Double-step horizontal well unstable seepage coupling calculation method and device

Abstract

The invention relates to a double-step horizontal well unstable seepage coupling calculation method and device. The method comprises the steps that a first unstable seepage model of a horizontal well at any position in an oil reservoir with closed upper and lower boundaries and unlimited horizontal size is established; the upper horizontal section and the lower horizontal section of the double-step horizontal well are divided into a plurality of infinitesimal sections, the pressure response value of each infinitesimal section is calculated, and a second unstable seepage model of the double-step horizontal well in the thin interbed oil reservoir is established; establishing a wellbore flow model of variable mass flow pressure drop loss in the wellbore; and establishing an unstable seepage coupling model based on the first unstable seepage model, the second unstable seepage model and the shaft flow model, and obtaining pressure distribution and flow distribution of the double-step horizontal well on the upper horizontal section and the lower horizontal section. According to the method, the influence of the distribution of the specific oil production indexes along the wellbore, the on-way pressure difference distribution, the pressure drop loss and the pressure drop loss type on the productivity is given, the position where water easily flows out of the wellbore is qualitatively given, and the productivity of the double-step horizontal well is rapidly calculated.

Description

Technical Field

[0001] This disclosure relates to the field of petroleum exploration and development technology, and in particular to a method and apparatus for calculating unstable seepage coupling in a two-step horizontal well. Background Technology

[0002] In oil exploration and development, finding remaining reserves, increasing drainage area, increasing production, and extracting reserves that cannot be extracted using conventional technologies are the challenges in developing unconventional oilfields. Correspondingly, unconventional well technology has not only become a breakthrough point but will also become an important oil development technology.

[0003] A stepped horizontal well is an unconventional well type, referring to a wellbore with two or more horizontal sections of a certain height difference drilled continuously within a single borehole, forming a wellbore trajectory with two or more steps (a horizontal well with two steps is also called a double-step horizontal well). This type of horizontal well is used to exploit or explore two or more layered or fault-block oil reservoirs using a single wellbore. A successful stepped horizontal well can replace the development of two or more horizontal wells, saving investment and achieving good economic benefits.

[0004] Currently, domestic and international research on stepped horizontal wells mainly focuses on improvements to drilling, completion, and oil production processes, while research on seepage patterns and productivity is relatively limited. Existing technology provides a scheme that uses the principle of potential superposition to derive a semi-analytical mathematical model of reservoir seepage coupling with variable-mass pipe flow in the horizontal section of a stepped horizontal well under open-hole completion, and provides a corresponding solution; however, this existing technology only addresses the steady-state scenario.

[0005] Furthermore, developing oil and gas reservoirs using stepped horizontal wells involves numerous issues, including determining reasonable operating procedures, calculating development indicators, predicting development dynamics, and formulating and adjusting development plans. Solving these problems is based on the formation flow patterns and productivity analysis of stepped horizontal wells. The lag in reservoir engineering theory research inevitably affects the application of stepped horizontal wells in oil and gas field development. Therefore, proposing a solution for the unstable flow and productivity of stepped horizontal wells has become a crucial issue that urgently needs to be addressed. Summary of the Invention

[0006] To solve the above-mentioned technical problems, or at least partially solve them, embodiments of this disclosure provide a method and apparatus for calculating unstable seepage coupling in a two-step horizontal well.

[0007] In a first aspect, embodiments of this disclosure provide a method for coupled calculation of unsteady seepage in a two-step horizontal well, the method comprising:

[0008] S1: Establish a first unsteady flow model for a horizontal well at any location in a reservoir with closed upper and lower boundaries and infinite horizontal size; wherein, the first unsteady flow model is obtained based on the first pressure response curve in Laplace space, and the first pressure response curve in Laplace space is transformed into the second pressure response curve in real space using the Stefest inversion algorithm;

[0009] S2: Divide the upper and lower horizontal sections of the double-step horizontal well into several micro-segments, calculate the pressure response value of each micro-segment, and establish a second unsteady flow model for the double-step horizontal well in a thin interbedded reservoir based on the calculated pressure response values ​​of each micro-segment.

[0010] S3: Establish a wellbore flow model for pressure drop loss due to variable mass flow within the wellbore, and calculate the wellbore pressure drop loss and wellbore flow rate for the upper horizontal section, lower horizontal section, and connecting section respectively;

[0011] S4: Based on the first unstable seepage model, the second unstable seepage model and the wellbore flow model, establish an unstable seepage coupling model and obtain the pressure distribution and flow distribution of the double-step horizontal well in the upper and lower horizontal sections.

[0012] In one possible implementation, after obtaining the pressure and flow distributions of the double-step horizontal well in the upper and lower horizontal sections, the method further includes:

[0013] Under constant bottom-hole flowing pressure production conditions, the two parameters of upper horizontal section pressure and lower horizontal section pressure in the coupled model are optimized by iterative method until the error between the upper horizontal section pressure and the previous upper horizontal section pressure is less than a first set error value and the error between the lower horizontal section pressure and the previous lower horizontal section pressure is less than a second set error value.

[0014] In one possible implementation, the step of establishing a first unsteady flow model for a horizontal well at any location in a horizontally infinite reservoir with closed upper and lower boundaries includes:

[0015]

[0016] in,

[0017]

[0018] The first unsteady flow model is established based on the first pressure response curve of the Laplace space shown in expression (1).

[0019] In one possible implementation, the step of dividing the upper and lower horizontal sections of the double-step horizontal well into several micro-segments, calculating the pressure response value of each micro-segment, and establishing a second unsteady flow model for the double-step horizontal well in a thin interbedded reservoir based on the calculated pressure response values ​​of each micro-segment includes:

[0020] Calculate the first pressure response value generated by the selected infinitesimal element at the current infinitesimal element location;

[0021] Calculate the second pressure response values ​​generated at the current micro-segment by several other micro-segments besides the selected micro-segment;

[0022] The first pressure response value and the second pressure response value are superimposed to obtain the true pressure response value of the current micro-segment.

[0023] In one possible implementation, the step of dividing the upper and lower horizontal sections of the double-step horizontal well into several micro-segments, calculating the pressure response value of each micro-segment, and establishing a second unsteady flow model for the double-step horizontal well in a thin interbedded reservoir based on the calculated pressure response values ​​of each micro-segment includes:

[0024] Under constant bottomhole flowing pressure production conditions, the second unsteady flow model of the double-step horizontal well in the thin interbedded reservoir is established according to the (N1+N2) order equations shown in expression (2):

[0025] Aq=P (2)

[0026]

[0027] Where, Δp upwfi The pressure drop at the midpoint of the i-th infinitesimal element of the upper horizontal segment is equal to p. i -p upwfi atm -1 ;Δp dnwfi The pressure drop at the midpoint of the i-th infinitesimal element of the lower horizontal segment is equal to p. i -p dnwfi atm -1 ;q uprj Let be the radial inflow of the j-th infinitesimal element in the upper horizontal segment, in cm. 3 / s;q dnrj Let J be the radial inflow of the j-th infinitesimal element in the lower horizontal segment, in cm. 3 / s;

[0028] C t The overall compression factor is atm. -1 h is the reservoir thickness, cm; L is the reference length, cm; K0(x) is the second-order deformed Bessel function, zeroth order; L hq represents the length of the horizontal well or micro-element, in cm; q represents the flow rate of the line source, surface source, or volume source, in cm. 3 / s; For the flow of a point source, cm 3 / s; s is about t D The Laplace variable; t is time, s; t D It is dimensionless time.

[0029] In one possible implementation, the step of establishing a wellbore flow model for variable mass flow pressure drop loss within the wellbore, and calculating the wellbore pressure drop loss and wellbore flow rate for the upper horizontal section, lower horizontal section, and connecting section respectively, includes:

[0030]

[0031] Calculate the total pressure drop loss of radial inflow into the wellbore according to expression (3).

[0032] In one possible implementation, the steps of establishing an unstable seepage coupling model based on the first unstable seepage model, the second unstable seepage model, and the wellbore flow model, and obtaining the pressure and flow distributions of the double-step horizontal well in the upper and lower horizontal sections, include:

[0033] Upper horizontal segment I:

[0034]

[0035]

[0036] Connecting section III:

[0037] Upper endpoint A (intersection with the upper horizontal segment):

[0038]

[0039] Lower endpoint B (intersection with the lower horizontal segment):

[0040] p mid1 =p mid2 +Δp midseg (7)

[0041] Lower horizontal section II:

[0042]

[0043]

[0044]

[0045] Based on the above expressions (4) to (10), (N1+N2) variables related to the unknown p are calculated.upwfi p dnwfj q upri and q dnrj The wellbore flow pressure drop equations are as follows:

[0046] F(p upwfi ,p dnwfj ,q upri ,q dnrj )=0 (11)

[0047] Solving equations (2) and (11) simultaneously yields the (N1+N2) unknowns p mentioned above. upwfi p dnwfj q upri and q dnrj The pressure and flow distributions of the upper and lower horizontal sections are obtained.

[0048] Secondly, embodiments of this disclosure provide a coupled calculation device for unstable seepage in a two-step horizontal well, comprising:

[0049] An unsteady flow modeling unit is used to establish a first unsteady flow model for a horizontal well at any location in a reservoir with closed upper and lower boundaries and infinite horizontal size. The first unsteady flow model is obtained based on a first pressure response curve in Laplace space, and the first pressure response curve in Laplace space is transformed into a second pressure response curve in real space using the Stefest inversion algorithm. Furthermore, the upper and lower horizontal sections of the double-step horizontal well are divided into several micro-segments, the pressure response value of each micro-segment is calculated, and a second unsteady flow model for a double-step horizontal well in a thin interbedded reservoir is established based on the calculated pressure response values ​​of each micro-segment.

[0050] The wellbore flow modeling unit is used to establish a wellbore flow model with variable mass flow pressure drop loss in the wellbore, and to calculate the wellbore pressure drop loss and wellbore flow rate in the upper horizontal section, lower horizontal section and connecting section respectively;

[0051] The coupling modeling unit is used to establish an unstable seepage coupling model based on the first unstable seepage model, the second unstable seepage model and the wellbore flow model, and to obtain the pressure distribution and flow distribution of the double-step horizontal well in the upper and lower horizontal sections.

[0052] Thirdly, embodiments of this disclosure provide an electronic device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus;

[0053] Memory, used to store computer programs;

[0054] The processor, when executing the program stored in memory, implements the above-mentioned method for calculating the unstable seepage coupling in a two-step horizontal well.

[0055] Fourthly, embodiments of this disclosure provide a computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the above-described method for calculating the coupling of unstable seepage in a two-step horizontal well.

[0056] Compared with the prior art, the technical solutions provided in this disclosure have at least some or all of the following advantages:

[0057] Developing oil and gas reservoirs using stepped horizontal wells involves numerous issues, including determining reasonable operating procedures, calculating development indicators, predicting development dynamics, and formulating and adjusting development plans. Solving these problems is based on the formation flow patterns and productivity analysis of stepped horizontal wells. Lagging research in reservoir engineering theory inevitably affects the application of stepped horizontal wells in oil and gas field development.

[0058] This disclosure establishes an unsteady flow coupling model for a two-step horizontal well under constant bottom-hole flowing pressure conditions and presents a calculation method for unsteady flow coupling in a two-step horizontal well based on this model. The study reveals the seepage characteristics of the two-step horizontal well, the distribution of the specific oil recovery index along the wellbore, the distribution of friction differential, the pressure drop loss, and the impact of pressure drop loss type on production capacity. It can qualitatively identify water-prone locations in the wellbore, rapidly calculate the production capacity of the two-step horizontal well, guide well location design, and determine reasonable operating conditions and development indicators for the oil well. The scheme provided in this disclosure is particularly suitable for the development and adjustment scheme design of three types of marginal reservoirs (layered or unconformable thin reservoirs, small fault-block reservoirs, and reservoirs where the upper oil layer has been cut off or pinched out but the lower layer is still exploitable), and can also be applied to well testing of two-step horizontal wells. Attached Figure Description

[0059] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0060] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0061] Figure 1 A schematic diagram illustrating the flow chart of a coupled unsteady flow calculation method for a two-step horizontal well according to an embodiment of the present disclosure is shown.

[0062] Figure 2This schematic diagram illustrates the xoz plane projection and segmentation of a double-step horizontal well at any location;

[0063] Figure 3 A schematic diagram illustrating the fluid flow in the i-th micro-element segment of the upper horizontal section of the wellbore is shown.

[0064] Figure 4 The flow rate of a two-step horizontal well over time is illustrated schematically.

[0065] Figure 5 The diagram schematically illustrates the production pressure differential distribution along the upper and lower horizontal sections of a double-step horizontal well.

[0066] Figure 6 This schematic diagram illustrates the distribution of the specific oil recovery index along the path in the double-step horizontal section;

[0067] Figure 7 A schematic diagram illustrates the structural block diagram of a dual-step horizontal well unsteady flow coupling calculation device according to an embodiment of the present disclosure; and

[0068] Figure 8 A schematic block diagram of an electronic device according to an embodiment of the present disclosure is shown. Detailed Implementation

[0069] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0070] Currently, domestic and international research on stepped horizontal wells mainly focuses on improvements to drilling, completion, and oil production processes, while research on seepage patterns and productivity is relatively limited. Existing technology provides a scheme that uses the principle of potential superposition to derive a semi-analytical mathematical model of reservoir seepage coupling with variable-mass pipe flow in the horizontal section of a stepped horizontal well under open-hole completion, and provides a corresponding solution; however, this existing technology only addresses the steady-state scenario.

[0071] Furthermore, developing oil and gas reservoirs using stepped horizontal wells involves numerous issues, including determining reasonable operating procedures, calculating development indicators, predicting development dynamics, and formulating and adjusting development plans. Solving these problems is based on the formation flow patterns and productivity analysis of stepped horizontal wells. The lag in reservoir engineering theory research inevitably affects the application of stepped horizontal wells in oil and gas field development. Therefore, proposing a solution for unstable flow and productivity in stepped horizontal wells has become a crucial issue that urgently needs to be addressed. To solve, or at least partially solve, the embodiments of this disclosure provide a coupled calculation method and apparatus for unstable flow in dual-step horizontal wells.

[0072] The following describes the method for calculating unstable seepage coupling in a two-step horizontal well provided by an embodiment of the present invention.

[0073] Example 1

[0074] See Figures 1 to 3 The embodiments of this disclosure provide a method for coupled calculation of unsteady seepage in a two-step horizontal well, including the following steps:

[0075] S1: Establish a first unsteady flow model for a horizontal well at any location in a reservoir with closed upper and lower boundaries and infinite horizontal size; wherein, the first unsteady flow model is obtained based on the first pressure response curve in Laplace space, and the first pressure response curve in Laplace space is transformed into the second pressure response curve in real space using the Stefest inversion algorithm.

[0076] S2: Divide the upper and lower horizontal sections of the double-step horizontal well into several micro-segments, calculate the pressure response value of each micro-segment, and establish a second unsteady flow model for the double-step horizontal well in a thin interbedded reservoir based on the calculated pressure response values ​​of each micro-segment.

[0077] S3: Establish a wellbore flow model with variable mass flow pressure drop loss, and calculate the wellbore pressure drop loss and wellbore flow rate for the upper horizontal section, lower horizontal section and connecting section respectively.

[0078] S4: Based on the first unstable seepage model, the second unstable seepage model and the wellbore flow model, establish an unstable seepage coupling model and obtain the pressure distribution and flow distribution of the double-step horizontal well in the upper and lower horizontal sections.

[0079] Developing oil and gas reservoirs using stepped horizontal wells involves numerous issues, including determining reasonable operating procedures, calculating development indicators, predicting development dynamics, and formulating and adjusting development plans. Solving these problems is based on the formation flow patterns and productivity analysis of stepped horizontal wells. Lagging research in reservoir engineering theory inevitably affects the application of stepped horizontal wells in oil and gas field development.

[0080] This disclosure establishes an unsteady flow coupling model for a two-step horizontal well under constant bottom-hole flowing pressure conditions and presents a calculation method for unsteady flow coupling in a two-step horizontal well based on this model. The study reveals the seepage characteristics, specific recovery index distribution along the wellbore, friction differential distribution, pressure drop loss, and the impact of pressure drop loss type on production capacity of the two-step horizontal well. It can qualitatively identify water-prone locations in the wellbore, rapidly calculate the production capacity of the two-step horizontal well, guide well location design, and determine reasonable operating regimes and development indicators for oil wells. The scheme provided in this disclosure is particularly suitable for the development and adjustment scheme design of three types of marginal reservoirs (layered or unconformable thin reservoirs, small fault-block reservoirs, and reservoirs with upper oil layers that have been cut off or pinched out but have exploitable lower layers), and can also be applied to well testing of two-step horizontal wells. Furthermore, it can be used to study the pressure distribution and production capacity evaluation of two-step horizontal wells. By studying the influence of wellbore diameter and well inclination angle on production capacity and seepage, it provides a basis for developing various reservoirs using stepped horizontal wells.

[0081] In one possible implementation, the step of establishing a first unsteady flow model for a horizontal well at any location in a horizontally infinite reservoir with closed upper and lower boundaries includes:

[0082]

[0083] in,

[0084]

[0085] The first unsteady flow model is established based on the first pressure response curve of the Laplace space shown in expression (1).

[0086] It should be noted that this disclosure is based on the unstable flow model and solution of a horizontal well at any location in a horizontally infinite reservoir with closed upper and lower boundaries. Based on the principle of potential superposition, an unstable flow model of the horizontal section of a double-step horizontal well in a thin interlayered reservoir is established. Based on the momentum theorem, a pressure drop calculation model along the shaft of a double-step horizontal well is established. Based on this, an unstable flow coupling model of a double-step horizontal well is derived, and a solution method for the model under constant pressure production conditions is given.

[0087] In one possible implementation, the step of dividing the upper and lower horizontal sections of the double-step horizontal well into several micro-segments, calculating the pressure response value of each micro-segment, and establishing a second unsteady flow model for the double-step horizontal well in a thin interbedded reservoir based on the calculated pressure response values ​​of each micro-segment includes:

[0088] (i) Calculate the first pressure response value generated by the selected infinitesimal element itself at the current infinitesimal element;

[0089] (ii) Calculate the second pressure response values ​​generated at the current micro-segment by several other micro-segments besides the selected micro-segment;

[0090] (iii) The first pressure response value and the second pressure response value are superimposed to obtain the true pressure response value of the current micro-segment.

[0091] In one possible implementation, the step of dividing the upper and lower horizontal sections of the double-step horizontal well into several micro-segments, calculating the pressure response value of each micro-segment, and establishing a second unsteady flow model for the double-step horizontal well in a thin interbedded reservoir based on the calculated pressure response values ​​of each micro-segment includes:

[0092] Under constant bottomhole flowing pressure production conditions, the second unsteady flow model of the double-step horizontal well in the thin interbedded reservoir is established according to the (N1+N2) order equations shown in expression (2):

[0093] Aq=P (2)

[0094]

[0095] Where, Δp upwfi The pressure drop at the midpoint of the i-th infinitesimal element of the upper horizontal segment is equal to p. i -p upwfi atm -1 ;Δp dnwfi The pressure drop at the midpoint of the i-th infinitesimal element of the lower horizontal segment is equal to p. i -p dnwfi atm -1 ;q uprj Let be the radial inflow of the j-th infinitesimal element in the upper horizontal segment, in cm. 3 / s;q dnrj Let J be the radial inflow of the j-th infinitesimal element in the lower horizontal segment, in cm. 3 / s;

[0096] C t The overall compression factor is atm. -1 h is the reservoir thickness, cm; L is the reference length, cm; K0(x) is the second-order deformed Bessel function, zeroth order; Lh q represents the length of the horizontal well or micro-element, in cm; q represents the flow rate of the line source, surface source, or volume source, in cm. 3 / s; For the flow of a point source, cm 3 / s; s is about t D The Laplace variable; t is time, s; t D It is dimensionless time.

[0097] In one possible implementation, the step of establishing a wellbore flow model for variable mass flow pressure drop loss within the wellbore, and calculating the wellbore pressure drop loss and wellbore flow rate for the upper horizontal section, lower horizontal section, and connecting section respectively, includes:

[0098]

[0099] Calculate the total pressure drop loss of radial inflow into the wellbore according to expression (3).

[0100] In the first implementation of this disclosure, for the upper horizontal segment, the wellbore pressure loss calculation model for the i-th segment of the upper horizontal segment can be obtained according to expression (3):

[0101]

[0102] Furthermore, according to expression (3), the axial flow rate at the downstream end of the first segment in the upper horizontal section, i.e., the total flow rate of the wellbore, is obtained as follows:

[0103]

[0104] In the second implementation of this disclosure, for the lower horizontal section, the axial flow rate at the downstream end of the first segment of the lower horizontal section can be obtained according to expression (3):

[0105]

[0106] The flow rate at the toe of the lower horizontal segment is 0, that is:

[0107] In the third implementation of this disclosure, since the radial flow rate from the reservoir into this section of the wellbore is 0, the flow velocity of the fluid within the connecting section can be considered constant. Only the direction of the flow velocity changes at the bends at both ends. Therefore, the pressure drop calculation model for the connecting section is as follows:

[0108]

[0109] Where f0 is the friction coefficient without radial inflow from the wall, and is dimensionless; Q dn The total flow rate of the lower horizontal section is equal to the axial flow rate at the downstream end of the first lower section.

[0110] It should be noted that in the first to third implementation methods described above in this disclosure, the symbols in the expressions are explained as follows: up represents the upper horizontal segment; l represents the axial direction; mid represents the middle connecting segment; dn represents the lower horizontal segment; r represents the radial direction; i, j, k represent the micro-element segment numbers; 1 represents the upstream end of the micro-element segment; 2 represents the downstream end of the micro-element segment.

[0111] In one possible implementation, the steps of establishing an unstable seepage coupling model based on the first unstable seepage model, the second unstable seepage model, and the wellbore flow model, and obtaining the pressure and flow distributions of the double-step horizontal well in the upper and lower horizontal sections, include:

[0112] Upper horizontal segment I:

[0113]

[0114] Connecting section III:

[0115] Upper endpoint A (intersection with the upper horizontal segment):

[0116]

[0117] Lower endpoint B (intersection with the lower horizontal segment):

[0118] p mid1 =p mid2 +Δp midseg (7)

[0119] Lower horizontal section II:

[0120]

[0121]

[0122]

[0123] Based on the above expressions (4) to (10), (N1+N2) variables related to the unknown p are calculated. upwfi p dnwfj q upri and q dnrj The wellbore flow pressure drop equations are as follows:

[0124] F(p upwfi ,p dnwfj ,q upri ,q dnrj )=0 (11)

[0125] Solving equations (2) and (11) simultaneously yields the (N1+N2) unknowns p mentioned above. upwfi pdnwfj q upri and q dnrj The pressure and flow distributions of the upper and lower horizontal sections are obtained.

[0126] In one possible implementation, after obtaining the pressure and flow distributions of the double-step horizontal well in the upper and lower horizontal sections, the method further includes:

[0127] Under constant bottom-hole flowing pressure production conditions, an iterative method is used to optimize the two parameters, upper horizontal section pressure and lower horizontal section pressure, in the coupled model until the error between the upper horizontal section pressure and the previous upper horizontal section pressure is less than a first preset error value, and the error between the lower horizontal section pressure and the previous lower horizontal section pressure is less than a second preset error value. Specifically, the parameter optimization and solution can be performed according to the following steps:

[0128] ① First, a set of p is given upwfi and p dnwfj The initial value (given the terminal flow pressure p) wf p upwfi and p dnwfj The initial value is given as p wf ), q is obtained by calculating using equation ②. upri and q dnrj ;

[0129] ②Then substitute it into the wellbore pressure drop calculation model (4) to (10) to calculate the pressure drop loss of each section of the wellbore;

[0130] ③ Calculate the wellbore pressure drop (i.e., the production pressure difference in each section) in equation ②:

[0131]

[0132] ④ Substitute into equation ② and recalculate to obtain p upwfi and p dnwfj This completes one iteration;

[0133] ⑤Then take the newly obtained p upwfi and p dnwfj Using this value as the new initial value, the above process is repeated until the error between two iterations is less than the allowable error. It should be noted that those skilled in the art can adjust the range of allowable error based on the accuracy requirements in actual production; this is not limited here.

[0134] It should be noted that, compared with existing methods, this disclosure considers the coupling between wellbore flow and formation seepage in the formation and connecting sections, and provides a real-space unsteady seepage coupling model under different pressures in the horizontal section and an iterative solution process for the model under constant bottom hole pressure. Through this iterative process, the coupling model is optimized and the accuracy of the model is improved.

[0135] Example 2

[0136] The following examples illustrate this. Figure 1 The method for calculating the unstable seepage coupling in a double-step horizontal well is further explained below.

[0137] Table 1 shows the production capacity calculation parameters for a two-step horizontal well. Formation parameters and drilling / completion data for one step horizontal well are also provided (see Table 1). Production is achieved at a constant bottomhole pressure of 11.6 MPa (Pheel = 11.6 MPa). The calculation is performed using a two-step horizontal well unsteady flow coupling model. The calculation results are shown below. Figures 4-6 .

[0138] Table 1:

[0139]

[0140] Note: The inclination angle of the connecting section is 60°.

[0141] Figure 4 The changes in wellbore flow rate over time were compared under the conditions of infinite conduction and considering wellbore pressure drop. The dashed line represents the case of infinite conduction. Figure 4 It can be seen that the total flow rate and the flow rate within the upper and lower horizontal segments both decrease with time; the flow rate under the unlimited flow condition is greater than the flow rate under the finite flow condition, and the difference between the two decreases with time.

[0142] Figure 5 The curves showing the variation of the production pressure difference along the upper and lower horizontal sections at different times are given. Figure 5 It can be seen that the pressure loss in the connecting section is relatively large, decreasing over time, and is approximately 0.0558 MPa, accounting for more than half of the total pressure drop loss within the wellbore. With increasing time, the pressure drop loss within the wellbore decreases from 0.1055 MPa (accounting for 7.04% of the formation pressure drop) to 0.0761 MPa (accounting for 5.08% of the formation pressure drop loss). The pressure gradient is smaller in the upper and lower horizontal sections near the toe, increasing along the flow direction. The pressure gradient is largest at the connecting section. Overall, the pressure gradient in the upper horizontal section is greater than that in the lower horizontal section. Therefore, for high-permeability formations, the pressure drop loss within the wellbore can significantly reduce production, especially in the initial stages of production, where its impact on productivity is more pronounced. Appropriately increasing the wellbore diameter can reduce pressure drop loss and increase production.

[0143] Furthermore, by Figure 6It is known that because the model established in this paper considers the pressure drop loss in the wellbore and the mutual interference between the micro-elements in the upper and lower horizontal sections during production, the specific oil recovery index is not uniformly distributed along the length of the wellbore, but roughly in a "U" shape, which is asymmetrical. The specific oil recovery index at the heel end is slightly higher than that at the toe end; as time increases, the specific oil recovery index decreases.

[0144] Example 3

[0145] The following describes the dual-step horizontal well unsteady seepage coupling calculation device provided in the embodiments of the present invention.

[0146] Please see Figure 7 The embodiments of this disclosure provide a coupled calculation device for unsteady seepage in a two-step horizontal well, comprising:

[0147] The unsteady flow modeling unit 10 is used to establish a first unsteady flow model for a horizontal well at any location in a reservoir with closed upper and lower boundaries and infinite horizontal size. The first unsteady flow model is obtained based on the first pressure response curve in Laplace space, and the first pressure response curve in Laplace space is transformed into a second pressure response curve in real space using the Stefest inversion algorithm. The upper and lower horizontal sections of the double-step horizontal well are divided into several micro-segments, the pressure response value of each micro-segment is calculated, and a second unsteady flow model for a double-step horizontal well in a thin interlayered reservoir is established based on the calculated pressure response values ​​of each micro-segment.

[0148] The wellbore flow modeling unit 20 is used to establish a wellbore flow model with variable mass flow pressure drop loss in the wellbore, and to calculate the wellbore pressure drop loss and wellbore flow rate in the upper horizontal section, lower horizontal section and connecting section respectively.

[0149] The coupling modeling unit 30 is used to establish an unstable seepage coupling model based on the first unstable seepage model, the second unstable seepage model and the wellbore flow model, and to obtain the pressure distribution and flow distribution of the double-step horizontal well in the upper and lower horizontal sections.

[0150] Developing oil and gas reservoirs using stepped horizontal wells involves numerous issues, including determining reasonable operating procedures, calculating development indicators, predicting development dynamics, and formulating and adjusting development plans. Solving these problems is based on the formation flow patterns and productivity analysis of stepped horizontal wells. Lagging research in reservoir engineering theory inevitably affects the application of stepped horizontal wells in oil and gas field development.

[0151] In one possible implementation, the unsteady seepage modeling unit 10 is further used for:

[0152]

[0153] in,

[0154]

[0155] The first unsteady flow model is established based on the first pressure response curve of the Laplace space shown in expression (1).

[0156] It should be noted that this disclosure is based on the unstable flow model and solution of a horizontal well at any location in a horizontally infinite reservoir with closed upper and lower boundaries. Based on the principle of potential superposition, an unstable flow model of the horizontal section of a double-step horizontal well in a thin interlayered reservoir is established. Based on the momentum theorem, a pressure drop calculation model along the shaft of a double-step horizontal well is established. Based on this, an unstable flow coupling model of a double-step horizontal well is derived, and a solution method for the model under constant pressure production conditions is given.

[0157] In one possible implementation, the unsteady seepage modeling unit 10 is further used for:

[0158] (i) Calculate the first pressure response value generated by the selected infinitesimal element itself at the current infinitesimal element;

[0159] (ii) Calculate the second pressure response values ​​generated at the current micro-segment by several other micro-segments besides the selected micro-segment;

[0160] (iii) The first pressure response value and the second pressure response value are superimposed to obtain the true pressure response value of the current micro-segment.

[0161] In one possible implementation, the unsteady seepage modeling unit 10 is further used for:

[0162] Under constant bottomhole flowing pressure production conditions, the second unsteady flow model of the double-step horizontal well in the thin interbedded reservoir is established according to the (N1+N2) order equations shown in expression (2):

[0163] Aq=P (2)

[0164]

[0165]

[0166] Where, Δp upwfi The pressure drop at the midpoint of the i-th infinitesimal element of the upper horizontal segment is equal to p. i -p upwfi atm -1 ;Δp dnwfi The pressure drop at the midpoint of the i-th infinitesimal element of the lower horizontal segment is equal to p. i -p dnwfi atm -1 ;quprj Let be the radial inflow of the j-th infinitesimal element in the upper horizontal segment, in cm. 3 / s;q dnrj Let J be the radial inflow of the j-th infinitesimal element in the lower horizontal segment, in cm. 3 / s;

[0167] C t The overall compression factor is atm. -1 h is the reservoir thickness, cm; L is the reference length, cm; K0(x) is the second-order deformed Bessel function, zeroth order; L h q represents the length of the horizontal well or micro-element, in cm; q represents the flow rate of the line source, surface source, or volume source, in cm. 3 / s; For the flow of a point source, cm 3 / s; s is about t D The Laplace variable; t is time, s; t D It is dimensionless time.

[0168] In one possible implementation, the wellbore flow modeling unit 20 is further used for:

[0169]

[0170] Calculate the total pressure drop loss of radial inflow into the wellbore according to expression (3).

[0171] In the first implementation of this disclosure, for the upper horizontal segment, the wellbore pressure loss calculation model for the i-th segment of the upper horizontal segment can be obtained according to expression (3):

[0172]

[0173] Furthermore, according to expression (3), the axial flow rate at the downstream end of the first segment in the upper horizontal section, i.e., the total flow rate of the wellbore, is obtained as follows:

[0174]

[0175] In the second implementation of this disclosure, for the lower horizontal section, the axial flow rate at the downstream end of the first segment of the lower horizontal section can be obtained according to expression (3):

[0176]

[0177] The flow rate at the toe of the lower horizontal segment is 0, that is:

[0178] In the third implementation of this disclosure, since the radial flow rate from the reservoir into this section of the wellbore is 0, the flow velocity of the fluid within the connecting section can be considered constant. Only the direction of the flow velocity changes at the bends at both ends. Therefore, the pressure drop calculation model for the connecting section is as follows:

[0179]

[0180] Where f0 is the friction coefficient without radial inflow from the wall, and is dimensionless; Q dn The total flow rate of the lower horizontal section is equal to the axial flow rate at the downstream end of the first lower section.

[0181] It should be noted that in the first to third implementation methods described above in this disclosure, the symbols in the expressions are explained as follows: up represents the upper horizontal segment; l represents the axial direction; mid represents the middle connecting segment; dn represents the lower horizontal segment; r represents the radial direction; i, j, k represent the micro-element segment numbers; 1 represents the upstream end of the micro-element segment; 2 represents the downstream end of the micro-element segment.

[0182] In one possible implementation, the coupling modeling unit 30 is used for:

[0183] Upper horizontal segment I:

[0184]

[0185]

[0186] Connecting section III:

[0187] Upper endpoint A (intersection with the upper horizontal segment):

[0188]

[0189] Lower endpoint B (intersection with the lower horizontal segment):

[0190] p mid1 =p mid2 +Δp midseg (7)

[0191] Lower horizontal section II:

[0192]

[0193]

[0194]

[0195] Based on the above expressions (4) to (10), (N1+N2) variables related to the unknown p are calculated. upwfi p dnwfj q upriand q dnrj The wellbore flow pressure drop equations are as follows:

[0196] F(p upwfi ,p dnwfj ,q upri ,q dnrj )=0 (11)

[0197] Solving equations (2) and (11) simultaneously yields the (N1+N2) unknowns p mentioned above. upwfi p dnwfj q upri and q dnrj The pressure and flow distributions of the upper and lower horizontal sections are obtained.

[0198] In one possible implementation, the coupling modeling unit 30 is further used for:

[0199] Under constant bottom-hole flowing pressure production conditions, an iterative method is used to optimize the two parameters, upper horizontal section pressure and lower horizontal section pressure, in the coupled model until the error between the upper horizontal section pressure and the previous upper horizontal section pressure is less than a first preset error value, and the error between the lower horizontal section pressure and the previous lower horizontal section pressure is less than a second preset error value. Specifically, the parameter optimization and solution can be performed according to the following steps:

[0200] ① First, a set of p is given upwfi and p dnwfj The initial value (given the terminal flow pressure p) wf p upwfi and p dnwfj The initial value is given as p wf ), q is obtained by calculating using equation ②. upri and q dnrj ;

[0201] ②Then substitute it into the wellbore pressure drop calculation model (4) to (10) to calculate the pressure drop loss of each section of the wellbore;

[0202] ③ Calculate the wellbore pressure drop (i.e., the production pressure difference in each section) in equation ②:

[0203]

[0204] ④ Substitute into equation ② and recalculate to obtain p upwfi and p dnwfj This completes one iteration;

[0205] ⑤Then take the newly obtained p upwfi and p dnwfjUsing this value as the new initial value, the above process is repeated until the error between two iterations is less than the allowable error. It should be noted that those skilled in the art can adjust the range of allowable error based on the accuracy requirements in actual production; this is not limited here.

[0206] This disclosure establishes an unsteady flow coupling model for a two-step horizontal well under constant bottom-hole flowing pressure conditions and presents a calculation method for unsteady flow coupling in a two-step horizontal well based on this model. The study reveals the seepage characteristics, specific recovery index distribution along the wellbore, friction differential distribution, pressure drop loss, and the impact of pressure drop loss type on production capacity of the two-step horizontal well. It can qualitatively identify water-prone locations in the wellbore, rapidly calculate the production capacity of the two-step horizontal well, guide well location design, and determine reasonable operating regimes and development indicators for oil wells. The scheme provided in this disclosure is particularly suitable for the development and adjustment scheme design of three types of marginal reservoirs (layered or unconformable thin reservoirs, small fault-block reservoirs, and reservoirs with upper oil layers that have been cut off or pinched out but have exploitable lower layers), and can also be applied to well testing of two-step horizontal wells. Furthermore, it can be used to study the pressure distribution and production capacity evaluation of two-step horizontal wells. By studying the influence of wellbore diameter and well inclination angle on production capacity and seepage, it provides a basis for developing various reservoirs using stepped horizontal wells.

[0207] The specific implementation process of the functions and roles of each unit in the above device can be found in the implementation process of the corresponding steps in the above method, and will not be repeated here.

[0208] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this disclosure according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0209] In the second embodiment described above, any plurality of the unsteady flow modeling unit 10, the wellbore flow modeling unit 20, and the coupling modeling unit 30 can be combined into one module, or any one of these modules can be split into multiple modules. Alternatively, at least part of the functionality of one or more of these modules can be combined with at least part of the functionality of other modules and implemented in one module. At least one of the unsteady flow modeling unit 10, the wellbore flow modeling unit 20, and the coupling modeling unit 30 can be at least partially implemented as hardware circuitry, such as a field-programmable gate array (FPGA), a programmable logic array (PLA), a system-on-a-chip, a system-on-a-substrate, a system-on-package, an application-specific integrated circuit (ASIC), or any other reasonable means of integrating or packaging circuitry, or implemented in software, hardware, or firmware, or in any appropriate combination of any of these three implementation methods. Alternatively, at least one of the unsteady flow modeling unit 10, the wellbore flow modeling unit 20, and the coupling modeling unit 30 can be at least partially implemented as a computer program module, which, when run, can perform corresponding functions.

[0210] Example 4

[0211] Based on the same inventive concept, referring to Figure 8 As shown, the third exemplary embodiment of this disclosure provides an electronic device including a processor 1110, a communication interface 1120, a memory 1130, and a communication bus 1140, wherein the processor 1110, the communication interface 1120, and the memory 1130 communicate with each other through the communication bus 1140.

[0212] Memory 1130 is used to store computer programs;

[0213] When processor 1110 executes the program stored in memory 1130, it implements the following method for calculating the coupling of unsteady seepage in a two-step horizontal well:

[0214] S1: Establish a first unsteady flow model for a horizontal well at any location in a reservoir with closed upper and lower boundaries and infinite horizontal size; wherein, the first unsteady flow model is obtained based on the first pressure response curve in Laplace space, and the first pressure response curve in Laplace space is transformed into the second pressure response curve in real space using the Stefest inversion algorithm;

[0215] S2: Divide the upper and lower horizontal sections of the double-step horizontal well into several micro-segments, calculate the pressure response value of each micro-segment, and establish a second unsteady flow model for the double-step horizontal well in a thin interbedded reservoir based on the calculated pressure response values ​​of each micro-segment.

[0216] S3: Establish a wellbore flow model for pressure drop loss due to variable mass flow within the wellbore, and calculate the wellbore pressure drop loss and wellbore flow rate for the upper horizontal section, lower horizontal section, and connecting section respectively;

[0217] S4: Based on the first unstable seepage model, the second unstable seepage model and the wellbore flow model, establish an unstable seepage coupling model and obtain the pressure distribution and flow distribution of the double-step horizontal well in the upper and lower horizontal sections.

[0218] The aforementioned communication bus 1140 can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus 1140 can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, it is represented by only one thick line in the figure, but this does not indicate that there is only one bus or one type of bus.

[0219] The communication interface 1120 is used for communication between the above-mentioned electronic device and other devices.

[0220] The memory 1130 may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory 1130 may also be at least one storage device located remotely from the aforementioned processor 1110.

[0221] The processor 1110 mentioned above can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0222] Example 5

[0223] Based on the same inventive concept, a fourth exemplary embodiment of this disclosure also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the double-step horizontal well unsteady flow coupling calculation method as described above.

[0224] The computer-readable storage medium may be included in the device / apparatus described in the above embodiments; or it may exist independently and not assembled into the device / apparatus. The computer-readable storage medium carries one or more programs that, when executed, implement the dual-step horizontal well unsteady flow coupling calculation method according to embodiments of this disclosure.

[0225] According to embodiments of this disclosure, the computer-readable storage medium can be a non-volatile computer-readable storage medium, such as including, but not limited to: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this disclosure, the computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0226] It should be noted that, in this document, relational terms such as "first" and "second" are used merely 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 a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0227] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for coupling calculation of unstable seepage in a double-step horizontal well, characterized in that, The method comprises: S1: establishing a first unstable percolation model of a horizontal well at any position in an upper and lower boundary closed and horizontally infinite reservoir; wherein the first unstable percolation model is based on a first pressure response curve in Laplace space, and the first pressure response curve in Laplace space is converted to a second pressure response curve in real space by using a Stefest inversion algorithm; S2: dividing the upper horizontal section and the lower horizontal section of the double-bench horizontal well into a plurality of micro-segments, calculating the pressure response value of each micro-segment, and establishing a second unstable percolation model of the double-bench horizontal well in the thin interbedded reservoir based on the calculated pressure response values of the micro-segments; S3: establishing a wellbore flow model of variable mass flow pressure drop loss in the wellbore, and calculating the wellbore pressure drop loss and the wellbore flow rate of the upper horizontal section, the lower horizontal section and the connecting section respectively; S4: establishing an unstable percolation coupling model based on the first unstable percolation model, the second unstable percolation model and the wellbore flow model, and obtaining the pressure distribution and the flow distribution of the double-bench horizontal well in the upper horizontal section and the lower horizontal section.

2. The method according to claim 1, wherein, After obtaining the pressure distribution and the flow distribution of the double-bench horizontal well in the upper horizontal section and the lower horizontal section, the method further comprises: Under the condition of constant bottom-hole flowing pressure production, the upper horizontal section pressure and the lower horizontal section pressure in the coupling model are optimized by using an iteration method until the error between the upper horizontal section pressure and the upper horizontal section pressure of the last time is less than a first set error value, and the error between the lower horizontal section pressure and the lower horizontal section pressure of the last time is less than a second set error value.

3. The method according to claim 1 or 2, characterized in that, The step of establishing the first unstable percolation model of the horizontal well at any position in the upper and lower boundary closed and horizontally infinite reservoir comprises: The first unstable percolation model is established according to the first pressure response curve in Laplace space shown in expression (1).

4. The method according to claim 1 or 2, wherein, The step of dividing the upper horizontal section and the lower horizontal section of the double-bench horizontal well into a plurality of micro-segments, calculating the pressure response value of each micro-segment, and establishing the second unstable percolation model of the double-bench horizontal well in the thin interbedded reservoir based on the calculated pressure response values of the micro-segments comprises: The first pressure response value generated by the selected micro-segment at the current micro-segment is calculated; The second pressure response values generated by the other micro-segments except the selected micro-segment at the current micro-segment are calculated; The first pressure response value and the second pressure response values are superimposed to obtain the real pressure response value of the current micro-segment.

5. The method according to claim 4, wherein, The step of dividing the upper horizontal section and the lower horizontal section of the double-bench horizontal well into a plurality of micro-segments, calculating the pressure response value of each micro-segment, and establishing the second unstable percolation model of the double-bench horizontal well in the thin interbedded reservoir based on the calculated pressure response values of the micro-segments comprises: Under the condition of constant bottom-hole flowing pressure production, the second unstable percolation model of the double-bench horizontal well in the thin interbedded reservoir is established according to the (N1+N2) order equation group shown in expression (2): where Δp upwfi is the pressure drop at the midpoint of the i-th microelement of the upper horizontal section, equal to p i -p upwfi , atm -1 ; Δp dnwfi is the pressure drop at the midpoint of the i-th microelement of the lower horizontal section, equal to p i -p dnwfi , atm -1 ; q uprj is the radial inflow of the j-th microelement of the upper horizontal section, cm 3 / s; q dnrj is the radial inflow of the j-th microelement of the lower horizontal section, cm 3 / s; C t is the integrated compressibility factor, atm -1 ; h is the reservoir thickness, cm; L is the reference length, cm; K0(x) is the second kind of modified Bessel function, zero order; L h is the length of the horizontal well or microelement, cm; q is the flow rate of a line source, area source or volume source, cm 3 / s; is the flow rate of a point source, cm 3 / s; s is the Laplace variable with respect to t D ; t is the time, s; t D is the dimensionless time.

6. The method according to claim 1 or 2, wherein, The step of establishing the wellbore flow model of the variable mass flow pressure drop loss in the wellbore and respectively calculating the wellbore pressure drop loss and wellbore flow of the upper horizontal section, the lower horizontal section and the connecting section comprises: The total radial inflow wellbore pressure drop loss is calculated according to expression (3).

7. The method according to claim 1 or 2, wherein, The step of establishing the unstable seepage coupling model based on the first unstable seepage model, the second unstable seepage model and the wellbore flow model and obtaining the pressure distribution and flow distribution of the double-step horizontal well in the upper horizontal section and the lower horizontal section comprises: Upper horizontal section I: Connecting section III: Upper end point A (intersection with the upper horizontal section): Lower end point B (intersection with the lower horizontal section): p mid1 = p mid2 + Δp midseg (7) Lower horizontal section II: Based on the above expressions (4) to (10), the wellbore flow pressure drop equations for (N1+N2) unknowns p upwfi , p dnwfj , q upri and q dnrj are calculated: F(p upwfi ,p dnwfj ,q upri ,q dnrj ) = 0 (11) Equations (2) and (11) are solved simultaneously to obtain the above-mentioned (N1+N2) unknowns p upwfi , p dnwfj , q upri and q dnrj , to obtain the pressure and flow distributions in the upper and lower horizontal sections.

8. A device for calculating unstable seepage coupling of a double-step horizontal well, characterized in that, Comprise: An unstable seepage modeling unit for establishing a first unstable seepage model of a horizontal well at an arbitrary position in an upper and lower boundary closed and horizontally infinite reservoir; wherein the first unstable seepage model is obtained based on a first pressure response curve in Laplace space and the first pressure response curve in Laplace space is converted to a second pressure response curve in real space by using a Stefest inversion algorithm; and the upper horizontal section and the lower horizontal section of the double-step horizontal well are divided into a plurality of micro-segments, the pressure response value of each micro-segment is calculated, and a second unstable seepage model of the double-step horizontal well in the thin interbedded reservoir is established based on the calculated pressure response values of the micro-segments; A wellbore flow model modeling unit for establishing a wellbore flow model of the variable mass flow pressure drop loss in the wellbore and respectively calculating the wellbore pressure drop loss and wellbore flow of the upper horizontal section, the lower horizontal section and the connecting section; A coupling modeling unit for establishing an unstable seepage coupling model based on the first unstable seepage model, the second unstable seepage model and the wellbore flow model and obtaining the pressure distribution and flow distribution of the double-step horizontal well in the upper horizontal section and the lower horizontal section.

9. An electronic device, comprising: The system comprises a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory complete mutual communication through the communication bus; The memory is used for storing a computer program; The processor is used for executing the program stored on the memory to realize the double-step horizontal well unstable seepage coupling calculation method in any one of claims 1-7.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to realize the double-step horizontal well unstable seepage coupling calculation method in any one of claims 1-7.

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