Tight reservoir vertical well group fracturing optimization design method

Abstract

The invention relates to the technical field of oil and gas field yield increase and transformation, in particular to a tight reservoir vertical well group fracturing optimization design method which comprises the following steps: collecting geological data and engineering data of a fracturing target block; a vertical well fracturing crack stress disturbance mathematical model is established, and reservoir disturbance stress distribution is simulated; establishing a crack support crack width attenuation mathematical model, and simulating a change rule of the support crack width along with time; combining engineering data with the stress disturbance mathematical model to determine a well group combination mode and a multi-well fracturing sequence of vertical well group fracturing; and based on the result of the fourth step, the fracturing time interval between the vertical wells in the well group is designed by combining the supporting seam width attenuation mathematical model. According to the method, the problems of well group combination mode, multi-well fracturing sequence, fracturing time interval and the like during tight reservoir vertical well group fracturing construction design are effectively solved, steering extension of fracturing cracks is achieved, the fracturing transformation effect of a reservoir is improved, and therefore the oil and gas yield of a single well is increased.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field production increase and transformation, and is a method for optimizing the design of tight reservoir vertical well group fracturing. Background Art

[0002] Carrying out large-scale hydraulic fracturing transformation and constructing a fracturing fracture network with high conductivity are the keys to achieving efficient development of tight reservoirs.

[0003] For tight reservoirs with large horizontal stress differences, strong reservoir heterogeneity, and deep reservoir burial depth, the fractures formed by conventional vertical well fracturing technology are simple in shape, mostly plane fractures, and it is difficult to form a complex fracture network to fully transform the reservoir. Field fracturing practice has shown that the use of vertical well group fracturing technology in tight reservoirs can effectively promote the diversion and extension of fractures, and the complexity of fracturing fractures and the production of single wells can be significantly improved. The principle of this process is to use fracturing fractures to generate stress disturbances on the reservoir, change the stress distribution in the reservoir, and then realize the diversion of fracturing fractures. Under the conditions of multi-well fracturing, it can reduce the horizontal stress difference and form a complex fracture network.

[0004] At present, the design of vertical well group fracturing construction in tight reservoirs is blind in terms of well group mode selection, fracturing sequence determination, construction parameter optimization, etc. The existing methods cannot effectively guide on-site fracturing practice, resulting in poor fracturing effects during actual application. Summary of the invention

[0005] The present invention provides a method for optimizing the design of vertical well group fracturing in a tight reservoir, which overcomes the shortcomings of the above-mentioned prior art and can effectively solve the problem that the prior method cannot effectively guide on-site fracturing practice, resulting in poor fracturing effect during actual application.

[0006] One of the technical solutions of the present invention is achieved by the following measures: A method for optimizing the design of a group fracturing of a vertical well in a tight reservoir comprises the following steps:

[0007] Step 1: Collect geological and engineering data of the target area for fracturing;

[0008] Step 2: Establish a mathematical model of vertical well fracturing fracture stress disturbance to simulate reservoir disturbance stress distribution;

[0009] Step 3: Establish a mathematical model for the attenuation of crack support width to simulate the change of support width over time;

[0010] Step 4: Determine the well group combination mode and multi-well fracturing sequence for vertical well group fracturing by combining engineering data with the stress disturbance mathematical model;

[0011] Step 5: Based on the results of step 4, the fracturing time interval between vertical wells in the well group is designed in combination with the mathematical model of support fracture width attenuation.

[0012] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions:

[0013] In step 1 above:

[0014] The geological data may include reservoir thickness, reservoir geostress parameters, reservoir rock mechanics parameters, and comprehensive fluid loss coefficient of fracturing fluid;

[0015] Engineering data parameters may include group fracturing well group combination mode, vertical well fracturing construction parameters, adjacent well fracturing crack length, crack width and crack height.

[0016] The above step 2 may specifically include the following steps:

[0017] The diameter pressure fracture is discretized in the plane, and multiple one-dimensional fracture units are used to represent the hydraulic fracture. The coordinate matrix of the midpoint of the fracture unit is:

[0018] [x i y i ](i=1,2,…,N)

[0019] The reservoir is divided into units using uniform grid units, and two-dimensional rectangular units are used to represent the plane reservoir. The center coordinates of the reservoir unit are:

[0020]

[0021] The semi-analytical induced stress calculation method is used to calculate the disturbance of reservoir stress under the condition of hydraulic fractures in the reservoir. The calculation formula of the disturbance stress field is:

[0022]

[0023] In the formula,

[0024]

[0025]

[0026]

[0027]

[0028] Among them, (x i ,y i ) represents the midpoint coordinate of the crack unit; N represents the number of crack units; is the center coordinate of the reservoir unit; M represents the number of reservoir units; represents the coordinates in the local coordinate system; β represents the angle between the local coordinates with the length direction of the crack unit j as the horizontal axis and the global coordinates; represents the disturbance stress field generated by hydraulic fracture unit j at reservoir unit i; C ij represents the displacement boundary influence coefficient; G ij Indicates the seam height correction factor; d ij represents the distance between the midpoint of fracture unit j and the center coordinate of reservoir unit i; H represents the height of hydraulic fracture; D n and D s represent the normal displacement and tangential displacement of the crack element respectively.

[0029] In step 3 above:

[0030] The calculation formula for the crack width distribution along the crack length direction can be:

[0031]

[0032] According to the fracturing construction parameters, the calculation formula of the support seam width under ideal filling conditions can be:

[0033] w1(x,y)=w0(x,y)·S

[0034] After the fracturing operation is completed, the fracture width decays over time, and the calculation formula can be:

[0035] w(t)=w1·F(t)

[0036] Where w0(x, y) and w1(x, y) represent the fracture width and propping width of the fracture unit at (x, y), respectively; w(t) represents the propping width at time t after the fracturing is completed; E is the Young's modulus of the reservoir rock; v is the Poisson's ratio of the reservoir rock; H is the height of the fracture; p f (x, y) and σ n (x, y) represent the fluid pressure and normal ground stress acting on the fracture unit at (x, y), respectively; L represents the half-length of the fracture; S represents the sand ratio of the fracturing fluid; t represents time; and F(t) represents the fracture width attenuation coefficient.

[0037] The above step 4 may specifically include the following steps:

[0038] Combining the engineering data of the target fracturing block with the mathematical model of vertical well fracturing fracture stress disturbance, the scope and distribution law of fracturing fracture disturbance stress under different fracturing construction conditions are analyzed;

[0039] Combine the geological characteristics of the fracturing block with the well pattern layout to determine the well group combination mode for vertical well group fracturing;

[0040] Based on the law of disturbance stress distribution and the well group pattern of group fracturing, the fracturing sequence of multiple wells in the well group is optimized with the goal of reducing horizontal stress difference, promoting fracture diversion and extension, and constructing a complex fracture network.

[0041] The above step 5 may specifically include the following steps:

[0042] Combined with the vertical well fracturing construction parameters of the adjacent wells in the target fracturing block and the monitoring results of the fracturing cracks in the adjacent wells, the width of the fracturing crack support is calculated;

[0043] According to the analysis of the fracturing construction pressure curve and the fitting fracture width attenuation coefficient of the indoor test, the variation law of the support fracture width after fracturing with time is calculated;

[0044] The support fracture width at different times is substituted into the mathematical model of vertical well fracturing fracture stress disturbance, and the law of disturbance stress in the reservoir at different times is calculated. The goal is to maximize the reduction of reservoir stress difference and achieve fracturing fracture diversion, and optimize the time interval of fracturing between the front and rear wells in the group's vertical well group.

[0045] The second technical solution of the present invention is achieved through the following measures: a terminal device includes a memory and a processor, the memory stores a program that can be run on the processor, and the processor implements the above-mentioned tight reservoir vertical well group fracturing optimization design method when executing the program.

[0046] The third technical solution of the present invention is achieved through the following measures: a storage medium, which stores one or more programs, and the one or more programs can be executed by one or more processors to implement the above-mentioned tight reservoir vertical well group fracturing optimization design method.

[0047] The present invention provides a method for optimizing the fracturing design of a group of vertical wells in a tight reservoir, which is used to optimize the well group combination mode, multi-well fracturing sequence and fracturing time interval in the fracturing process of a group of vertical wells in a tight reservoir, avoid blindness in the fracturing construction design of a group of vertical wells, make full use of the interference effect between fractures to increase the complexity of the fracture network, improve the reservoir transformation volume and resource mobilization degree, and realize the efficient development of tight reservoirs. The present invention innovatively proposes a method for optimizing the fracturing design of a group of vertical wells in a tight reservoir, which effectively solves the problems of the well group combination mode, multi-well fracturing sequence, and fracturing time interval in the fracturing construction design of a group of vertical wells in a tight reservoir by comprehensively considering the stress disturbance of the fracturing fractures on the reservoir and the attenuation change of the supporting fractures over time, realizes the steering extension of the fracturing fractures, improves the fracturing transformation effect of the reservoir, thereby increasing the oil and gas production of a single well, reducing the overall cost, and realizing efficient development. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Attached Figure 1 It is a schematic flow chart of a method for optimizing the design of a group fracturing of a vertical well in a tight reservoir according to an embodiment of the present invention.

[0049] Attached Figure 2 Schematic diagram of the discrete hydraulic fracture unit of an embodiment of the present invention.

[0050] Attached Figure 3 Schematic diagram of reservoir unit discreteness according to an embodiment of the present invention.

[0051] Attached Figure 4 Schematic diagram of stress disturbance of a single fracture in a reservoir according to an embodiment of the present invention.

[0052] Attached Figure 5 Schematic diagram of the distribution of the seam width along the seam length under different fluid pressures according to an embodiment of the present invention.

[0053] Attached Figure 6 Schematic diagram of stress disturbance distribution along the y direction under ventilated net pressure in a single slit mode according to an embodiment of the present invention.

[0054] Attached Figure 7 Schematic diagram of stress disturbance distribution along the y direction under ventilated net pressure in the double-slit mode of an embodiment of the present invention.

[0055] Attached Figure 8 It is a schematic diagram of the vertical well group fracturing well group combination mode of an embodiment of the present invention.

[0056] Attached Fig. 9 Schematic diagram of stress disturbance caused by well group combination mode 1 according to an embodiment of the present invention.

[0057] Attached Fig.10 Schematic diagram of stress disturbance caused by well group combination mode 2 according to an embodiment of the present invention.

[0058] Attached Fig.11 Schematic diagram of stress disturbance caused by well group combination mode 3 according to an embodiment of the present invention.

[0059] Attached Fig.12 This is a schematic diagram of stress disturbance in the reservoir at time T1 according to an embodiment of the present invention.

[0060] Attached Fig.13 This is a schematic diagram of stress disturbance in the reservoir at time T2 according to an embodiment of the present invention.

[0061] Attached Fig.14 This is a schematic diagram of stress disturbance in the reservoir at time T3 according to an embodiment of the present invention. DETAILED DESCRIPTION

[0062] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0063] The present invention will be further described below in conjunction with embodiments and drawings:

[0064] Embodiment 1: As attached Figure 1 As shown, the tight reservoir vertical well group fracturing optimization design method includes the following steps:

[0065] Step 1: Collect geological and engineering data of the target area for fracturing;

[0066] Step 2: Establish a mathematical model of vertical well fracturing fracture stress disturbance to simulate reservoir disturbance stress distribution;

[0067] Step 3: Establish a mathematical model for the attenuation of crack support width to simulate the change of support width over time;

[0068] Step 4: Determine the well group combination mode and multi-well fracturing sequence for vertical well group fracturing by combining engineering data with the stress disturbance mathematical model;

[0069] Step 5: Based on the results of step 4, the fracturing time interval between vertical wells in the well group is designed in combination with the mathematical model of support fracture width attenuation.

[0070] In step 1, geological data include reservoir thickness, reservoir geostress parameters, reservoir rock mechanics parameters, comprehensive loss coefficient of fracturing fluid, etc.; engineering data parameters include group fracturing well group combination mode, vertical well fracturing construction parameters, adjacent well fracturing crack length, crack width and crack height and other monitoring results. In the embodiment of the present invention, the geological and engineering basic parameters related to the tight reservoir of a certain block are collected as shown in Table 1.

[0071] Table 1 Basic parameters

[0072] parameter Numeric unit Reservoir thickness 27.5 m Maximum horizontal principal stress 75.8 MPa Minimum horizontal principal stress 61.5 MPa Fracturing fluid loss coefficient <![CDATA[4.55×10 -4 ]]> <![CDATA[m.min -0.5 ]]> Rock elastic modulus 32.6 GPa Rock Poisson's ratio 0.245 - Fracturing monitoring crack length 180.0～240.0 m Fracturing monitoring fracture height 25.0～40.0 m Net pressure in fracture 4.0～12.0 MPa

[0073] In step 2, the hydraulic fractures and reservoirs are divided into units, and a uniform grid division method is used to obtain one-dimensional fracture units and two-dimensional reservoir units, respectively, such as Figure 2 and Figure 3 As shown, the coordinate matrix of the midpoint of the fracture unit and the center of the reservoir unit is:

[0074] [x i y i ](i=1,2,…,N)

[0075]

[0076] Among them, (x i ,y i ) represents the midpoint coordinate of the crack unit; N represents the number of crack units; are the center coordinates of the reservoir unit; M represents the number of reservoir units.

[0077] The calculation formula of the disturbance stress field of the hydraulic fracture is:

[0078]

[0079] In the formula,

[0080]

[0081]

[0082]

[0083]

[0084] in, represents the coordinates in the local coordinate system; β represents the angle between the local coordinates with the length direction of the crack unit j as the horizontal axis and the global coordinates; represents the disturbance stress field generated by hydraulic fracture unit j at reservoir unit i; C ij represents the displacement boundary influence coefficient; G ij Indicates the seam height correction factor; d ij represents the distance between the midpoint of fracture unit j and the center coordinate of reservoir unit i; H represents the height of hydraulic fracture; D n and D s They represent the normal displacement and tangential displacement of the crack unit respectively, and the normal displacement is the crack width.

[0085] In the embodiment of the present invention, there is one hydraulic fracture, the fracture height is 30.5 m, the fracture half length is 100 m, the net pressure in the fracture is 5.0 MPa, the Young's modulus is 32.6 GPa, the Poisson's ratio is 0.245, and the distribution of the disturbed stress field of the fracture in the reservoir is calculated based on the disturbed stress field of the hydraulic fracture. The results are as follows: Figure 4 As shown, the crack is along the direction of the maximum horizontal principal stress, that is, the x-axis direction. It can be found that the normal disturbance stress σ of the hydraulic fracture in the y direction yy The affected area is wide, and the degree of change in reservoir stress is large. However, the normal disturbance stress and shear stress in the x direction only exist in a small range of the fracturing cracks, and cannot constitute an effective disturbance to the adjacent well groups of group fracturing.

[0086] In step three, a calculation model for the width of the fracture along the length of the fracture is first established, and then the width of the support fracture at the end of the fracturing construction is calculated based on the field engineering parameters. The change of the width of the support fracture over time after the completion of the fracturing construction is further calculated by combining the fracture width attenuation coefficient obtained by the fracturing construction pressure curve analysis and the indoor test fitting. The relevant calculation formula is as follows:

[0087]

[0088] w1(x,y)=w0(x,y)·S

[0089] w(t)=w1·F(t)

[0090] Where w0(x, y) and w1(x, y) represent the fracture width and propping width of the fracture unit at (x, y), respectively; w(t) represents the propping width at time t after the fracturing is completed; E is the Young's modulus of the reservoir rock; v is the Poisson's ratio of the reservoir rock; H is the height of the fracture; p f (x, y) and σ n (x, y) represent the fluid pressure and normal ground stress acting on the fracture unit at (x, y), respectively; L represents the half-length of the fracture; S represents the sand ratio of the fracturing fluid; t represents time; and F(t) represents the fracture width attenuation coefficient.

[0091] In the embodiment of the present invention, the maximum horizontal principal stress is 75.8 MPa, the minimum horizontal principal stress is 61.5 MPa, and considering the uniform distribution of the fluid pressure in the seal, the fluid pressure is set to 62.5 MPa, 64.5 MPa, and 66.5 MPa, respectively, and the fracture width distribution under different fracture fluid pressures is obtained, as shown in FIG. Figure 5 As shown in the figure, the fluid pressure in the fracture is positively correlated with the fracture width. Increasing the fluid pressure will increase the fracture width, thereby increasing the stress disturbance effect between fractures.

[0092] In step four, firstly, the engineering data of the target fracturing block and the mathematical model of vertical well fracturing fracture stress disturbance are combined to analyze the scope and distribution law of fracturing fracture disturbance stress under different fracturing construction conditions; then, the well group combination mode of vertical well group fracturing is determined in combination with the geological characteristics and well network layout of the fracturing block; finally, based on the distribution law of disturbance stress and the well group mode of group fracturing, the fracturing sequence of multiple wells in the well group is optimized with the goal of reducing horizontal stress difference, promoting fracture turning and extension, and constructing a complex fracture network.

[0093] Combined with the mathematical model of vertical well fracturing fracture stress disturbance, the net pressure (i.e., p f (x,y)-σ n (x, y)) are the stress disturbances caused by single fracture and double fractures on the reservoir under the conditions of 3MPa, 6MPa and 9MPa, respectively. Figure 6 and Figure 7 As shown in the figure, the distance between the two cracks is 30m. As the net pressure in the crack increases, the range and value of the disturbance stress increase, and the crack stress disturbance is more obvious under the double-crack condition.

[0094] Combined with the engineering data of the fracturing block, it is found that there are three main types of fracturing well group combination modes in tight reservoir vertical well groups, such as Figure 8 As shown in the figure, the spacing between parallel cracks is 50m, the half-length of the crack is 100m, and the net pressure in the crack (i.e., p f (x,y)-σ n (x,y)) is 10MPa, and the stress disturbance distribution diagram along the y-axis direction under different well group combination modes is calculated based on the mathematical model of vertical well fracturing fracture stress disturbance, as shown in Figures 9 to 11 As shown. Under the condition that the number of wells in the well group is 5, when the well group combination mode 1 is adopted, the largest stress disturbance overlap area can be generated between adjacent vertical wells, and the disturbance effect generated at this time is the strongest; when the well group combination mode 2 is adopted, under the condition of staggered seams, the length of the overlap area of ​​the stress disturbance area along the x-axis is about half the seam length, and only the half-wing crack can be turned in the disturbance area; when the well group combination mode 3 is adopted, the two wells with a long distance, such as well A and well D, well B and well E, have less disturbance effect between the wells, while well C in the middle position can receive the maximum stress disturbance, and the two-wing cracks can be effectively deflected, which is easy to form complex fractures, but well A, well B, well D and well E cannot make the fractures turn in the effective stress disturbance area. Therefore, the analysis shows that the well group combination mode 1 is more suitable.

[0095] Combined with the distribution law of disturbance stress generated under single fracture and double fracture conditions and the well layout plan in well group combination mode 1, in order to fully reduce the horizontal stress difference and promote the diversion and extension of fractures, the cross fracturing mode can achieve better results. Figure 8 Taking the five wells of the well group combination mode 1 as an example, the specific steps include: (1) firstly, fracturing construction is carried out on well A. After the construction is completed, the fracturing cracks will form stress disturbance in the reservoir; (2) then fracturing construction is carried out on well C at a separated position. Under the condition of small well spacing, the disturbance stress generated by well A in well C will be diverted to a certain extent; (3) then fracturing operation is carried out on well C. Since well C is located between well A and well C, the horizontal stress difference in the well C area is significantly reduced due to the influence of the disturbance stress. The cracks in the fracturing can fully communicate the weak structural surface and divert to form a complex fracture network; (4) the same mode is adopted to fracturing well E at a separated position. After the construction is completed, well D in the overlapping area of ​​reservoir stress disturbance is fracturing. This mode is adopted to complete the fracturing operation of all vertical wells in the vertical well group fracturing well group.

[0096] In step five, the support width of the fracturing crack is calculated based on the fracturing construction parameters of the vertical wells in the target fracturing block and the monitoring results of the fracturing cracks in the adjacent wells. The change law of the support width after fracturing with time is calculated based on the analysis of the fracturing construction pressure curve and the fitting width attenuation coefficient of the indoor test. The support width at different times is substituted into the mathematical model of the vertical well fracturing crack stress disturbance, and the law of the disturbance stress in the reservoir at different times is calculated. With the goal of maximizing the reduction of reservoir stress difference and achieving fracturing crack diversion, the time interval of fracturing between the front and rear wells in the group's vertical well group is optimized.

[0097] Under the condition of well group combination mode 1 and staggered staged fracturing, when the fracturing of Well A is completed, the fracturing of Well C is immediately started. After the fracturing of Well C is completed, the propped fracture width attenuation function is used to calculate the propped fracture width values of Well A and Well C at three moments T1, T2, and T3 starting from the completion of the fracturing of Well C, where T1 < T2 < T3. Then, the mathematical model of stress disturbance of the fracturing fracture in a vertical well is used to calculate the distribution of reservoir disturbance stress at the three moments T1, T2, and T3, as Figure 12 to Figure 14 shown. It can be found that as time goes by (T1 < T2 < T3), the disturbance stress in the reservoir gradually decreases with the attenuation of the propped fracture width. To maximize the reduction of the reservoir stress difference and achieve the diversion of the fracturing fracture, it is recommended to start the fracturing of Well B at T1. The specific fracturing timing needs to be calculated by combining the fracture width attenuation coefficient obtained from on-site fitting to obtain the decreasing propped fracture width.

[0098] The embodiment of the present invention is based on the situation of only one fracturing crew. If there are multiple fracturing crews, it is recommended that the two fracturing crews operate simultaneously. Under the condition of well group combination mode 1, based on the analysis results, the fracturing sequence of multiple wells should be: Well A and Well C perform fracturing operations simultaneously, and after they are completed collaboratively, the fracturing construction of Well B and Well E is started, and the fracturing of the entire well group is completed in this order. The design of the fracturing time interval can be optimized according to Step 5.

[0099] The embodiment of the present invention provides an optimization design method for the staged fracturing of vertical wells in a tight reservoir, which is used to optimize the well group combination mode, the fracturing sequence of multiple wells, and the fracturing time interval in the staged fracturing process of vertical wells in a tight reservoir, avoid blindness in the construction design of the staged fracturing of vertical wells, make full use of the interference between fractures to increase the complexity of the fracture network, improve the reservoir stimulation volume and the degree of resource utilization, and achieve the efficient development of the tight reservoir. The embodiment of the present invention innovatively proposes an optimization design method for the staged fracturing of vertical wells in a tight reservoir. By comprehensively considering the stress disturbance of the fracturing fracture to the reservoir and the attenuation change of the propped fracture with time, it effectively solves the problems such as the well group combination mode, the fracturing sequence of multiple wells, and the fracturing time interval existing in the construction design of the staged fracturing of vertical wells in a tight reservoir, realizes the diversion and extension of the fracturing fracture, improves the fracturing effect of the reservoir, thereby increasing the single-well oil and gas production, reducing the comprehensive cost, and achieving benefit development.

[0100] Embodiment 2: The embodiment of the present invention provides a terminal device, which includes a memory, a processor, a communication interface, and a communication bus. A program that can run on the processor is stored in the memory. When the processor executes the program, it implements the optimization design method for the staged fracturing of vertical wells in a tight reservoir described in the above embodiment.

[0101] The processor may be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, field programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or a combination of the above chips.

[0102] The memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer executable programs and units, such as the corresponding program units in the above method embodiments of the present invention. The processor executes various functional applications of the processor and works data processing by running the non-transitory software programs, instructions and modules stored in the memory, that is, realizing the optimization design method for vertical well group fracturing in tight reservoirs described in the above embodiments.

[0103] The memory may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required by at least one function; the data storage area may store data created by the processor, etc. In addition, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. The memory may optionally include a memory remotely arranged relative to the processor, and these remote memories may be connected to the processor via a network. The one or more programs are stored in the memory, and when executed by the processor, the method for optimizing the design of the fracturing of a dense reservoir vertical well group described in the above embodiment is executed.

[0104] Embodiment 3: The embodiment of the present invention provides a storage medium for computer-readable storage, wherein the storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the method for optimizing the design of fracturing of a vertical well group in a tight reservoir as described in any one of the above method embodiments.

[0105] The storage medium may be an internal storage unit of the terminal device, such as a hard disk or memory of the terminal device. The storage medium may also be an external storage device of the terminal device, such as a plug-in hard disk, smart memory card, secure digital card, flash memory card, etc. equipped on the terminal device.

[0106] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A method for optimizing the design of vertical well fracturing in a tight reservoir, characterized in that The following steps are involved: Step 1: Collect geological and engineering data of the target area for fracturing; Step 2: Establish a mathematical model of vertical well fracturing fracture stress disturbance to simulate reservoir disturbance stress distribution; Step 3: Establish a mathematical model for the attenuation of crack support width to simulate the change of support width over time; Step 4: Determine the well group combination mode and multi-well fracturing sequence for vertical well group fracturing by combining engineering data with the stress disturbance mathematical model; Step 5: Based on the results of step 4, the fracturing time interval between vertical wells in the well group is designed in combination with the mathematical model of support fracture width attenuation.

2. The method for optimizing the design of a group of vertical well fracturing in a tight reservoir according to claim 1, characterized in that In step one: The geological data include reservoir thickness, reservoir geostress parameters, reservoir rock mechanics parameters, and comprehensive filtration coefficient of fracturing fluid; The engineering data parameters include the group fracturing well group combination mode, vertical well fracturing construction parameters, adjacent well fracturing crack length, crack width and crack height.

3. The method for optimizing the design of a group of vertical well fracturing in a tight reservoir according to claim 1 or 2, characterized in that Step 2 specifically includes the following steps: The diameter pressure fracture is discretized in the plane, and multiple one-dimensional fracture units are used to represent the hydraulic fracture. The coordinate matrix of the midpoint of the fracture unit is: [x i y i ](i=1,2,…,N) The reservoir is divided into units using uniform grid units, and two-dimensional rectangular units are used to represent the plane reservoir. The center coordinates of the reservoir unit are: The semi-analytical induced stress calculation method is used to calculate the disturbance of reservoir stress under the condition of hydraulic fractures in the reservoir. The calculation formula of the disturbance stress field is: In the formula, Among them, (x i ,y i ) represents the midpoint coordinate of the crack unit; N represents the number of crack units; is the center coordinate of the reservoir unit; M represents the number of reservoir units; represents the coordinates in the local coordinate system; β represents the angle between the local coordinates with the length direction of the crack unit j as the horizontal axis and the global coordinates; represents the disturbance stress field generated by hydraulic fracture unit j at reservoir unit i; C ij represents the displacement boundary influence coefficient; G ij Indicates the seam height correction factor; d ij represents the distance between the midpoint of fracture unit j and the center coordinate of reservoir unit i; H represents the height of hydraulic fracture; D n and D s represent the normal displacement and tangential displacement of the crack element respectively.

4. The method for optimizing the design of a group of vertical well fracturing in a tight reservoir according to claim 1 or 2, characterized in that In step three: The calculation formula for the crack width distribution along the crack length direction is: According to the fracturing construction parameters, the calculation formula of the support seam width under ideal filling conditions is: w1(x,y)=w0(x,y)·S After the fracturing operation is completed, the fracture width decays over time, and the calculation formula is: w(t)=w1·F(t) Where w0(x, y) and w1(x, y) represent the fracture width and propping width of the fracture unit at (x, y), respectively; w(t) represents the propping width at time t after the fracturing is completed; E is the Young's modulus of the reservoir rock; v is the Poisson's ratio of the reservoir rock; H is the height of the fracture; p f (x, y) and σ n (x, y) represent the fluid pressure and normal ground stress acting on the fracture unit at (x, y), respectively; L represents the half-length of the fracture; S represents the sand ratio of the fracturing fluid; t represents time; and F(t) represents the fracture width attenuation coefficient.

5. The method for optimizing the design of a group of vertical well fracturing in a tight reservoir according to claim 3, characterized in that In step three: The calculation formula for the crack width distribution along the crack length direction is: According to the fracturing construction parameters, the calculation formula of the support seam width under ideal filling conditions is: w1(x,y)=w0(x,y)·S After the fracturing operation is completed, the fracture width decays over time, and the calculation formula is: w(t)=w1·F(t) Where w0(x, y) and w1(x, y) represent the fracture width and propping width of the fracture unit at (x, y), respectively; w(t) represents the propping width at time t after the fracturing is completed; E is the Young's modulus of the reservoir rock; v is the Poisson's ratio of the reservoir rock; H is the height of the fracture; p f (x, y) and σ n (x, y) represent the fluid pressure and normal ground stress acting on the fracture unit at (x, y), respectively; L represents the half-length of the fracture; S represents the sand ratio of the fracturing fluid; t represents time; and F(t) represents the fracture width attenuation coefficient.

6. The method for optimizing the design of a group of vertical well fracturing in a tight reservoir according to claim 1, 2 or 5, characterized in that Step 4 specifically includes the following steps: Combining the engineering data of the target fracturing block with the mathematical model of vertical well fracturing fracture stress disturbance, the scope and distribution law of fracturing fracture disturbance stress under different fracturing construction conditions are analyzed; Combine the geological characteristics of the fracturing block with the well pattern layout to determine the well group combination mode for vertical well group fracturing; Based on the distribution law of disturbance stress and the well group pattern of group fracturing, the fracturing sequence of multiple wells in the well group is optimized with the goal of reducing horizontal stress difference, promoting fracture diversion and extension, and constructing a complex fracture network.

7. The method for optimizing the design of a group of vertical well fracturing in a tight reservoir according to claim 3, characterized in that Step 4 specifically includes the following steps: Combining the engineering data of the target fracturing block with the mathematical model of vertical well fracturing fracture stress disturbance, the scope and distribution law of fracturing fracture disturbance stress under different fracturing construction conditions are analyzed; Combine the geological characteristics of the fracturing block with the well pattern layout to determine the well group combination mode for vertical well group fracturing; Based on the distribution law of disturbance stress and the well group pattern of group fracturing, the fracturing sequence of multiple wells in the well group is optimized with the goal of reducing horizontal stress difference, promoting fracture diversion and extension, and constructing a complex fracture network.

8. The method for optimizing the design of a group of vertical well fracturing in a tight reservoir according to claim 1, 2, 5 or 7, characterized in that Step 5 specifically includes the following steps: Combined with the vertical well fracturing construction parameters of the adjacent wells in the target fracturing block and the monitoring results of the fracturing cracks in the adjacent wells, the width of the fracturing crack support is calculated; According to the analysis of the fracturing construction pressure curve and the fitting fracture width attenuation coefficient of the indoor test, the variation law of the support fracture width after fracturing with time is calculated; The support fracture width at different times is substituted into the mathematical model of vertical well fracturing fracture stress disturbance, and the law of disturbance stress in the reservoir at different times is calculated. The goal is to maximize the reduction of reservoir stress difference and achieve fracturing fracture diversion, and optimize the time interval of fracturing between the front and rear wells in the group's vertical well group.

9. A terminal device, comprising a memory and a processor, wherein the memory stores a program that can be run on the processor, characterized in that: When the processor executes the program, the method for optimizing the design of fracturing of a vertical well group in a tight reservoir as described in any one of claims 1 to 8 is implemented.

10. A storage medium, characterized in that: The storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the method for optimizing the design of vertical well fracturing in a tight reservoir as described in any one of claims 1 to 8.

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