A method and apparatus for deep shale fracturing

Abstract

This invention provides a method and apparatus for deep shale fracturing. The method includes: collecting relevant parameters of the current fracturing section; calculating the real-time net pressure of the fracture body during fracturing operations at the current and previous times based on the relevant parameters, obtaining the net pressure change rate of the fracture body at the current time; monitoring the fracture volume on both sides of the wellbore at the current time, calculating the degree of non-uniform distribution of the fracture body at the current time; determining the state of the fracture body on both sides of the wellbore at the current time based on the degree of non-uniform distribution and the net pressure change rate, and taking corresponding construction optimization measures based on the state of the fracture body on both sides of the wellbore at the current time; and continuing the above steps until the fracturing operation of the current section is completed. The advantages of this invention are: judging the fracture body state and optimizing construction by using the net pressure change rate and the degree of fracture distribution in the wellbore improves the accuracy of the judgment results and facilitates on-site operation.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling and production technology, and more specifically, to a method and apparatus for deep shale fracturing. Background Technology

[0002] my country possesses significant potential for deep shale gas resources and will be the mainstay of future shale gas production capacity development. Hydraulic fractures are the flow channels for shale gas production, and complex fracture networks play a decisive role in the effectiveness of stimulation. According to statistics from deep shale gas reservoirs in Sichuan, Chongqing, and Hubei, the reservoir closure pressure (90-100 MPa) is generally 10-25 MPa higher than that of shallower reservoirs, and the horizontal stress difference (16-35 MPa) is 6-10 MPa higher, making fracture propagation more difficult and hindering the formation of complex fractures. As the stress difference increases, core fracturing tests and numerical simulations show that the fracture morphology changes from "main fracture + branch fractures" to "main fracture." Microseismic monitoring results from most deep shale gas wells indicate simple fracturing morphology and small stimulation volume, which is a key factor determining the tested production level. Currently, the main fracturing technology for deep shale formations employs a multi-cluster, high-volume, high-intensity proppant injection, and temporary plugging and redirection fracturing model within a single segment. This model utilizes a composite temporary plugging and redirection fracturing process primarily based on soluble plugging balls and soluble plugging agents to increase the volume of fracturing and fracture complexity. For fracture monitoring, methods such as microseismic analysis, tracers, and distributed optical fiber are used for assessment. However, tracers and distributed optical fiber only provide effective guidance during the flowback phase after fracturing operations. During hydraulic fracturing, fracture propagation is often monitored using single microseismic monitoring for fracture morphology. However, the number of microseismic events per segment is relatively small, sometimes insufficient to effectively assess fracture propagation, and the method is limited and has a certain time lag.

[0003] Therefore, based on the above problems, a new method is needed to guide on-site construction optimization and solve the problems of uneven fracture propagation morphology, low fracture complexity, and low stimulation volume during deep shale fracturing. This method provides a new fracture evaluation method for deep shale based on comprehensive monitoring and real-time fracturing data. By combining monitoring and real-time fracturing data to comprehensively evaluate fracture morphology, composite temporary plugging can be used in a timely manner to improve uneven fracture propagation, increase fracture complexity, and improve stimulation volume.

[0004] Chinese patent application CN201810225668.4, publication number CN108959679A, entitled "An Evaluation Method and Device for the Fracturing Effect of Shale Gas Wells," discloses an evaluation method and device for the fracturing effect of shale gas wells, relating to the field of hydraulic fracturing construction technology. However, this evaluation method does not specify any related optimization schemes. Furthermore, this technical solution utilizes flowback data after shale gas well fracturing for evaluation, which introduces a certain degree of lag.

[0005] Application number "CN202010121944.X" and titled "A Fracturing Method for Increasing the Stimulation Volume of Deep Shale Gas Reservoirs" discloses a fracturing method for increasing the stimulation volume of deep shale gas reservoirs, comprising the following steps: perforation operation; acid treatment; creating the main fracture using a high-viscosity adhesive; injecting low-viscosity slickwater carrying 40-70 mesh proppant for end-sand removal operation; injecting acid; injecting low-viscosity slickwater carrying 140-230 mesh proppant; injecting medium-viscosity and high-viscosity slickwater carrying 70-140 mesh proppant; injecting high-viscosity adhesive carrying 40-70 mesh proppant; performing displacement operation; inserting a bridge plug; and repeating the above steps until all sections are constructed. This invention utilizes an end-sand removal method to increase the net pressure within the fracture, reducing the difficulty of opening bedding fractures and high-angle fractures, and increasing fracture complexity. Simultaneously, by using slickwater of varying viscosities and proppant of different particle sizes, it achieves saturated filling of multi-scale fractures, significantly increasing the effective stimulation volume of deep shale gas reservoirs. However, this method and the technology described in this application belong to completely different fields. Summary of the Invention

[0006] The purpose of this invention is to address at least one of the aforementioned shortcomings of the prior art. For example, an objective of this invention is to provide a convenient and accurate method for deep shale fracturing, and another objective of this invention is to provide a convenient and accurate device for deep shale fracturing.

[0007] To achieve the above objectives, the present invention provides a method for deep shale fracturing, the fracturing method comprising the following steps:

[0008] Collect relevant parameters for the current fracturing operation section;

[0009] Based on the relevant parameters, calculate the real-time net pressure of the fracture body during the fracturing operation at the current moment and the previous moment, and obtain the rate of change of net pressure of the fracture body at the current moment.

[0010] Monitor the volume of fractures on both sides of the wellbore at the current moment, and calculate the degree of non-uniform distribution of fractures at the current moment based on the volume of fractures on both sides of the wellbore at the current moment;

[0011] Based on the degree of non-uniform distribution of the fracture body and the rate of change of net pressure at the current moment, the state of the fracture body on both sides of the wellbore at the current moment is determined, and corresponding construction optimization measures are taken according to the state of the fracture body on both sides of the wellbore at the current moment.

[0012] Continue the above steps until the fracturing operation of the current well section is completed.

[0013] In an exemplary embodiment of the present invention, the relevant parameters may include one or more of the following: displacement, pump pressure, liquid viscosity, density, proppant density, concentration, length of the modified section, inclination depth, vertical depth, formation pressure, horizontal stress difference, casing size, number of perforation clusters, perforation location, number of perforations, fracture extension pressure, pump shutdown pressure, wellhead pressure, fracturing fluid hydrostatic pressure, fracturing fluid friction, perforation orifice friction, near-wellbore bending friction, and closure pressure.

[0014] In an exemplary embodiment of the present invention, the real-time net pressure can be calculated using Equation 1, which is:

[0015] P net =P wh +P h -P f -P perf -P near -P c

[0016] Among them, P net Real-time net pressure, MPa; P wh P represents the wellhead pressure, in MPa. h P is the hydrostatic pressure of the fracturing fluid, in MPa; f For fracturing fluid friction, MPa; P perf The friction of the perforation hole is measured in MPa and P. near Near-well bending friction, MPa; P c The closing pressure is MPa.

[0017] In an exemplary embodiment of the present invention, monitoring the fracture volume on both sides of the wellbore at the current moment may include:

[0018] By combining ground-based dense array energy scanning four-dimensional imaging for fracturing fracture monitoring and wide-area electromagnetic monitoring, the distribution of fractures during fracturing operations can be monitored, and the length, width, and height of fractures on both sides of the wellbore can be obtained, thereby determining the volume of the fractures.

[0019] In an exemplary embodiment of the present invention, the degree of non-uniform distribution of the crack body can be calculated by Equation 2, which is:

[0020] V i =ΔV / V=|V e -V w | / (V e +V w )

[0021] Among them, V i The degree of non-uniformity of the crack distribution at the current moment; ΔV is the change in crack volume, in meters. 3 V represents the crack volume, in meters. 3 Ve V w These represent the volumes of the fractures on both sides of the wellbore, in meters. 3 .

[0022] In an exemplary embodiment of the present invention, determining the state of the fractures on both sides of the wellbore at the current moment based on the degree of non-uniform distribution of the fractures and the net pressure change rate at the current moment may include:

[0023] If the non-uniformity of the crack distribution has not reached the critical point at the current moment, determine the magnitude of the change in net pressure and take corresponding optimized construction measures based on the magnitude of the change in net pressure.

[0024] When the non-uniform distribution of the crack body reaches a critical point at the current moment, corresponding optimized construction measures are taken according to the change in net pressure.

[0025] Among them, determining whether the degree of non-uniform distribution of the crack body has reached the critical point includes:

[0026] When V i When x < x, the degree of non-uniform distribution of the crack body has not reached the critical point;

[0027] When V i When x ≥ x, the degree of non-uniform distribution of the crack body reaches the critical point;

[0028] Among them, V i The degree of non-uniform distribution of the crack body is represented by %, and x is the critical point, where 15% ≤ x ≤ 25%.

[0029] In an exemplary embodiment of the present invention, the net pressure change rate can be calculated using Equation 3, which is:

[0030]

[0031] Where P(i) is the net pressure change rate, %; ΔPnet is the net pressure change value, MPa; and Pnet(i) is the net pressure change value. i Net pressure of the fracture body at time t, MPa; Pnet(ia) is t i-a The net pressure of the fracture body at any given time, in MPa; 'a' is the time interval.

[0032] In an exemplary embodiment of the present invention, the method may further include repeating the above steps to complete the fracturing construction of all well sections, thereby achieving a higher fracture sweep range for a single well and increasing the stimulation volume of deep shale gas wells.

[0033] In an exemplary embodiment of the present invention, when the degree of non-uniformity of the crack body has not reached a critical point at the current moment, determining the magnitude of the change in net pressure and taking corresponding optimized construction measures based on the magnitude of the change in net pressure may include:

[0034] When the degree of non-uniform distribution of fractures has not reached the critical point and the net pressure change rate is <10%, it is judged that the expansion on both sides of the wellbore is relatively uniform and the net pressure change value is small, and the pumping procedure can be implemented according to the original plan.

[0035] When the degree of non-uniform distribution of fractures has not reached the critical point and 10% < net pressure change rate < 20%, it is judged that the expansion on both sides of the wellbore is relatively uniform but the fluctuation of net pressure value is small. If the fluctuation frequency is high, general strength reversal can be implemented.

[0036] When the degree of non-uniform distribution of the fracture body has not reached the critical point and the net pressure change rate is >20%, it is judged that the expansion on both sides of the wellbore is relatively uniform but the net pressure value fluctuates greatly. If the fluctuation frequency is high, the construction pressure limit and the size of the current construction pressure safety window are calculated. If conditions permit, high-intensity diversion can be implemented.

[0037] In an exemplary embodiment of the present invention, when the non-uniform distribution of the crack body reaches a critical point at the current moment, the corresponding optimized construction measures that can be taken according to the change in net pressure include:

[0038] When the degree of non-uniform distribution of fractures reaches the critical point and the net pressure change rate is <10%, it is determined that the expansion on both sides of the wellbore is severely uneven but the net pressure change value is small, and general strength diversion can be implemented.

[0039] When the degree of non-uniform distribution of fractures reaches the critical point and 10% < net pressure change rate < 20%, it is judged that the expansion on both sides of the wellbore is severely uneven and the fluctuation of net pressure value is small, and a medium-intensity diversion is implemented.

[0040] When the degree of non-uniform distribution of the fracture reaches the critical point and the net pressure change is greater than 20%, it is determined that the expansion on both sides of the wellbore is relatively uniform but the net pressure value fluctuates greatly. The construction pressure limit and the size of the current construction pressure safety window are calculated, and high-intensity diversion is implemented when conditions permit.

[0041] In an exemplary embodiment of the present invention, the fracturing construction method may further include a step of determining whether the fracture body covers the current fracturing construction section during the fracturing construction process, and stopping the fracturing construction when the fracture body has covered the entire modified section.

[0042] Another aspect of the present invention provides a deep shale fracturing construction device, the device comprising:

[0043] The acquisition module can be used to obtain relevant parameters of the current fracturing operation section;

[0044] The monitoring module can be used to monitor the volume of fractures on both sides of the wellbore at the current moment and whether the fractures cover the current fracturing operation section.

[0045] The calculation module can be used to calculate the net pressure change rate of the fracture body and the degree of non-uniform distribution of the fracture body at the current moment based on the relevant parameters of the current fracturing operation well section.

[0046] The judgment module can be used to determine the state of the crack body based on the net pressure variation rate of the crack body at the current moment and the degree of non-uniform distribution of the crack body, and output the next construction optimization measures instruction according to the state of the crack body.

[0047] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0048] (1) Combining the net pressure change rate with the degree of non-uniform crack propagation to evaluate and analyze crack propagation improves the accuracy of the evaluation results;

[0049] (2) By analyzing the net pressure change rate and the degree of non-uniform crack propagation, optimization and repeated optimization are carried out in real time under different judgment conditions, so as to conduct a more intuitive analysis of crack propagation. Attached Figure Description

[0050] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings and examples, wherein:

[0051] Figure 1 A schematic flowchart of a deep shale fracturing construction method according to an exemplary embodiment of the present invention is shown;

[0052] Figure 2 This paper illustrates a crack state judgment and construction optimization measures when the crack body has not reached the critical point, according to an exemplary embodiment of the present invention.

[0053] Figure 3 The present invention illustrates a crack state judgment and construction optimization measures when a crack reaches a critical point according to an exemplary embodiment of the present invention.

[0054] Figure 4 A schematic diagram of the extended volume of the fracture body on both sides of the wellbore obtained according to a specific example of the present invention is shown;

[0055] Figure 5a A schematic diagram of the crack ripples on both sides of the wellbore before temporary plugging is shown in a specific example according to the present invention;

[0056] Figure 5b This diagram illustrates a comparison of the crack ripples on both sides of the wellbore before and after temporary plugging, according to a specific example of the present invention.

[0057] Figure 6 A schematic diagram illustrating the determination of stable net pressure with relatively uniform extension on both sides according to a specific example of the present invention is shown, and the original pumping procedure is implemented accordingly.

[0058] Figure 7a This diagram illustrates a comparison of the implementation of a composite temporary shunting procedure before and after a slight increase in net pressure and uneven extension on both sides, according to a specific example of the present invention.

[0059] Figure 7b Another schematic diagram shows a comparison before and after implementing a composite temporary blockage and steering procedure in a specific example of the present invention, where the net pressure rises slightly and the uneven extension extends on both sides, thus optimizing the pumping procedure.

[0060] Figure 8 It shows Figure 7b Schematic diagram of crack extension before and after the first and second temporary plugging. Detailed Implementation

[0061] In the following sections, a deep shale fracturing construction method and apparatus of the present invention will be described in detail with reference to exemplary embodiments.

[0062] It should be noted that terms such as "first" and "second" are merely for ease of description and distinction, and should not be interpreted as indicating or implying relative importance. Terms such as "upper," "lower," "inner," and "outer" are merely for ease of description and to establish relative orientation or positional relationships, and do not indicate or imply that the component referred to must have that specific orientation or position.

[0063] Figure 1 A schematic flowchart of a deep shale fracturing construction method according to an exemplary embodiment of the present invention is shown; Figure 2 This paper illustrates a crack state judgment and construction optimization measures when the crack body has not reached the critical point, according to an exemplary embodiment of the present invention. Figure 3 This paper illustrates a method for judging the state of a crack body when it reaches a critical point and optimizing construction, according to an exemplary embodiment of the present invention.

[0064] In a first exemplary embodiment of the present invention, as Figure 1 As shown, the deep shale fracturing construction method may include the following steps:

[0065] First, collect relevant parameters for the current fracturing section. These parameters may include one or more of the following: flow rate, pump pressure, fluid viscosity, density, proppant density, concentration, length of the fracturing section, inclination depth, vertical depth, formation pressure, horizontal stress difference, casing size, number of perforation clusters, perforation location, number of perforations, fracture propagation pressure, pump shutdown pressure, wellhead pressure, fracturing fluid hydrostatic pressure, fracturing fluid friction, perforation hole friction, near-wellbore tortuosity friction, and closure pressure. Among these, flow rate, pump pressure, fluid viscosity, density, proppant density, concentration, fracture propagation pressure, pump shutdown pressure, wellhead pressure, fracturing fluid hydrostatic pressure, fracturing fluid friction, perforation hole friction, near-wellbore tortuosity friction, and closure pressure are real-time values ​​that vary over time.

[0066] Secondly, based on the relevant parameters collected in the previous step, the real-time net pressure of the fracture body during the fracturing operation is calculated between the current moment and the previous moment, thus obtaining the rate of change of net pressure of the fracture body at the current moment. Here, the time interval between the current moment and the previous moment can be 3 to 7 seconds, for example, 5 seconds. Specifically, the real-time net pressure value at the current moment during the operation is calculated by combining parameters such as fracturing operation parameters, wellbore parameters, geological parameters, fracture extension pressure, and pump shutdown pressure, and the net pressure change value of the fracture body within the 3 to 7 second time interval between the current moment and the current moment, thereby obtaining the rate of change of net pressure of the fracture body at the current moment.

[0067] During construction, the volume of the cracks on both sides of the wellbore is monitored at all times, and the degree of non-uniform distribution of the cracks at the current moment is calculated based on the current volume of the cracks on both sides of the wellbore.

[0068] Based on the degree of non-uniform distribution of the fracture body and the rate of change of net pressure at the current moment, the state of the fracture body on both sides of the wellbore at the current moment is determined, and corresponding construction optimization measures are then taken based on the state of the fracture body on both sides of the wellbore at the current moment. Specifically, based on the degree of non-uniform distribution of the fracture body and the range of the rate of change of net pressure, it is determined whether the non-uniform expansion on both sides of the wellbore of the fractured modified body is serious, whether it has not covered the entire modified section, and whether the net pressure has changed significantly. The next construction step is optimized under different judgment conditions.

[0069] Continue the above steps until the fracturing operation of the current well section is completed. Finally, repeat the above steps to optimize the fracturing process for each section, providing real-time guidance for the on-site fracturing operation, thereby achieving a higher fracture reach and larger volume of workpieces per well.

[0070] In this exemplary embodiment, the real-time net pressure can be calculated using Equation 1, which is:

[0071] P net =P wh +P h -P f -P perf -P near -P c

[0072] Among them, P net Real-time net pressure, MPa; P wh P represents the wellhead pressure, in MPa. h P is the hydrostatic pressure of the fracturing fluid, in MPa; f For fracturing fluid friction, MPa; P perf The friction of the perforation hole is measured in MPa and P. near Near-well bending friction, MPa; P cThe closing pressure is measured in MPa. Here, the closing pressure is obtained through pre-construction fracturing curve G-function testing or micro-injection testing (DFIT). Testing the fracturing flow reduction can correct for fluid friction, near-wellbore friction, and perforation friction.

[0073] In this exemplary embodiment, monitoring the fracture volume on both sides of the wellbore at the current moment may include:

[0074] This invention utilizes a combination of ground-based dense array energy scanning four-dimensional imaging for fracturing fracture monitoring and wide-area electromagnetic monitoring to jointly monitor fracture distribution during fracturing operations. This allows for the determination of the length, width, and height of fractures on both sides of the wellbore, thus providing the fracture volume. Currently, fracture monitoring primarily employs methods such as microseismic monitoring, tracers, and distributed optical fiber. However, tracers and distributed optical fiber only provide effective guidance after the fracturing operation and during the flowback phase. During hydraulic fracturing, fracture propagation is often monitored using single microseismic monitoring for fracture morphology. However, the number of individual microseismic events is limited, sometimes failing to provide effective assessment of fracture propagation, and the methods are limited and have a certain time lag. This invention combines ground-based dense array energy scanning four-dimensional imaging for fracturing fracture monitoring with wide-area electromagnetic monitoring to jointly monitor fracture propagation, providing accurate and timely results. By incorporating real-time net pressure changes during fracturing operations to determine the fracture state, the accuracy of the assessment is improved. This method is intuitive and convenient for on-site operation, and is beneficial for increasing the complexity of deep shale fracturing fractures and the volume of impact, thereby achieving production targets.

[0075] In this exemplary embodiment, the degree of non-uniform distribution of the crack body can be calculated using Equation 2, which is:

[0076] V i =ΔV / V=|V e -V w | / (V e +V w )

[0077] Among them, V i The degree of non-uniformity of the crack distribution at the current moment; ΔV is the change in crack volume, in meters. 3 V represents the volume of the crack, in meters. 3 V e V w These represent the volumes of fractures on both sides of the wellbore, in meters. 3 Here, by defining the degree of non-uniform distribution of the crack body, a method is provided to quantitatively describe the uniformity of the crack body.

[0078] In this exemplary embodiment, determining the state of the fractures on both sides of the wellbore at the current moment based on the degree of non-uniform distribution of the fractures and the net pressure change rate at the current moment may include:

[0079] If the non-uniform distribution of the crack body has not reached the critical point at the current moment, determine the magnitude of the change in net pressure, and take corresponding optimized construction measures based on the magnitude of the change in net pressure.

[0080] When the non-uniform distribution of the crack reaches a critical point at the current moment, corresponding optimized construction measures are taken based on the change in net pressure.

[0081] Specifically, based on the comprehensive monitoring of the modified volume and the real-time net pressure change value, it is determined whether the non-uniform expansion on both sides of the wellbore of the fracture modified body is serious, whether there are individual clusters of dominant expansion that do not cover the entire modified section, and whether the net pressure changes significantly. Under different judgment conditions, the next construction steps are optimized, and composite temporary plugging is carried out in a timely manner to improve the perforation cluster opening rate, the uniform extension of the fractures on both sides of the wellbore, and to try to affect the unmodified blank areas, thereby increasing the scope of the modification.

[0082] Among them, determining whether the degree of non-uniform distribution of the crack body has reached the critical point includes:

[0083] When V i When x < x, the degree of non-uniform distribution of the crack body has not reached the critical point;

[0084] When V i When x ≥ x, the degree of non-uniform distribution of the crack body reaches the critical point;

[0085] Among them, V i The degree of non-uniform distribution of the crack body is represented by %, and x is the critical point, where 15% ≤ x ≤ 25%.

[0086] In this exemplary embodiment, the net pressure change rate can be calculated using Equation 3, which is:

[0087]

[0088] Where P(i) is the net pressure change rate, %; ΔPnet is the net pressure change value, MPa; and Pnet(i) is the net pressure change value. i Net pressure of the fracture body at time t, MPa; Pnet(ia) is t i-a The net pressure of the fracture body at any given time, in MPa; 'a' is the time interval.

[0089] Here, by dividing the range of net pressure change values ​​within the crack body and setting different ranges of net pressure change rates, the influence of natural cracks on the corresponding construction process in different ranges is refined. Here, t is denoted as... i If t is the current time, then i+1 This refers to the previous time point, which is a predetermined time interval from the current time.

[0090] In this exemplary embodiment, the method may further include repeating the above steps to complete fracturing operations in all well sections, achieving a higher fracture reach in a single well and increasing the stimulation volume of deep shale gas wells. Specifically, the method optimizes the fracturing process for all well sections by repeating the fracturing steps for a single well section, providing real-time guidance for the on-site fracturing process, thereby achieving a higher fracture reach and stimulation volume in a single well.

[0091] In this exemplary embodiment, determining the magnitude of the change in net pressure when the non-uniform distribution of the crack body has not reached a critical point at the current moment, and taking corresponding optimized construction measures based on the magnitude of the change in net pressure, may include:

[0092] When the degree of non-uniform distribution of fractures has not reached the critical point and the net pressure change rate is <10%, it is judged that the expansion on both sides of the wellbore is relatively uniform and the net pressure change value is small, and the pumping procedure can be implemented according to the original plan.

[0093] When the degree of non-uniform distribution of fractures has not reached the critical point and 10% < net pressure change rate < 20%, it is judged that the expansion on both sides of the wellbore is relatively uniform but the fluctuation of net pressure value is small. If the fluctuation frequency is large, general intensity reversal can be implemented.

[0094] When the degree of non-uniform distribution of the fracture body has not reached the critical point and the net pressure change rate is >20%, it is judged that the expansion on both sides of the wellbore is relatively uniform but the net pressure value fluctuates greatly. If the fluctuation frequency is high, the construction pressure limit and the size of the current construction pressure safety window are calculated. If conditions permit, high-intensity diversion can be implemented.

[0095] Specifically, such as Figure 2 As shown, when the degree of non-uniform distribution of the fracture body does not reach the critical point, i.e., ΔV / V < 20%, the net pressure change rate P(i) < 10%, which indicates that the expansion on both sides of the wellbore is relatively uniform and the net pressure change value is small and less affected by natural fractures. The fracturing operation is carried out according to the original pumping procedure.

[0096] When the non-uniform distribution of fractures has not reached the critical point (ΔV / V < 20%), and 10% < P(i) < 20%, it indicates that the wellbore expansion is relatively uniform on both sides, but the net pressure value fluctuates slightly, which is influenced to some extent by natural fractures. If the fluctuation frequency is high (e.g., the net pressure value fluctuates up and down within several predetermined time intervals), general intensity redirection can be considered. Here, general intensity redirection refers to redirecting the fractures by deploying a smaller amount of temporary plugging balls and plugging agents to suppress non-uniform fracture expansion and achieve more uniform reservoir stimulation. The amount of temporary plugging material needs to be optimized in real time on site; for example, it is advisable to increase the construction pressure by 1-3 MPa after the temporary plugging material is in place.

[0097] When the non-uniform distribution of the fracture body has not reached the critical point, i.e., ΔV / V < 20%, and P(i) > 20%, it indicates that the expansion on both sides of the wellbore is relatively uniform, but the net pressure value fluctuates greatly, and is greatly affected by natural fractures. If the fluctuation frequency is high, calculate the construction pressure limit and the size of the current construction pressure safety window, and consider high-strength diversion under the condition that allows.

[0098] In this exemplary embodiment, a high-intensity diversion can be achieved by deploying a larger amount of temporary plugging material. Once the temporary plugging material is in place, the construction pressure at the same displacement increases by more than 5 MPa, thus achieving high-intensity diversion. Here, high-intensity diversion refers to deploying a larger amount of temporary plugging balls and plugging agent to divert the flow, sealing more perforations after temporary plugging. This is equivalent to first sealing the original dominant fluid inlet orifice, modifying previously unmodified areas. Typically, the overall construction pressure will increase somewhat, thus suppressing non-uniform fracture propagation and achieving more uniform reservoir modification. The amount of temporary plugging material used needs to be optimized in real-time on-site; for example, it is advisable to achieve a pressure increase of more than 5 MPa at the same displacement after the temporary plugging material is in place.

[0099] Furthermore, the high-strength diversion involves applying a larger amount of temporary plugging material for diversion. After temporary plugging, a significant number of perforations are sealed, essentially sealing the original dominant fluid inlet and modifying previously untouched areas. This typically increases the overall construction pressure, suppressing non-uniform fracture propagation and achieving more uniform reservoir modification. The amount of temporary plugging material used needs to be determined based on real-time optimization on-site.

[0100] In this exemplary embodiment, when the non-uniform distribution of the crack body reaches a critical point at the current moment, the corresponding optimized construction measures that can be taken based on the change in net pressure include:

[0101] When the degree of non-uniform distribution of fractures reaches the critical point and the net pressure change rate is <10%, it is determined that the expansion on both sides of the wellbore is severely uneven but the net pressure change value is small, and general strength diversion can be implemented.

[0102] When the degree of non-uniform distribution of fractures reaches the critical point and 10% < net pressure change rate < 20%, it is determined that the expansion on both sides of the wellbore is severely uneven and the fluctuation of net pressure value is small, and a medium-intensity diversion is implemented.

[0103] In this exemplary embodiment, a preset amount of temporary blocking material can be added. When the temporary blocking material is in place, the construction pressure increases by 3 to 5 MPa for the same displacement, thus achieving a medium-intensity turn.

[0104] Furthermore, the medium-intensity diversion involves applying a pre-measured amount of temporary plugging material to divert the flow. This temporary plugging seals a significant number of perforations, essentially sealing the original dominant fluid inlet and modifying previously untouched areas. This typically increases the overall construction pressure, suppressing non-uniform fracture propagation and achieving more uniform reservoir modification. The amount of temporary plugging material used needs to be determined based on real-time optimization on-site.

[0105] When the degree of non-uniform distribution of the fracture reaches the critical point and the net pressure change is greater than 20%, it is determined that the expansion on both sides of the wellbore is relatively uniform but the net pressure value fluctuates greatly. The construction pressure limit and the size of the current construction pressure safety window are calculated, and high-intensity diversion is implemented when conditions permit.

[0106] Specifically, such as Figure 3 As shown, when the degree of non-uniform fracture distribution reaches the critical point (ΔV / V ≥ 20%), and the net pressure change rate P(i) < 10%, it indicates that the expansion on both sides of the wellbore is severely uneven, but the net pressure change value is small and less affected by natural fractures. Therefore, general intensity redirection should be considered. Here, general intensity redirection refers to using a smaller amount of temporary plugging balls and plugging agent to redirect the fracture, thereby suppressing non-uniform fracture expansion and achieving more uniform reservoir stimulation. The amount of temporary plugging material needs to be optimized in real-time on-site; for example, it is advisable to increase the construction pressure by 1–3 MPa at the same displacement after the temporary plugging material is in place.

[0107] When the non-uniform distribution of fractures has not reached the critical point (ΔV / V ≥ 20%), and 10% < P(i) < 20%, it indicates severe uneven expansion on both sides of the wellbore and slight fluctuations in net pressure, which is influenced to some extent by natural fractures. In this case, a medium-intensity diversion should be considered. Here, medium-intensity diversion refers to deploying a certain amount of temporary plugging balls and plugging agent to divert the flow. After temporary plugging, many perforations are sealed, essentially sealing the original dominant fluid inlet and modifying previously unmodified areas. This typically leads to a certain increase in overall construction pressure, suppressing non-uniform fracture expansion and achieving more uniform reservoir modification. The amount of temporary plugging material needs to be optimized in real-time on-site; for example, a 3-5 MPa increase in construction pressure at the same flow rate after the temporary plugging material is in place is preferable.

[0108] When the non-uniform distribution of fractures has not reached the critical point (ΔV / V ≥ 20%), and P(i) > 20%, it indicates that the expansion on both sides of the wellbore is relatively uniform, but the net pressure value fluctuates significantly, indicating a large influence from natural fractures. The construction pressure limit and the current safe pressure window should be calculated, and high-intensity diversion should be considered if conditions permit. Here, high-intensity diversion refers to diverting the flow by deploying a larger amount of temporary plugging balls and plugging agents. After temporary plugging, more perforations are sealed, essentially sealing the original dominant fluid inlet and modifying previously unmodified areas. This typically increases the overall construction pressure, thus suppressing non-uniform fracture expansion and achieving more uniform reservoir modification. The amount of temporary plugging material needs to be optimized in real-time on-site; for example, it is advisable to increase the construction pressure by more than 5 MPa at the same flow rate after the temporary plugging material is in place.

[0109] In this exemplary embodiment, the fracturing construction method may further include a step of determining whether the fracture body covers the current fracturing construction section during the fracturing construction process, and stopping the fracturing construction when the fracture body has covered the entire modified section.

[0110] In a second exemplary embodiment of the present invention, the deep shale fracturing construction device includes an acquisition module, a monitoring module, a calculation module, and a judgment module.

[0111] The acquisition module can be used to obtain relevant parameters for the current fracturing operation section. These parameters include fracturing operation parameters, wellbore parameters, and geological parameters.

[0112] The monitoring module can be used to monitor the volume of fractures on both sides of the wellbore at the current moment and whether the fractures cover the current fracturing operation section.

[0113] The calculation module can be used to calculate the net pressure change rate of the fracture body and the degree of non-uniform distribution of the fracture body at the current moment based on the relevant parameters of the current fracturing construction well section.

[0114] The judgment module can be used to determine the state of the crack body based on the net pressure variation rate of the crack body at the current moment and the degree of non-uniform distribution of the crack body, and output the next construction optimization measures instruction according to the state of the crack body.

[0115] Figure 4 A schematic diagram of the extended volume of the fracture body on both sides of the wellbore obtained according to a specific example of the present invention is shown; Figure 5a A schematic diagram of the crack ripples on both sides of the wellbore before temporary plugging is shown in a specific example according to the present invention; Figure 5b This diagram illustrates a comparison of the crack ripples on both sides of the wellbore before and after temporary plugging, according to a specific example of the present invention. Figure 6 A schematic diagram illustrating the determination of stable net pressure with relatively uniform extension on both sides according to a specific example of the present invention is shown, and the original pumping procedure is implemented accordingly. Figure 7aA comparative schematic diagram (wide-area electromagnetic monitoring) is shown before and after implementing a composite temporary blockage and steering procedure in a specific example of the present invention, where the net pressure rises slightly and extends unevenly on both sides. Figure 7b Another schematic diagram showing the comparison before and after implementing the composite temporary blockage and steering procedure for optimizing the pumping procedure with a slight increase in net pressure and uneven extension on both sides according to a specific example of the present invention (ground-based dense array energy scanning four-dimensional image monitoring); Figure 8 It shows Figure 7b Schematic diagram of crack extension before and after the first and second temporary plugging.

[0116] To better understand the exemplary embodiments of the present invention described above, further explanation is provided below with reference to specific examples.

[0117] Taking the fracturing and stimulation of the 13th section of well XX as an example, the critical point x of this section is taken as 20%, the monitoring time step is taken as 5s, and the fracturing displacement is 18m³. 3 / min, pump pressure 74~78MPa, liquid viscosity 3mPa·s, density 1000kg / m³ 3 The unit proppant density is 70 / 140, and the bulk density of the quartz sand is 1.38 g / cm³. 3 The bulk density of 70 / 140 mesh ceramsite is 1.43 g / cm³. 3 The bulk density of 40 / 70 mesh ceramsite is 1.43 g / cm³. 3 Concentration of 200 kg / m³ 3 The unit has a modified section length of 70m, an inclination depth of 4550~4620m, a vertical depth of 3570.39~3572.20m, a formation pressure of 71.6MPa, a horizontal stress difference of 14MPa, a casing size of 5 1 / 2, a perforation cluster of 9, a perforation cluster spacing of 7.5m, and a total of 45 perforations.

[0118] The real-time net pressure and net pressure change rate during construction were calculated, as shown in Table 1. The volume of the fractures on both sides of the wellbore and the degree of non-uniform distribution of the fractures at the current moment were obtained through comprehensive monitoring of the modified volume. Table 2 shows the corresponding net pressure and net pressure change rate of the fractures in Table 1. In Table 2, a time step of 5 seconds is defined as t. i Net pressure at time and t i-5s The absolute value of the change in net pressure at any given time is the change in net pressure ΔPne, and the rate of change in net pressure is defined as P(i).

[0119] Table 1: t i The relevant parameters of the fracture bodies on both sides of the wellbore and the degree of non-uniform distribution of the fracture bodies are recorded.

[0120]

[0121] Table 2: Net pressure and net pressure change rate of the corresponding fracture body in Table 1

[0122]

[0123] During the construction process, the results of comprehensive monitoring of the modified volume using ground-based dense array energy scanning four-dimensional imaging fracturing crack monitoring and wide-area electromagnetic monitoring showed that the non-uniform distribution of the cracks on both sides of the wellbore reached the critical point ΔV / V≥20%, and the net pressure change rate P(i) reached 12.5%. This indicates that the two non-uniform expansions of the wellbore were quite severe and greatly affected by natural cracks, requiring strong temporary plugging and diversion. After the temporary plugging ball and temporary plugging agent were added, the construction pressure for the same displacement needed to be increased by more than 5MPa to achieve the effect of increasing the overall modified volume.

[0124] like Figure 7a As shown, according to wide-area electromagnetic monitoring, the fracture volume before the first temporary plugging was 31×10⁻⁶. 4 m 3 The fracture volume was 44×10 mm before the second temporary plugging, after the first temporary plugging. 4 m 3 After the second temporary plugging, the fracture volume was 54×10. 4 m 3 .like Figure 7b As shown, based on the ground-based dense array energy scanning four-dimensional image monitoring of fracturing fractures, the fracture volume before the first temporary plugging was 62×10⁻⁶. 4 m 3 The fracture volume was 83×10 mm before the second temporary plugging, after the first temporary plugging. 4 m 3 After the second temporary plugging, the fracture volume was 97×10. 4 m 3 As can be seen, although the crack volume obtained by the two monitoring methods differs significantly, the net pressure change rate is very close, which improves the accuracy of the composite temporary plugging steering.

[0125] In summary, the advantages proposed by this invention include at least the following:

[0126] (1) The present invention can solve the problems of the current method of crack morphology monitoring and propagation based on single microseismic monitoring, which is limited in number of single microseismic events and sometimes cannot provide effective judgment on crack propagation, and has a certain time lag. By monitoring crack propagation together with two crack monitoring methods and cooperating with real-time net pressure determination during fracturing construction, the accuracy of judgment is improved. It is intuitive and easy to operate on site, which is conducive to improving the complexity of deep shale fracturing cracks and the volume of the transformation wave.

[0127] (2) The present invention can timely and effectively determine the underground crack expansion state by adopting the method of comprehensive monitoring of deep shale and real-time data crack evaluation of fracturing, which is conducive to the optimization of composite temporary plugging machine and provides real-time and accurate guidance for subsequent construction pump sequence optimization.

[0128] Although a deep shale fracturing construction method and apparatus of the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A method of fracturing a deep shale formation, the method comprising: The fracturing operation method comprises the steps of: collecting relevant parameters of the current fracturing operation well section; calculating the real-time net pressure of the fracture body in the current time and the last time in the fracturing operation process according to the relevant parameters, and obtaining the net pressure change rate of the fracture body in the current time; The real-time net pressure is calculated by formula 1, formula 1 is, wherein, is the real-time net pressure, Mpa; is the wellhead pressure, Mpa; is the fracturing fluid hydrostatic pressure, Mpa; is the fracturing fluid friction, ; is the perforation hole friction, Mpa; is the near-wellbore tortuosity friction, Mpa; is the closure pressure, Mpa; The net pressure change rate can be calculated by formula 3, formula 3 is: wherein, is the net pressure change rate, %; is the net pressure change value, Mpa; is is the net pressure of the fracture body at the moment, Mpa; is is the net pressure of the fracture body at the moment, Mpa; a is the time interval; monitoring the volume of the fracture body on both sides of the wellbore at the current time, and calculating the non-uniform distribution degree of the fracture body at the current time according to the volume of the fracture body on both sides of the wellbore at the current time; The monitoring of the volume of the fracture body on both sides of the wellbore at the current time comprises: monitoring the fracture body distribution in the fracturing operation process by using ground dense array energy scanning four-dimensional image fracturing fracture monitoring and wide area electromagnetic monitoring, obtaining the length, width and height of the fracture body on both sides of the wellbore, and thus obtaining the volume of the fracture body; The non-uniform distribution degree of the fracture body is calculated by formula 2, formula 2 is, wherein, is the degree of non-uniform distribution of the fracture body at the current time; is the fracture volume change amount, m 3 ; is the fracture volume, m 3 ; , are the fracture volumes on both sides of the wellbore, m 3 ; According to the non-uniform distribution degree and the net pressure change rate of the fracture body at the current time, the state of the fracture body on both sides of the wellbore at the current time is judged, and corresponding operation optimization measures are taken according to the state of the fracture body on both sides of the wellbore at the current time; The above steps are continuously performed until the fracturing operation of the current well section is completed.

2. The deep shale fracturing job method of claim 1, wherein, The relevant parameters include one or more of displacement, pump pressure, liquid viscosity, density, proppant density, concentration, reformation section length, inclination depth, vertical depth, formation pressure, horizontal stress difference, casing size, perforation cluster number, perforation position, perforation hole number, fracture extension pressure, pump shutdown pressure, wellhead pressure, fracturing fluid hydrostatic pressure, fracturing fluid friction, perforation hole friction, near-wellbore tortuosity friction, and closure pressure.

3. The deep shale fracturing job method of claim 1, wherein, The judgment of the state of the fracture body on both sides of the wellbore at the current time according to the non-uniform distribution degree and the net pressure change rate of the fracture body at the current time comprises: In the case that the non-uniform distribution degree of the fracture body at the current time does not reach the critical point, the change amplitude of the net pressure is judged, and corresponding optimization operation measures are taken according to the change amplitude of the net pressure; In the case that the non-uniform distribution degree of the fracture body at the current time reaches the critical point, corresponding optimization operation measures are taken according to the change amplitude of the net pressure; Wherein, whether the non-uniform distribution degree of the fracture body reaches the critical point comprises: When ＜x The degree of non-uniform distribution of the fracture body does not reach the critical point. When ≥x The degree of non-uniform distribution of the fracture body reaches a critical point. wherein, is the degree of non-uniform distribution of the cracks, x is the critical point, 15%≤ x ≤25%.

4. The deep shale fracturing job method of claim 1, wherein, The method further comprises repeating the above steps to complete the fracturing operation of all well sections, to achieve higher fracture sweep range of a single well, and to improve the reformation volume of deep shale gas wells.

5. The deep shale fracturing job method of claim 3, wherein, The judgment of the change amplitude of the net pressure in the case that the non-uniform distribution degree of the fracture body at the current time does not reach the critical point, and the corresponding optimization operation measures taken according to the change amplitude of the net pressure comprise: When the non-uniform distribution degree of the fracture body does not reach the critical point and the net pressure change rate is less than 10%, it is judged that the expansion on both sides of the wellbore is relatively uniform and the net pressure change value is small, and the original pumping program is implemented; When the non-uniform distribution degree of the fracture body does not reach the critical point and 10% < net pressure change rate < 20%, it is judged that the expansion on both sides of the wellbore is relatively uniform but the fluctuation amplitude of the net pressure value is small, and if the fluctuation frequency is high, general intensity steering is implemented; When the non-uniform distribution degree of the fracture body does not reach the critical point and the net pressure change rate is greater than 20%, it is judged that the expansion on both sides of the wellbore is relatively uniform, but the fluctuation range of the net pressure value is large, if the fluctuation frequency is high, the construction limited pressure and the size of the safe window of the current construction pressure are calculated, and high-intensity steering is implemented under the condition of allowing.

6. The deep shale fracturing job method of claim 3, wherein, The corresponding optimization construction measures according to the change range of the net pressure when the non-uniform distribution degree of the fracture body at the current moment reaches the critical point include: When the non-uniform distribution degree of the fracture body reaches the critical point and the net pressure change rate is less than 10%, it is judged that the expansion on both sides of the wellbore is seriously non-uniform, but the net pressure change value is small, and general-intensity steering is implemented. When the non-uniform distribution degree of the fracture body reaches the critical point and the net pressure change rate is greater than 20%, it is judged that the expansion on both sides of the wellbore is relatively uniform, but the fluctuation range of the net pressure value is large, the construction limited pressure and the size of the safe window of the current construction pressure are calculated, and high-intensity steering is implemented under the condition of allowing. The fracturing construction method further includes the step of judging whether the fracture body covers the current fracturing construction well section during the fracturing construction, and stopping the fracturing construction when the fracture body has covered the entire reconstruction section.

7. The deep shale fracturing job method of claim 1, wherein, The device includes:

8. A deep shale fracturing apparatus, characterized by, An acquisition module for acquiring relevant parameters of the current fracturing construction well section; A monitoring module for monitoring the volume of the fracture body on both sides of the wellbore at the current moment and whether the fracture body covers the current fracturing construction well section; The monitoring of the volume of the fracture body on both sides of the wellbore at the current moment includes: The length, width and height of the fracture body on both sides of the wellbore are obtained by using the ground dense array energy scanning four-dimensional image fracturing fracture monitoring and wide-area electromagnetic monitoring to monitor the distribution of the fracture body during the fracturing construction, so as to obtain the volume of the fracture body; A calculation module for calculating the net pressure change rate of the fracture body at the current moment and the non-uniform distribution degree of the fracture body based on the relevant parameters of the current fracturing construction well section; The net pressure change rate can be calculated by formula 3, and formula 3 is: The non-uniform distribution degree of the fracture body is calculated by formula 2, and formula 2 is, wherein, is the net pressure change rate, %; is the net pressure change value, Mpa; is is the net pressure of the fracture body at the moment, Mpa; is is the net pressure of the fracture body at the moment, Mpa; a is the time interval; A judgment module for judging the state of the fracture body based on the net pressure change rate of the fracture body at the current moment and the non-uniform distribution degree of the fracture body, and outputting the next step construction optimization measure instruction according to the state of the fracture body. wherein, is the degree of non-uniform distribution of the fracture body at the current time; is the fracture volume change amount, m 3 ; is the fracture volume, m 3 ; , are the fracture volumes on both sides of the wellbore, m 3 ; ​

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