Method for selecting compact reservoir pressure-maintaining and shape-maintaining coring sleeve based on CT scanning

Abstract

The application discloses a kind of based on CT scanning's compact reservoir pressure-maintaining shape coring sleeve material selection method, comprising the following steps: determine pressure-maintaining shape coring sleeve material evaluation parameter type and withstand pressure range requirement;Select the sleeve of corresponding material type and carry out stress deformation experiment, obtain the development condition of each kind of sleeve microcrack network, establish the CT gray model of sleeve crack development;Establish the three-dimensional model of crack network after each kind of sleeve deformation, establish the fitting function of stress-strain and crack development rate of each kind of material sleeve;The coupling relationship between stress-strain, crack development rate of different material types, different thicknesses is simulated by applying multi-parameter synergistic modeling method, and the applicable pressure-maintaining shape coring sleeve is selected;To establish the accurate evaluation technology and standard of local compact reservoir pressure-maintaining shape coring sleeve material selection, improve the efficiency of oil and gas exploration in compact oil and gas enrichment and preservation favorable block, reduce oil and gas exploration, drilling cost.

Description

Technical Field

[0001] This invention belongs to the field of drilling engineering design technology and relates to a method for selecting materials and types of coring sleeves for pressure-maintaining and shape-preserving drilling in tight reservoirs based on CT scanning. Background Technology

[0002] The selection of materials and types for pressure- and shape-preserving coring sleeves in tight reservoirs has long been a global technical challenge in oil and gas drilling engineering. Due to limitations in current ultrasonic testing methods, the development network of microfractures within the coring sleeve during core extraction cannot be directly and effectively obtained, hindering the resolution of geological issues related to pressure and shape preservation. This results in inconsistent accuracy between subsequent geological research results and the actual original condition of the underground oil and gas reservoir. The advent of CT non-destructive testing technology, combined with deep learning simulation technology, has provided technical support for the selection of pressure- and shape-preserving coring sleeves in tight reservoirs. As oil and gas exploration deepens, the areas available for conventional oil and gas exploration are decreasing, and new discoveries are becoming increasingly difficult. Therefore, unconventional oil and gas exploration is gradually becoming a key exploration area now and in the future, and the difficulty of coring will gradually increase. The stress-strain strength of the coring sleeve is the foundation for pressure- and shape-preserving coring in tight reservoirs and is one of the key aspects of oil and gas well drilling engineering.

[0003] Existing ultrasonic testing technology cannot effectively predict the development network of microfractures inside the core sleeve, and can only provide qualitative results. This makes it impossible to effectively implement pressure-preserving and shape-preserving core sampling. The oil and gas conservation enrichment detected on the surface cannot reach the original state underground, resulting in low success rate and efficiency of oil and gas exploration.

[0004] Therefore, there is an urgent need to develop a new method for selecting core sleeves that maintain pressure and shape in tight reservoirs. This method can accurately determine the stress deformation, fracture status, and pressure and shape maintenance of the core sleeve, clearly indicating the degree of consistency between the detected oil and gas enrichment and the original underground state. This will provide accurate geological information for tight oil and gas exploration and the evaluation of favorable targets, better guide the deep exploration of tight oil and gas, improve efficiency, and reduce risks. Summary of the Invention

[0005] To achieve the above objectives, this invention provides a method for selecting and choosing materials for pressure-preserving and shape-preserving coring sleeves in tight reservoirs based on CT scanning. This method aims to establish accurate evaluation technology and standards for selecting and choosing materials for pressure-preserving and shape-preserving coring sleeves in tight reservoirs in this region, thereby improving the efficiency of oil and gas exploration in favorable blocks for the enrichment and preservation of tight oil and gas, and reducing the costs of oil and gas exploration and drilling.

[0006] The technical solution adopted in this invention is a method for selecting and choosing materials for pressure-maintaining and shape-preserving coring sleeves in tight reservoirs based on CT scanning, comprising the following steps:

[0007] Step 1: Determine the material evaluation parameters and pressure range requirements for the pressure-holding and shape-preserving coring sleeve;

[0008] Step 2: Select the appropriate material type of sleeve, conduct stress deformation experiments on each type of core sleeve, and then use CT scanning technology to scan the stress-deformed core sleeve to obtain the development status of microcrack network of each type of sleeve and establish a CT grayscale model of sleeve crack development.

[0009] Step 3: Establish a three-dimensional model of the crack network after deformation of various sleeves. Based on the experimental data of stress-deformation rupture and the three-dimensional model of the crack network, establish a fitting function for the relationship between stress-strain and crack development rate of sleeves of various materials.

[0010] Step 4: Apply the multi-parameter synergistic modeling method to simulate the coupling relationship between stress and strain and crack non-development rate of different material types and thicknesses, and select a suitable pressure-holding and shape-preserving coring sleeve.

[0011] Furthermore, step one specifically involves: based on the geological background of the oil and gas reservoir, and based on drilling geology and engineering design, obtaining the tight reservoir rock type, burial depth, formation temperature, formation pressure, coring requirements, experimental analysis requirements, drilling method and well type; and determining the evaluation parameter type and pressure range requirements of the pressure-maintaining and shape-preserving coring sleeve material based on the above parameters.

[0012] Furthermore, in step two, the selection criterion for identifying the grayscale value of the sleeve crack development in the CT grayscale model is: the grayscale value of the sleeve crack development needs to identify the three-dimensional network of the sleeve crack and its changes.

[0013] Furthermore, in step two, after the stress deformation experiment, the threshold pressure, rupture pressure and their changes of the core sleeves of various types of materials after stress deformation are obtained, as well as the comparison and differences of the threshold pressure and rupture pressure of the core sleeves of different materials after stress deformation crack development.

[0014] Furthermore, in step two, after the stress deformation experiment, core sleeves of the same material with different thicknesses are obtained, and the threshold pressure, rupture pressure and their changes in crack development are obtained, as well as the degree of difference in crack development of core sleeves of the same material with different thicknesses under the same pressure.

[0015] Furthermore, the method for establishing the three-dimensional model of the crack network in step three is as follows: based on the established CT grayscale model of crack development, training samples of crack grayscale values ​​are manually extracted based on the Retina-Net deep learning method to establish a grayscale function model of sleeve crack development using the Retina-Net algorithm deep learning, and then deep learning is performed to establish a three-dimensional model of the crack network after various sleeve deformations.

[0016] Furthermore, the CT grayscale model is a CT grayscale model of crack development under the threshold pressure of the core sleeve for various types of materials.

[0017] Furthermore, after selecting a core sleeve that is less prone to crack development in step three, the method further includes: studying the relationship between stress and strain of the core sleeve material and model and crack development rate, in order to establish a method for selecting sleeve materials and models in the region.

[0018] The beneficial effects of this invention are:

[0019] 1) It fills the gap in the quantitative evaluation method for the selection of materials and types of coring sleeves for pressure-preserving and shape-preserving core sampling in tight reservoirs. It utilizes quantitative indicators of the fracture development network and gray-scale space changes of the coring sleeves for pressure-preserving and shape-preserving core sampling in tight reservoirs, collected by CT scans, and uses deep learning to accurately understand the fracture development network and gray-scale space changes of the coring sleeves for pressure-preserving and shape-preserving core sampling in tight reservoirs, as well as the characteristics and laws of fracture development and evolution with pressure changes, thus providing more effective technical information for tight oil and gas exploration.

[0020] 2) Improve the efficiency of oil and gas exploration and drilling, and reduce costs. This invention organically integrates mechanical experiments and CT crack detection in the study of core sleeve stress fracture. It applies deep learning methods to establish a comprehensive parameter evaluation index for stress fracture of pressure-preserving and shape-preserving core sleeve, and establishes a stress fracture evaluation method and technical standard for pressure-preserving and shape-preserving core sleeve that conforms to the geological conditions of the region. This improves the accuracy of drilling prediction in favorable blocks, increases the drilling efficiency of oil and gas exploration, and reduces the cost of oil and gas exploration. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart of the method for selecting and choosing materials for pressure-maintaining and shape-preserving coring sleeves in tight reservoirs based on CT scanning, provided in an embodiment of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figure 1 As shown, this invention provides a method for selecting and choosing materials for pressure-maintaining and shape-preserving coring sleeves in tight reservoirs based on CT scanning, comprising the following steps:

[0025] Step 1: Based on the geological background of the oil and gas reservoir, and based on drilling geology and engineering design, obtain information such as tight reservoir rock type, burial depth, formation temperature, formation pressure, coring requirements, experimental analysis requirements, drilling method and well type. Based on the above parameters, determine the evaluation parameter type and pressure range requirements of the pressure-maintaining and shape-preserving coring sleeve material.

[0026] Step 2: Based on the evaluation parameters of the pressure-holding and shape-preserving core sleeve and the requirements of the pressure range, select the appropriate material type of sleeve, conduct stress deformation experiments on various core sleeves, and then use CT scanning technology to scan the stress-deformed core sleeves to obtain the development status of the microcrack network of various sleeves and establish a CT grayscale model of sleeve crack development.

[0027] In some implementations, in step two, the selection criterion for identifying the sleeve crack development grayscale value in the CT grayscale model of sleeve and crack development is: the sleeve crack development grayscale value needs to be able to identify the three-dimensional network of sleeve cracks and its changes.

[0028] In some implementations, the purpose of the stress deformation experiment in step two is to obtain the threshold pressure, rupture pressure and their changes in the crack development of cored sleeves of various types of materials after stress deformation, as well as the comparison and differences in the threshold pressure and rupture pressure of different material sleeves after stress deformation crack development.

[0029] In some implementations, the purpose of the stress-deformation experiment in step two is to obtain the threshold pressure, rupture pressure and their changes for cored sleeves of different material thicknesses with the same material, and to determine the degree of difference in crack development under the same pressure on cored sleeves of different material thicknesses.

[0030] Step 3: Based on the established CT grayscale model of crack development, training samples of crack grayscale values ​​are manually extracted using the Retina-Net deep learning method to establish a grayscale function model of sleeve crack development using the Retina-Net deep learning algorithm. Deep learning is then performed to establish a three-dimensional crack network model for various sleeves after deformation. This three-dimensional crack network model is used to calculate the crack development rate. Based on the stress-deformation rupture experimental data and the three-dimensional crack network model, a fitting function is established to determine the relationship between stress and strain of various material sleeves and the crack development rate (the crack development rate is calculated based on the three-dimensional crack network model after sleeve deformation). Suitable cored sleeves with low crack development are then selected.

[0031] In some implementations, in step three, the CT grayscale model refers to the CT grayscale model of crack development at the threshold pressure of the core sleeve rupture for different types of materials. That is, the CT grayscale model of the initial development of cracks for each type of material is the CT grayscale model used to establish the grayscale function model for that type of material.

[0032] In some implementations, in step three, the grayscale function model of deep learning should be different for each stage of the development and evolution of cracks in the coring sleeve.

[0033] In some implementations, in step three, the relationship between stress and strain and crack development rate of the core sleeve material and model is studied to establish a method for selecting sleeve materials and models in this region.

[0034] Step four: Apply the multi-parameter synergistic modeling method to simulate the coupling relationship between different sleeve material types, different thicknesses of stress and strain, and crack non-development rate, and establish a qualification rate evaluation standard for pressure-maintaining and shape-preserving coring sleeve types and models that conform to the geological conditions of this region, so as to select suitable pressure-maintaining and shape-preserving coring sleeves.

[0035] The present invention provides a method for selecting and constructing pressure-maintaining and shape-preserving coring sleeves for tight reservoirs based on CT scanning. This method utilizes quantitative indicators of fracture development grayscale obtained from CT scans and employs deep learning to determine the stress-induced fracture and its standard in pressure-maintaining and shape-preserving coring sleeves. It accurately evaluates the threshold pressure, fracture pressure, and their variation patterns of fracture development in coring sleeves under stress, as well as compares and compares the threshold pressure and fracture pressure of fracture development in sleeves made of different materials, thereby improving the accuracy of tight oil and gas drilling evaluation, increasing the efficiency of oil and gas exploration, and reducing the cost of oil and gas exploration and drilling.

[0036] As shown in Table 1, the selection criteria for core sleeves in a certain region are established based on the method of the present invention. In actual work, suitable core sleeves can be reasonably selected according to the criteria in Table 1 to improve the efficiency of oil and gas exploration and reduce the cost of oil and gas exploration and drilling.

[0037] Table 1. Selection Standards for Core Sleeves in a Certain Region

[0038]

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for selecting and choosing materials for pressure-maintaining and shape-preserving coring sleeves in tight reservoirs based on CT scanning, characterized in that, include: Step 1: Determine the type of evaluation parameters and pressure range requirements for the pressure-holding and shape-preserving coring sleeve material; Step 2: Based on the evaluation parameters of the pressure-holding and shape-preserving core sleeve and the requirements of the pressure range, select the appropriate material type of sleeve, conduct stress deformation experiments on various core sleeves, and then use CT scanning technology to scan the stress-deformed core sleeves to obtain the development status of the microcrack network of various sleeves and establish a CT grayscale model of the sleeve crack development. The selection criteria for grayscale identification of sleeve crack development in CT grayscale model of sleeve and crack development is: the grayscale value of sleeve crack development needs to be able to identify the three-dimensional network of sleeve cracks and its changes. The purpose of the stress-deformation experiment is to obtain the threshold pressure, rupture pressure and their changes in the crack development of cored sleeves of various types of materials after stress-deformation, as well as the comparison and differences in the threshold pressure and rupture pressure of the crack development of sleeves of different materials after stress-deformation. The purpose of the stress-deformation experiment is to obtain the threshold pressure, rupture pressure and their changes in core sleeves of the same material with different thicknesses for crack development; and to determine the degree of difference in crack development under the same pressure on core sleeves of the same material with different thicknesses. Step 3: Based on the established CT grayscale model of crack development, training samples of crack grayscale values ​​are manually extracted using the Retina-Net deep learning method to establish a grayscale function model of sleeve crack development using the Retina-Net deep learning algorithm. Deep learning is then performed to establish a three-dimensional crack network model for various sleeves after deformation. This three-dimensional crack network model is used to calculate the crack development rate. Based on the stress-deformation rupture experimental data and the three-dimensional crack network model, a fitting function for the relationship between stress-strain and crack development rate for various material sleeves is established, and suitable cored sleeves with low crack development rates are selected. The CT grayscale model refers to the different grayscale models of crack development at the threshold pressure of the core sleeve rupture for different types of materials. That is, the CT grayscale model of the initial development of cracks for each type of material is the CT grayscale model used to establish the grayscale function model for that type of material. The gray-scale function model of deep learning is different for each stage of the development and evolution of cracks in the core-taking sleeve. This study investigates the relationship between stress and strain and crack development rate of core sleeve materials and models in order to establish a method for selecting sleeve materials and models. Step four: Apply the multi-parameter synergistic modeling method to simulate the coupling relationship between different sleeve material types, different thicknesses of stress and strain, and crack non-development rate, and select a suitable pressure-maintaining and shape-preserving coring sleeve.

2. The method for selecting and choosing materials for pressure-maintaining and shape-preserving coring sleeves in tight reservoirs based on CT scanning, as described in claim 1, is characterized in that... The first step is as follows: Based on the geological background of the oil and gas reservoir, and based on drilling geology and engineering design, obtain the tight reservoir rock type, burial depth, formation temperature, formation pressure, coring requirements, experimental analysis requirements, drilling method and well type, and determine the evaluation parameter type and pressure range requirements of the pressure-maintaining and shape-maintaining coring sleeve material.

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