Method and device for determining flow conductivity of acid-etched fracture

Abstract

The invention provides a method and a device for determining the flow conductivity of an acid-etched fracture. The method comprises the following steps: acquiring rock mineral composition, porosity, permeability, formation Young modulus, formation closing stress, formation Poisson's ratio and acid etching fracture goodness of a work area; determining the width of the acid etching crack of the work area based on the rock mineral composition, the porosity and the permeability; determining the tortuosity of the acid etching fracture surface of the work area based on the formation Young modulus, the formation closing stress and the formation Poisson's ratio; and determining the flow conductivity of the acid-etched crack of the work area based on the crack width of the acid-etched crack of the work area, the tortuosity of the acid-etched crack surface of the work area and the goodness of fit of the acid-etched crack of the work area. According to the method, the influence of factors such as rock lithology, stratum physical property, fracture surface spatial form and rock mechanical parameters on the acid-etched fracture conductivity is fully considered, and the acid-etched fracture conductivity can be rapidly and accurately determined.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum extraction, and in particular relates to a method and a device for determining the conductivity of an acid-etched fracture. Background Art

[0002] Carbonate reservoirs have large oil and gas reserves, accounting for about 48% of the world's crude oil reserves and 28% of natural gas reserves. They have high single-well production and are receiving increasing attention in the world's oil and gas industry. Acid fracturing is one of the key technologies for reservoir reconstruction. The fracture morphology, rock mineral content, porosity and permeability conditions, and rock mechanical parameters after acid erosion will affect the conductivity of acid erosion fractures, and the conductivity of acid erosion fractures has become one of the important indicators for evaluating acid fracturing technology.

[0003] At present, there are defects in the characterization methods of acid-etched fracture space. Most of them take the contour features of a single fracture surface or a single fracture surface as the characteristics of the fracture space, such as roughness, fractal dimension, peak value, tortuosity, etc. Although the degree of fit can characterize the closure characteristics of both sides of the fracture, it cannot reflect the morphology of the fracture space. At present, the conductivity models of acid-etched fractures used to determine the conductivity of acid-etched fractures are mostly empirical models or their improved models, and there is a common problem of inaccurate results in determining the conductivity of acid-etched fractures. The spatial morphology of acid-etched fractures, rock mechanical parameters, closure stress, and fracture contact state can all affect the conductivity of acid-etched fractures. At present, it is still necessary to study technical solutions that can accurately determine the conductivity of acid-etched fractures. Summary of the invention

[0004] The purpose of the present invention is to provide a technical solution that can accurately determine the conductivity of acid-etched cracks. In order to achieve the above purpose, the present invention provides the following five technical solutions.

[0005] In a first aspect, the present invention provides a method for determining conductivity of an acid-etched fracture, the method comprising:

[0006] Obtain the rock mineral composition, porosity, permeability, formation Young's modulus, formation closure stress, formation Poisson's ratio and acid-etched fracture consistency of the work area;

[0007] Determine the width of acid-etched cracks in the work area based on rock mineral composition, porosity, and permeability;

[0008] Based on the formation Young's modulus, formation closure stress, and formation Poisson's ratio, the tortuosity of the acid-etched fracture surface in the work area is determined;

[0009] The conductivity of the acid-etched cracks in the work area is determined based on the width of the acid-etched cracks in the work area, the tortuosity of the acid-etched crack surfaces in the work area, and the consistency of the acid-etched cracks in the work area.

[0010] In a second aspect, the present invention provides a device for determining conductivity of an acid-etched fracture, the device comprising:

[0011] Data acquisition module: used to obtain the rock mineral composition, porosity, permeability, formation Young's modulus, formation closure stress, formation Poisson's ratio and acid-etched fracture conformity (i.e., the contact ratio between the two sides of the fracture) of the work area;

[0012] Fracture width determination module: used to determine the width of acid-etched cracks in the work area based on rock mineral composition, porosity, and permeability;

[0013] Tortuosity determination module: used to determine the tortuosity of the acid-etched fracture surface in the work area based on the formation Young's modulus, formation closure stress, and formation Poisson's ratio;

[0014] Fracture conductivity determination module: used to determine the conductivity of the acid-etched cracks in the work area based on the width of the acid-etched cracks in the work area, the tortuosity of the acid-etched crack surfaces in the work area, and the consistency of the acid-etched cracks in the work area.

[0015] In a third aspect, the present invention provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method for determining the conductivity of acid-etched fractures provided in the first aspect is implemented.

[0016] In a fourth aspect, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the method for determining the conductivity of acid-etched fractures provided in the first aspect.

[0017] In a fifth aspect, the present invention provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, it implements the method for determining the conductivity of acid-etched fractures provided in the first aspect.

[0018] The technical solution provided by the present invention fully considers the influence of factors such as rock lithology, formation physical properties, fracture surface spatial morphology and rock mechanical parameters on the conductivity of acid-etched fractures, overcomes the defects of insufficient consideration in previous models, and can quickly and accurately determine the conductivity of acid-etched fractures, providing a basis for accurately analyzing the effective action distance of acid etching and optimizing the liquid parameters of the acid fracturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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 prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0020] Figure 1This is the conductivity-closure stress diagram of acid-etched cracks.

[0021] Figure 2 This is the relationship diagram between conductivity and porosity of acid-etched fractures.

[0022] Figure 3 This is the relationship diagram between conductivity and permeability of acid-etched fractures.

[0023] Figure 4 This is the relationship diagram between acid-etched crack conductivity and Young's modulus.

[0024] Figure 5 This is the relationship diagram between conductivity of acid-etched cracks and Poisson's ratio. DETAILED DESCRIPTION

[0025] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0026] In the description of this specification, the terms "include", "including", "have", "contain", etc. are all open terms, which mean including but not limited to. The descriptions with reference to the terms "one embodiment", "a specific embodiment", "some embodiments", "for example", etc. mean that the specific features, structures or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. The order of steps involved in each embodiment is used to schematically illustrate the implementation of the present application, and the order of steps is not limited and can be appropriately adjusted as needed.

[0027] An embodiment of the present invention provides a method for determining conductivity of an acid-etched fracture, the method comprising the following steps:

[0028] Step 101, obtaining the rock mineral composition, porosity, permeability, formation Young's modulus, formation closure stress, formation Poisson's ratio and acid-etched fracture conformity (i.e., the contact ratio between the two sides of the fracture) of the work area;

[0029] Step 102, determining the width of the acid-etched cracks in the work area based on the rock mineral composition, porosity, and permeability;

[0030] Step 103, determining the tortuosity of the acid-etched fracture surface in the work area based on the formation Young's modulus, the formation closure stress, and the formation Poisson's ratio;

[0031] Step 104, determining the conductivity of the acid-etched cracks in the work area based on the width of the acid-etched cracks in the work area, the tortuosity of the acid-etched crack surface in the work area, and the conformity of the acid-etched cracks in the work area.

[0032] Existing methods for determining the conductivity of acid-etched fractures usually ignore the influence of rock lithology, formation physical properties, acid-etched fracture surface morphology, etc. on the conductivity of acid-etched fractures. However, carbonate rocks with different lithology and physical properties will produce fracture surfaces with different morphologies, and the morphology of acid-etched fracture surfaces will greatly affect the conductivity of rocks and the effective action distance of acid-etching. The above-mentioned technical solution provided by the present invention fully considers the influence of factors such as rock lithology, formation physical properties, fracture surface spatial morphology and rock mechanical parameters on the conductivity of acid-etched fractures, overcomes the defects of insufficient consideration of previous models, can quickly and accurately determine the conductivity of acid-etched fractures, and provides a basis for accurately analyzing the effective action distance of acid-etching and optimizing the liquid parameters of the acid fracturing process.

[0033] In one embodiment, in step 102, determining the width of the acid-etched crack based on the rock mineral composition, porosity, and permeability includes:

[0034] Step 1021, based on the rock mineral composition, porosity, and permeability of the work area, the fractal dimension of the fracture wall of the work area is determined by using a relationship model between the fractal dimension of the fracture wall and the rock mineral composition, porosity, and permeability;

[0035] Step 1022, based on the fractal dimension of the crack wall in the work area, the average curvature of the acid-etched crack space in the work area is determined using a relationship model between the average curvature of the acid-etched crack space and the fractal dimension of the crack wall;

[0036] Step 1023, based on the average curvature of the acid-etched crack space in the work area, the width of the acid-etched crack in the work area is determined using a relationship model between the width of the acid-etched crack and the average curvature of the acid-etched crack space in the work area.

[0037] In one embodiment, in step 1021, the relationship model between the fracture wall fractal dimension and the rock mineral composition, porosity, and permeability is:

[0038]

[0039] Where, X i is the content of the ith mineral, dimensionless; is porosity, dimensionless; K is permeability, mD; a i , b1, b2 are coefficients; D is the fractal dimension of the crack wall, dimensionless;

[0040] Furthermore, the rock mineral composition includes N-1 carbonate minerals, X1 to X N-1 are the contents of these N-1 carbonate minerals, X N is the non-carbonate mineral content;

[0041] For example, the relationship model between the fractal dimension of the fracture wall and the rock mineral composition, porosity, and permeability is:

[0042]

[0043] Where, X1 is the calcite content, dimensionless; X2 is the dolomite content, dimensionless; X3 is the non-carbonate mineral content, dimensionless; is the porosity, dimensionless; K is the permeability, mD; D is the fractal dimension of the fracture wall, dimensionless.

[0044] In one embodiment, in step 1022, the relationship model between the average curvature of the acid-etched crack space and the fractal dimension of the crack wall is:

[0045] K a =mD+n

[0046] In the formula, K a is the average curvature of the acid-etched crack space, dimensionless; m and n are coefficients; D is the fractal dimension of the crack wall, dimensionless;

[0047] For example, the relationship model between the average curvature of the acid-etched crack space and the fractal dimension of the crack wall is:

[0048] K a =0.4524D-0.3937

[0049] In the formula, K a is the spatial average curvature of the acid-etched crack, dimensionless; D is the fractal dimension of the crack wall, dimensionless.

[0050] In one embodiment, in step 1023, the relationship model between the acid-etched crack width and the average curvature of the acid-etched crack space in the work area is:

[0051] w=pK a +q

[0052] In the formula, K a is the average curvature of the acid-etched crack space, dimensionless; p and q are coefficients; w is the width of the acid-etched crack, dimensionless;

[0053] For example, the relationship model between the width of the acid-etched crack and the average curvature of the acid-etched crack space in the work area is:

[0054] w=8.0667K a -0.5974

[0055] In the formula, K a is the spatial average curvature of the acid-etched crack, dimensionless; D is the fractal dimension of the crack wall, dimensionless; w is the width of the acid-etched crack, unit: mm.

[0056] In one embodiment, in step 103, the tortuosity of the acid-etched fracture surface in the work area is determined by the following formula:

[0057]

[0058] Wherein, τ is the tortuosity of the acid-etched fracture surface, dimensionless; P is the formation closure stress, MPa; ν is the formation Poisson's ratio, dimensionless; E is the formation Young's modulus, GPa.

[0059] In one embodiment, in step 104, the conductivity of the acid-etched fractures in the work area is determined by the following formula:

[0060]

[0061] Wherein, τ is the tortuosity of the acid-etched crack surface, dimensionless; c is the conformity of the acid-etched crack, dimensionless; α is the shape factor (the crack is usually taken as 3), dimensionless; w is the width of the acid-etched crack, unit is mm; W kf is the conductivity of acid-etched cracks, μm 2 ·cm.

[0062] In one embodiment, X-ray diffraction experiments are used to determine the rock mineral composition of the work area.

[0063] In one embodiment, porosity and permeability of a work area are determined using a porosimetry test.

[0064] In one embodiment, a 3D scanner is used to determine the wall morphology of the acid-etched cracks in the work area, and then determine the conformity of the acid-etched cracks in the work area;

[0065] In one embodiment, the formation Young's modulus, formation closure stress, and formation Poisson's ratio may be measured using conventional Young's modulus, closure stress, and Poisson's ratio testing methods, which are not limited herein.

[0066] The present invention also provides an acid-etched crack conductivity determination device, as described in the following embodiments. Since the principle of the device to solve the problem is similar to the method for determining the conductivity of an acid-etched crack, the implementation of the device can refer to the implementation of the method for determining the conductivity of an acid-etched crack, and the repeated parts will not be repeated.

[0067] An embodiment of the present invention provides a device for determining conductivity of an acid-etched fracture, which may specifically include:

[0068] Data acquisition module 201: used to obtain rock mineral composition, porosity, permeability, formation Young's modulus, formation closure stress, formation Poisson's ratio and acid-etched fracture conformity (i.e., contact ratio between two sides of the fracture) of the work area;

[0069] The crack width determination module 202 is used to determine the crack width of the acid-etched cracks in the work area based on the rock mineral composition, porosity and permeability;

[0070] The tortuosity determination module 203 is used to determine the tortuosity of the acid-etched fracture surface in the work area based on the formation Young's modulus, the formation closure stress, and the formation Poisson's ratio;

[0071] The fracture conductivity determination module 204 is used to determine the conductivity of the acid-etched fractures in the work area based on the width of the acid-etched fractures in the work area, the tortuosity of the acid-etched fracture surfaces in the work area, and the conformity of the acid-etched fractures in the work area.

[0072] In one embodiment, the seam width determination module 202 includes:

[0073] Fractal dimension determination submodule 2021: used to determine the fractal dimension of the fracture wall in the work area based on the rock mineral composition, porosity and permeability of the work area and using the relationship model between the fractal dimension of the fracture wall and the rock mineral composition, porosity and permeability;

[0074] The average curvature determination submodule 222 is used to determine the average curvature of the acid-etched crack space in the work area based on the fractal dimension of the crack wall in the work area and using the relationship model between the average curvature of the acid-etched crack space and the fractal dimension of the crack wall;

[0075] The crack width determination submodule 2023 is used to determine the crack width of the acid-etched cracks in the work area based on the average curvature of the acid-etched crack space in the work area and using a relationship model between the crack width of the acid-etched cracks and the average curvature of the acid-etched crack space in the work area.

[0076] In one embodiment, the relationship model between the fracture wall fractal dimension and the rock mineral composition, porosity, and permeability is:

[0077]

[0078] Where, X i is the content of the ith mineral, dimensionless; is porosity, dimensionless; K is permeability, mD; a i , b1, b2 are coefficients; D is the fractal dimension of the crack wall, dimensionless;

[0079] Furthermore, the rock mineral composition includes N-1 carbonate minerals, X1 to X N-1 are the contents of these N-1 carbonate minerals, X N is the non-carbonate mineral content;

[0080] For example, the relationship model between the fractal dimension of the fracture wall and the rock mineral composition, porosity, and permeability is:

[0081]

[0082] Where, X1 is the dolomite content, dimensionless; X2 is the calcite content, dimensionless; X3 is the non-carbonate mineral content, dimensionless; is the porosity, dimensionless; K is the permeability, mD; D is the fractal dimension of the fracture wall, dimensionless.

[0083] In one embodiment, the relationship model between the average curvature of the acid-etched crack space and the fractal dimension of the crack wall is:

[0084]

[0085] In the formula, K a is the average curvature of the acid-etched crack space, dimensionless; m and n are coefficients; D is the fractal dimension of the crack wall, dimensionless;

[0086] For example, the relationship model between the average curvature of the acid-etched crack space and the fractal dimension of the crack wall is:

[0087] K a =0.4524D-0.3937

[0088] In the formula, K a is the average curvature of the acid-etched crack space, dimensionless; D is the fractal dimension of the crack wall, dimensionless. In one embodiment, the relationship model between the width of the acid-etched crack and the average curvature of the acid-etched crack space in the work area is:

[0089] w=pK a +q

[0090] In the formula, K a is the average curvature of the acid-etched crack space, dimensionless; p and q are coefficients; w is the width of the acid-etched crack, dimensionless;

[0091] For example, the relationship model between the width of the acid-etched crack and the average curvature of the acid-etched crack space in the work area is:

[0092] w=8.0667K a -0.5974

[0093] In the formula, K a is the spatial average curvature of the acid-etched crack, dimensionless; D is the fractal dimension of the crack wall, dimensionless; w is the width of the acid-etched crack, unit: mm.

[0094] In one embodiment, the tortuosity determination module 203 determines the tortuosity of the acid-etched fracture surface in the work area by the following formula:

[0095]

[0096] Wherein, τ is the tortuosity of the acid-etched fracture surface, dimensionless; P is the formation closure stress, MPa; ν is the formation Poisson's ratio, dimensionless; E is the formation Young's modulus, GPa.

[0097] In one embodiment, the fracture conductivity determination module 204 determines the conductivity of the acid-etched fractures in the work area by the following formula:

[0098]

[0099] Wherein, τ is the tortuosity of the acid-etched crack surface, dimensionless; c is the conformity of the acid-etched crack, dimensionless; α is the shape factor (the crack is usually taken as 3), dimensionless; w is the width of the acid-etched crack, unit is mm; W kf is the conductivity of acid-etched cracks, μm 2 ·cm.

[0100] In one embodiment, X-ray diffraction experiments are used to determine the rock mineral composition of the work area.

[0101] In one embodiment, porosity and permeability of a work area are determined using a porosimetry test.

[0102] In one embodiment, a 3D scanner is used to determine the wall morphology of the acid-etched cracks in the work area, and then determine the conformity of the acid-etched cracks in the work area;

[0103] In one embodiment, the formation Young's modulus, formation closure stress, and formation Poisson's ratio may be measured using conventional Young's modulus, closure stress, and Poisson's ratio testing methods, which are not limited herein.

[0104] An embodiment of the present invention further provides a computer device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned method for determining conductivity of acid-etched fractures when executing the computer program.

[0105] An embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned method for determining the conductivity of acid-etched fractures is implemented.

[0106] An embodiment of the present invention further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the above-mentioned method for determining the conductivity of acid-etched fractures is implemented.

[0107] Embodiment 1:

[0108] This embodiment provides a method for determining conductivity of an acid-etched fracture, the method comprising:

[0109] 1. Obtain the rock mineral composition, porosity, permeability, formation Young's modulus, formation closure stress, formation Poisson's ratio and acid-etched fracture fit (i.e., the contact ratio between the two sides of the fracture) of the work area.

[0110] Among them, X-ray diffraction experiments were used to determine the mineral composition of rocks; porosity and permeability were determined by pore permeability measurement experiments; 3D scanners were used to determine the wall morphology of acid-etched cracks in the work area, and then the consistency of acid-etched cracks in the work area was determined;

[0111] The results are shown in Table 1.

[0112] Table 1

[0113] Physical parameters Unit symbol Numeric Formation closure stress (MPa) P 5-50 <![CDATA[Permeability (um 3 )]]> K 1 Porosity(%) Φ 0.7 Young's modulus of formation (GPa) E 50 Formation Poisson's ratio ν 0.25 Acid etch crack fit c 0.7 Calcite content (decimal) <![CDATA[X1]]> 0.2 Dolomite content (decimal) <![CDATA[X2]]> 0.6 Non-carbonate mineral content (decimal) <![CDATA[X3]]> 0.2

[0114] 2. Fitting to determine the relationship model between the fractal dimension of the crack wall and the rock mineral composition, porosity, and permeability, fitting to determine the relationship model between the average curvature of the acid-etched crack space and the fractal dimension of the crack wall, fitting to determine the relationship model between the width of the acid-etched crack and the average curvature of the acid-etched crack space in the work area; specifically including:

[0115] 12 cores were obtained from the work area and numbered 1-12;

[0116] The rock mineral composition, porosity, permeability, average curvature of the acid-etched crack space, fractal dimension of the crack wall and width of the acid-etched crack of these 12 cores were determined through indoor experiments. The results are shown in Tables 2 to 4.

[0117] Table 2

[0118]

[0119] Table 3

[0120]

[0121]

[0122] Table 4

[0123] Core number Fractal dimension Space curvature Average seam width 1 1.14915 0.14 0.4802 2 1.133633 0.128933 0.4561 3 1.096333 0.116967 0.4133 4 1.072 0.106867 0.3291 5 1.071967 0.0992 0.2344 6 1.0887 0.092567 0.1778 7 1.106967 0.0913 0.1478 8 1.107167 0.0927 0.0886 9 1.107333 0.097333 0.1558 10 1.1053 0.099333 0.1812 11 1.105433 0.101 0.2101 12 1.1044 0.103467 0.1986

[0124] From Table 2-fitting we get:

[0125]

[0126] Where, X1 is the calcite content, dimensionless; X2 is the dolomite content, dimensionless; X3 is the non-carbonate mineral content, dimensionless; is the porosity, dimensionless; K is the permeability, mD; D is the fractal dimension of the fracture wall, dimensionless;

[0127] K a=0.4524D-0.3937

[0128] In the formula, K a is the average curvature of the acid-etched crack space, dimensionless; D is the fractal dimension of the crack wall, dimensionless;

[0129] w=8.0667K a -0.5974

[0130] In the formula, K a is the spatial average curvature of the acid-etched crack, dimensionless; D is the fractal dimension of the crack wall, dimensionless; w is the width of the acid-etched crack, unit: mm.

[0131] 3. Based on the rock mineral composition, porosity and permeability of the work area, the fractal dimension of the fracture wall in the work area is determined by using the relationship model between the fitted fracture wall fractal dimension and the rock mineral composition, porosity and permeability;

[0132] Based on the fractal dimension of the crack wall in the work area, the average curvature of the acid-etched crack space in the work area is determined by using the relationship model between the average curvature of the acid-etched crack space and the fractal dimension of the crack wall obtained by fitting.

[0133] Based on the average curvature of the acid-etched crack space in the work area, the width of the acid-etched crack in the work area is determined by using the fitted relationship model between the width of the acid-etched crack and the average curvature of the acid-etched crack space in the work area.

[0134] 4. Based on the Young's modulus, closure stress and Poisson's ratio of the formation, the tortuosity of the acid-etched fracture surface in the work area is determined by the following formula:

[0135]

[0136] Wherein, τ is the tortuosity of the acid-etched fracture surface, dimensionless; P is the formation closure stress, MPa; ν is the formation Poisson's ratio, dimensionless; E is the formation Young's modulus, GPa.

[0137] 5. Based on the width of the acid-etched cracks in the work area, the tortuosity of the acid-etched crack surface in the work area and the consistency of the acid-etched cracks in the work area, the conductivity of the acid-etched cracks in the work area is determined by the following formula:

[0138]

[0139] Wherein, τ is the tortuosity of the acid-etched crack surface, dimensionless; c is the conformity of the acid-etched crack, dimensionless; α is the shape factor (taken as 3), dimensionless; w is the width of the acid-etched crack, unit: mm; W kf is the conductivity of acid-etched cracks, μm 2 cm;

[0140] The results are as follows Figure 1 shown.

[0141] Example 2

[0142] This embodiment provides a method for determining conductivity of an acid-etched fracture, the method comprising:

[0143] 1. Obtain the rock mineral composition, porosity, permeability, formation Young's modulus, formation closure stress, formation Poisson's ratio and acid-etched fracture fit (i.e., the contact ratio between the two sides of the fracture) of each work area.

[0144] Among them, X-ray diffraction experiments were used to determine the mineral composition of rocks; porosity and permeability were determined by pore permeability measurement experiments; 3D scanners were used to determine the wall morphology of acid-etched cracks in the work area, and then the consistency of acid-etched cracks in the work area was determined;

[0145] The results are shown in Table 5.

[0146] Table 5

[0147]

[0148]

[0149] 2. Based on the rock mineral composition, porosity and permeability of the work area, the fractal dimension of the fracture wall in the work area is determined by using the relationship model between the fracture wall fractal dimension fitted in Example 1 and the rock mineral composition, porosity and permeability;

[0150] Based on the fractal dimension of the crack wall in the work area, the average curvature of the acid-etched crack space in the work area is determined using the relationship model between the average curvature of the acid-etched crack space and the fractal dimension of the crack wall obtained by fitting in Example 1;

[0151] Based on the average curvature of the acid-etched crack space in the work area, the relationship model between the acid-etched crack width and the average curvature of the acid-etched crack space in the work area obtained by fitting in Example 1 is used to determine the acid-etched crack width in the work area.

[0152] 4. Based on the Young's modulus, closure stress and Poisson's ratio of the formation, the tortuosity of the acid-etched fracture surface in the work area is determined by the following formula:

[0153]

[0154] Wherein, τ is the tortuosity of the acid-etched fracture surface, dimensionless; P is the formation closure stress, MPa; ν is the formation Poisson's ratio, dimensionless; E is the formation Young's modulus, GPa.

[0155] 5. Based on the width of the acid-etched cracks in the work area, the tortuosity of the acid-etched crack surface in the work area and the consistency of the acid-etched cracks in the work area, the conductivity of the acid-etched cracks in the work area is determined by the following formula:

[0156]

[0157] Wherein, τ is the tortuosity of the acid-etched crack surface, dimensionless; c is the conformity of the acid-etched crack, dimensionless; α is the shape factor (taken as 3), dimensionless; w is the width of the acid-etched crack, unit: mm; W kf is the conductivity of acid-etched cracks, μm 2 cm;

[0158] The results are as follows Figure 2 shown.

[0159] Example 3

[0160] This embodiment provides a method for determining the conductivity of acid-etched cracks. The difference between this method and embodiment 2 is that the values ​​of the parameters obtained in step 1 are different. The results are shown in Table 6:

[0161] Table 6

[0162]

[0163]

[0164] The final results of the conductivity of the acid-etched fractures are as follows: Figure 3 shown.

[0165] Example 4

[0166] This embodiment provides a method for determining the conductivity of acid-etched cracks. The difference between this method and embodiment 2 is that the values ​​of the parameters obtained in step 1 are different. The results are shown in Table 7:

[0167] Table 7

[0168] Physical parameters Unit symbol Numeric Formation closure stress (MPa) P 10-50 Young's modulus of formation (GPa) E 20-50 Porosity Φ 0.7 <![CDATA[Permeability (um 3 )]]> K 1 Formation Poisson's ratio ν 0.25 Acid etch crack fit c 0.7 Calcite content (decimal) <![CDATA[X1]]> 0.2 Dolomite content (decimal) <![CDATA[X2]]> 0.6 Non-carbonate mineral content (decimal) <![CDATA[X3]]> 0.2

[0169] The final results of the conductivity of the acid-etched fractures are as follows: Figure 4 shown.

[0170] Example 5

[0171] This embodiment provides a method for determining the conductivity of acid-etched cracks. The difference between this method and embodiment 2 is that the values ​​of the parameters obtained in step 1 are different. The results are shown in Table 8:

[0172] Table 8

[0173]

[0174]

[0175] The final results of the conductivity of the acid-etched fractures are as follows: Figure 5 shown.

[0176] Depend on Figure 2-Figure 5It can be seen that as the Young's modulus increases, the conductivity increases. When the Young's modulus is small, the conductivity increases more, and when the Young's modulus is large, the conductivity increases less. As the Young's modulus of rock increases, the conductivity increases in a fourth-order linear relationship; for every 10GPa increase in Young's modulus, the conductivity increases by about 1%-52%; for every 10MPa increase in closure stress, the conductivity decreases by about 8%-52%. As the Poisson's ratio of rock increases, the conductivity decreases linearly; for every 0.02 increase in Poisson's ratio, the conductivity decreases by about 1%-5%, and for every 10MPa increase in closure stress, the conductivity decreases by 14%-20%.

[0177] When the Young's modulus is small, the conductivity changes greatly with the change of the Young's modulus, because when the Young's modulus is small, the rock's ability to resist deformation is poor, and the rock deformation is large, so the conductivity changes greatly. When the Young's modulus is 50GPa, the rock's ability to resist deformation is strong, and the Poisson's ratio has little effect on the conductivity.

[0178] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented 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.

[0179] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0180] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0181] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0182] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific 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 should be included in the scope of protection of the present invention.

Claims

1. A method for determining the conductivity of an acid-etched fracture, the method comprising: Obtain the rock mineral composition, porosity, permeability, formation Young's modulus, formation closure stress, formation Poisson's ratio and acid-etched fracture consistency of the work area; Determine the width of acid-etched cracks in the work area based on rock mineral composition, porosity, and permeability; Based on the formation Young's modulus, formation closure stress, and formation Poisson's ratio, the tortuosity of the acid-etched fracture surface in the work area is determined; The conductivity of the acid-etched cracks in the work area is determined based on the width of the acid-etched cracks in the work area, the tortuosity of the acid-etched crack surfaces in the work area, and the consistency of the acid-etched cracks in the work area.

2. The method according to claim 1, wherein: Determining the width of the acid-etched crack based on the rock mineral composition, porosity, and permeability includes: Based on the rock mineral composition, porosity and permeability of the work area, the fractal dimension of the fracture wall in the work area is determined by using the relationship model between the fractal dimension of the fracture wall and the rock mineral composition, porosity and permeability. Based on the fractal dimension of the crack wall in the work area, the average curvature of the acid-etched crack space in the work area is determined using the relationship model between the average curvature of the acid-etched crack space and the fractal dimension of the crack wall. Based on the average curvature of the acid-etched crack space in the work area, the width of the acid-etched crack in the work area is determined using the relationship model between the width of the acid-etched crack and the average curvature of the acid-etched crack space in the work area.

3. The method according to claim 2, wherein: The relationship model between the fracture wall fractal dimension and rock mineral composition, porosity, and permeability is: In the formula, Xi is the content of the i-th mineral, dimensionless; is porosity, dimensionless; K is permeability, mD; a i , b1, b2 are coefficients; D is the fractal dimension of the crack wall, dimensionless; Preferably, the rock mineral composition includes N-1 carbonate minerals, X1 to X N-1 are the contents of these N-1 carbonate minerals, X N It is the non-carbonate mineral content.

4. The method according to claim 2, wherein: The relationship model between the average curvature of the acid-etched crack space and the fractal dimension of the crack wall is: K α =mD+n In the formula, K a is the spatial average curvature of the acid-etched crack, dimensionless; m and n are coefficients; D is the fractal dimension of the crack wall, dimensionless.

5. The method according to claim 2, wherein: The width of the acid-etched crack and the average curvature of the acid-etched crack space in the work area are: w=pK a +q In the formula, K a is the spatial average curvature of the acid-etched crack, dimensionless; p and q are coefficients; w is the width of the acid-etched crack, dimensionless.

6. The method according to claim 1, wherein: The tortuosity of the acid-etched crack surface in the work area is determined by the following formula: Wherein, τ is the tortuosity of the acid-etched fracture surface, dimensionless; P is the formation closure stress, MPa; ν is the formation Poisson's ratio, dimensionless; E is the formation Young's modulus, GPa.

7. The method according to claim 1, wherein: The conductivity of the acid-etched cracks in the work area is determined by the following formula: Wherein, τ is the tortuosity of the acid-etched crack surface, dimensionless; c is the conformity of the acid-etched crack, dimensionless; α is the shape factor (the crack is usually taken as 3), dimensionless; w is the width of the acid-etched crack, unit is mm; W kf is the conductivity of acid-etched cracks, μm 2 ·cm.

8. A device for determining conductivity of an acid-etched fracture, the device comprising: Data acquisition module: used to obtain the rock mineral composition, porosity, permeability, formation Young's modulus, formation closure stress, formation Poisson's ratio and acid-etched fracture conformity (i.e., the contact ratio between the two sides of the fracture) of the work area; Fracture width determination module: used to determine the width of acid-etched cracks in the work area based on rock mineral composition, porosity, and permeability; Tortuosity determination module: used to determine the tortuosity of the acid-etched fracture surface in the work area based on the formation Young's modulus, formation closure stress, and formation Poisson's ratio; Fracture conductivity determination module: used to determine the conductivity of the acid-etched cracks in the work area based on the width of the acid-etched cracks in the work area, the tortuosity of the acid-etched crack surfaces in the work area, and the consistency of the acid-etched cracks in the work area.

9. The device according to claim 8, wherein: The seam width determination module includes: Fractal dimension determination submodule: It is used to determine the fractal dimension of the fracture wall in the work area based on the rock mineral composition, porosity and permeability of the work area, and by using the relationship model between the fractal dimension of the fracture wall and the rock mineral composition, porosity and permeability; Average curvature determination submodule: used to determine the average curvature of the acid-etched crack space in the work area based on the fractal dimension of the crack wall in the work area and using the relationship model between the average curvature of the acid-etched crack space and the fractal dimension of the crack wall; The crack width determination submodule is used to determine the width of the acid-etched cracks in the work area based on the average curvature of the acid-etched crack space in the work area and using the relationship model between the width of the acid-etched cracks and the average curvature of the acid-etched crack space in the work area.

10. The device according to claim 9, wherein: The relationship model between fracture width and rock mineral composition, porosity, and permeability is: Where, X i is the content of the ith mineral, dimensionless; is porosity, dimensionless; K is permeability, mD; a i , b1, b2 are coefficients; w is the seam width, cm; Preferably, the rock mineral composition includes N-1 carbonate minerals, X1 to X N-1 are the contents of these N-1 carbonate minerals, X N is the non-carbonate mineral content; Preferably, the relationship model between fracture width and rock mineral composition, porosity, and permeability is: Where, X1 is the dolomite content, dimensionless; X2 is the calcite content, dimensionless; X3 is the non-carbonate mineral content, dimensionless; is the porosity, dimensionless; K is the permeability, mD; ai, b1, b2 are coefficients; w is the fracture width, cm.

11. The device according to claim 9, wherein: The relationship model between the average curvature of the acid-etched crack space and the fractal dimension of the crack wall is: K a =mD+n In the formula, K a is the spatial average curvature of the acid-etched crack, dimensionless; m and n are coefficients; D is the fractal dimension of the crack wall, dimensionless.

12. The device according to claim 9, wherein: The width of the acid-etched crack and the average curvature of the acid-etched crack space in the work area are: w=pK a +q In the formula, K a is the spatial average curvature of the acid-etched crack, dimensionless; p and q are coefficients; w is the width of the acid-etched crack, dimensionless.

13. The device according to claim 8, wherein: The tortuosity determination module determines the tortuosity of the acid-etched crack surface in the work area through the following formula: Wherein, τ is the tortuosity of the acid-etched fracture surface, dimensionless; P is the formation closure stress, MPa; ν is the formation Poisson's ratio, dimensionless; E is the formation Young's modulus, GPa.

14. The device according to claim 8, wherein: The fracture conductivity determination module 204 determines the conductivity of the acid-etched fractures in the work area by the following formula: Wherein, τ is the tortuosity of the acid-etched crack surface, dimensionless; c is the conformity of the acid-etched crack, dimensionless; α is the shape factor, dimensionless; w is the width of the acid-etched crack, unit: mm; W kf is the conductivity of acid-etched cracks, μm 2 ·cm.

15. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method for determining the conductivity of acid-etched fractures according to any one of claims 1 to 7 is implemented.

16. A computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the method for determining conductivity of acid-etched fractures according to any one of claims 1 to 7.

17. A computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the method for determining conductivity of an acid-etched fracture according to any one of claims 1 to 7 is implemented.

Images