A deep coal bed gas reservoir multi-zone coupling productivity evaluation method, system, processing device and storage medium

Abstract

The present application relates to a kind of deep coal bed gas reservoir multi-zone coupling productivity evaluation method, system, processing device and storage medium, it is characterized in that, the method includes: according to the fracture network characteristics and fluid percolation characteristics after deep coal reservoir fracturing, establish the four-zone physical model of deep coal reservoir, including four regions of fracture zone, heavy reconstruction zone, weak reconstruction zone and matrix zone;Based on the four-zone physical model of deep coal reservoir, according to the fracture network parameters after deep coal reservoir fracturing, the range and equivalent percolation parameters of four regions of deep coal reservoir are calculated;Based on the range and equivalent percolation parameters of four regions of deep coal reservoir, establish the percolation mathematical model of four regions of deep coal reservoir, and the gas production of four regions of deep coal reservoir is obtained by solving;According to the gas production of four regions of deep coal reservoir, the gas production of single fracturing section of deep coal reservoir is obtained, and then the gas production of multi-stage fracturing horizontal well of deep coal reservoir is obtained, the present application can be widely applied in coal bed gas development field.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coalbed methane development, and particularly to a deep coalbed methane reservoir multi-zone coupled productivity evaluation method and system, a processing device and a storage medium. BACKGROUND

[0002] China is rich in deep coalbed methane resources, and coalbed methane development is gradually extending from shallow to deep, and exploration and development practice shows that deep coalbed methane has undergone great changes from fracturing concept to post-fracturing fluid seepage mode.

[0003] However, the existing shallow coalbed methane reservoir productivity evaluation method simply equates different scale fractures after fracturing to a main fracture, which is not applicable to the complex fracture network formed by large-scale fracturing in deep coalbed methane reservoirs. Moreover, the existing method mostly uses numerical methods for solving, which has a complex model establishment process, large calculation amount and slow calculation speed. Therefore, there is currently a lack of a method suitable for deep coalbed methane that can accurately and quickly predict deep coalbed methane productivity. SUMMARY

[0004] To solve the above problems, the present application aims to provide a deep coalbed methane reservoir multi-zone coupled productivity evaluation method and system, a processing device and a storage medium, which can accurately and quickly predict deep coalbed methane productivity.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: In a first aspect, a deep coalbed methane reservoir multi-zone coupled productivity evaluation method is provided, comprising:

[0006] According to the fracture network characteristics and fluid seepage characteristics of the deep coal reservoir after fracturing, a four-zone physical model of the deep coal reservoir is established, including four regions of a fracture zone, a heavy reconstruction zone, a weak reconstruction zone and a matrix zone;

[0007] Based on the four-zone physical model of the deep coal reservoir, the ranges and equivalent seepage parameters of the four regions of the deep coal reservoir are calculated according to the fracture network parameters of the deep coal reservoir after fracturing;

[0008] Based on the ranges and equivalent seepage parameters of the four regions of the deep coal reservoir, a seepage mathematical model of the four regions of the deep coal reservoir is established, and the gas production of the four regions of the deep coal reservoir is obtained by solving;

[0009] According to the gas production of the four regions of the deep coal reservoir, the gas production of a single fracturing section of the deep coal reservoir is obtained as the multi-zone coupled productivity.

[0010] Further, the fracture network characteristics refer to the fracture morphology and fracture parameters of the deep coal reservoir after fracturing, the fracture morphology is a four-level complex fracture network of "high conductivity main fracture + branch fracture + shear self-supporting fracture + cleat", and the fracture parameters include the length, opening, height and conductivity of each level of fracture;

[0011] The crack zone is a high-conductivity main crack area formed by fracturing near the wellbore, mainly free gas, and gas flow follows Darcy's law;

[0012] The heavy reconstruction zone is a branch crack area filled with proppants and its surrounding reconstructed area, where free gas and desorbed gas coexist, free gas follows Darcy's law, and desorbed gas flows according to the "desorption-diffusion-seepage" rule;

[0013] The weak reconstruction zone is a shear self-supporting crack area where proppants are difficult to enter and its surrounding reconstructed area, where free gas and desorbed gas exist;

[0014] The matrix zone is an area that is not affected by fracturing of the original reservoir, where free gas and desorbed gas coexist.

[0015] Further, the range of the crack zone is the length, width and height of the high-conductivity main crack, and the equivalent seepage parameters of the crack zone are the equivalent permeability and equivalent porosity of the high-conductivity main crack;

[0016] The range of the matrix zone is determined according to the well control area, the equivalent permeability of the matrix zone is the permeability of the original reservoir, and the equivalent porosity of the matrix zone is the porosity of the original reservoir.

[0017] Further, there are several branch cracks and small flow areas in the surrounding cleavages in the heavy reconstruction zone, which are equivalent to two-dimensional elliptical radial flow as a whole, and the range of the heavy reconstruction zone is a two-dimensional ellipse with the endpoints of the high-conductivity main crack as foci;

[0018] The equivalent seepage parameter calculation process of the heavy reconstruction zone is:

[0019] The equivalent permeability of the multiple branch cracks in the heavy reconstruction zone is calculated;

[0020] Based on the equivalent permeability of the multiple branch cracks in the heavy reconstruction zone, the equivalent permeability of the branch cracks and the surrounding reconstruction area in the heavy reconstruction zone is calculated;

[0021] The equivalent porosity of the multiple branch cracks in the heavy reconstruction zone is calculated;

[0022] Based on the equivalent porosity of the multiple branch cracks in the heavy reconstruction zone, the equivalent porosity of the heavy reconstruction zone is calculated.

[0023] Further, the weak reconstruction zone is equivalent to an ellipse with the endpoints of the long axis of the heavy reconstruction zone ellipse as foci;

[0024] The equivalent seepage parameter calculation process of the weak reconstruction zone is:

[0025] The equivalent permeability of the multiple shear cracks in the weak reconstruction zone is calculated;

[0026] The equivalent permeability of the shear fracture and the surrounding reconstruction area in the weak reconstruction area is calculated based on the equivalent permeability of multiple shear fractures in the weak reconstruction area.

[0027] The equivalent porosity of multiple shear fractures in the weak reconstruction area is calculated.

[0028] The equivalent porosity of the weak reconstruction area is calculated based on the equivalent porosity of multiple shear fractures in the weak reconstruction area.

[0029] Further, the seepage mathematical model of the fracture area is:

[0030]

[0031] In the formula, p F is the pressure of the fracture area; k F is the equivalent permeability of the fracture area; φ F is the porosity of the fracture area; x F is the half length of the high-conductivity main fracture; h F is the height of the high-conductivity main fracture; Z is the gas compression factor; μ g is the gas viscosity; C r , C g are the compression coefficients of the pores and the gas respectively; S g is the gas saturation; t is time; p e is the original reservoir pressure; p wf is the bottom-hole flowing pressure; Q gsc is the gas production of the fracture area; T is the reservoir temperature; p sc is the pressure under standard conditions; Z sc is the deviation factor under standard conditions; T sc is the temperature under standard conditions.

[0032] The seepage mathematical model of the heavy reconstruction area includes a free gas equation and a desorbed gas equation, and the free gas equation is:

[0033]

[0034] In the formula, r is the position with a seepage radius of r in the gas reservoir; p fn is the pressure of the heavy reconstruction area; ρ gsc is the density of the gas under standard conditions; r fn is the radius of the heavy reconstruction area elliptical flow range equivalent to a circular supply; φ fn is the equivalent porosity of the heavy reconstruction area; h fn is the average height of multiple branch fractures; k fn is the equivalent permeability of the branch fracture in the heavy reconstruction area and the surrounding reconstruction area; q dfn is the desorbed gas of the heavy reconstruction area; ξ fn is the equivalent seepage radius of the equivalent two-dimensional ellipse of the heavy reconstruction area.

[0035] The desorbed gas equation in the mathematical model of seepage in the heavy reconstruction zone is:

[0036]

[0037] In the formula, p cd is the critical desorption pressure; V L is the Langmuir volume; p L is the Langmuir pressure;

[0038] The mathematical model of seepage in the weak reconstruction zone includes a free gas equation and a desorbed gas equation, and the free gas equation is:

[0039]

[0040] In the formula, k mf is the equivalent permeability of the shear fracture in the weak reconstruction zone and the surrounding reconstruction zone; p mf is the pressure of the weak reconstruction zone; r mf is the radius of the elliptical flow range of the weak reconstruction zone corresponding to the circular supply; q dmf is the desorbed gas of the weak reconstruction zone; ξ mf is the equivalent seepage radius of the weak reconstruction zone; φ mf is the equivalent porosity of the weak reconstruction zone; h mf is the average height of the multiple shear fractures;

[0041] The desorbed gas equation in the mathematical model of seepage in the weak reconstruction zone is:

[0042]

[0043] The mathematical model of seepage in the matrix zone includes a free gas equation and a desorbed gas equation, and the free gas equation is:

[0044]

[0045] In the formula, p m is the pressure of the matrix zone; q dm is the desorbed gas of the matrix zone; ξ m is the equivalent seepage radius of the matrix zone; k m is the equivalent permeability of the matrix zone; φ m is the equivalent porosity of the matrix zone;

[0046] The desorbed gas equation in the mathematical model of seepage in the matrix zone is:

[0047]

[0048] Further, the multi-zone coupled production capacity is:

[0049]

[0050] wherein, ψ F is the pseudo pressure of the fracture zone; ψ wf is the pseudo pressure corresponding to the bottom hole flowing pressure; R F is the seepage resistance of the fracture zone; R fn is the seepage resistance term of the heavy reformation zone; Q dfb is the desorption diffusion term of the heavy reformation zone; R mf is the seepage resistance term of the weak reformation zone; Q dmf is the desorption diffusion term of the weak reformation zone; R m is the seepage resistance term of the matrix zone; Q dm is the desorption diffusion term of the matrix zone.

[0051] In a second aspect, a deep coal bed gas reservoir multi-zone coupled productivity evaluation system is provided, comprising:

[0052] A four-zone physical model establishing module is configured to establish a four-zone physical model of the deep coal reservoir according to the fracture network characteristics and fluid seepage characteristics of the deep coal reservoir after fracturing, including four zones of a fracture zone, a heavy reformation zone, a weak reformation zone and a matrix zone.

[0053] A parameter calculating module is configured to calculate the ranges and equivalent seepage parameters of the four zones of the deep coal reservoir according to the fracture network parameters of the deep coal reservoir after fracturing based on the four-zone physical model of the deep coal reservoir.

[0054] A seepage mathematical model establishing module is configured to establish a seepage mathematical model of the four zones of the deep coal reservoir based on the ranges and equivalent seepage parameters of the four zones of the deep coal reservoir, and to solve the gas production of the four zones of the deep coal reservoir.

[0055] A gas production solving module is configured to obtain the gas production of a single fracturing section of the deep coal reservoir as the multi-zone coupled productivity according to the gas production of the four zones of the deep coal reservoir.

[0056] In a third aspect, a processing device is provided, comprising computer program instructions, wherein the computer program instructions are used to implement the steps corresponding to the deep coal bed gas reservoir multi-zone coupled productivity evaluation method when the processing device executes the computer program instructions.

[0057] In a fourth aspect, a computer readable storage medium is provided, wherein the computer readable storage medium stores computer program instructions, and the computer program instructions are used to implement the steps corresponding to the deep coal bed gas reservoir multi-zone coupled productivity evaluation method when the processor executes the computer program instructions.

[0058] The present application has the following advantages due to the above technical solutions:

[0059] 1. The present application considers that the four-level complex fracture network of 'high conductivity main fracture + branch fracture + shear self-supporting fracture + cleat' is formed after large-scale volume fracturing of deep coalbed methane reservoirs, and divides the fracture zone, heavy reconstruction zone, weak reconstruction zone and matrix zone into four regions, which is more in line with the fracture characteristics after fracturing in the mine than the existing productivity model which simply equates different scale fractures to one fracturing main fracture and cleat, and improves the accuracy of deep coalbed methane reservoir productivity prediction.

[0060] 2. The present application uses the equivalent seepage resistance method for multi-zone coupling analytical solution, which is simpler, faster in calculation and more convenient for field application than numerical solution method.

[0061] 3. The present application can be applied to other deep coalbed methane reservoirs, tight gas reservoirs and other fields developed by directional wells, horizontal wells, vertical wells and the like, and only needs to substitute the corresponding parameters.

[0062] In summary, the present application can be widely applied in the field of coalbed methane development. BRIEF DESCRIPTION OF DRAWINGS

[0063] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments and are not intended to limit the scope of the present application. Throughout the drawings, same reference numerals are used for same components. In the drawings:

[0064] Figure 1 is a complex fracture network schematic diagram formed after fracturing of a deep coal reservoir provided by an embodiment of the present application;

[0065] Figure 2 is a four-zone physical model schematic diagram of a deep coal reservoir provided by an embodiment of the present application;

[0066] Figure 3 is a heavy reconstruction zone equivalent range calculation schematic diagram of a deep coal reservoir provided by an embodiment of the present application;

[0067] Figure 4 is a weak reconstruction zone equivalent range calculation schematic diagram of a deep coal reservoir provided by an embodiment of the present application;

[0068] Figure 5 is a calculation daily production and actual daily production comparison schematic diagram provided by an embodiment of the present application. DETAILED DESCRIPTION

[0069] Exemplary embodiments of the present application will be described more fully hereinafter with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it is to be understood that the present application can be embodied in many forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the present application to those skilled in the art.

[0070] It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "includes", "including" and the like are to be construed to be inclusive (i.e., to include both instances of open ended terms and instances of terms limiting to a specific number) unless otherwise indicated as otherwise limited by context. The methods described herein can be implemented as a method, an apparatus, a system, a computer program product, or any combination thereof. The methods described herein can be implemented using a computer- implemented process scheme involving one or more physical and / or logical operations.

[0071] Although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first", "second", and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0072] The existing shallow coalbed methane reservoir productivity evaluation method simply equates different scale fractures after fracturing to a main fracture, and is not applicable to the complex fracture network formed under large-scale fracturing of deep coalbed methane reservoirs. Moreover, the existing method is mostly solved by numerical method, and the model establishment process is complex, the calculation amount is large, and the calculation speed is slow. Embodiments of the present application provide a deep coalbed methane reservoir multi-zone coupled productivity evaluation method, comprising: according to the fracture network characteristics and fluid seepage characteristics of the deep coal reservoir after fracturing, establishing a four-zone physical model of the deep coal reservoir, including four regions of a fracture zone, a heavy reconstruction zone, a weak reconstruction zone and a matrix zone; based on the four-zone physical model of the deep coal reservoir, according to the fracture network parameters of the deep coal reservoir after fracturing, calculating the ranges and equivalent seepage parameters of the four regions of the deep coal reservoir; based on the ranges and equivalent seepage parameters of the four regions of the deep coal reservoir, establishing a seepage mathematical model of the four regions of the deep coal reservoir, and solving to obtain the gas production of the four regions of the deep coal reservoir; according to the gas production of the four regions of the deep coal reservoir, obtaining the gas production of a single fracturing section of the deep coal reservoir as the multi-zone coupled productivity. The present application can further improve the accuracy and solving speed of the deep coalbed methane reservoir productivity prediction, and promote the process of efficient development of deep coalbed methane.

[0073] Embodiment 1

[0074] The present embodiment provides a deep coalbed methane reservoir multi-zone coupled productivity evaluation method, comprising the following steps:

[0075] 1) According to the fracture network characteristics and fluid seepage characteristics of the deep coal reservoir after fracturing, a four-zone physical model of the deep coal reservoir is established, including four regions of a fracture zone, a heavy reconstruction zone, a weak reconstruction zone and a matrix zone.

[0076] Specifically, the fracture network characteristics refer to the fracture morphology and fracture parameters of the deep coal reservoir after fracturing, the fracture morphology is a four-level complex fracture network of "high conductivity main fracture + branch fracture + shear self-supporting fracture + cleat", and the fracture parameters include the length, opening, height and conductivity of each level of fracture.

[0077] Specifically, the fluid seepage characteristics refer to the occurrence characteristics and flow mode of gas in the four regions of the fracture zone, the heavy reconstruction zone, the weak reconstruction zone and the matrix zone. The fracture zone only has free gas and no adsorbed gas, and is in Darcy seepage; the heavy reconstruction zone, the weak reconstruction zone and the matrix zone have both adsorbed gas and free gas, the free gas is in Darcy seepage, and the adsorbed gas is in desorption-diffusion-seepage flow.

[0078] Specifically, under large-scale volume fracturing technology, a four-level complex fracture network of "high conductivity main fracture + branch fracture + shear self-supporting fracture + cleat" is formed, such as Figure 1The length, opening, height, and conductivity of each fracture after fracturing of the deep coal reservoir are different, and the degree of reconstruction around the fractures of different levels is also different. Based on the zoning idea, the deep coal reservoir after fracturing is divided into four regions, i.e., a fracture region, a heavy reconstruction region, a weak reconstruction region, and a matrix region, as shown in FIG. 1, which are defined as follows: Figure 2

[0079] 1.1) Fracture region: a high-conductivity main fracture region formed by fracturing in the near-wellbore zone, mainly free gas, and gas flow follows Darcy's law.

[0080] 1.2) Heavy reconstruction region: a region of branch fractures filled with proppants and the surrounding reconstructed region (double medium of matrix and cleats), where free gas and desorbed gas coexist, and there are a large number of branch fractures. With the large output of free gas, the reservoir pressure will quickly drop to the critical desorption pressure, and the adsorbed gas begins to desorb and diffuse into the cleats and branch fractures, making up for the decrease in free gas. Free gas follows Darcy's law, and desorbed gas flows according to the "desorption-diffusion-seepage" law.

[0081] 1.3) Weak reconstruction region: a shear self-supporting fracture and the surrounding reconstructed region where proppants are difficult to enter in the far-wellbore zone. The reservoir reconstruction degree in this region is lower than that in the heavy reconstruction region, the reservoir pressure drop speed is lower than that in the heavy reconstruction region, and there are free gas and slowly desorbed adsorbed gas.

[0082] 1.4) Matrix region: a region not affected by fracturing of the original reservoir, where free gas and desorbed gas coexist. The cleat and matrix conductivity of the coal reservoir in this region is very low, and the gas production is very low before the desorption of adsorbed gas, which is similar to the depressurization desorption development mode of medium and shallow coal seams.

[0083] 2) Based on the four-region physical model of the deep coal reservoir, the range and equivalent seepage parameters of the four regions of the deep coal reservoir are calculated according to the fracture network parameters after fracturing of the deep coal reservoir, wherein the fracture network parameters after fracturing of the deep coal reservoir include the length, opening, height, and conductivity of each fracture.

[0084] Specifically, the range of the fracture region is the volume of the fracture region, and the range of the heavy reconstruction region, the weak reconstruction region, and the matrix region is the equivalent seepage radius of the heavy reconstruction region, the weak reconstruction region, and the matrix region; the equivalent seepage parameters of the four regions include equivalent permeability and equivalent porosity. The range and equivalent seepage parameters of the four regions of the deep coal reservoir are calculated as follows:

[0085] 2.1) Fracture region

[0086] Specifically, the range of the fracture region is the length, width, and height of the high-conductivity main fracture. The volume of the fracture region is:

[0087] V F = 2(x F -r w )ω​F h F (1)

[0088] Where V F is the volume of the crack area, in m 3 ;x F 、ω F 、h F are the half-length, opening and height of the high conductivity main fracture, respectively, in m; r w is the wellbore radius, in m.

[0089] Specifically, the equivalent permeability of the fracture zone is the initial permeability k of the high conductivity main fracture F Since all fracture zones are high-conductivity main fractures, the equivalent porosity of the fracture zone is φ F is the equivalent porosity of the high conductivity main fracture.

[0090] 2.2) Reconstruction area:

[0091] 2.2.1) The calculation process of the scope of the reconstruction area is as follows:

[0092] like Figure 3 As shown in the figure, there are several branch fractures and small flow areas in the surrounding cleats in the remodeled area, which is equivalent to a two-dimensional elliptical radial flow, that is, a two-dimensional ellipse with the two end points of the high conductivity main fracture as the focus. The equivalent seepage radius of the two-dimensional ellipse equivalent to the remodeled area is ξ fn for:

[0093]

[0094] Where a fn and b fn are the major and minor axes of the ellipse in the remodeling area, respectively, in meters. Based on the length and azimuth of multiple branch fractures in the remodeling area, the calculation diagram is shown in the figure below. Figure 3 As shown, where x fi is the length of the branch fracture; Δx fi is the starting coordinate of the branch seam; θ fi is the branch seam angle.

[0095] 2.2.2) The calculation process of equivalent seepage parameters in the reconstructed area is as follows:

[0096] 2.2.2.1) Calculate the equivalent permeability k of multiple branch fractures in the reconstructed area f :

[0097]

[0098] Where w fi is the width of each branch seam; unit is m; D fDf is the fractal dimension of the branch fracture, dimensionless; D t Df is the fractal dimension of the branch fracture, dimensionless; D f is the distance from the center position of each branch fracture to the starting point of the secondary fracture.

[0099] 2.2.2.2) Based on the equivalent permeability k of multiple branch fractures in the heavy reconstruction area f , the equivalent permeability k of the branch fracture in the heavy reconstruction area and the surrounding reconstruction area is calculated fn :

[0100]

[0101] wherein, and are the average length, width and height of the branch fracture, respectively, in units of m; H is the effective thickness of the reservoir, in units of m; k m-fn is the permeability of the surrounding reconstruction area of the branch fracture, in units of 10 -3 μm 2 .

[0102] 2.2.2.3) Calculate the equivalent porosity φ of multiple branch fractures in the heavy reconstruction area in the heavy reconstruction area f :

[0103]

[0104] wherein, ρ f is the branch fracture density, i.e. the number of branch fractures per unit area.

[0105] 2.2.2.4) Based on the equivalent porosity φ of multiple branch fractures in the heavy reconstruction area in the heavy reconstruction area f , the equivalent porosity φ of the heavy reconstruction area is calculated fn :

[0106]

[0107] 2.3) Weak reconstruction area:

[0108] 2.3.1) The calculation process of the range of the weak reconstruction area is:

[0109] The weak reconstruction area is similar to the heavy reconstruction area, and the weak reconstruction area is equivalent to an ellipse with the end points of the major axis of the heavy reconstruction area as the foci, as shown in Figure 4 . Specifically, the equivalent seepage radius ξ mf of the weak reconstruction area is:

[0110]

[0111] wherein, a mf and b mfrespectively, the long axis and the short axis of the ellipse of the weak reformation region, unit: m. According to the approximate calculation of the length and azimuth angle of multiple shear fractures, the calculation schematic diagram is shown in Figure 4 , wherein x fsi is the length of the shear fracture; and θ fsi is the angle of the shear fracture.

[0112] 2.3.2) The calculation process of the equivalent seepage parameters of the weak reformation region is as follows:

[0113] 2.3.2.1) The equivalent permeability k fs of multiple shear fractures in the weak reformation region is calculated.

[0114]

[0115] In the formula, w fsi is the width of each shear fracture, unit: m; D fs is the fractal dimension of the shear fracture, dimensionless; D ts is the fractal exponent of the shear fracture, dimensionless; Δx fsi is the horizontal coordinate of the starting point of the shear fracture; Δy fsi is the vertical coordinate of the starting point of the shear fracture; and XX fs is the distance from the center position of each shear fracture to the starting point of the shear fracture.

[0116] 2.3.2.2) Based on the equivalent permeability k fs of multiple shear fractures in the weak reformation region, the equivalent permeability k mf of the shear fracture and the surrounding reformation region in the weak reformation region is calculated.

[0117]

[0118] In the formula, L and H are the average length, width and height of the shear fracture, unit: m; and k m-mf is the permeability of the surrounding reformation region of the shear fracture, unit: 10 -3 μm 2 .

[0119] 2.3.2.3) The equivalent porosity φ fs of multiple shear fractures in the weak reformation region is calculated.

[0120]

[0121] In the formula, ρ fs is the branch fracture density, that is, the number of shear fractures per unit area.

[0122] 2.3.2.4) Based on the equivalent porosity φ fs of multiple shear fractures in the weak reformation region, the equivalent porosity φ of the weak reformation region is calculated.mf :

[0123]

[0124] 2.4) Matrix zone:

[0125] 2.4.1) The range calculation process of the matrix zone is as follows:

[0126] The range of the matrix zone is determined according to the well control area A weil . Specifically, the equivalent seepage radius ξ m of the matrix zone is:

[0127]

[0128] In the formula, r e is the radius of the matrix zone elliptical flow range equivalent to the circular supply; a e is the semi-major axis of the matrix zone ellipse.

[0129] 2.4.2) The equivalent seepage parameter calculation process of the matrix zone is as follows:

[0130] The equivalent permeability of the matrix zone is the permeability k m of the original reservoir, and the equivalent porosity of the matrix zone is the porosity φ m of the original reservoir.

[0131] 3) Based on the ranges and equivalent seepage parameters of the four zones of the deep coal reservoir, the seepage mathematical model of the four zones of the deep coal reservoir is established, and the gas production of the four zones of the deep coal reservoir is obtained.

[0132] 3.1) Based on the range and equivalent seepage parameter of the fracture zone of the deep coal reservoir, the seepage mathematical model of the fracture zone of the deep coal reservoir is established, and the gas production of the fracture zone of the deep coal reservoir is obtained:

[0133] 3.1.1) Based on the range and equivalent seepage parameter of the fracture zone of the deep coal reservoir, the seepage mathematical model of the fracture zone of the deep coal reservoir is established:

[0134]

[0135] In the formula, p F is the pressure of the fracture zone; k F is the equivalent permeability of the fracture zone; φ F is the porosity of the fracture zone; x F is the half length of the high-conductivity main fracture; h F is the height of the high-conductivity main fracture; Z is the gas compression factor; μ g is the gas viscosity, with the unit of mPa·s; C r , C g are the compression coefficients of the pores and the gas, respectively, with the unit of MPa-1 ; S g is gas saturation, dimensionless; t is time; p e is initial reservoir pressure, MPa; p wf is bottom hole flowing pressure, MPa; Q Fgsc is gas production of fracture zone; T is reservoir temperature, K; p sc is pressure at standard condition, MPa; Z sc is deviation factor at standard condition, dimensionless; T sc is temperature at standard condition, K.

[0136] Specifically, the nonlinear equations (14) and (15) caused by the change of gas physical property parameters with pressure are introduced, and the pressure and time of each zone are converted into pseudo-pressure and pseudo-time by substituting the pressure of each zone and the parameters such as gas viscosity and compressibility factor at each pressure into the equations (14) and (15), and the equations of the four zones are general:

[0137]

[0138] In the formula, ψ (p) is pseudo-pressure; P is pressure; μ (p) is gas viscosity; Z (p) is gas compressibility factor; t a is pseudo-time; the subscripts ini、 respectively represent the initial formation pressure and the gas parameters at the average pressure in each zone at each time.

[0139] 3.1.2) Based on the nonlinear equations of pseudo-pressure and pseudo-time and the mathematical model of seepage flow in the fracture zone, the gas production Q Fgsc of the fracture zone is solved at each small time step by considering that the pressure is constant.

[0140]

[0141] In the formula, ψ F is the pseudo-pressure of the fracture zone; ψ wf is the pseudo-pressure corresponding to the bottom hole flowing pressure; R F is the seepage resistance of the fracture zone.

[0142] 3.2) Based on the range and equivalent seepage parameters of the deep coal reservoir reformation zone, the mathematical model of seepage flow in the deep coal reservoir reformation zone is established, and the gas production of the deep coal reservoir reformation zone is solved, wherein the mathematical model of seepage flow in the reformation zone includes free gas equation and desorbed gas equation:

[0143] 3.2.1) Based on the range and equivalent seepage parameters of the deep coal reservoir reformation zone, the free gas equation in the mathematical model of seepage flow in the reformation zone is established:

[0144]

[0145] where r is the position of the seepage radius r in the gas reservoir; p fn is the pressure in the heavy reformation zone; p gsc is the density of the gas in the standard state, in kg / m 3 ; r fn is the radius of the equivalent circular supply of the elliptical flow range in the heavy reformation zone; h fn is the average height of the multiple branch fractures, i.e., h k fn is the equivalent permeability of the branch fractures in the heavy reformation zone and the surrounding reformation zone; q dfn is the desorbed gas in the heavy reformation zone; Q fngsc is the gas production in the heavy reformation zone.

[0146] 3.2.2) Based on the range and equivalent seepage parameters of the heavy reformation zone of the deep coal reservoir, a desorbed gas equation in the seepage mathematical model of the heavy reformation zone is established:

[0147]

[0148] where p cd is the critical desorption pressure, in MPa; V L is the Langmuir volume, in m 3 / m 3 ; p L is the Langmuir pressure, in MPa.

[0149] 3.2.3) Based on the free gas equation and the desorbed gas equation in the seepage mathematical model of the heavy reformation zone and the nonlinear formula of the pseudo-pressure and pseudo-time, at each small time step, the gas production Q fngsc of the heavy reformation zone is solved by considering the constant pressure as follows:

[0150]

[0151] where ψ fn is the pseudo-pressure of the heavy reformation zone; R fn is the seepage resistance term of the heavy reformation zone; Q dfn is the desorbed diffusion term of the heavy reformation zone.

[0152] 3.3) Based on the range and equivalent seepage parameters of the weak reformation zone of the deep coal reservoir, a seepage mathematical model of the weak reformation zone of the deep coal reservoir is established, and the gas production of the weak reformation zone of the deep coal reservoir is solved, wherein the seepage mathematical model of the weak reformation zone includes a free gas equation and a desorbed gas equation:

[0153] 3.3.1) Based on the range and equivalent seepage parameters of the weakly reconstructed area of the deep coal reservoir, a free gas equation in the seepage mathematical model of the weakly reconstructed area is established:

[0154]

[0155] In the formula, k mf is the equivalent permeability of the shear fracture in the weakly reconstructed area and the surrounding reconstructed area; p mf is the pressure of the weakly reconstructed area; r mf is the radius of the elliptical flow range of the weakly reconstructed area corresponding to the circular supply; q dmf is the desorbed gas of the weakly reconstructed area; h mf is the average height of the multiple shear fractures; Q mfgsc is the gas production of the weakly reconstructed area.

[0156] 3.3.2) Based on the range and equivalent seepage parameters of the weakly reconstructed area of the deep coal reservoir, a desorbed gas equation in the seepage mathematical model of the weakly reconstructed area is established:

[0157]

[0158] 3.3.3) Based on the free gas equation and the desorbed gas equation in the seepage mathematical model of the weakly reconstructed area and the nonlinear formula of the pseudo-pressure and pseudo-time, the gas production Q mfgsc of the weakly reconstructed area is solved as follows:

[0159]

[0160] In the formula, ψ mf is the pseudo-pressure of the weakly reconstructed area; R mf is the seepage resistance term of the weakly reconstructed area; Q dmf is the desorption diffusion term of the weakly reconstructed area.

[0161] 3.4) Based on the range and equivalent seepage parameters of the matrix area of the deep coal reservoir, a seepage mathematical model of the matrix area of the deep coal reservoir is established, and the gas production of the matrix area of the deep coal reservoir is solved, wherein the seepage mathematical model of the matrix area includes a free gas equation and a desorbed gas equation:

[0162] 3.4.1) Based on the range and equivalent seepage parameters of the matrix area of the deep coal reservoir, a free gas equation in the seepage mathematical model of the matrix area is established:

[0163]

[0164] In the formula, p m is the pressure of the matrix area; q dm is the desorbed gas of the matrix area; Q mgsc is the gas production of the matrix area.

[0165] 3.4.2) Based on the scope of the matrix zone of the deep coal reservoir and the equivalent seepage parameters, a desorption gas equation in the seepage mathematical model of the matrix zone is established:

[0166]

[0167] 3.4.3) Based on the free gas equation and the desorption gas equation in the seepage mathematical model of the matrix zone and the nonlinear formula of the pseudo-pressure and the pseudo-time, the gas production Q of the matrix zone is solved mgsc is:

[0168]

[0169] In the formula, R m is the seepage resistance term of the matrix zone; Q dm is the desorption diffusion term of the matrix zone.

[0170] 4) According to the gas production of the four regions of the deep coal reservoir, the gas production of a single fracturing section of the deep coal reservoir, that is, the multi-region coupling productivity, is obtained, and then the gas production of the multi-section fracturing horizontal well of the deep coal reservoir is obtained, which is specifically:

[0171] 4.1) According to the equivalent seepage resistance method, the four regions supply gas in series and the pressure at the interface is equal, and the gas production equations of the four regions of the deep coal reservoir are solved to obtain:

[0172]

[0173] 4.2) Based on the above solved gas production equation (26), the gas production of a single fracturing section of the deep coal reservoir as the multi-region coupling productivity is obtained:

[0174]

[0175] 4.3) Without considering the inter-fracture interference, based on the gas production Q gsc of a single fracturing section of the deep coal reservoir and the number of fracturing sections NF, the gas production NQ gsc of the multi-section fracturing horizontal well of the deep coal reservoir is obtained:

[0176]

[0177] Wherein, NF is the number of fracturing sections.

[0178] The following takes a deep coal bed methane well in China as an example, the fracturing reservoir parameters, gas PVT parameters, multi-section fracturing horizontal well parameters and four region parameters equivalent to the complex fracture network distribution after fracturing shown in Table 1 are used to calculate the daily production of the horizontal well, which illustrates the effectiveness of the method, and it should be noted that the horizontal well is taken as an example in the embodiment, but the method can be applied to each type of well such as horizontal well, vertical well and directional well:

[0179] Table 1: Gas PVT parameters, horizontal well and fractured reservoir parameters

[0180]

[0181]

[0182] Using the data in Table 1 above, the time step is set to 1 day, and the total time length is 360 days, and the daily production of the horizontal well is calculated. The comparison results of the calculated daily production of the horizontal well and the actual daily production are shown in Figure 5 From Figure 5 It can be seen that the calculation results are highly consistent with the actual data, verifying the accuracy of the method.

[0183] Example 2

[0184] The embodiment provides a deep coalbed gas reservoir multi-zone coupled productivity evaluation system, comprising:

[0185] The four-zone physical model establishing module is configured to establish a four-zone physical model of the deep coal reservoir according to the fracture network characteristics and fluid percolation characteristics of the deep coal reservoir after fracturing, including four regions of a fracture region, a heavy reconstruction region, a weak reconstruction region, and a matrix region.

[0186] The parameter calculation module is configured to calculate the ranges and equivalent percolation parameters of the four regions of the deep coal reservoir based on the four-zone physical model of the deep coal reservoir and according to the fracture network parameters of the deep coal reservoir after fracturing.

[0187] The percolation mathematical model establishing module is configured to establish a percolation mathematical model of the four regions of the deep coal reservoir based on the ranges and equivalent percolation parameters of the four regions of the deep coal reservoir, and solve the gas production of the four regions of the deep coal reservoir.

[0188] The gas production solving module is configured to obtain the gas production of a single fracturing section of the deep coal reservoir as the multi-zone coupled productivity according to the gas production of the four regions of the deep coal reservoir.

[0189] The system provided in the embodiment is used to execute the above-mentioned method embodiments, and the specific process and detailed content are referred to the above-mentioned embodiments, which will not be described here.

[0190] Example 3

[0191] The embodiment provides a processing device corresponding to the deep coalbed gas reservoir multi-zone coupled productivity evaluation method provided in the embodiment 1. The processing device can be applied to the processing device of the client, such as a mobile phone, a notebook computer, a tablet computer, a desktop computer, etc., to execute the method of the embodiment 1.

[0192] The processing device includes a processor, a memory, a communication interface and a bus, the processor, the memory and the communication interface are connected through the bus to complete the communication between each other. The memory stores a computer program which can run on the processing device, and the processing device executes the deep coalbed gas reservoir multi-zone coupling productivity evaluation method provided in the embodiment 1 when running the computer program.

[0193] In some implementations, the memory can be a high-speed random access memory (RAM), and can also include a non-volatile memory, such as at least one disk memory.

[0194] In other implementations, the processor can be a central processing unit (CPU), a digital signal processor (DSP) or various types of general-purpose processors, which are not limited here.

[0195] In addition, the logical instructions in the memory described above can be implemented in the form of a software functional unit and sold or used as an independent product, which can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application or the part of the prior art that essentially contributes to the prior art or part of the technical solutions can be embodied in the form of a software product, which is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0196] Those skilled in the art can understand that the structure of the computing device described above is only part of the structure related to the present application scheme, and does not constitute a limitation on the computing device to which the present application scheme is applied. The specific computing device can include more or fewer components, or combine certain components, or have a different component arrangement.

[0197] Embodiment 4

[0198] The embodiment provides a computer program product corresponding to the deep coalbed gas reservoir multi-zone coupling productivity evaluation method provided in the embodiment 1, and the computer program product can include a computer readable storage medium, which is loaded with computer readable program instructions for executing the deep coalbed gas reservoir multi-zone coupling productivity evaluation method described in the embodiment 1.

[0199] The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium can be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof.

[0200] The computer readable storage medium provided by the above embodiment has similar implementation principles and technical effects to the above method embodiments, and thus will not be described here.

[0201] The present application is described in reference to flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts 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, 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 produce a device that implements the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs the functions specified in one or more flows or blocks.

[0202] These computer program instructions can also be stored in a computer readable memory that can direct the computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce a manufactured product including instruction apparatus, which implements the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs the functions specified in one or more flows or blocks.

[0203] These computer program instructions can also be loaded into a computer or other programmable data processing device, so that a series of operation steps are performed on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide a process for implementing the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that performs the functions specified in one or more flows or blocks.

[0204] The above embodiments are only used to illustrate the present application, and the structure, connection mode and manufacturing process of each component can be changed. Any equivalent transformation and improvement based on the technical solutions of the present application should not be excluded from the protection scope of the present application.

Claims

1. A method for evaluating the multi-zone coupled productivity of deep coalbed methane reservoirs, characterized in that: include: Based on the fracture network characteristics and fluid seepage characteristics of deep coal reservoirs after fracturing, a four-zone physical model of deep coal reservoirs was established, including the fracture zone, the heavily reformed zone, the weakly reformed zone and the matrix zone. Based on the four-zone physical model of deep coal reservoirs and the fracture network parameters after fracturing, the ranges and equivalent seepage parameters of the four zones of deep coal reservoirs are calculated; Based on the range and equivalent seepage parameters of the four regions of deep coal reservoir, a mathematical model of seepage in the four regions of deep coal reservoir was established, and the gas production of the four regions of deep coal reservoir was obtained. According to the gas production of the four zones in the deep coal reservoir, the gas production of a single fracturing section in the deep coal reservoir is obtained as the multi-zone coupling capacity.

2. The method for evaluating the multi-zone coupled productivity of a deep coalbed methane reservoir according to claim 1, wherein: The fracture network characteristics refer to the fracture morphology and fracture parameters after hydraulic fracturing of deep coal reservoirs. The fracture morphology is a four-level complex fracture network consisting of "high-conductivity main fractures + branch fractures + shear self-supporting fractures + cleats". The fracture parameters include the length, aperture, height and conductivity of each level of fracture. The fracture zone is the high-conductivity main fracture area formed by hydraulic fracturing near the wellbore, which is mainly composed of free gas and the gas flow follows Darcy's law; The heavily reformed area is the branch fracture filled with proppant and the surrounding reformed area. Free gas and desorbed gas coexist. The free gas follows Darcy's law, while the desorbed gas flows according to the "desorption-diffusion-seepage" law. The weakly stimulated area is the shear self-propped fracture and the surrounding stimulated area in the far wellbore area where proppant is difficult to enter, and there are free gas and desorbed gas; The matrix zone is the area not affected by the original reservoir fracturing, where free gas and desorbed gas coexist.

3. A method for evaluating the multi-zone coupled productivity of a deep coalbed methane reservoir according to claim 2, characterized in that: The range of the fracture zone is the length, width and height of the high conductivity main fracture, and the equivalent seepage parameters of the fracture zone are the equivalent permeability and equivalent porosity of the high conductivity main fracture; The range of the matrix zone is determined according to the well control area. The equivalent permeability of the matrix zone is the permeability of the original reservoir, and the equivalent porosity of the matrix zone is the porosity of the original reservoir.

4. The method for evaluating the multi-zone coupled productivity of a deep coalbed methane reservoir according to claim 2, wherein: There are several branch fractures and small flow areas in the surrounding cleats in the remodeling zone, which is equivalent to a two-dimensional elliptical radial flow. The range of the remodeling zone is a two-dimensional ellipse with the two end points of the high-conductivity main fracture as the focus; The calculation process of the equivalent seepage parameters in the reconstructed area is as follows: Calculate the equivalent permeability of multiple branch fractures in the remodeled area; Based on the equivalent permeability of multiple branch fractures in the heavily reconstructed area, the equivalent permeability of the branch fractures in the heavily reconstructed area and the surrounding reconstructed area is calculated; Calculate the equivalent porosity of multiple branch fractures in the reconstructed area; The equivalent porosity of the heavily reformed area is calculated based on the equivalent porosity of multiple branch fractures in the heavily reformed area.

5. The method for evaluating the multi-zone coupled productivity of a deep coalbed methane reservoir according to claim 4, wherein: The weakly reformed area is equivalent to an ellipse with the endpoint of the major axis of the heavily reformed area ellipse as the focus; The calculation process of the equivalent seepage parameters in the weakly transformed area is as follows: Calculate the equivalent permeability of multiple shear fractures in the weak transformation area; Based on the equivalent permeabilities of multiple shear fractures in the weakly reformed area, the equivalent permeabilities of the shear fractures in the weakly reformed area and the surrounding reformed areas are calculated; Calculate the equivalent porosity of multiple shear fractures in the weakly reformed area; Based on the equivalent porosity of multiple shear fractures in the weakly reformed zone, the equivalent porosity of the weakly reformed zone is calculated.

6. The method for evaluating the multi-zone coupled productivity of a deep coalbed methane reservoir according to claim 2, wherein: The mathematical model of seepage in the fracture zone is: Where p F is the pressure in the crack area; k F is the equivalent permeability of the fracture zone; φ F is the porosity of the fracture zone; x F is the half length of the high conductivity main crack; h F is the height of the high conductivity main fracture; Z is the gas compressibility factor; μ g is the gas viscosity; C r 、C g are the compressibility coefficients of pores and gas, respectively; S g is gas saturation; t is time; p e is the original reservoir pressure; p wf is the bottom hole pressure; Q Fgsc is the gas production in the fracture zone; T is the reservoir temperature; p sc is the pressure under standard conditions; Z sc is the deviation factor under standard conditions; T sc is the temperature under standard conditions; The mathematical model of seepage in the reconstructed area includes the free gas equation and the desorbed gas equation. The free gas equation is: Where r is the position with seepage radius r in the gas reservoir; p fn is the pressure in the remodeling area; ρ gsc is the density of the gas under standard conditions; r fn The elliptical flow range of the remodeling area is equivalent to the radius of the circular supply; φ fn is the equivalent porosity of the reconstructed area; h fn is the average height of multiple branch fractures; k fn is the equivalent permeability of the branch fractures in the heavily reconstructed area and the surrounding reconstructed area; q dfn It is the desorbed gas in the heavy reforming area; fn is the equivalent seepage radius of the two-dimensional ellipse equivalent to the remodeling area; Q fngsc is the gas production in the heavy transformation area; The desorption gas equation in the mathematical model of seepage in the reconstructed area is: Where p cd is the critical desorption pressure; V L is the Langmuir volume; p L is the Langmuir pressure; The mathematical model of seepage in the weakly reformed zone includes the free gas equation and the desorbed gas equation. The free gas equation is: Where k mf is the equivalent permeability of the shear fracture in the weakly reformed area and the surrounding reformed area; p mf is the pressure in the weak transformation zone; r mf The elliptical flow range of the weak transformation zone is equivalent to the radius of the circular supply; q dmf is the desorbed gas in the weak reformation zone; ξ mf is the equivalent seepage radius of the weakly transformed zone; φ mf is the equivalent porosity of the weakly reformed zone; h mf is the average height of multiple shear joints; Q mfgsc is the gas production in the weakly reformed area; The desorption gas equation in the mathematical model of seepage in the weak reformed area is: The mathematical model of seepage in the matrix zone includes the free gas equation and the desorbed gas equation. The free gas equation is: Where p m is the matrix pressure; q dm is the desorbed gas in the matrix region; ξ m is the equivalent seepage radius of the matrix area; k m is the equivalent permeability of the matrix area; φ m is the equivalent porosity of the matrix area; Q mgsc is the gas production in the matrix area; The desorption gas equation in the matrix area seepage mathematical model is:

7. A method for evaluating the multi-zone coupled productivity of a deep coalbed methane reservoir according to claim 6, characterized in that: The multi-zone coupling capacity is: Among them, ψ F is the pseudo-pressure in the fracture zone; ψ wf is the pseudo-pressure corresponding to the bottom hole flowing pressure; R F is the seepage resistance in the fracture area; R fn is the seepage resistance term in the heavily renovated area; Q dfn is the desorption and diffusion term in the heavy reformation zone; R mf is the seepage resistance term in the weakly transformed area; Q dmf is the desorption and diffusion term in the weakly reformed zone; R m is the seepage resistance term in the matrix area; Q dm is the desorption diffusion term in the matrix region.

8. A multi-zone coupled productivity evaluation system for deep coalbed methane reservoirs, characterized by: include: The four-zone physical model establishment module is used to establish a four-zone physical model of deep coal reservoirs based on the fracture network characteristics and fluid seepage characteristics of deep coal reservoirs after fracturing, including the fracture zone, heavily reformed zone, weakly reformed zone and matrix zone; A parameter calculation module is used to calculate the range and equivalent seepage parameters of the four regions of the deep coal reservoir based on the four-region physical model of the deep coal reservoir and the fracture network parameters of the deep coal reservoir after fracturing; A seepage mathematical model building module is used to build a seepage mathematical model of the four areas of the deep coal reservoir based on the ranges and equivalent seepage parameters of the four areas of the deep coal reservoir, and to solve and obtain the gas production of the four areas of the deep coal reservoir; The gas production calculation module is used to obtain the gas production of a single fracturing section in the deep coal reservoir based on the gas production of the four areas of the deep coal reservoir, and then obtain the gas production of a multi-section fracturing horizontal well in the deep coal reservoir.

9. A processing device, characterized in that: It comprises computer program instructions, wherein when the computer program instructions are executed by a processing device, they are used to implement the steps corresponding to the multi-zone coupling productivity evaluation method for deep coalbed methane reservoirs according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer program instructions, wherein the computer program instructions, when executed by a processor, are used to implement the steps corresponding to the multi-zone coupled productivity evaluation method for deep coalbed methane reservoirs according to any one of claims 1 to 7.

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