Well group refracturing method and oil exploitation method

Abstract

The invention provides a well group refracturing method and an oil exploitation method. The well group refracturing method comprises the steps that n oil wells to be taken are determined in m oil wells according to the oil production; characteristic indexes of the n oil wells to be taken are obtained, and energy complementation operation is conducted on the n oil wells to be taken according to the characteristic indexes; utilizing fracturing software to determine fracturing construction parameters of each oil well in the n oil wells to be measured according to the measured well spacing and row spacing of the well pattern, reservoir physical property parameters of each oil well in the n oil wells to be measured and a set target coverage rate of a fracture covering well pattern area; and performing repeated fracturing construction on the oil wells to be taken according to the fracturing construction parameters of each oil well to be taken. By supplementing energy before fracturing, complex cracks can be formed more easily during fracturing, and construction of an underground complex crack network is achieved. The set target coverage rate of the area of the well pattern covered by the cracks serves as the target, the fracturing scale of the well pattern is planned and optimized as a whole, the overall oil extraction speed of the well pattern can be increased, and the recovery efficiency of the well pattern is improved.

Description

Technical Field

[0001] The invention relates to the technical field of oil production, and in particular to a well group repeated fracturing method and an oil production method. Background Art

[0002] During the development process of many oil fields, the reservoir as a whole may show "double low" development characteristics. At present, there are many low-yield wells in ultra-low permeability reservoirs, accounting for a large proportion, and the low average daily production of a single well is the main problem that plagues oil extraction. At present, low-yield wells are distributed in clusters in some blocks, and these low-yield wells distributed in clusters are the main targets for measures to tap their potential. Conventional measures mainly focus on repeated fracturing, but the existing repeated fracturing method has a small lateral sweep range (30 meters), an effective rate of 81%, and a daily increase of 0.9t / d per well. The fracturing measures of the existing technology have low efficiency and oil increase, and they decrease rapidly, and cannot achieve the purpose of improving the overall development effect of the reservoir. Therefore, there is an urgent need for a well group repeated fracturing method that can increase the lateral sweep volume of the fracture, mobilize the lateral residual oil, and thus improve the overall development effect of the well group, so as to achieve overall production and efficiency improvement in low-yield areas. Summary of the invention

[0003] In view of this, the present invention provides a well group repeated fracturing method and an oil production method, which solves the problem that the efficiency and oil increase of fracturing measures in the existing oil production field are low, the decline is fast, and the overall development effect of the oil reservoir cannot be improved.

[0004] In order to solve the above technical problems, a specific embodiment of the present invention provides a well group repeated fracturing method, wherein the well group includes a well network consisting of m oil wells, m is an integer greater than or equal to 1, and the well group repeated fracturing method includes: determining n simulated measure oil wells among the m oil wells according to oil production, wherein n is an integer greater than or equal to 1 and less than or equal to m; obtaining characteristic indicators of the n simulated measure oil wells, and performing energy replenishment operations on the n simulated measure oil wells according to the characteristic indicators; using fracturing software, according to the measured well spacing, row spacing and reservoir physical properties of each oil well in the n simulated measure oil wells, and the set target coverage rate of fractures covering the well network area, determining the fracturing construction parameters of each oil well in the n simulated measure oil wells; and performing repeated fracturing construction on the simulated measure oil wells according to the fracturing construction parameters of each of the simulated measure oil wells.

[0005] According to the well group refracturing method of the embodiments of the present invention, n proposed measure wells can be determined from m oil wells according to the oil production; by obtaining the characteristic indexes of the n proposed measure wells, energy supplement operations can be performed on the n proposed measure wells according to the characteristic indexes; by supplementing energy before fracturing, the two-way stress difference in the near-wellbore area can be reduced, and during fracturing, it is easier to form complex fractures and realize the construction of an underground complex fracture network. Using fracturing software, according to the well spacing, row spacing of the well pattern measured, and the reservoir physical property parameters of each of the n proposed measure wells, as well as the target coverage rate of the fracture coverage area of the well pattern set, the fracturing construction parameters of each of the n proposed measure wells can be determined; thus, refracturing construction can be carried out on the proposed measure wells according to the fracturing construction parameters of each proposed measure well. It can be understood that taking the target coverage rate of the fracture coverage area of the well pattern set, such as 60%, as the goal, overall optimizing the fracturing scale of the well pattern can construct an underground fracture network system of the well pattern, thereby improving the overall oil production rate of the well pattern, increasing the recovery rate of the well pattern, and realizing the effective treatment of regional contiguous low-yield wells.

[0006] In some examples, the step of obtaining the characteristic indexes of the n proposed measure wells and performing energy supplement operations on the n proposed measure wells according to the characteristic indexes includes: obtaining the characteristic indexes of each of the proposed measure wells, calculating the pressure maintenance level of each of the proposed measure wells according to the characteristic indexes; determining the energy supplement liquid volume value of each of the proposed measure wells according to the pressure maintenance level and the mapping relationship between the energy supplement liquid volume and the pressure maintenance level; and injecting energy supplement liquid into each of the proposed measure wells according to the energy supplement liquid volume value.

[0007] In some examples, the step of obtaining the characteristic indexes of each of the proposed measure wells and calculating the pressure maintenance level of each of the proposed measure wells according to the characteristic indexes includes: obtaining the shut-in pressure, pay zone depth, fluid level height, density of the oil-water mixture in the well, and original formation pressure of each of the proposed measure wells; and calculating the pressure maintenance level of each of the proposed measure wells according to the shut-in pressure, the pay zone depth, the fluid level height, the density of the oil-water mixture in the well, and the original formation pressure.

[0008] In some examples, the well pattern is a rhombus, m is 8, one oil well is arranged at each of the 4 vertices of the rhombus, and one oil well is arranged at the midpoint of each of the 4 sides of the rhombus. The step of injecting energy supplement liquid into each of the proposed measure wells according to the energy supplement liquid volume value includes: supplementing energy to the proposed measure wells at the two vertices connected by the long diagonal of the rhombus; supplementing energy to the proposed measure wells at the two vertices connected by the short diagonal of the rhombus; and supplementing energy to the proposed measure wells on the 4 sides of the rhombus.

[0009] In some examples, before the step of performing refracturing on each of the proposed treatment wells according to the fracturing construction parameters of each of the proposed treatment wells, the well group refracturing method further includes: detecting the water content of each of the proposed treatment wells to obtain a water content detection result; and when the water content detection result meets a set threshold range, taking a precipitation measure corresponding to the threshold range.

[0010] In some examples, the step of taking a precipitation measure corresponding to the threshold range when the water content detection result meets the set threshold range includes: when the water content detection result is greater than 60%, placing a water control material in the corresponding proposed treatment well; when the water content detection result is greater than 30% and less than or equal to 60%, adding a temporary plugging agent to the fractures in the corresponding proposed treatment well in multiple times.

[0011] In some examples, the fracturing construction parameters include the amount of fracturing sand, the amount of fracturing fluid, and the displacement of the mixture composed of fracturing sand and fracturing fluid.

[0012] In some examples, when performing refracturing on each of the proposed treatment wells according to the fracturing construction parameters of each of the proposed treatment wells, an adjacent well synchronous construction strategy is adopted.

[0013] The specific embodiment of the present invention provides an oil extraction method, including: according to the well group refracturing method as described above; performing shut-in on each of the wells after fracturing, and when the shut-in meets the end condition, the shut-in ends and oil extraction begins.

[0014] According to the oil extraction method of the embodiment of the present invention, performing shut-in on each of the wells after fracturing, and when the shut-in meets the end condition, the shut-in ends and oil extraction begins. It can reduce the adverse effects caused by too long shut-in on the reservoir, thereby facilitating the smooth progress of oil extraction.

[0015] In some examples, the step of performing shut-in on each of the wells after fracturing, and when the shut-in meets the end condition, the shut-in ends and oil extraction begins includes: installing a pressure gauge at the wellhead of each of the wells after fracturing; drawing a pressure-time curve in real time according to the value of the pressure gauge, and when the slope of the pressure-time curve changes, the shut-in ends and oil extraction begins.

[0016] It should be understood that the above general description and the following specific embodiments are only exemplary and explanatory, and they cannot limit the scope claimed by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 Schematically shown is a flowchart of a method for repeated fracturing of a well group according to an embodiment of the present invention.

[0019] Figure 2 Schematically shown is a flowchart of steps for obtaining characteristic indexes of n proposed treatment oil wells and performing energy supplementation operations on the n proposed treatment oil wells according to the characteristic indexes according to an embodiment of the present invention.

[0020] Figure 3 Schematically shown is a flowchart of steps for obtaining characteristic indexes of each proposed treatment oil well and calculating the pressure maintenance level of each proposed treatment oil well according to the characteristic indexes according to an embodiment of the present invention.

[0021] Figure 4 Schematically shown is a pre-fracturing energy increase - pressure level diagram according to an embodiment of the present invention.

[0022] Figure 5 Schematically shown is a schematic diagram of a well group according to an embodiment of the present invention.

[0023] Figure 6 Schematically shown is a flowchart of steps for injecting energy supplementation fluid into each proposed treatment oil well according to the energy supplementation fluid volume value according to an embodiment of the present invention.

[0024] Figure 7 Schematically shown is a flowchart of a method for repeated fracturing of a well group according to an embodiment of the present invention.

[0025] Figure 8 Schematically shown is a flowchart of a petroleum extraction method according to an embodiment of the present invention.

[0026] Figure 9 Schematically shown is a flowchart of steps for shutting in each fractured oil well, and when the shut-in meets the end condition, the shut-in ends and petroleum extraction begins according to an embodiment of the present invention. Detailed implementation manners

[0027] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0028] The following detailed descriptions are all exemplary descriptions, aiming to provide further details of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. The terms used in the present invention are only for describing specific embodiments and are not intended to limit the exemplary embodiments of the present invention.

[0029] The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not limit the present invention. Additionally, elements / components with the same or similar reference numerals used in the drawings and embodiments are used to represent the same or similar parts.

[0030] Regarding the "first", "second",... used herein, they do not particularly refer to the meaning of order or sequence, nor are they used to limit the present invention. They are only used to distinguish elements or operations described with the same technical terms.

[0031] Regarding the directional terms used herein, such as: up, down, left, right, front or back, etc., they are only references to the directions in the drawings. Therefore, the directional terms used are for explanation and not for limiting the creation.

[0032] Regarding the "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, that is, they mean including but not limited to.

[0033] Regarding the "and / or" used herein, it includes any one or all combinations of the described things.

[0034] Regarding the "multiple" herein, it includes "two" and "more than two"; regarding the "multiple groups" herein, it includes "two groups" and "more than two groups".

[0035] Regarding the terms "substantially", "about", etc. used herein, they are used to modify any quantity or error that can vary slightly, but these slight variations or errors will not change their essence. Generally, the range of such slight variations or errors modified by such terms can be 20% in some embodiments, 10% in some embodiments, 5% in some embodiments, or other values in some embodiments. Those skilled in the art should understand that the aforementioned values can be adjusted according to actual needs and are not limited thereto.

[0036] All terms used herein (including technical and scientific terms) have the meaning commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used here should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0037] Those skilled in the art will also appreciate that any transitional conjunction and / or phrase that represents two or more optional items, whether in the specification, claims or drawings, should be understood to include the possibility of one of these items, either of these items, or both items. For example, the phrase "A or B" should be understood to include the possibility of "A" or "B", or "A and B".

[0038] During the development process of many oil fields, the reservoir as a whole may show "double low" development characteristics. At present, there are many low-yield wells in ultra-low permeability reservoirs, accounting for a large proportion, and the low average daily production of a single well is the main problem that plagues oil extraction. At present, low-yield wells are distributed in clusters in some blocks, and these low-yield wells distributed in clusters are the main targets for measures to tap their potential. Conventional measures mainly focus on repeated fracturing, but the existing repeated fracturing method has a small lateral sweep range (30 meters), the measure has an efficiency of 81%, and the daily oil increase of a single well is 0.9t / d. The efficiency and oil increase of the existing technology are low and decrease rapidly, and cannot achieve the purpose of improving the overall development effect of the reservoir. Therefore, there is an urgent need for a well group repeated fracturing method that can increase the lateral sweep volume of the fracture, mobilize the lateral residual oil, and thus improve the overall development effect of the well group, so as to achieve overall production and efficiency improvement in low-yield areas.

[0039] Reference below Figures 1-9 A well group re-fracturing method and an oil production method according to an embodiment of the present invention are described.

[0040] Figure 1 The flowchart of the well group repeated fracturing method according to an embodiment of the present invention is schematically shown. The well group includes a well pattern consisting of m oil wells, where m is an integer greater than or equal to 1.

[0041] like Figure 1 As shown, the well group repeated fracturing method of this embodiment includes operations S110 to S140.

[0042] In operation S110, n proposed oil wells are determined from the m oil wells according to the oil production, where n is an integer greater than or equal to 1 and less than or equal to m. It can be understood that the oil production can be daily oil production, monthly oil production or annual oil production, which can be obtained according to measurement.

[0043] In some examples, when the oil production of an oil well is less than a set threshold, the oil production of the oil well is considered to be low, and therefore measures need to be taken to improve the oil production of the oil well whose oil production is less than the set threshold, and the oil well whose oil production is less than the set threshold is determined as a proposed measure well.

[0044] In operation S120, characteristic indicators of n pseudo-measure oil wells are obtained, and energy replenishment operations are performed on the n pseudo-measure oil wells according to the characteristic indicators.

[0045] As a possible implementation method,Figure 2 As shown in Figure 2 , the steps of operation S120 to obtain the characteristic indexes of n proposed measure oil wells and perform energy supplementation operations on the n proposed measure oil wells according to the characteristic indexes include operations S121 to S123.

[0046] In operation S121, obtain the characteristic indexes of each proposed measure oil well, and calculate the pressure maintenance level of each proposed measure oil well according to the characteristic indexes.

[0047] In some specific examples, such as Figure 3 As shown in Figure 3 , the steps of operation S121 to obtain the characteristic indexes of each proposed measure oil well and calculate the pressure maintenance level of each proposed measure oil well according to the characteristic indexes include operations S1211 and S1212.

[0048] In operation S1211, obtain the shut-in pressure, pay zone depth, flowing fluid level height, density of the oil-water mixture in the well, and original formation pressure of each proposed measure oil well. Here, the original formation pressure can be understood as the pressure in the well measured after the new drilling of the oil well is successful.

[0049] In operation S1212, calculate the pressure maintenance level of each proposed measure oil well according to the shut-in pressure, pay zone depth, flowing fluid level height, density of the oil-water mixture in the well, and original formation pressure.

[0050] It can be understood that the shut-in pressure, pay zone depth, flowing fluid level height, and density of the oil-water mixture in the well can all be measured. Thus, the pressure maintenance level of each proposed measure oil well can be obtained through formula (1). Here, the pressure maintenance level can be represented by P, the shut-in pressure by P1, the pay zone depth by H, the flowing fluid level height by h, the density of the oil-water mixture in the well by ρ, the original formation pressure by P i represented by P0, and the gravity coefficient by g.

[0051]

[0052] Thus, through operations S1211 and S1212, it is convenient to obtain the characteristic indexes of each proposed measure oil well and calculate the pressure maintenance level of each proposed measure oil well according to the characteristic indexes.

[0053] In operation S122, determine the energy supplementation liquid volume value of each proposed measure oil well according to the pressure maintenance level and the mapping relationship between the energy supplementation liquid volume and the pressure maintenance level.

[0054] In some examples, the mapping relationship between the energy supplementation liquid volume and the pressure maintenance level can be in the form of a table, and the mapping relationship between the energy supplementation liquid volume and the pressure maintenance level can also be in the form of a graph, such as Figure 4 the pre-fracture energy increase - pressure level graph shown in Figure 4 . Figure 4The vertical coordinate pressure level in it is the pressure holding level, and the abscissa pre-pressure increased energy is the energy supplement liquid volume. Therefore, after obtaining the pressure holding level, through Figure 4 the required energy supplement liquid volume can be obtained.

[0055] In operation S123, according to the energy supplement liquid volume value, inject energy supplement liquid into each planned measure oil well.

[0056] As an implementable way, such as Figure 5 shown, the well pattern can be diamond-shaped, m is 8, one oil well is arranged at each of the 4 vertices of the diamond, and one oil well is arranged at the midpoint of each of the 4 sides of the diamond. As Figure 6 shown, the steps of operation S123 injecting energy supplement liquid into each planned measure oil well according to the energy supplement liquid volume value include operations S1231 to S1233.

[0057] In operation S1231, perform energy supplementation on the planned measure oil wells at the two vertices connected by the long diagonal of the diamond.

[0058] In operation S1232, perform energy supplementation on the planned measure oil wells at the two vertices connected by the short diagonal of the diamond.

[0059] In operation S1233, perform energy supplementation on the planned measure oil wells on the 4 sides of the diamond.

[0060] It can be understood that by designing the well pattern as a diamond shape and performing energy supplementation through operations S1231 to S1233, the overall pressure balance of the well pattern can be achieved, thereby achieving the overall fracture extension balance of the well pattern.

[0061] Through operations S121 to S123, it is convenient to obtain the characteristic indexes of n planned measure oil wells, and perform energy supplementation operations on the n planned measure oil wells according to the characteristic indexes.

[0062] In operation S130, using fracturing software, according to the measured well spacing, row spacing of the well pattern, and reservoir physical property parameters of each oil well in the n planned measure oil wells, as well as the set target coverage rate of the fracture covering the well pattern area, determine the fracturing construction parameters of each oil well in the n planned measure oil wells. It can be understood that the well spacing is the distance between two adjacent oil wells in the well pattern. For example, in a diamond-shaped well pattern, the well spacing can be the distance between two adjacent oil wells on each side of the diamond. The row spacing can be understood as the distance between two adjacent rows of oil wells in the well pattern. The reservoir physical property parameters can include porosity, permeability, rock brittleness, Poisson's ratio, Young's modulus, etc. Input the well spacing, row spacing of the well pattern, reservoir physical property parameters of each oil well in the n planned measure oil wells, and the set target coverage rate of the fracture covering the well pattern area into the fracturing software, and the fracturing software can analyze the corresponding fracturing construction parameters.

[0063] In some examples, the fracturing construction parameters may include the amount of fracturing sand, the amount of fracturing fluid, and the displacement of the mixture composed of fracturing sand and fracturing fluid.

[0064] In operation S140, refracturing construction is carried out on the wells to be treated according to the fracturing construction parameters of each well to be treated.

[0065] According to the well group refracturing method of the embodiments of the present invention, n wells to be treated can be determined from m wells according to the oil production; by obtaining the characteristic indexes of the n wells to be treated, energy supplementation operations can be carried out on the n wells to be treated according to the characteristic indexes; by supplementing energy before fracturing, the two-way stress difference in the near-well zone can be reduced, and when fracturing, it is easier to form complex fractures, realizing the construction of an underground complex fracture network. Using fracturing software, according to the well spacing, row spacing of the well pattern measured, the reservoir physical property parameters of each well among the n wells to be treated, and the set target coverage rate of the fracture covering the well pattern area, the fracturing construction parameters of each well among the n wells to be treated can be determined; thus, refracturing construction can be carried out on the wells to be treated according to the fracturing construction parameters of each well to be treated. It can be understood that taking the set target coverage rate of the fracture covering the well pattern area, such as 60%, as the target, overall optimizing the fracturing scale of the well pattern, an underground fracture network system of the well pattern can be constructed, thereby improving the overall oil production rate of the well pattern, increasing the recovery rate of the well pattern, and realizing the effective treatment of regional contiguous low-yield wells.

[0066] According to some embodiments of the present invention, before the step of carrying out refracturing construction on the wells to be treated according to the fracturing construction parameters of each well to be treated in operation S140, as Figure 7 shown, the well group refracturing method further includes operation S001 and operation S002.

[0067] In operation S001, the water content of each well to be treated is detected to obtain the water content detection result.

[0068] In operation S002, when the water content detection result meets the set threshold range, the corresponding water precipitation measure is taken. Thus, through operation S001 and operation S002, water precipitation measures can be taken for the excess water affecting the oil production of the wells, thereby increasing the oil production of the well pattern.

[0069] In some specific examples, the step of taking the corresponding water precipitation measure when the water content detection result meets the set threshold range in operation S002 includes operation S0021 and operation S0022.

[0070] In operation S0021, when the water content detection result is greater than 60%, a water control material is placed in the corresponding well to be treated, and the water control material can absorb water, thereby realizing water control and oil increase.

[0071] In operation S0022, when the water content detection result is greater than 30% and less than or equal to 60%, the temporary plugging agent is added to the fractures in the corresponding candidate wells in multiple times, thereby improving the lateral transformation ability and the transformation effect.

[0072] According to some embodiments of the present invention, when performing refracturing construction on candidate wells according to the fracturing construction parameters of each candidate well, the strategy of synchronous construction of adjacent wells is adopted. Thereby, the well interference can be utilized to form more complex fractures.

[0073] As Figure 8 shown, the oil production method according to the embodiment of the present invention includes the well group refracturing method and operation S200 as described above.

[0074] In operation S200, each well that has completed fracturing is shut in. When the shut-in meets the end condition, the shut-in ends and the oil production begins.

[0075] As a possible implementation manner, as Figure 9 shown, the step of operation S200 of shutting in each well that has completed fracturing and ending the shut-in and starting the oil production when the shut-in meets the end condition includes operation S201 and operation S202.

[0076] In operation S201, a pressure gauge is installed at the wellhead of each well that has completed fracturing.

[0077] In operation S202, a pressure-time curve is plotted in real time according to the value of the pressure gauge. When the slope of the pressure-time curve changes, the shut-in ends and the oil production begins.

[0078] It can be understood that during the shut-in, in the dialysis replacement stage, the pressure drop changes rapidly; after the dialysis equilibrium, the pressure drop slows down. Therefore, when the slope of the pressure-time curve changes, it indicates that the dialysis replacement stage has turned to the dialysis equilibrium stage, and the oil production can be carried out after the dialysis equilibrium. Taking the change of the slope of the pressure-time curve as the end condition of the shut-in can optimize the optimal shut-in time and avoid the adverse effects on the reservoir caused by over-long shut-in.

[0079] According to the oil production method of the embodiment of the present invention, each well that has completed fracturing is shut in. When the shut-in meets the end condition, the shut-in ends and the oil production begins. It can reduce the adverse effects on the reservoir caused by over-long shut-in, thereby facilitating the smooth progress of oil production.

[0080] As is known to those skilled in the art, the present invention can be implemented by other embodiments that do not depart from its spiritual essence or essential features. Therefore, the above-disclosed embodiments are illustrative in all aspects and not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that modifications or equivalent substitutions can still be made to the specific embodiments of the present invention. Any modification or equivalent substitution that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for repeated fracturing of a well group, the well group comprising a well pattern composed of m oil wells, where m is an integer greater than or equal to 1, characterized in that, The well group refracturing method includes the following steps: Determine n candidate wells to be treated among the m oil wells according to the oil production, where n is an integer greater than or equal to 1 and less than or equal to m; Obtain the characteristic indexes of the n candidate wells to be treated, and perform energy replenishment operations on the n candidate wells to be treated according to the characteristic indexes; Using fracturing software, determine the fracturing construction parameters for each of the n candidate wells to be treated according to the measured well spacing, row spacing of the well pattern, reservoir physical property parameters of each of the n candidate wells to be treated, and the target coverage rate of the fractures covering the well pattern area; and Perform refracturing construction on the candidate wells to be treated according to the fracturing construction parameters of each candidate well to be treated.

2. The method for repeated fracturing of a well group according to claim 1, characterized in that, The steps of obtaining the characteristic indexes of the n candidate wells to be treated and performing energy replenishment operations on the n candidate wells to be treated according to the characteristic indexes include: Obtain the characteristic indexes of each candidate well to be treated, and calculate the pressure maintenance level of each candidate well to be treated according to the characteristic indexes; Determine the energy replenishment fluid volume value for each candidate well to be treated according to the pressure maintenance level and the mapping relationship between the energy replenishment fluid volume and the pressure maintenance level; and Inject energy replenishment fluid into each candidate well to be treated according to the energy replenishment fluid volume value.

3. The method for repeated fracturing of a well group according to claim 2, characterized in that, The steps of obtaining the characteristic indexes of each candidate well to be treated and calculating the pressure maintenance level of each candidate well to be treated according to the characteristic indexes include: Obtain the shut-in pressure, pay zone depth, flowing fluid level height, density of the oil-water mixture in the well, and original formation pressure of each candidate well to be treated; and Calculate the pressure maintenance level of each candidate well to be treated according to the shut-in pressure, the pay zone depth, the flowing fluid level height, the density of the oil-water mixture in the well, and the original formation pressure.

4. The method for repeated fracturing of a well group according to claim 2, characterized in that, The well pattern is a rhombus, m is 8, one oil well is arranged at each of the 4 vertices of the rhombus, and one oil well is arranged at the midpoint of each of the 4 sides of the rhombus. The steps of injecting energy replenishment fluid into each candidate well to be treated according to the energy replenishment fluid volume value include: Perform energy replenishment on the candidate wells to be treated at the two vertices connected by the long diagonal of the rhombus; Perform energy replenishment on the candidate wells to be treated at the two vertices connected by the short diagonal of the rhombus; Perform energy replenishment on the candidate wells to be treated on the 4 sides of the rhombus.

5. The method for repeated fracturing of a well group according to claim 1, wherein Before the step of performing refracturing construction on the candidate wells to be treated according to the fracturing construction parameters of each candidate well to be treated, the well group refracturing method further includes: Detect the water content of each candidate well to be treated to obtain a water content detection result; and When the water content detection result meets the set threshold range, take the precipitation measures corresponding to the threshold range.

6. The method for repeated fracturing of a well group according to claim 5, wherein, The steps of taking the precipitation measures corresponding to the threshold range when the water content detection result meets the set threshold range include: When the water content detection result is greater than 60%, place water control materials in the corresponding candidate well to be treated; When the water content detection result is greater than 30% and less than or equal to 60%, add temporary plugging agents to the fractures in the corresponding candidate well to be treated in multiple times.

7. The method for repeated fracturing of a well group according to claim 1, wherein The fracturing construction parameters include the amount of fracturing sand, the amount of fracturing fluid, and the displacement of the mixture composed of fracturing sand and fracturing fluid.

8. The method for repeated fracturing of a well group according to any one of claims 1 to 7, characterized in that, When performing repeated fracturing construction on the proposed treatment oil wells according to the fracturing construction parameters of each proposed treatment oil well, a strategy of synchronous construction of adjacent oil wells is adopted.

9. An oil extraction method, characterized in that, including: The method for repeated fracturing of a well group according to any one of claims 1 to 8; Each of the fractured oil wells is shut in. When the shut-in meets the end condition, the shut-in ends and oil production begins.

10. The oil extraction method according to claim 9, characterized in that, The step of shutting in each of the fractured oil wells and starting oil production when the shut-in meets the end condition includes: Install a pressure gauge at the wellhead of each of the fractured oil wells; Draw a pressure-time curve in real time according to the value of the pressure gauge. When the slope of the pressure-time curve changes, the shut-in ends and oil production begins.

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