A radial multi-hole composite reservoir cave calculation method, system, device and medium

Abstract

The application discloses a kind of radial multi-hole composite oil reservoir cave calculation method, system, equipment and medium, S1, fracture-cave carbonate rock oil and gas reservoir is divided into two parts, one part is cave and matrix, another part is the region where fracture is, fracture-cave carbonate rock multi-hole oil and gas reservoir is simplified as single-hole composite oil and gas reservoir;S2, the dimensionless pressure solution of well bottom of single-hole composite oil and gas reservoir is calculated;S3, the derivative curve of well bottom dimensionless pressure solution is obtained, and the derivative curve of well bottom dimensionless pressure is fitted measured well bottom pressure and its derivative curve, when two double logarithmic curves coincide, the simplified cave radius is inverted, to obtain cave volume.Can accurately calculate the cave volume when cave is individually distributed in stratum.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas reservoir development and relates to a method, system, equipment and medium for calculating karst caverns in radially multi-cavity composite oil reservoirs. Background Technology

[0002] Carbonate oil and gas reservoirs refer to the accumulation of oil and gas within carbonate rock traps. General oil and gas reservoir classifications cannot fully represent all the characteristics of carbonate oil and gas reservoirs, such as reef-type reservoirs. Therefore, some scholars have independently classified carbonate oil and gas reservoirs in addition to the general classifications: ① Carbonate oil and gas reservoirs associated with large uplifts; ② Fracture (fractured-vuggy) type oil and gas reservoirs; ③ Bioherm type oil and gas reservoirs; ④ Ancient buried hill oil and gas reservoirs; ⑤ Oil and gas reservoirs associated with diagenesis or epigenetic processes, etc.

[0003] Statistics show that carbonate oil and gas reservoirs currently account for more than 50% of the world's proven oil and gas reservoirs, with fractured-vuggy carbonate oil and gas reservoirs accounting for more than 60% of these. Fractured-vuggy reservoirs possess complex pore structures, various fracture-vuggy connection forms, diverse flow mechanisms, and extremely strong formation heterogeneity, making their study a current focus of oil and gas reservoir development. Because fractured-vuggy carbonate reservoirs commonly contain dispersed caverns, conventional research methods are not applicable; therefore, establishing suitable well test models is crucial for reservoir property evaluation.

[0004] Transient pressure analysis has become a common and important method for studying formation characteristics, and various well test models have been proposed to describe flow and migration processes in formations. To date, most models proposed for complex reservoirs still differ in terms of solution methods, computational accuracy requirements, and tractable degrees of freedom. Regarding the study of flow processes in formations with multiple caverns, the tricontinent and multicontinent models are currently the most widely used. However, the tricontinent and multicontinent theories are only applicable within certain ranges. When the size of the caverns is between a few meters and tens of meters, the theory cannot provide a reasonable description, and the cavern volume, a crucial piece of information for oil extraction, cannot be obtained. Currently, there is no reliable method to calculate the cavern volume when caverns are distributed individually within the formation. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method, system, equipment and medium for calculating karst caves in radially multi-cavitary composite reservoirs, which can accurately calculate the volume of karst caves when they are distributed individually in the strata.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A method for calculating karst cavern in radially porous composite reservoirs includes the following steps:

[0008] S1 divides fractured-vuggy carbonate oil and gas reservoirs into two parts: one part is the cavern and matrix, and the other part is the fracture area. This simplifies fractured-vuggy carbonate multi-cavity oil and gas reservoirs into single-cavity composite oil and gas reservoirs.

[0009] S2, calculate the dimensionless pressure solution at the bottom of the well for a single-cavity composite oil and gas reservoir;

[0010] S3. Obtain the derivative curve of the dimensionless pressure solution at the bottom of the well. Fit the dimensionless pressure and its derivative curve at the bottom of the well to the measured bottom pressure and its derivative curve. When the two double logarithmic curves coincide, the simplified radius of the karst cave is obtained, thus obtaining the volume of the karst cave.

[0011] Preferably, in S1, the fractured-vuggy carbonate oil and gas reservoir is divided as follows: the single-vuggy composite oil and gas reservoir is centered on the wellbore, and from the inside out, it consists of the wellbore, fracture zone 1, cavern, and fracture zone 2.

[0012] Preferably, in S2, the process of calculating the bottom hole pressure solution for a single-cavity composite oil and gas reservoir is as follows:

[0013] S21, Establish the flow equations for crack region 1 and crack region 2;

[0014] S22, by defining the parameters in the flow equations in a dimensionless manner, we obtain a set of dimensionless equations;

[0015] S23. The dimensionless equation system is transformed by the dimensionless time Laplace transform to obtain the governing equations in Laplace space.

[0016] S24, Solve the governing equations to obtain the expressions for the inner and outer boundaries;

[0017] S25, the bottom hole pressure solution is obtained by calculating the expression of the inner and outer boundaries.

[0018] Furthermore, the flow equations for crack region 1 and crack region 2 are as follows:

[0019]

[0020]

[0021] Where r is a variable, subscripts 1 and 2 represent fracture region 1 and fracture region 2 respectively, p is pressure, t is time, φ is porosity, and c t denoted as the comprehensive compressibility coefficient, k as the permeability, and μ as the crude oil viscosity.

[0022] Furthermore, the dimensionless system of equations:

[0023]

[0024] Where r is a variable, subscripts 1 and 2 represent crack region 1 and crack region 2 respectively, p is pressure, t is time, and c t The comprehensive compressibility coefficient is given by k, permeability is given by D, dimensionless quantity is given by w, wellbore is given by q, flow rate is given by V, and cave parameters are given by C. v ω is the cavern storage constant, M is the mobility ratio, and ω is the storage capacity ratio.

[0025] Furthermore, the governing equations are:

[0026]

[0027]

[0028]

[0029]

[0030] Where r is a variable, subscripts 1 and 2 represent crack region 1 and crack region 2 respectively, p is pressure, t is time, and c t The comprehensive compressibility coefficient is given by k, permeability is given by D, dimensionless quantity is given by w, wellbore is given by q, flow rate is given by V, and cave parameters are given by C. v ω is the cavern storage constant, M is the mobility ratio, ω is the storage capacity ratio, "—" indicates the Laplace transform, and u is the Laplace operator.

[0031] Furthermore, the bottom hole pressure solution is:

[0032]

[0033] Where p is pressure, subscript D indicates a dimensionless quantity, subscript w indicates wellbore, "-" indicates Laplace transform, u is the Laplace operator, I and K are Bessel functions, and subscripts 0 and 1 represent the order.

[0034] A calculation system for radially multi-cavitary composite reservoir karst cavern includes:

[0035] The oil and gas reservoir division module is used to divide fractured-vuggy carbonate oil and gas reservoirs into two parts: one part is the cave and matrix, and the other part is the fracture area. It simplifies fractured-vuggy carbonate multi-cavity oil and gas reservoirs into single-cavity composite oil and gas reservoirs.

[0036] The bottom-hole dimensionless pressure solution calculation module is used to calculate the bottom-hole dimensionless pressure solution of a single-cavity composite oil and gas reservoir.

[0037] The cavity volume acquisition module is used to obtain the derivative curve of the dimensionless pressure solution at the bottom of the well. The dimensionless pressure and its derivative curve at the bottom of the well are fitted to the measured bottom pressure and its derivative curve. When the two double logarithmic curves coincide, the simplified cavity radius is obtained, thus yielding the cavity volume.

[0038] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the radial multi-cavity composite reservoir karst cavern calculation method as described in any of the preceding claims.

[0039] A computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the radial multi-cavity composite reservoir cavern calculation method as described in any of the preceding claims.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] This invention addresses the shortcomings of conventional well test models by extending multi-cavitary carbonate reservoirs to a new type of composite reservoir. It establishes a new well test model for radially multi-cavitary composite reservoirs, namely a simplified physical model of single-cavitary composite oil and gas reservoirs. By calculating the dimensionless pressure solution at the bottom of the well for single-cavitary composite oil and gas reservoirs, and fitting the dimensionless pressure solution and the derivative double logarithmic curve, it is possible to accurately calculate the volume of cavities when they are individually distributed in the formation. This solves the problem of studying the flow process when multiple cavities exist in the formation. This invention is applicable to well test fitting in actual field operations for fractured-vuggy reservoirs, as well as dynamic data inversion. Attached Figure Description

[0042] Figure 1 This is a simplified physical plane model of a single hole according to the present invention;

[0043] Figure 2 This is a double logarithmic curve of bottom hole pressure and derivative in a fractured-vuggy reservoir according to the present invention;

[0044] Figure 3 This is a curve fitting diagram of an example well of the present invention; Detailed Implementation

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0046] It should be noted that the terms “front,” “back,” “left,” “right,” “up,” and “down” used in the following description refer to the directions shown in the attached diagram, while the terms “inside” and “outside” refer to the directions toward or away from the geometric center of a specific component, respectively.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0048] The radial multi-cavity composite reservoir karst cave calculation method of the present invention can accurately calculate the volume of karst caves when they are distributed individually in the formation, and includes the following process:

[0049] 1) To make the problem easier to handle and facilitate the development of a simplified physical model for a single-cavity formation, several assumptions and simplifications are made regarding the actual flow process in a multi-cavity formation: (1) The formation is an isotropic concentric cylinder with a constant thickness. There is a constant flow oil well at the center of the formation. (2) Formation properties, such as permeability and porosity, are constant. The fluid is a compressible single-phase fluid. At the same time, the compressibility coefficient and viscosity of the fluid are also constant. (3) Gravity and capillary effects can be ignored. (4) The original formation pressure at each location is uniform. (5) The entire formation fluid flow process satisfies Darcy's law and is an isothermal process.

[0050] 2) The fractured-vuggy carbonate oil and gas reservoir is divided into two parts: one part consists of caves and matrix scattered throughout the formation, and the other part is the area where the fractures are located. Caves at the same or similar distance from the wellbore are grouped into one cavity and simplified as a hollow cylinder. This method simplifies multi-cavity fractured-vuggy carbonate oil and gas reservoirs into single-cavity composite oil and gas reservoirs, forming a simplified single-cavity physical model.

[0051] like Figure 1 As shown, the planar shape of the simplified physical model of a single cavity is centered on the well shaft, and from the inside out are the well shaft, fracture region 1, the cave, and fracture region 2.

[0052] 3) The bottom hole pressure solution p obtained using the simplified physical model of a single hole D (t D ).

[0053] Bottom hole pressure solution p D (t D This is derived from the following process:

[0054] For the single-hole model, the flow equations for regions 1 and 2 are:

[0055]

[0056]

[0057] Where r is a variable, subscripts 1 and 2 represent regions 1 and 2 respectively, p is pressure (unit: MPa), t is time (unit: h), φ is porosity, and c t The overall compressibility factor (unit: MPa) -1 ), k is the permeability (unit: mD), and μ is the crude oil viscosity (unit: mPa·s).

[0058] The initial conditions are:

[0059] p1(r, t=0)=p2(r, t=0)=p i (3)

[0060] Where, p i Initial formation pressure (unit: MPa).

[0061] The oil flow within the cave can be considered to be the same as the flow in the pipe; therefore, the oil velocity within the cave is much higher than that of Darcy flow, which means that the pressure drop within the cave is smaller. Therefore, the pressure relationship at the interface is:

[0062] p1(r=r1,t)=p2(r=r v ,t)=p v (4)

[0063] In this context, the subscript V represents the parameters of the karst cave.

[0064] The continuity of traffic on the interface can be described as

[0065]

[0066] Among them, C v Storage constant of the cavern (unit: m) 3 / MPa), where the force is the formation thickness (unit: m).

[0067] The following dimensionless definition is adopted:

[0068] Dimensionless time

[0069] Dimensionless pressure

[0070] dimensionless radius

[0071] Dimensionless mobility ratio

[0072] Dimensionless storage ratio

[0073] Dimensionless cave storage constant

[0074] In this context, the subscript D represents a dimensionless quantity, the subscript w represents the wellbore, and q represents the flow rate.

[0075] Based on this, equations (1)-(5) can be transformed into a dimensionless system of equations:

[0076]

[0077] The expression for the inner boundary condition is as follows (wellbore reservoir and skin factor are not considered for the time being):

[0078]

[0079] The expression for the outer boundary condition is:

[0080] (1) For an infinitely large oil reservoir:

[0081] p 2D (r D →∞,t D )=0 (8)

[0082] (2) For closed reservoirs:

[0083]

[0084] In this context, the subscript 'e' represents the boundary parameter.

[0085] The Laplace transform of dimensionless time tD is performed using the following equation:

[0086]

[0087] Where “-” represents the Laplace transform and u is the Laplace operator.

[0088] Taking the Laplace transform of equation (6), we obtain the governing equation:

[0089]

[0090]

[0091]

[0092]

[0093] The expression for the inner boundary condition is:

[0094]

[0095] The expression for the outer boundary condition is:

[0096] (1) For an infinitely large oil reservoir

[0097]

[0098] (2) For closed reservoirs:

[0099]

[0100] (3) For constant pressure reservoirs:

[0101]

[0102] The final solution is:

[0103]

[0104] Where I and K are Bessel functions, and the subscripts 0 and 1 represent the order.

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111] Laplace numerical inversion was performed on the bottom hole pressure (19) in the Laplace space, and the solution of the bottom hole pressure in the real space can be obtained by Stehfest numerical inversion technique.

[0112] 4) Based on the analytical solution of the bottom hole pressure, a dimensionless bottom hole pressure curve and its derivative curve with respect to dimensionless time can be plotted. The dimensionless bottom hole pressure and its derivative curve can then be fitted to the measured bottom hole pressure and its derivative curve, such as... Figure 2 As shown, when the two double logarithmic curves coincide, the simplified radius of the cave can be derived, thus obtaining the volume of the cave.

[0113] This embodiment verifies the model based on production data from a fractured-vuggy carbonate oil well in western China, including the following steps:

[0114] 1) Conduct field measurements on the oil well to obtain on-site data. Firstly, through geological methods, the following known data can be obtained: wellbore radius 0.0603 meters, intermediate depth 7562.32 meters, formation thickness 10 meters, original formation pressure 86.66 MPa, porosity 5%, crude oil viscosity 0.0002 Pa·s, formation volume index 2.2574, and fluid compressibility coefficient 0.0022 MPa. -1The example well began production in 2017, with a constant flow rate of 80 m³ / min. 3 / d. The well was shut in after 30 days of production, and pressure recovery data was recorded using a high-precision pressure gauge for 200 hours.

[0115] 2) Based on the on-site data curves, a single-cavity model was selected for simulation. The results are shown in Table 1, with the cavity volume being 25407 m³. 3 From cave to well (r v The distance is 38.4163m. Figure 3 The figure shows the curve fitting of an example well. As can be seen from the figure, the results obtained by the model are basically consistent with the field data.

[0116] Table 1. Well Interpretation Results of Examples

[0117]

[0118] The following are embodiments of the apparatus of the present invention, which can be used to execute embodiments of the method of the present invention. For details not omitted in the apparatus embodiments, please refer to the embodiments of the method of the present invention.

[0119] In another embodiment of the present invention, a radial multi-cavity composite reservoir cavern calculation system is provided. This radial multi-cavity composite reservoir cavern calculation system can be used to implement the above-mentioned radial multi-cavity composite reservoir cavern calculation method. Specifically, the radial multi-cavity composite reservoir cavern calculation system includes an oil and gas reservoir partitioning module, a well bottom dimensionless pressure solution calculation module, and a cavern volume acquisition module.

[0120] The oil and gas reservoir division module is used to divide fractured-vuggy carbonate oil and gas reservoirs into two parts: one part is the cave and matrix, and the other part is the area where the fractures are located, simplifying fractured-vuggy carbonate multi-cavity oil and gas reservoirs into single-cavity composite oil and gas reservoirs.

[0121] The dimensionless pressure solution calculation module at the bottom of the well is used to calculate the dimensionless pressure solution at the bottom of the well for single-cavity composite oil and gas reservoirs.

[0122] The cavity volume acquisition module is used to obtain the derivative curve of the dimensionless pressure solution at the bottom of the well. The dimensionless pressure and its derivative curve at the bottom of the well are fitted to the measured bottom pressure and its derivative curve. When the two double logarithmic curves coincide, the simplified cavity radius is obtained, thus yielding the cavity volume.

[0123] In another embodiment of the present invention, a terminal device is provided, comprising a processor and a memory. The memory stores a computer program, the computer program including program instructions, and the processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), or field-programmable gate arrays (FPGAs). Gate Array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc., are the computing core and control core of the terminal. They are suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions to realize the corresponding method flow or corresponding function. The processor described in this embodiment of the invention can be used for the operation of the radial multi-cavity composite oil reservoir cavern calculation method, including: S1, dividing the fractured-cavity carbonate oil and gas reservoir into two parts, one part being the cavern and matrix, and the other part being the fracture area, simplifying the fractured-cavity carbonate multi-cavity oil and gas reservoir into a single-cavity composite oil and gas reservoir; S2, calculating the dimensionless pressure solution at the bottom of the well for the single-cavity composite oil and gas reservoir; S3, obtaining the derivative curve of the dimensionless pressure solution at the bottom of the well, fitting the dimensionless pressure and its derivative curve at the bottom of the well to the measured bottom of the well pressure and its derivative curve, and when the two double logarithmic curves coincide, the simplified cavern radius is inverted, thereby obtaining the cavern volume.

[0124] In another embodiment, the present invention also provides a computer-readable storage medium (Memory), which is a memory device in a terminal device for storing programs and data. It is understood that the computer-readable storage medium here may include both the built-in storage medium in the terminal device and extended storage media supported by the terminal device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, the storage space also stores one or more instructions suitable for loading and execution by a processor, which may be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here may be high-speed RAM or non-volatile memory, such as at least one disk storage device.

[0125] One or more instructions stored in a computer-readable storage medium can be loaded and executed by the processor to implement the corresponding steps of the radial multi-cavity composite oil reservoir cavern calculation method in the above embodiments; one or more instructions in the computer-readable storage medium are loaded and executed by the processor as follows: S1, divide the fractured-cavity carbonate oil and gas reservoir into two parts, one part being the cavern and matrix, and the other part being the fracture area, simplifying the fractured-cavity carbonate multi-cavity oil and gas reservoir into a single-cavity composite oil and gas reservoir; S2, calculate the dimensionless pressure solution at the bottom of the well for the single-cavity composite oil and gas reservoir; S3, obtain the derivative curve of the dimensionless pressure solution at the bottom of the well, fit the dimensionless pressure and its derivative curve at the bottom of the well to the measured bottom of the well pressure and its derivative curve, and when the two double logarithmic curves coincide, the simplified cavern radius is inverted, thereby obtaining the cavern volume.

[0126] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0127] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0128] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0129] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0130] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0131] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this teaching should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. A method for calculating karst caverns in radially porous composite oil reservoirs, characterized in that, Includes the following processes: S1 divides fractured-vuggy carbonate oil and gas reservoirs into two parts: one part is the cavern and matrix, and the other part is the fracture area. This simplifies fractured-vuggy carbonate multi-cavity oil and gas reservoirs into single-cavity composite oil and gas reservoirs. The classification of fractured-vuggy carbonate oil and gas reservoirs is as follows: a single-vuggy composite oil and gas reservoir is centered on the wellbore, and from the inside out are the wellbore, fracture zone one, cavern and fracture zone two. S2, calculate the dimensionless pressure solution at the bottom of the well for a single-cavity composite oil and gas reservoir; S21, Establish the flow equations for crack region one and crack region two; S22, by defining the parameters in the flow equations in a dimensionless manner, we obtain a set of dimensionless equations; S23. Perform a dimensionless time Laplace transform on the dimensionless system of equations to obtain the governing equations in Laplace space. S24, Solve the governing equations to obtain the expressions for the inner and outer boundaries; S25, the bottom hole pressure solution is obtained by calculating the expression of the inner and outer boundaries; S3. Obtain the derivative curve of the dimensionless pressure solution at the bottom of the well. Fit the dimensionless pressure and its derivative curve at the bottom of the well to the measured bottom pressure and its derivative curve. When the two double logarithmic curves coincide, the simplified radius of the karst cave is obtained, thus obtaining the volume of the karst cave.

2. The method for calculating karst caverns in radially porous composite reservoirs according to claim 1, characterized in that, The flow equations for crack region one and crack region two are: ； ； in, r As variables, subscripts 1 and 2 represent crack region one and crack region two, respectively. p For pressure, t For time, Porosity c t The overall compression coefficient is... k For penetration rate, This refers to the viscosity of crude oil.

3. The method for calculating karst caverns in radially porous composite reservoirs according to claim 1, characterized in that, Dimensionless system of equations: ； in, r As variables, subscripts 1 and 2 represent crack region one and crack region two, respectively. p For pressure, t For time, c t The overall compression coefficient is... k For penetration rate, subscript D To indicate a dimensionless quantity, use the subscript. w Indicates wellbore, subscript v Represents parameters of the karst cave. C v The storage constant of the cave is... M ω is the mobility ratio, and ω is the storage capacity ratio.

4. The method for calculating karst caverns in radially porous composite reservoirs according to claim 1, characterized in that, The governing equations are: ； Where r is a variable, and the subscripts 1 and 2 represent crack region one and crack region two, respectively. p For pressure, t For time, c t The overall compression coefficient is... k For penetration rate, subscript D To indicate a dimensionless quantity, use the subscript. w Indicates wellbore, subscript v Represents parameters of the karst cave. C v The storage constant of the cave is... M Here, ω is the mobility ratio, ω is the storage capacity ratio, and "—" denotes the Laplace transform. u For the Laplace operator.

5. The method for calculating karst caverns in radially porous composite reservoirs according to claim 1, characterized in that, The bottom hole pressure solution is: ； in, p For pressure, subscript D To indicate a dimensionless quantity, use the subscript. w "—" represents the wellbore, and "—" represents the Laplace transform. u Let I be the Laplace operator, and K be the Bessel functions. The subscripts 0 and 1 represent the order.

6. A calculation system for radially multi-cavitary composite reservoir karst cavern based on the method of claim 1, characterized in that, include: The oil and gas reservoir division module is used to divide fractured-vuggy carbonate oil and gas reservoirs into two parts: one part is the cave and matrix, and the other part is the fracture area. It simplifies fractured-vuggy carbonate multi-cavity oil and gas reservoirs into single-cavity composite oil and gas reservoirs. The bottom-hole dimensionless pressure solution calculation module is used to calculate the bottom-hole dimensionless pressure solution of a single-cavity composite oil and gas reservoir. The cavity volume acquisition module is used to obtain the derivative curve of the dimensionless pressure solution at the bottom of the well. The dimensionless pressure and its derivative curve at the bottom of the well are fitted to the measured bottom pressure and its derivative curve. When the two double logarithmic curves coincide, the simplified cavity radius is obtained, thus yielding the cavity volume.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the radial multi-cavity composite reservoir karst cave calculation method as described in any one of claims 1 to 5.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the radial multi-cavity composite reservoir karst cave calculation method as described in any one of claims 1 to 5.

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