Method and device for determining production condition of horizontal well and electronic equipment

Abstract

The invention relates to the technical field of oil and gas field development, and discloses a horizontal well production condition determination method and device and electronic equipment. The method comprises the steps that an oil reservoir and horizontal well coupling model with fractal characteristics is determined according to a preset model construction strategy; and according to preset horizontal well production conditions and the oil reservoir and horizontal well coupling model, the on-way flow and pressure distribution condition of the horizontal well during production are determined. According to the method and device for determining the production condition of the horizontal well and the electronic equipment, the on-way flow and the pressure distribution condition of the horizontal well during production are determined through the predetermined oil reservoir and horizontal well coupling model with the fractal characteristics, and the influence of fractal parameters on the yield and the on-way flow of the horizontal well is analyzed; and the pressure distribution and flow distribution conditions of the horizontal well during production can be more accurately predicted, so that accurate evaluation on the horizontal well in a highly heterogeneous reservoir is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas field development, and in particular to a method, a device and an electronic device for determining the production status of a horizontal well. Background Art

[0002] In describing the complexity of oil and gas reservoirs, classical seepage mechanics considers porous media as symmetrical, uniform, and with a certain characteristic scale. However, actual observation data show that the porous media of oil reservoirs are mostly disordered. Therefore, when the reservoir is approximated as a homogeneous model, it is impossible to accurately describe the actual characteristics of the reservoir. A large number of theoretical and practical studies have shown that porous media in oil and gas reservoirs have fractal characteristics, which are mainly reflected in the self-similarity of the permeability and pore distribution of oil and gas reservoirs. Within a certain pore radius range, the fractal dimension can be used to characterize the pore distribution characteristics of the reservoir, such as the degree of homogeneity.

[0003] In recent years, the application of fractals in the oil industry has been widely studied, with application scenarios ranging from geology, geophysical exploration to reservoir development. Since actual geological bodies have fractal structures that cannot be described by classical pore structures, the application of fractal theory to establish various reservoir models has become a research hotspot in reservoir engineering. Yortsos et al. first used the concept of fractals to describe natural fractured reservoirs, using mass dimensions to quantitatively characterize the degree of irregularity of the self-similarity of natural porous media in reservoirs, and introduced fractal indices to reflect the conductivity anomalies in natural porous media [Chang J, Yortsos Y C. Pressure transient analysis of fractal reservoirs [J]. SPE Formation Evaluation, 1990, 5 (1): 31-38]. S. Aprilian et al. used fractal-based reservoir well test analysis methods to interpret the well test results of complex reservoirs that were difficult to interpret using conventional well test methods in the mine, and obtained results consistent with the measured data [Application of Fractal Reservoir Model for Interference Test Analysis in Kamojang Geothermal Field (Indonesia), SPE 26465, 1993].

[0004] Horizontal wells are an important technology for improving oil and gas field recovery. Since the 1980s, horizontal wells have developed rapidly with their unique effects and advantages, especially for the development of non-uniform reservoirs, thin oil layer reservoirs, fault block reservoirs, low permeability reservoirs, bottom water reservoirs, heavy oil reservoirs and shale gas reservoirs. In recent years, with the advancement of technology, the production cost of horizontal wells has been greatly reduced, and the use of horizontal wells to exploit oil reservoirs has become increasingly widespread. Whether horizontal wells can be reasonably designed and their production capacity can be correctly predicted has become a key issue affecting the expected development effect of oil fields.

[0005] Although existing analysis methods take into account the influence of the fractal characteristics of the natural porous media of the reservoir, they mostly assume that the horizontal well is a single line source and are usually based on establishing theoretical well test curves. They cannot accurately predict the pressure distribution and flow distribution of the horizontal well during production, and thus cannot accurately evaluate the horizontal wells in strongly heterogeneous reservoirs.

[0006] Therefore, a new method for determining the production status of horizontal wells is urgently needed to solve the current technical problem of being unable to accurately predict the pressure distribution and flow distribution of horizontal wells in highly heterogeneous reservoirs. Summary of the invention

[0007] In response to the above problems, the present invention provides a method, device and electronic equipment for determining the production status of horizontal wells, which can accurately predict the flow rate and pressure distribution along the horizontal well during production through a predetermined reservoir and horizontal well coupling model with fractal characteristics, thereby realizing rapid evaluation of horizontal wells in highly heterogeneous reservoirs and guiding well site deployment.

[0008] The present invention provides a method for determining the production status of a horizontal well, the method comprising:

[0009] Determine the reservoir and horizontal well coupling model with fractal characteristics according to the preset model building strategy;

[0010] The flow rate and pressure distribution along the horizontal well during production are determined according to the preset horizontal well production conditions and the reservoir and horizontal well coupling model; wherein the preset horizontal well production conditions include the total flow rate of the horizontal well or the minimum bottom hole pressure of the horizontal well.

[0011] Furthermore, the preset model building strategy includes:

[0012] Establish point source solution of reservoir seepage model with fractal characteristics;

[0013] Divide the horizontal well into multiple well sections, and determine a first pressure drop determination model according to a point source solution when all well sections are producing simultaneously; wherein the first pressure drop determination model is used to determine the pressure drop at any position of the reservoir when a point source in the reservoir is producing;

[0014] Determine a second pressure drop determination model according to the flow law of the fluid in the horizontal well; wherein the second pressure drop determination model is used to determine the pressure drop between adjacent well sections in the horizontal well;

[0015] The first pressure drop determination model and the second pressure drop determination model are used as reservoir and horizontal well coupling models.

[0016] Further, the first pressure drop determination model includes:

[0017]

[0018] Among them, ΔP i For oil reservoirs in (x i ,y i ,z i ) position;

[0019] i=1,2,…,n seg , n seg is the total number of well sections in the horizontal well;

[0020] P ini is the initial pressure of the reservoir;

[0021] q j is the wellbore flow rate of the jth well section;

[0022] (x0, y0, z0) are the position coordinates of the point source in the reservoir;

[0023] A ij (x i ,y i ,z i ,t) is the jth well section causing the oil reservoir in (x i ,y i ,z i ) at time t, φ is the porosity of the reservoir, c f is the fluid compressibility coefficient, L j is the length of the jth well section, S1, S2, S3 represent the instantaneous point source function at (x0, y0, z0), and the instantaneous point source function at (x0, y0, z0) is determined according to the point source solution.

[0024] Furthermore, in an infinite reservoir, the point source solution includes:

[0025]

[0026]

[0027]

[0028] Among them, dx ,d y ,d z are the fractal dimensions in the x, y, and z directions respectively;

[0029] δ x , δ y , δ z are the PW numbers of the reservoir in the x, y, and z directions, respectively;

[0030] η x , η y , η z are the pressure conductivity coefficients in the x, y and z directions respectively;

[0031] Γ() is the gamma function;

[0032] x, y, and z are the distances between an arbitrary position in the reservoir and the point source in the x, y, and z directions, respectively;

[0033] K1, K2, and K3 are all constants.

[0034] Furthermore, the coordinates of the two endpoints of the jth well section are (x0, y j,1 ,z0)、(x0,y j,2 ,z0), in an infinite reservoir, the instantaneous point source function at (x0,y0,z0) determined by the point source solution includes:

[0035]

[0036]

[0037]

[0038] Further, the second pressure drop determination model includes:

[0039]

[0040] Where j = 1, 2, ..., n seg -1,n seg is the total number of well sections in the horizontal well;

[0041] P j is the wellbore pressure of the jth well section;

[0042] P j+1 is the wellbore pressure of the j+1th well section;

[0043] D is the wellbore diameter;

[0044] L j is the length of the jth well section;

[0045] L j+1 is the length of the j+1th well section;

[0046] f j is the friction factor of the jth well section;

[0047] is the main flow rate of the wellbore;

[0048] ρ is the fluid density;

[0049] K4, K5, K6, K7, K8, K9, K 10 , K 11 , K 12 , K 13 , K 14 are all constants.

[0050] Furthermore, the flow rate and pressure distribution along the horizontal well during production are determined according to the preset horizontal well production conditions and the reservoir and horizontal well coupling model, including:

[0051] According to the first pressure drop determination model, the second pressure drop determination model and the preset horizontal well production conditions, the wellbore pressure and wellbore flow corresponding to each well section are determined to determine the flow and pressure distribution along the horizontal well during production.

[0052] The present invention also provides a device for determining the production status of a horizontal well, the device comprising:

[0053] A model determination module is used to determine a reservoir and horizontal well coupling model with fractal characteristics according to a preset model building strategy;

[0054] The production situation determination module is used to determine the flow rate and pressure distribution along the horizontal well during production according to the preset horizontal well production conditions and the reservoir and horizontal well coupling model; wherein the preset horizontal well production conditions include the total flow rate of the horizontal well or the minimum bottom hole pressure of the horizontal well.

[0055] The present invention also provides a computer-readable storage medium, wherein the computer program stored in the computer-readable storage medium implements the steps of the above method when executed by one or more processors.

[0056] The present invention also provides an electronic device, comprising a memory and one or more processors, wherein a computer program is stored in the memory, and when the computer program is executed by the one or more processors, the steps of the above method are executed.

[0057] The method, device and electronic equipment for determining the production status of a horizontal well provided by the present invention have at least the following beneficial effects:

[0058] (1) The flow rate and pressure distribution along the horizontal well during production are determined by a pre-determined reservoir and horizontal well coupling model with fractal characteristics. The influence of fractal parameters on the production and flow rate along the horizontal well is analyzed. The pressure distribution and flow rate distribution of the horizontal well during production can be predicted more accurately, thereby achieving accurate evaluation of horizontal wells in highly heterogeneous reservoirs.

[0059] (2) The determined reservoir and horizontal well coupling model involves few parameters and has a fast calculation speed. It can quickly evaluate horizontal wells in highly heterogeneous reservoirs and guide well deployment. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0061] It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the drawings. The drawings constituting a part of the specification of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions in the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0062] Figure 1 A flowchart of the method for determining the production status of a horizontal well provided in the first embodiment of the present invention;

[0063] Figure 2 A flow chart of the steps of building a preset model strategy provided in the first embodiment of the present invention;

[0064] Figure 3 It is a schematic diagram of capillary pressure curve;

[0065] Figure 4 It is a schematic diagram of the fractal characteristic curve of the core;

[0066] Figure 5 It is a schematic diagram of the horizontal well model in the reservoir with fractal characteristics;

[0067] Figure 6 is the fractal dimension d f Schematic diagram of the impact of changes on horizontal well production;

[0068] Figure 7 is the fractal dimension d f Schematic diagram of the effect of changes on wellbore flow distribution;

[0069] Figure 8Schematic diagram of the effect of the change of abnormal diffusion index θ on the bottom hole pressure difference;

[0070] Fig. 9 Schematic diagram of the effect of the change of abnormal diffusion index θ on the wellbore flow distribution;

[0071] Fig.10 A schematic diagram of the structure of a device for determining the production status of a horizontal well provided in Embodiment 3 of the present invention;

[0072] Fig.11 This is a schematic diagram of the structure of an electronic device provided in Embodiment 6 of the present invention;

[0073] Reference numerals:

[0074] Fig.10 In: 1001-model determination module, 1002-production situation determination module;

[0075] Fig.11 In it: 1100 - electronic device, 1101 - processor, 1102 - communication bus, 1103 - user interface, 1104 - communication interface, 1105 - memory. DETAILED DESCRIPTION

[0076] The present invention will be further described below in conjunction with the embodiments shown in the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described here.

[0077] It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0078] Those skilled in the art will understand that the terms "first" and "second" in the embodiments of the present invention are only used to distinguish different steps, devices or modules, etc., and neither represent any specific technical meaning nor indicate the necessary logical order between them.

[0079] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more, unless explicitly limited or otherwise indicated in the context.

[0080] It should also be understood that the description of the various embodiments of the present invention focuses on the differences between the various embodiments, and the same or similar aspects thereof can be referenced to each other, and for the sake of brevity, they will not be described one by one.

[0081] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0082] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0083] Embodiments of the present invention can be applied to electronic devices such as terminal devices, computer systems, servers, etc., which can operate with many other general or special computing system environments or configurations. Examples of well-known terminal devices, computing systems, environments and / or configurations suitable for use with electronic devices such as terminal devices, computer systems, servers, etc. include, but are not limited to: personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network personal computers, small computer systems, large computer systems, and distributed cloud computing technology environments including any of the above systems, etc.

[0084] Electronic devices such as terminal devices, computer systems, servers, etc. can be described in the general context of computer system executable instructions (such as program modules) executed by computer systems. Generally, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in a distributed cloud computing environment, where tasks are performed by remote processing devices linked through a communication network. In a distributed cloud computing environment, program modules can be located on local or remote computing system storage media including storage devices.

[0085] Embodiment 1

[0086] In the first embodiment of the present invention, Figure 1 As shown, a method for determining the production status of a horizontal well is provided, and the method specifically comprises the following steps:

[0087] Step S101: Determine a reservoir and horizontal well coupling model with fractal characteristics according to a preset model building strategy.

[0088] Step S102: Determine the flow rate and pressure distribution along the horizontal well during production according to the preset horizontal well production conditions and the reservoir and horizontal well coupling model.

[0089] Among them, the preset horizontal well production conditions include the total flow rate of the horizontal well or the minimum bottom hole pressure of the horizontal well.

[0090] Optionally, in one implementation, as Figure 2 As shown, the preset model building strategy specifically includes the following steps:

[0091] Step S201: Establishing a point source solution of an oil reservoir seepage model with fractal characteristics.

[0092] Step S202: Divide the horizontal well into multiple well sections, and determine a first pressure drop determination model based on a point source solution when all well sections are producing simultaneously.

[0093] The first pressure drop determination model is used to determine the pressure drop at any position of the reservoir when a point source in the reservoir is producing.

[0094] Step S203: Determine a second pressure drop determination model according to the flow law of the fluid in the horizontal well.

[0095] The second pressure drop determination model is used to determine the pressure drop between adjacent well sections in a horizontal well.

[0096] Step S204: using the first pressure drop determination model and the second pressure drop determination model as a reservoir and horizontal well coupling model.

[0097] In step S201, taking an infinite reservoir (reservoir boundary condition) as an example, a point source solution of a reservoir seepage model with fractal characteristics is established, including:

[0098] Assuming the density of the single-phase slightly compressible liquid is ρ, considering the diffusion of the fluid on the three-dimensional anisotropic fractal medium, the fractal medium is divided into x, y, and z planes.

[0099] If S is used to describe a certain symmetry (S = A, 2πh, 4π respectively describe linear symmetry, cylindrical symmetry and spherical symmetry), then the thickness is D x The volume of the microelement is:

[0100] V x =SD x (1)

[0101] Applying the differential mass conservation principle to the infinitesimal body, the continuity equation is:

[0102]

[0103] In formula (2), n(x) is the cell density in the x direction, which is defined as:

[0104]

[0105] In formula (3), parameter a is related to reservoir porosity, d is x is the fractal dimension in the x direction, and x is the distance between any point in the reservoir and the point source in the x direction.

[0106] The volume flow rate in the x direction is defined as:

[0107] Q x =Sxd-1 q x (4)

[0108] In formula (4), d is the Euclidean dimension of the fractal embedding space (e.g., if embedded in a two-dimensional plane, d = 2);

[0109] q x is the flow velocity in the x direction, defined as:

[0110]

[0111] In formula (5), μ is the fluid viscosity, k x is the permeability in the x direction.

[0112] The permeability in the x-direction can be expressed as:

[0113]

[0114] In formula (6), θ x is the anomalous diffusion index related to the x direction; m x It is a parameter related to the fractal network structure, similar to the traditional Euclidean permeability (x direction).

[0115] For slightly compressible fluids, the continuity equation (2) can be approximated as:

[0116]

[0117] In formula (7), c f is the fluid compressibility coefficient,

[0118] Define the following variables:

[0119]

[0120]

[0121] In formula (8) and (9), d x d y d z are the fractal dimensions in the x, y, and z directions respectively; δ x , δ y , δ z is the Pd number of the reservoir in the x, y, and z directions; η x , η y , η z is the pressure conductivity in the x, y, and z directions. m y 、m z are parameters related to the fractal network structure, similar to the traditional Euclidean permeability (m y Corresponding to the y direction, mz Corresponding to z direction)

[0122] Let Δp = p i -p, the diffusion equation in the x direction is obtained as follows:

[0123]

[0124] Among them, p i is the original formation pressure, and p is the pressure at a certain moment.

[0125] The point source solution of the above diffusion equation in the x direction is:

[0126]

[0127] In formula (11), Γ() is the Gamma function; Γ(1)=1, K1, K2, K3 are all constants; preferably, K1, K2, K3 can be 2.

[0128] When x =1, θ=0, K1, K2, K3 are 2, equation (11) can be transformed into the solution under one-dimensional normal conditions:

[0129]

[0130] Similarly, replacing x with y and z, we can get the diffusion equations in the y and z directions as:

[0131]

[0132]

[0133] Furthermore, the point source solutions of the diffusion equations in the y and z directions are:

[0134]

[0135]

[0136] In step S202, the horizontal well is divided into multiple well sections. When all well sections are producing simultaneously, a first pressure drop determination model is determined according to a point source solution, specifically including:

[0137] Assume that the initial pressure of the heterogeneous anisotropic reservoir is P ini , the porosity is φ, and the fractal dimension is first determined by analyzing the capillary pressure curve or thin-section photos of the reservoir.

[0138] A horizontal well is producing in an oil reservoir with fractal characteristics. The coordinates of the heel and toe of the horizontal well are (x0, y1, z0) and (x0, y2, z0) respectively.

[0139] Divide the horizontal wells into n seg Segment. Assume that at t = 0, the fluid in the jth well segment is produced at a unit flow rate, and the well segment is parallel to the y-axis and its position is from (x0, y j,1 ,z0) to (x0,y j,2 ,z0)(that is, the coordinates of the two end points of the jth well section are (x0,y j,1 ,z0)、(x0,y j,2 ,z0)), length is L j .

[0140] Applying Green's function and Newman product principle, this well section causes the reservoir to be i ,y i ,z i ) at any time (t>0) is:

[0141]

[0142] Where φ is the porosity of the reservoir, c f is the fluid compressibility coefficient, L j is the length of the jth well section, S1, S2, and S3 represent the instantaneous point source function at (x0, y0, z0).

[0143] The instantaneous point source function at (x0, y0, z0) is determined from the point source solution, so in an infinite reservoir:

[0144]

[0145]

[0146]

[0147] Where (x0, y0, z0) is the position coordinate of the point source in the reservoir. S1, S2 and S3 represent the instantaneous point source function at the point (x0, y0, z0). The integral in the formula can be numerically calculated using the Simpson integral formula.

[0148] It should be noted that the horizontal segment can be regarded as a line connected by point sources, so in equation (18) it is necessary to change y0 from y j,1 To j,2 Perform integration.

[0149] Using the principle of spatial superposition, when multiple well sections are producing simultaneously, point (x i ,y i ,z i The pressure drop at ) (that is, the first pressure drop determination model) can be expressed as:

[0150]

[0151] Among them, ΔP i For oil reservoirs in (x i ,y i ,z i ) position;

[0152] i=1,2,…,n seg , n seg is the total number of well sections in the horizontal well;

[0153] q j is the flow rate of the jth well section.

[0154] Further, in step S203, a second pressure drop determination model is determined according to the flow law of the fluid in the horizontal well, specifically including:

[0155] From the toe end to the heel end of the horizontal well, the flow rate in the wellbore gradually increases. Considering the flow of fluid in the horizontal wellbore, there is a pressure drop between each well section, and the following relationship can be obtained:

[0156]

[0157] Where j = 1, 2, ..., n seg -1,n seg is the total number of well sections in the horizontal well;

[0158] P j is the wellbore pressure of the jth well section;

[0159] P j+1 is the wellbore pressure of the j+1th well section;

[0160] D is the wellbore diameter, in m;

[0161] L j is the length of the jth well section, in m;

[0162] L j+1 is the length of the j+1th well section, in meters;

[0163] f j is the friction factor of the jth well section, dimensionless;

[0164] is the main flow rate of the wellbore, in m 3 / d;

[0165] ρ is the fluid density, in kg / m 3 ;

[0166] K4, K5, K6, K7, K8, K9, K10 , K 11 , K 12 , K 13 , K 14 are all constants; preferably, the value of K4 can be 4, the value of K5 can be 2, the value of K6 can be 2, the value of K7 can be 5, the value of K8 can be 32, the value of K9 can be 2, and the value of K 10 The value of can be 4, K 11 The value can be 16, K 12 The value of K can be 2, 13 The value of K can be 2, 14 The value of can be 5.

[0167] Furthermore, in step S102, the flow rate and pressure distribution along the horizontal well during production are determined according to the preset horizontal well production conditions and the reservoir and horizontal well coupling model, including:

[0168] According to the first pressure drop determination model, the second pressure drop determination model and the preset horizontal well production conditions, the wellbore pressure and wellbore flow corresponding to each well section are determined to determine the flow and pressure distribution along the horizontal well during production.

[0169] Specifically, the preset horizontal well production conditions include: the total flow rate of the horizontal well or the minimum bottom hole pressure of the horizontal well.

[0170] In one implementation, if the preset horizontal well production conditions include the total flow rate of the horizontal well, then:

[0171]

[0172] Among them, Q total is the total volume of horizontal wells given in advance.

[0173] According to equations (20), (21) and (22), we can solve 2n seg unknown quantities. Specifically, 2n seg The unknown quantities include the wellbore pressure in each well section. and wellbore flow When solving the problem, Newton's iteration method can be used.

[0174] In another implementation, if the preset horizontal well production conditions include the minimum bottom hole pressure of the horizontal well, there is a bottom hole flow pressure constraint equation:

[0175] P1=P wf,min (twenty three)

[0176] Among them, P1 is the wellbore pressure of the first well section, P wf,min is the predetermined minimum bottom hole pressure of the horizontal well; that is, the wellbore pressure of the first well section is equal to the predetermined minimum bottom hole pressure of the horizontal well.

[0177] According to equations (20), (21) and (23), we can solve 2n seg unknown quantities. Specifically, 2n seg The unknown quantities include the wellbore pressure in each well section. and wellbore flow When solving the problem, Newton's iteration method can be used.

[0178] Furthermore, if the preset horizontal well production conditions include the minimum bottom hole pressure of the horizontal well, after solving the wellbore flow rate of each well section, the wellbore flow rates of all well sections can be added together to obtain the total horizontal well flow rate (that is, the horizontal well production capacity).

[0179] In step S102, the preset horizontal well production conditions may be determined by those skilled in the art according to actual needs, and the embodiment of the present invention does not specifically limit this.

[0180] It should be noted that before step S102, it is also necessary to determine the values ​​of other parameters in the reservoir and horizontal well coupling model except for the unknown quantities pressure and flow, such as determining the value of the fractal dimension of the reservoir, determining the values ​​of other reservoir parameters (such as porosity, initial pressure, etc.) and determining the values ​​of horizontal well parameters (such as wellbore diameter, length of each well section, friction factor, etc.).

[0181] Furthermore, the fractal dimension of the reservoir can be determined by analyzing the capillary pressure curve or thin-section photograph of the reservoir.

[0182] At present, pore structure analysis often divides pores into different pore size intervals, and then the microscopic pore structure of rocks is quantitatively studied based on the ratio of different pore size intervals. In the high-pressure mercury injection experiment, mercury is used as a non-wetting phase. Under the action of external pressure, mercury is injected into the core sample, and the volume of mercury entering the rock under different injection pressures is recorded to obtain the capillary pressure curve (see Figure 3 , where the permeability is 0.2mD and the porosity is 10.5%).

[0183] The pore structure of the core can be considered to have fractal characteristics within a certain range, so the fractal theory can be used to test the rationality of the selection of the inflection point of the capillary pressure curve.

[0184] The fractal calculation formula of pore structure is:

[0185]

[0186] In the above formula, S is the wetting phase saturation in the reservoir, %; P c is the capillary pressure, MPa; P min is the maximum pore size in the reservoir maxThe corresponding capillary pressure, i.e. the threshold capillary pressure, is in MPa; D is the fractal dimension.

[0187] By taking the logarithm of both sides, the above formula can be transformed into:

[0188] lgS=(3-D)lgP min +(D-3)lgP c

[0189] Therefore, we can plot lg(1-S)-lgP c Curve, perform linear regression fitting, calculate the curve slope k, then the fractal dimension D = 3 + k.

[0190] Figure 4 This is the fractal characteristic curve of the core (fractal dimension fitting of the core pore throat). The influence of the core end effect has been removed, and the fractal characteristics of the capillary pressure section after the fluid enters the core are mainly considered. The pore throat intervals divided according to the inflection point of the capillary pressure curve are divided into two categories: micron-scale pore throats and nano-scale pore throats. From the fitting curve, it can be seen that the fractal dimension of the micron-scale pore throats is 2.52, and the fractal dimension of the nano-scale pore throats is 2.17. The size of the fractal dimension characterizes the complexity of the pore structure. The smaller the fractal dimension, the more complex the pore structure. The pore fractal dimension of the nano-scale pore throat interval is smaller, and the pore structure of this type of pore throat is complex and highly heterogeneous. If it is assumed that the fractal dimensions in all directions are the same, the one-dimensional space fractal dimensions of the micron-scale pore throats and nano-scale pore throats are 0.84 and 0.72, respectively, and the micron-scale pore throats are the main flow channels.

[0191] The method for determining the production of horizontal wells provided in this embodiment determines the flow rate and pressure distribution along the horizontal well during production through a predetermined reservoir and horizontal well coupling model with fractal characteristics, analyzes the influence of fractal parameters on the production and flow rate along the horizontal well, and can more accurately predict the pressure distribution and flow distribution of the horizontal well during production, thereby achieving accurate evaluation of horizontal wells in strong heterogeneous reservoirs. In addition, the determined reservoir and horizontal well coupling model involves few parameters and has a fast calculation speed, which can quickly evaluate horizontal wells in strong heterogeneous reservoirs and guide well deployment.

[0192] Embodiment 2

[0193] Embodiment 2 of the present invention provides a specific example of determining the production status of a horizontal well by the method for determining the production status of a horizontal well in Embodiment 1, and illustrates the influence of changes in the fractal dimension of the reservoir on the horizontal well production and wellbore flow distribution, and the influence of changes in the anomalous diffusion index on the bottom hole pressure difference and wellbore flow distribution.

[0194] Figure 5 Schematic diagram of the horizontal well model in the reservoir with fractal characteristics used in this example.

[0195] The horizontal well production and flow distribution along the horizontal well are calculated using the reservoir, fluid and horizontal well parameters in Table 1. The total length of the horizontal well is 1830m, and the number of horizontal well segments is set to 30.

[0196] Table 1 Basic parameters of reservoir and wellbore

[0197] Initial reservoir pressure 30MPa Composite compression factor <![CDATA[4.35×10 -4 MPa -1 ]]> Formation volume factor <![CDATA[1.05m 3 / m 3 ]]> Crude oil viscosity 1.0mPa.s Crude oil density under reservoir conditions <![CDATA[960kg / m 3 <!-- 10 -->]]> Maximum daily oil production <![CDATA[1000m 3 / d]]> Minimum bottom hole pressure 10MPa Horizontal well length 1830m Wellbore diameter 0.1m Wellbore roughness 0.0005 <![CDATA[Fractal dimension d x > 0.8～1.0 <![CDATA[Fractal dimension d y > 0.8～1.0 <![CDATA[Fractal dimension d z > 0.8～1.0 <![CDATA[Anomalous diffusion exponent θ x > 0～0.2 <![CDATA[Anomalous diffusion exponent θ y > 0～0.2 <![CDATA[Anomalous diffusion exponent θ z > 0～0.2 <![CDATA[Piezometric coefficient η x > 2.1e+6 <![CDATA[Guiding pressure coefficient η y > 2.1e+6 <![CDATA[Hydraulic diffusivity η z > 2.1e+6

[0198] d f is the fractal dimension of the reservoir (d f =d x +d y +d z ),Depend on Figure 6 It can be seen that with d f As d increases, the flow distribution in each well section becomes more uneven. This is because as d f As the porosity of the reservoir increases, it becomes easier to drive the fluid into the wellbore. Under flow restriction conditions, the flow in each section of the wellbore becomes unbalanced. Figure 7 is the fractal dimension d f The impact of changes on the wellbore flow distribution, d f The smaller it is, the greater the interference between segments and the more unbalanced the traffic distribution.

[0199] θ(θ=θ x =θ y =θ z ) is a parameter related to the pore network topology, which describes the connectivity of the pores and also provides dynamic information, reflecting the anomalies of seepage in the fractal network. Figure 8 It can be seen that as the anomalous diffusion index θ increases, the flow rate becomes balanced. This is because as θ increases, the connectivity between pores becomes worse, and it becomes difficult to drive distant fluids into the wellbore. When flow constraints are used, a larger pressure difference is required to drive the fluid to flow into the wellbore. Fig. 9 is the influence of the change of the abnormal diffusion index θ on the wellbore flow distribution. The larger θ is, the greater the interference between the sections is, and the more unbalanced the flow distribution is.

[0200] Embodiment 3

[0201] Embodiment 3 of the present invention also provides a device for determining the production status of a horizontal well, such as Fig.10 As shown, the device comprises:

[0202] The model determination module 1001 is used to determine the reservoir and horizontal well coupling model with fractal characteristics according to a preset model building strategy;

[0203] The production status determination module 1002 is used to determine the flow rate and pressure distribution along the horizontal well during production according to the preset horizontal well production conditions and the reservoir and horizontal well coupling model, wherein the preset horizontal well production conditions include the total flow rate of the horizontal well or the minimum bottom hole pressure of the horizontal well.

[0204] Optionally, the preset model building strategy specifically includes:

[0205] (1) Establish a point source solution for the reservoir seepage model with fractal characteristics.

[0206] (2) Divide the horizontal well into multiple well sections, and determine the first pressure drop determination model based on the point source solution when all well sections are producing at the same time. The first pressure drop determination model is used to determine the pressure drop at any position in the reservoir when a point source is producing in the reservoir.

[0207] (3) Determine a second pressure drop determination model according to the flow law of the fluid in the horizontal well. The second pressure drop determination model is used to determine the pressure drop between adjacent well sections in the horizontal well;

[0208] (4) The first pressure drop determination model and the second pressure drop determination model are used as a coupling model of the reservoir and the horizontal well.

[0209] Optionally, the first pressure drop determination model includes:

[0210]

[0211] Among them, ΔP i For oil reservoirs in (x i ,y i ,z i ) position;

[0212] i=1,2,…,n seg , n seg is the total number of well sections in the horizontal well;

[0213] P ini is the initial pressure of the reservoir;

[0214] q j is the wellbore flow rate of the jth well section;

[0215] A ij (x i ,y i ,z i ,t) is the jth well section causing the oil reservoir in (x i ,y i ,z i ) at time t, φ is the porosity of the reservoir, c f is the fluid compressibility coefficient, Lj is the length of the jth well section, S1, S2, S3 represent the instantaneous point source function at (x0, y0, z0), and the instantaneous point source function at (x0, y0, z0) is determined according to the point source solution;

[0216] (x0, y0, z0) are the position coordinates of the point source in the reservoir.

[0217] Alternatively, in an infinite reservoir, the point source solution includes:

[0218]

[0219]

[0220]

[0221] Among them, d x d y d z are the fractal dimensions in the x, y, and z directions respectively;

[0222] δ x , δ y , δ z are the PW numbers of the reservoir in the x, y, and z directions, respectively;

[0223] η x , η y , η z are the pressure conductivity coefficients in the x, y and z directions respectively;

[0224] Γ() is the gamma function;

[0225] x, y, and z are the distances between an arbitrary position in the reservoir and the point source in the x, y, and z directions, respectively;

[0226] K1, K2, and K3 are all constants.

[0227] Optionally, the coordinates of the two endpoints of the jth well section are (x0, y j,1 ,z0)、(x0,y j,2 ,z0), in an infinite reservoir, the instantaneous point source function at (x0,y0,z0) determined by the point source solution includes:

[0228]

[0229]

[0230]

[0231] Optionally, the second pressure drop determination model includes:

[0232] Where j = 1, 2, ..., n seg -1,n seg is the total number of well sections in the horizontal well;

[0233] P j is the wellbore pressure of the jth well section;

[0234] P j+1 is the wellbore pressure of the j+1th well section;

[0235] D is the wellbore diameter;

[0236] L j is the length of the jth well section;

[0237] L j+1 is the length of the j+1th well section;

[0238] f j is the friction factor of the jth well section;

[0239] is the main flow rate of the wellbore;

[0240] ρ is the fluid density;

[0241] K4, K5, K6, K7, K8, K9, K 10 , K 11 , K 12 , K 13 , K 14 are all constants.

[0242] Optionally, the flow rate and pressure distribution along the horizontal well during production are determined according to the preset horizontal well production conditions and the reservoir and horizontal well coupling model, including:

[0243] According to the first pressure drop determination model, the second pressure drop determination model and the preset horizontal well production conditions, the wellbore pressure and wellbore flow corresponding to each well section are determined to determine the flow and pressure distribution along the horizontal well during production.

[0244] The horizontal well production situation determination device provided in this embodiment determines the flow rate and pressure distribution along the horizontal well during production through a predetermined reservoir and horizontal well coupling model with fractal characteristics, analyzes the influence of fractal parameters on the horizontal well production and flow rate along the horizontal well, and can more accurately predict the pressure distribution and flow distribution of the horizontal well during production, thereby realizing accurate evaluation of horizontal wells in strong heterogeneous reservoirs. In addition, the preset reservoir and horizontal well coupling model established involves few parameters and has a fast calculation speed, which can quickly evaluate horizontal wells in strong heterogeneous reservoirs and guide well deployment.

[0245] Embodiment 4

[0246] In the fourth embodiment of the present invention, a computer program product is also provided. The computer program product includes a computer program or instructions. When the computer program or instructions are executed by a processor, all or part of the steps of the method in the above method embodiment are implemented. This embodiment will not be repeated here.

[0247] Further, the computer program product may include one or more computer executable components configured to execute the embodiments when the program is run; the computer program product may also include a computer program tangibly contained on a readable medium, the computer program including program code for executing any method in the embodiments of the present invention. In such an embodiment, the computer program may be downloaded and installed from a network through a communication part, and / or installed from a removable medium.

[0248] Embodiment 5

[0249] In the fifth embodiment of the present invention, a computer-readable storage medium is also provided. The computer program stored in the computer-readable storage medium, when executed by one or more processors, implements all or part of the steps of the method for determining the production status of a horizontal well described in the above embodiment. This embodiment will not be repeated here.

[0250] Each functional unit in each embodiment of the present invention may be integrated into a processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. If the functions are implemented in the form of software functional units and sold or used as independent products, they may be stored in a computer-readable storage medium.

[0251] Computer readable storage media can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can include, for example, but is not limited to, a system, device or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0252] Embodiment 6

[0253] In the sixth embodiment of the present invention, an electronic device 1100 is also provided, which may be a mobile phone, a computer, or a tablet computer. Fig.11 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention is shown in FIG. Fig.11 As shown, the electronic device 1100 includes: at least one processor 1101, at least one communication bus 1102, a user interface 1103, at least one external communication interface 1104, and a memory 1105. Among them, the communication bus 1102 is configured to realize the connection and communication between these components. Among them, the user interface 1103 may include a display screen, and the external communication interface 1104 may include a standard wired interface and a wireless interface. A computer program is stored in the memory 1105, and the memory 1105 and one or more processors 1101 are connected to each other in communication. When the computer program is executed by one or more processors, the processor 1101 is configured to execute the computer program stored in the memory to implement all or part of the steps of the method for determining the production status of horizontal wells in the above-mentioned embodiment, which will not be repeated in this embodiment.

[0254] The processor can be an application specific integrated circuit (ASIC), a digital signal processor (DSP), a programmable logic device (PLD), a field programmable gate array (FPGA), a controller, a microcontroller, a microprocessor or other electronic components, and is used to perform all or part of the steps of the method for determining the production status of a horizontal well described in the above embodiment. The specific implementation steps of the method for determining the production status of a horizontal well can refer to the corresponding contents in the above embodiment 1, and will not be repeated here.

[0255] The memory can be implemented by any type of volatile or non-volatile storage device or a combination of them, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk or optical disk.

[0256] The method, device and electronic device for determining the production situation of a horizontal well provided by the present invention introduce fractal theory into the oil reservoir to study the coupled flow between the oil reservoir and the horizontal wellbore, and use an analytical method to solve the Green function of a point source in the oil reservoir with fractal characteristics, taking into account the influence of friction, acceleration, fluid inflow and bottom hole flow pressure on the production, and determining the coupling model of the oil reservoir and the horizontal well, and the flow rate and pressure profile along the horizontal well can be calculated. The influence of fractal parameters on the production and flow rate along the horizontal well is analyzed. When the fractal characteristics of the oil reservoir are considered, the calculated horizontal well production is reduced, and overestimation of the horizontal well production can be avoided. By analyzing the pore structure of the highly heterogeneous oil reservoir and obtaining the fractal dimension, the present invention can be applied to the rapid evaluation of horizontal wells in the highly heterogeneous oil reservoir to guide the well site deployment.

[0257] The flow rate and pressure distribution along the horizontal well during production are determined by using a pre-determined reservoir and horizontal well coupling model with fractal characteristics, and the influence of fractal parameters on the production and flow rate along the horizontal well is analyzed. This can more accurately predict the pressure distribution and flow distribution of the horizontal well during production, and thus accurately evaluate the horizontal wells in the strong heterogeneous reservoir. In addition, the determined reservoir and horizontal well coupling model involves few parameters and has a fast calculation speed, which can quickly evaluate the horizontal wells in the strong heterogeneous reservoir and guide the well deployment.

[0258] The basic principles of the present invention are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present invention are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present disclosure. In addition, the specific details disclosed above are only for the purpose of illustration and facilitation of understanding, and are not limiting. The above details do not limit the present invention to being implemented by adopting the above specific details.

[0259] The block diagrams of the devices, apparatuses, equipment, and systems involved in the present invention are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems may be connected, arranged, and configured in any manner. Words such as "including," "comprising," "having," and the like are open-ended words, meaning "including but not limited to," and may be used interchangeably therewith.

[0260] It should also be noted that in the apparatus, device and method disclosed herein, each component or each step can be decomposed and / or reassembled, and such decomposition and / or reassembly should be regarded as an equivalent solution of the present invention.

[0261] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present invention. Therefore, the present invention is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0262] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present invention to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A method for determining the production status of a horizontal well, characterized in that: The method comprises: Determine the reservoir and horizontal well coupling model with fractal characteristics according to the preset model building strategy; The flow rate and pressure distribution along the horizontal well during production are determined according to the preset horizontal well production conditions and the reservoir and horizontal well coupling model; wherein the preset horizontal well production conditions include the total flow rate of the horizontal well or the minimum bottom hole pressure of the horizontal well.

2. The method for determining the production status of a horizontal well according to claim 1, characterized in that: The preset model building strategy includes: Establish point source solution of reservoir seepage model with fractal characteristics; Divide the horizontal well into multiple well sections, and determine a first pressure drop determination model according to the point source solution when all well sections are producing at the same time; wherein the first pressure drop determination model is used to determine the pressure drop at any position of the reservoir when a point source in the reservoir is producing; Determine a second pressure drop determination model according to the flow law of the fluid in the horizontal well; wherein the second pressure drop determination model is used to determine the pressure drop between adjacent well sections in the horizontal well; The first pressure drop determination model and the second pressure drop determination model are used as the oil reservoir and horizontal well coupling model.

3. The method for determining the production status of a horizontal well according to claim 2, characterized in that: The first pressure drop determination model includes: Among them, ΔP i For oil reservoirs in (x i ,y i ,z i ) position; i=1,2,…,n seg , n seg is the total number of well sections in the horizontal well; P ini is the initial pressure of the reservoir; q j is the wellbore flow rate of the jth well section; (x0, y0, z0) are the position coordinates of the point source in the reservoir; A ij (x i ,y i ,z i ,t) is the jth well section causing the oil reservoir in (x i ,y i ,z i ) at time t, φ is the porosity of the reservoir, c f is the fluid compressibility coefficient, L j is the length of the jth well section, S1, S2, S3 represent the instantaneous point source function at (x0, y0, z0), and the instantaneous point source function at (x0, y0, z0) is determined according to the point source solution.

4. The method for determining the production status of a horizontal well according to claim 3, characterized in that: In an infinite reservoir, the point source solution includes: Among them, d x ,d y ,d z are the fractal dimensions in the x, y, and z directions respectively; δ x , δ y , δ z are the PW numbers of the reservoir in the x, y, and z directions, respectively; η x , η y , η z are the pressure conductivity coefficients in the x, y and z directions respectively; Γ() is the gamma function; x, y, and z are the distances between an arbitrary position in the reservoir and the point source in the x, y, and z directions, respectively; K1, K2, and K3 are all constants.

5. The method for determining the production status of a horizontal well according to claim 4, characterized in that: The coordinates of the two end points of the jth well section are (x i ,y j,1 ,z0)、(x0,y j,2 ,z0), in an infinite reservoir, the instantaneous point source function at (x0,y0,z0) determined by the point source solution include:

6. The method for determining the production status of a horizontal well according to claim 2, characterized in that: The second pressure drop determination model includes: Where j = 1, 2, ..., n seg -1,n seg is the total number of well sections in the horizontal well; P j is the wellbore pressure of the jth well section; P j+1 is the wellbore pressure of the j+1th well section; D is the wellbore diameter; L j is the length of the jth well section; L j+1 is the length of the j+1th well section; f j is the friction factor of the jth well section; is the main flow rate of the wellbore; ρ is the fluid density; K4, K5, K6, K7, K8, K9, K 10 , K 11 , K 12 , K 13 , K 14 are all constants.

7. The method for determining the production status of a horizontal well according to claim 2, characterized in that: The method of determining the flow rate and pressure distribution along the horizontal well during production according to the preset horizontal well production conditions and the reservoir and horizontal well coupling model includes: According to the first pressure drop determination model, the second pressure drop determination model and the preset horizontal well production conditions, the wellbore pressure and wellbore flow corresponding to each well section are determined to determine the flow and pressure distribution along the horizontal well during production.

8. A device for determining the production status of a horizontal well, characterized in that: The device comprises: A model determination module is used to determine a reservoir and horizontal well coupling model with fractal characteristics according to a preset model building strategy; The production situation determination module is used to determine the flow rate and pressure distribution along the horizontal well during production according to the preset horizontal well production conditions and the reservoir and horizontal well coupling model; wherein the preset horizontal well production conditions include the total flow rate of the horizontal well or the minimum bottom hole pressure of the horizontal well.

9. A computer-readable storage medium, characterized in that: The computer program stored in the computer-readable storage medium, when executed by one or more processors, implements the steps of the method according to any one of claims 1 to 7.

10. An electronic device, characterized in that: The method comprises a memory and one or more processors, wherein a computer program is stored in the memory, and when the computer program is executed by the one or more processors, the steps of the method according to any one of claims 1 to 7 are performed.

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