress, the Poisson's ratio of the formation is calculated according to the formation confining pressure formula.
9. The method for determining mechanical parameters according to claim 8, characterized in that, The formula for calculating the pressure exerted on the rock by the overlying strata is as follows: in, g It is the acceleration due to gravity. This refers to the density of the formation rocks measured in density logging data. z The depth is denoted as 0-. h .
10. The method for determining mechanical parameters according to claim 8, characterized in that, The calculation of the formation pressure on the rock includes: Calculate the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure based on the mechanical specific energy value; The formation pressure equivalent drilling fluid density is calculated by using the actual drilling fluid density and the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure; and The formation pressure on the rock is calculated using the formation pressure equivalent drilling fluid density and well depth.
11. The method for determining mechanical parameters according to claim 10, characterized in that, The formula for calculating the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure based on the mechanical specific energy value is as follows: Where HMSE is the mechanical specific energy value, HMSEr is the mechanical specific energy value of the normal trend line, and n is the number of drill bit nozzles; The formula for calculating the formation pressure equivalent drilling fluid density by means of the actual drilling fluid density and the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure is as follows: in, The drilling fluid density is the equivalent of formation pressure. This represents the actual drilling fluid density. This is the pressure difference between the hydrostatic pressure of the drilling fluid column and the formation pressure. h For well depth; The formula for calculating the formation pressure on the rock by using the formation pressure equivalent drilling fluid density and the well depth is as follows: in, The formation pressure exerted on the rock. Let g be the drilling fluid density equivalent to formation pressure, and g be the acceleration due to gravity. h The depth of the well.
12. The method for determining mechanical parameters according to claim 8, characterized in that, The formula for calculating the confining pressure at the well depth where the rock is located is as follows: in, The confining pressure of the formation at the depth of the well where the rock is located. The Poisson's ratio of the rock is given. The pressure exerted on the rock by the overlying strata. The formation pressure exerted on the rock is denoted as .
13. The method for determining mechanical parameters according to claim 12, characterized in that, The formula for calculating the Poisson's ratio of the formation is as follows: in, The Poisson's ratio of the rock is given. The pressure exerted on the rock by the overlying strata. The formation pressure exerted on the rock. The minimum horizontal stress is approximately determined as the confining pressure of the formation at the depth of the well where the rock is located.