Shaft crack control method and system for petroleum perforation operation

Abstract

The invention relates to the technical field of petroleum perforation operation, and provides a shaft crack control method and system for petroleum perforation operation, and the method comprises the steps: collecting the spatial position of a perforation cluster of the petroleum perforation operation, calculating the shadow intensity value of the perforation cluster, selecting a standard perforation cluster, calculating the closing pressure increment, and calculating the net pressure compensation amount of the perforation cluster; the sequence of fracturing the perforation clusters in sequence is determined, high-compensation clusters are screened, the specific fracturing process is determined, a temporary plugging agent is put synchronously, and fracturing of the perforation clusters is completed; the method comprises the following steps: collecting a pumping pressure curve in a fracturing process, collecting backflow particle concentration in the fracturing process and after fracturing pump stop, positioning a microseism event, combining the pumping pressure curve and the backflow particle concentration, judging whether a high compensation cluster is activated or not, if so, judging that the operation reaches the standard, and if not, reversely updating a calibration coefficient. According to the invention, shaft crack control of petroleum perforation operation can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil perforation operation, in particular to a wellbore fracture control method and system for oil perforation operation. BACKGROUND

[0002] The oil perforation operation is a process of using special perforating bullets to penetrate the oil well casing, cement ring and part of the formation rock through the perforating gun to produce a channel in the rock mass, establish a communication channel between the formation and the wellbore, and promote the reservoir fluid to enter the wellbore. After the perforation operation, high-pressure fluid is injected into the well, and when the bottom hole pressure exceeds the formation fracture pressure, a network of opening-type fractures extending along the direction of the minimum principal stress will be induced around the well wall. The length, width and flow conductivity of the wellbore fracture directly determine the seepage resistance of oil and gas from the matrix to the perforation hole. By reducing the cluster spacing, increasing the number of fractures and optimizing the perforation parameters, the maximum fracture-controlled reserves can be achieved. Therefore, it is necessary to quantitatively control the opening degree of each cluster fracture, improve the reserve producing degree and the ultimate recovery rate, and at the same time, avoid casing deformation and wellhead overpressure. At the same time, the use of nano-fracturing fluid, combined proppant and temporary plugging agent further optimizes the complexity and control volume of the fracture, and increases the gas production.

[0003] Due to the influence of stress shadow effect in the multi-cluster perforation fracturing process, the middle cluster fractures are disturbed by the stress of the two side fractures, and the stress shadow will significantly increase the closure pressure of the middle fractures, reduce their flow conductivity, so the fracturing fluid and proppant tend to enter the outer fractures, resulting in uneven expansion of the wellbore fractures and affecting the overall fracturing effect. SUMMARY

[0004] The present application provides a wellbore fracture control method and system for oil perforation operation to solve the problem of uneven expansion of wellbore fractures caused by the influence of stress shadow superposition of the middle cluster due to the dynamic interference of adjacent cluster stress shadow in the wellbore fracture of oil perforation operation. The technical solution adopted is as follows: In a first aspect, an embodiment of the present application provides a wellbore fracture control method for oil perforation operation, which comprises the following steps: The spatial position of each perforation of all perforation clusters in the oil perforation operation is collected, the shadow intensity value of each perforation cluster is calculated according to the spatial position difference of the perforations of different perforation clusters, the standard perforation cluster is selected according to the value of the shadow intensity value, the closure pressure increment of the standard perforation cluster is obtained, the net pressure compensation amount of each perforation cluster is calculated respectively in combination with the shadow intensity value of the perforation cluster, and a calibration coefficient is set. According to the value of the net pressure compensation amount of the perforation cluster, the order of sequentially fracturing each perforation cluster is determined, and a high compensation cluster is screened from the perforation clusters, according to the net pressure compensation amount of the high compensation cluster, the specific process of fracturing is determined, while fracturing each perforation cluster, the temporary plugging agent is synchronously put and the bottom hole pressure is collected, according to the change of the bottom hole pressure, the volume of the temporary plugging agent put into the perforation cluster is determined, and a calibration coefficient is set, and the fracturing of each perforation cluster is completed; During the fracturing process, the pump pressure curve is collected, and the backflow particle concentration is collected during the fracturing process and after the pump is stopped, the microseismic event is located, the pump pressure curve and the backflow particle concentration are combined, and it is determined whether the high compensation cluster is activated, if yes, it is determined that the operation meets the standard, and if not, the calibration coefficient is updated in reverse.

[0005] Further, the specific method of separately calculating the shadow intensity value of each perforation cluster and selecting a standard perforation cluster according to the value of the shadow intensity value comprises: The Euclidean distance between the spatial positions of different perforation clusters is recorded as the cluster distance between different perforation clusters, and the ratio of the preset crack size to the cluster distance between different perforation clusters is recorded as the shadow contribution of different perforation clusters; The cumulative sum of the shadow contribution of the same perforation cluster and all other perforation clusters is recorded as the shadow intensity value of the same perforation cluster; The perforation cluster with the maximum shadow intensity value is recorded as the standard perforation cluster.

[0006] Further, the specific method of obtaining the closure pressure increment of the standard perforation cluster comprises: A micro-fracturing experiment is performed on the standard perforation cluster, the instantaneous shut-in pressure response after the pump is stopped is obtained, and the closure pressure increment of the standard perforation cluster is obtained by using a G function.

[0007] Further, the specific method of obtaining the net pressure compensation amount of the perforation cluster comprises: The ratio of the closure pressure increment of the standard perforation cluster to the shadow intensity value is recorded as a standard ratio, and the product of the shadow intensity value of the perforation cluster and the standard ratio is recorded as the net pressure compensation amount of the perforation cluster.

[0008] Further, the specific method of determining the order of sequentially fracturing each perforation cluster according to the value of the net pressure compensation amount of the perforation cluster, and screening a high compensation cluster from the perforation clusters comprises: Each perforation cluster is sequentially fractured in the order from large to small according to the net pressure compensation amount of the perforation cluster; The upward rounding value of 20% of the number of all perforation clusters of the oil perforation operation is recorded as a first value, and the first value of the perforation cluster with the maximum net pressure compensation amount is recorded as a high compensation cluster.

[0009] Further, the specific process of fracturing specifically comprises: Confirming wellbore integrity; pumping all preflush; dividing a short-time high-rate pulse window for each high-compensation cluster; pumping the cluster with the sand slurry; arranging the transition section; compensating the high-compensation cluster; completing the remaining fracture fracturing; and pumping the displacement fluid.

[0010] Further, the specific method for obtaining the volume of the temporary plugging agent is as follows: The temporary plugging agent is pumped into the layer section that has been fractured but not yet fractured, and the bottom hole pressure is collected in real time at a preset design rate until the temporary plugging agent reaches the perforation hole, the volume of the temporary plugging agent at this time is recorded as a first volume, the difference between the bottom hole pressure at this time and the bottom hole pressure when the temporary plugging agent is started to be pumped in is recorded as a bottom hole pressure difference, the ratio of the first volume to the bottom hole pressure difference is recorded as a first ratio, and the product of the net pressure compensation amount of the perforation cluster and the first ratio is recorded as the volume of the temporary plugging agent pumped into the perforation cluster.

[0011] Further, the specific steps for determining whether the high-compensation cluster is activated include: The average pumping pressure is calculated according to the pumping pressure, and when a continuous rising part with a time length greater than one-third of the pulse window and a rising amplitude greater than or equal to one-half of the net pressure compensation amount of the pulse window appears, it is determined that the compensation is successful, which is recorded as the first criterion being met. The average backflow particle concentration is calculated according to the backflow particle concentration before the fracturing pump is stopped, the relative proportion of the peak area of the cluster to the total amount of the cumulative backflow sand is recorded as a first proportion of the cluster, and when the backflow particle concentration of the cluster corresponding to the tracer particle diameter section or the fluorescence channel is greater than or equal to twice the average backflow particle concentration, and the first proportion of the cluster is greater than the sum of the average value of the first proportions of the other clusters and the standard deviation of the first proportions of all the clusters, it is determined that the cluster has absorbed the proppant and participated in the flow conduction, which is recorded as the second criterion being met. The microseismic events are located, the microseismic cloud map along the wellbore is obtained, and it is determined whether the fracture is started. The event density per 100 meters of the whole section is taken as a background value, and if the number of microseismic events in the range of ± 25 meters near the target well section is more than 1 times the background density, and at the same time, the event with the maximum magnitude appears in the magnitude distribution of the region, it is determined that the fracture is started, which is recorded as the third criterion being met. When at least two criteria are met, it is determined that the high-compensation cluster is activated.

[0012] Further, the specific steps for updating the calibration coefficient in reverse include: The calibration coefficient includes a standard ratio and a first ratio. The standard ratio of the high-compensation cluster corresponding to the determination of the non-appearance of the compensation success is improved, and the first ratio of the high-compensation cluster corresponding to the determination of the non-appearance of the cluster having absorbed the proppant and participated in the flow conduction is improved.

[0013] In a second aspect, the embodiments of the present application also provide a wellbore fracture control system for oil perforation operation, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the steps of the method according to any one of the preceding aspects when executing the computer program.

[0014] The present application has the following beneficial effects: The present application first quantifies the strength of the perforation cluster subjected to the additional closure stress of the adjacent perforation cluster, obtains the shadow intensity value of the perforation cluster, when the shadow intensity value of the perforation cluster is greater, the perforation cluster is subjected to the more intense additional closure stress from the adjacent perforation cluster, then evaluates the influence degree of the adjacent perforation cluster on the closure pressure of the standard perforation cluster, obtains the closure pressure increment, and further calculates the net pressure compensation amount of each perforation cluster, the net pressure compensation amount can be calibrated by the data results of a micro fracturing experiment at the construction site without the need for large-scale numerical simulation, reduces the failure risk of the middle cluster, and improves the effectiveness of the overall fracture network; the perforation clusters are fractured in turn according to the order of the net pressure compensation amount of the perforation cluster from large to small, the high compensation cluster breaks through the liquid, and a certain amount of temporary plugging agent is synchronously put, a short-time high-flow pulse is applied at the front of each injection cycle, the stress shadow is forcibly broken through in the window period of sufficient liquid volume and the overall consumption of bottom hole pressure, at the same time, the temporary plugging agent temporarily plugs the low shadow perforation, the degradable temporary plugging agent is put into the low compensation perforation which has been opened and has a higher flow rate, a temporary plugging is quickly formed, the local friction increases, the liquid volume is redistributed in the order of high pressure first, plugging later, and then turning, so that the middle cluster which is most likely to fail is preferentially cracked and continuously sucks the proppant without increasing the total liquid volume, thereby optimizing the fracture development effect; finally, whether the high compensation cluster is activated is determined according to the microseismic event, pump pressure curve and backflow particle concentration, if yes, it is determined that the operation is up to standard, if not, the calibration coefficient is updated in reverse, thereby solving the problem of stress shadow superposition caused by the dynamic interference of the middle cluster to the stress shadow of the adjacent cluster in the wellbore fracture of the oil perforation operation, and realizing the wellbore fracture control of the oil perforation operation. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0016] Figure 1 The flowchart of the wellbore fracture control method for oil perforation operation provided by an embodiment of the present application; Figure 2 The shadow intensity value acquisition flowchart provided by one embodiment of the present application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0018] Please refer to Figure 1 The wellbore fracture control method flowchart for oil perforation operation provided by one embodiment of the present application comprises the following steps: In step S001, the spatial positions of each perforation of all perforation clusters in oil perforation operation are collected, the shadow intensity values of each perforation cluster are calculated according to the spatial position differences of the perforations of different perforation clusters, the standard perforation cluster is selected according to the value selection standard of the shadow intensity values, the closure pressure increment of the standard perforation cluster is obtained, the net pressure compensation amount of each perforation cluster is calculated respectively in combination with the shadow intensity values of the perforation clusters, and the calibration coefficient is set.

[0019] In the wellbore fracture control process of oil perforation operation, the perforation cluster refers to a group of perforations arranged around the wellbore according to certain rules and design requirements. The spatial positions of all perforations are obtained from the design file of the perforations in oil perforation operation, and the spatial position of the middle perforation in the perforation cluster is recorded as the spatial position of the perforation cluster.

[0020] It should be understood that most shale horizontal wells adopt single-section multi-cluster coplanar perforation, all perforation clusters are located in the same horizontal section and have small elevation difference, so different fractures can be regarded as geometric coplanar fractures, and the cluster-to-cluster distance between different perforation clusters is directly calculated according to the spatial position differences of the different perforation clusters while ignoring the vertical additional stress.

[0021] The fracture scale represents the expected fracture extension scale of the perforation cluster under non-interference condition, and is generally greater than or equal to 10 meters and less than or equal to 40 meters. In this embodiment, the value of the fracture scale is 15 meters.

[0022] The Euclidean distance between the spatial positions of different perforation clusters is recorded as the cluster-to-cluster distance of the different perforation clusters, the ratio of the fracture scale to the cluster-to-cluster distance of the different perforation clusters is recorded as the shadow contribution of the different perforation clusters, and the cumulative sum of the shadow contributions of the same perforation cluster and all other perforation clusters is recorded as the shadow intensity value of the same perforation cluster.

[0023] In the ratio calculation process, in order to avoid the case that the denominator is zero, a preset value needs to be added to the denominator, and an embodiment of the preset value is 0.1 meters.

[0024] The shadow intensity value acquisition flowchart is shown in Figure 2 The shadow intensity value of the perforation cluster represents the intensity of the additional closure stress of the perforation cluster from the adjacent perforation cluster, and is a data quantification result of the invisible stress interference. When the shadow intensity value of the perforation cluster is larger, the perforation cluster receives more intense additional closure stress from the adjacent perforation cluster.

[0025] For all perforation clusters of the oil perforation operation, the perforation cluster with the largest shadow intensity value is recorded as a standard perforation cluster, a micro-fracturing experiment or a diagnostic injection DFIT experiment is performed on the standard perforation cluster, an instantaneous shut-in pressure response after pump stop is obtained, a closure pressure increment of the standard perforation cluster is obtained by using a G function or a pressure derivative method according to the instantaneous shut-in pressure response after pump stop. The ratio of the closure pressure increment of the standard perforation cluster to the shadow intensity value is recorded as a standard ratio, and the product of the shadow intensity value of the perforation cluster and the standard ratio is recorded as a net pressure compensation amount of the perforation cluster.

[0026] It should be noted that the standard ratio is one of the calibration coefficients.

[0027] It can be understood that the closure pressure increment reflects the influence degree of the adjacent perforation cluster on the closure pressure of the standard perforation cluster, the net pressure compensation amount can be calibrated by the data results of one micro-fracturing experiment on the construction site without large-scale numerical simulation, the risk of intermediate cluster failure is reduced, and the effectiveness of the overall fracture network is improved; the net pressure compensation amount of the standard perforation cluster is equal to the value of the closure pressure increment of the standard perforation cluster.

[0028] The larger the net pressure compensation amount of the perforation cluster is, the more bottom hole net pressure needs to be compensated for the perforation cluster to open and extend the fracture of the perforation cluster.

[0029] At this point, the net pressure compensation amount of the perforation cluster is obtained.

[0030] In step S002, the order of fracturing the perforation clusters in turn is determined according to the value of the net pressure compensation amount of the perforation cluster, and a high compensation cluster is selected from the perforation clusters, the specific process of fracturing is determined according to the net pressure compensation amount of the high compensation cluster, the temporary plugging agent is put in synchronously while fracturing each perforation cluster, the bottom hole pressure is collected, the volume of the temporary plugging agent put into the perforation cluster is determined according to the change of the bottom hole pressure, and the calibration coefficient is set, so as to complete the fracturing of each perforation cluster.

[0031] Generally, in the conventional multi-cluster perforation fracturing process, the perforation clusters are fractured in turn according to the order from low to high of the initiation pressure of different perforation clusters, but this process only considers the friction of different perforation clusters and does not consider the dynamic interference of the stress shadow of adjacent perforation clusters, often leading to the middle cluster being affected by the superposition of stress shadows and becoming the cluster with the highest actual fracture pressure, thereby easily causing the failure of the central cluster of fracturing. Further, when multiple clusters simultaneously compete for liquid volume, if the high shadow crack does not obtain sufficient net pressure and flow rate in time, the tip will be pressed back by the additional closing stress induced by the adjacent cluster, and it is also difficult to reopen with subsequent liquid supplement. Therefore, the traditional multi-cluster perforation fracturing method has limitations, and a more precise dynamic analysis and optimization strategy is needed to improve the fracturing effect.

[0032] According to the order from large to small of the net pressure compensation amount of the perforation cluster, the perforation clusters are fractured in turn, and a certain amount of temporary plugging agent is simultaneously put in, a short-time high-flow pulse is applied at the front of each injection cycle, and the stress shadow is forcibly broken in the window period when the liquid volume is sufficient and the bottom hole pressure has not been consumed as a whole. At the same time, the temporary plugging agent temporarily plugs the low shadow perforation, forming a liquid volume redistribution of high pressure first, plugging later, and turning later, so as to ensure that the middle cluster which is most likely to fail is preferentially fractured and continuously sucks in proppant without increasing the total liquid volume.

[0033] The specific steps of putting the temporary plugging agent are: after the bridge plug is set and sealed, first, the constant low displacement ( ) is used to test and break, and the wellbore integrity is confirmed, then the displacement is increased to the design displacement ( ) at one time, all the preflush, sand slurry and displacement fluid are continuously pumped in turn at the design displacement, the proppant is uniformly mixed according to the uniform sand ratio, and the temporary plugging agent is put in at one time according to experience.

[0034] Specifically, the constant low displacement should be greater than or equal to 1 and less than or equal to 2 , and the design displacement should be greater than or equal to 3 and less than or equal to 6 .

[0035] Specifically, in the whole injection and fracturing process, the fracturing fluid serves as the base fluid, which is composed of water, thickening agent and additives; the proppant is used to support the crack and does not close, the material is resin-coated sand or ceramic particles; the temporary plugging agent is used for temporary plugging of the crack, the material is degradable polymer, heat-sensitive material or composite chemical reagent, etc.; the preflush is used to break the rock and only contains the fracturing fluid, the sand slurry is used to carry the proppant and contains the fracturing fluid and the proppant, and the temporary plugging agent can also be added; the displacement fluid is used to top the remaining sand into the crack and only contains the fracturing fluid.

[0036] The up-round value of 20% of the number of all perforation clusters of the oil perforation operation is recorded as a first value, and the first value of the perforation cluster with the maximum net pressure compensation amount is recorded as a high compensation cluster.

[0037] A continuous fracturing process specifically includes: confirming wellbore integrity; pumping all preflush; dividing a short high-displacement pulse window for each high compensation cluster, pumping sand slurry for the pulse window; arranging a transition section; compensating the high compensation cluster; completing the remaining fracture fracturing; and pumping a displacement fluid. The wellbore integrity confirmation can ensure the safety of the wellbore structure and lay the foundation for subsequent fracturing operations; pumping all preflush can break the rock and prepare for subsequent sand slurry injection; compensating the high compensation cluster can enhance its liquid inlet capacity; completing the remaining fracture fracturing means continuing to pump the remaining sand slurry at the designed displacement to open other fractures after the high compensation cluster is processed; and pumping the displacement fluid can push the remaining proppant into the fracture to complete the fracturing.

[0038] Preferably, as an embodiment of the present application, the total amount of sand slurry is set to 600 , the design displacement is set to 5 , and the sand slurry pumping duration is set to 120 .

[0039] For example, if the oil perforation operation has a total of 12 perforations, i.e., a total of 12 perforation clusters, the three perforation clusters with the largest net pressure compensation amount are high compensation clusters, and three pulse windows are divided for the three high compensation clusters. 10% of the sand slurry is taken to compensate the high compensation cluster, i.e., 60 of the sand slurry is taken to compensate the high compensation cluster, 20 of the sand slurry is taken for each pulse window, and the displacement is increased to 1.5 times the value of the original design displacement in the pulse window, so that the duration of each pulse window is about 2.7 , and a transition section of 30 seconds is reserved between every two pulse windows to reduce the displacement to the design displacement, so that the temporary plugging agent can be fully settled at a low flow rate, and the temporary plugging agent is prevented from being washed away by the high pressure of the next window.

[0040] It can be understood that the high compensation clusters are broken through in the order of the net pressure compensation amount from large to small, there is a transition section between different high compensation clusters, until all pulse windows are completed, the entire sand slurry is pumped at the designed displacement to open other fractures, and finally, the displacement fluid is pumped.

[0041] Further, in the process of fracturing the perforation clusters in turn, the calculation method of the volume of the temporary plugging agent put is: For the fractured but not yet blown-out sections, a temporary plugging agent is injected at the preset design displacement and the bottom hole pressure is collected in real time until the temporary plugging agent reaches the perforation. The volume of the temporary plugging agent injected at this time is recorded as the first volume. At the same time, the difference between the bottom hole pressure at this time and the bottom hole pressure at the beginning of the injection of the temporary plugging agent is recorded as the bottom hole pressure difference. The ratio of the first volume to the bottom hole pressure difference is recorded as the first ratio. The product of the net pressure compensation of the perforation cluster and the first ratio is recorded as the second volume of the perforation cluster.

[0042] It is important to understand that the second volume of the perforation cluster is the volume of the temporary plugging agent added to the perforation cluster, and the temporary plugging agent with the second volume is added to the corresponding perforation cluster within the first 30-50 seconds of the pulse window.

[0043] Because the pressure propagation speed at the bottom of the well is much greater than the redistribution speed of fluid friction, under continuous horizontal pumping, the wellbore pressure will instantly spread to all orifices. At this time, whether fluid enters the orifice depends only on the local breakthrough pressure. The earlier the high pressure is applied, the earlier the high compensation cluster will break through.

[0044] At the baseline discharge rate, the bottom hole net pressure cannot reach the breakthrough threshold of the high-compensation cluster. However, the perforation cluster has already opened and is continuously injecting fluid. When the discharge rate suddenly increases, the bottom hole pressure will also jump instantaneously, thus exceeding the breakthrough threshold of the high-compensation cluster. At this time, the fractures in the perforation cluster already exist. Therefore, when the pressure rises, its volume expansion demand is greater, which will lead to a pressure response lag. The newly broken high-compensation cluster fractures are in the initial fracture stage, the fractures are narrower, and the response to pressure jumps is more sensitive, thus absorbing additional fluid volume to achieve the purpose of compensation.

[0045] Meanwhile, the biodegradable temporary plugging agent introduced into the pulse window can preferentially enter the already opened, low-compensation orifice with a higher flow rate, quickly forming a temporary seal. This increases local friction, essentially closing the first-opened door, forcing subsequent liquid flow to the still-open, high-compensation orifice. The flow rate at the high-compensation orifice is relatively low, and the newly broken crack is narrow, resulting in a low probability of temporary plugging agent retention. This achieves a temporary sealing effect, i.e., redistribution of liquid volume and optimization of crack development.

[0046] At this point, the fracturing of each perforation cluster is complete.

[0047] Step S003: Collect pump pressure curves during fracturing, collect backflow particle concentrations during fracturing and after pump shutdown, locate microseismic events, and determine whether high-compensation clusters are activated by combining pump pressure curves and backflow particle concentrations. If so, determine that the operation meets the standards; otherwise, update the calibration coefficients in reverse.

[0048] During the sequential fracturing of each perforation cluster, the pump pressure curve is collected by the surface high-pressure pump inlet pressure sensor. The pump pressure curve is a curve that continuously records the change of wellhead pressure over time.

[0049] Preferably, as an embodiment of this application, the sampling frequency of wellhead pressure should be greater than or equal to 1Hz and less than or equal to 10Hz. In this embodiment, the sampling frequency of wellhead pressure is set to 5Hz. The average value of all pump pressures collected in the first 30 seconds within the same pulse window is recorded as the average pump pressure. When a continuous rise in pressure occurs with a duration greater than one-third of the pulse window, and the rise amplitude is greater than or equal to half of the net pressure compensation amount of the pulse window, the compensation is deemed successful. When the compensation is deemed successful, it is recorded as the first criterion being met.

[0050] During and after fracturing, a laser particle size analyzer installed in the wellhead backflow line is used to continuously detect the number and concentration of proppant particles in the backflow fluid to obtain the backflow particle concentration.

[0051] The sampling frequency for the backflow particle concentration was 1 Hz. It is understood that fluorescent tracer sand was added before collecting the backflow particle concentration data, and different fluorescent agents were added at different pulse windows to distinguish different clusters. In fracturing operations, a "cluster" represents a region or stage in the fracturing fracture occupied by different fluorescent tracer sands. Each cluster is distinguished by different pulse windows or tracing methods. By continuously monitoring the signal in the backflow fluid, the proppant distribution and flow participation of each cluster can be analyzed.

[0052] The average concentration of all backflow particles collected within 5 minutes before fracturing pump shutdown is taken as the average backflow particle concentration. The relative proportion of the peak area of ​​a cluster to the total cumulative reverse sand discharge is recorded as the first proportion of the cluster. When the backflow particle concentration of the tracer particle size segment or fluorescence channel corresponding to a cluster is greater than or equal to twice the average backflow particle concentration, and the first proportion of the cluster is greater than the sum of the average of the first proportions of other clusters and the standard deviation of the first proportions of all clusters, it is determined that the cluster has absorbed proppant and participated in flow conduction. When a cluster has absorbed proppant and participated in flow conduction, it is recorded that the second criterion is met.

[0053] Microseismic events are weak seismic wave signals generated by rock fracturing during hydraulic fracturing operations. Microseismic events reflect the rock fracturing process and help assess fracturing effectiveness and fracture propagation.

[0054] During the fracturing process of each perforation cluster, each pumped in A microseismic event is located using fluid volume analysis, and a microseismic cloud map is obtained showing the distribution along the wellbore. Based on the microseismic cloud map, fracture initiation is determined. The event density per 100 meters of the entire well section is used as the background value. If, within a range of ±25 meters near the target well section, the number of microseismic events is more than twice the background density, and the maximum magnitude event appears in the magnitude distribution of that area, fracture initiation is determined. When fracture initiation occurs, the third criterion is considered met.

[0055] The method for locating microseismic events is a well-known technique and will not be elaborated further. Specifically, by capturing weak seismic waves generated by rock fracturing using a detector array installed downhole, the location of the microseismic event's source, the time of occurrence, and the magnitude are calculated using travel-time inversion technology, and a microseismic cloud map distributed along the wellbore is obtained. In this embodiment, events exceeding 70% of the maximum magnitude are defined as events of the maximum magnitude.

[0056] When at least two criteria are met, the high-compensation cluster is determined to be activated. The number of high-compensation clusters corresponding to the met criteria is counted, and the ratio of the number of high-compensation clusters corresponding to the met criteria to the total number of high-compensation clusters is recorded as the activation rate. When the activation rate is greater than the third quartile of the activation rate of the drilled wells in the oil perforation operation, the operation is determined to be compliant. When the activation rate is less than or equal to the third quartile of the activation rate of the drilled wells in the oil perforation operation, the operation is determined to be non-compliant, and the calibration coefficient is updated in reverse.

[0057] The specific steps for reverse updating the calibration coefficients are as follows: Increase the standard ratio of the high-compensation clusters corresponding to the cases where compensation failure did not occur by 0.05. The first ratio of the high-compensation clusters corresponding to the criteria that no clusters have been observed to have absorbed proppant and participated in diversion is increased by 0.05. .

[0058] It should be noted that the increase in the standard ratio should be greater than or equal to 0.02. And less than or equal to 0.06 The increase in the first ratio should be greater than or equal to 0.02. And less than or equal to 0.06 .

[0059] Understandably, if the net pressure compensation of the high-compensation cluster corresponding to the failure to achieve compensation success has not overcome the stress shadow, increasing the standard ratio of the high-compensation cluster corresponding to the failure to achieve compensation success can obtain greater compensation pressure under the same shadow intensity. If the cluster has absorbed proppant and participated in flow, it indicates that the volume of temporary plugging agent is insufficient, the low-compensation orifice has not been effectively blocked, and it is still consuming liquid. Increasing the first ratio of the high-compensation cluster corresponding to the failure to absorb proppant and participate in flow can release more temporary plugging agent, increase the flow resistance of non-high-compensation clusters, and force the liquid to flow towards high-compensation clusters.

[0060] This achieves wellbore fracture control during oil perforation operations.

[0061] Based on the same inventive concept as the above methods, embodiments of the present invention also provide a wellbore fracture control system for oil perforation operations, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above-described wellbore fracture control methods for oil perforation operations.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wellbore fracture control method for oil perforating operations, characterized by, The method comprises the following steps: The method comprises the following steps: According to the difference in the spatial positions of the perforations of different perforation clusters, the shadow intensity value of each perforation cluster is calculated respectively, a standard perforation cluster is selected according to the value of the shadow intensity value, the closed pressure increment of the standard perforation cluster is obtained, the net pressure compensation amount of each perforation cluster is calculated respectively in combination with the shadow intensity value, and the calibration coefficient is set; The order of sequentially fracturing each perforation cluster is determined according to the value of the net pressure compensation amount of the perforation cluster, and a high compensation cluster is screened from the perforation cluster, the specific process of fracturing is determined according to the net pressure compensation amount of the high compensation cluster, the fracturing of each perforation cluster is completed while the temporary plugging agent is synchronously put in, the bottom hole pressure is collected, the volume of the temporary plugging agent put into the perforation cluster is determined according to the change of the bottom hole pressure, and the calibration coefficient is set.

2. The wellbore fracture control method for oil perforation operations of claim 1, wherein, The pump pressure curve is collected during the fracturing process, the backflow particle concentration is collected during the fracturing process and after the pump is stopped, the microseismic event is located, and whether the high compensation cluster is activated is determined in combination with the pump pressure curve and the backflow particle concentration; if yes, it is determined that the operation meets the standard, and if no, the calibration coefficient is updated reversely. The specific method for calculating the shadow intensity value of each perforation cluster and selecting the standard perforation cluster according to the value of the shadow intensity value comprises the following steps: The Euclidean distance between the spatial positions of different perforation clusters is recorded as the cluster distance of different perforation clusters, and the ratio of the preset crack size to the cluster distance of different perforation clusters is recorded as the shadow contribution of different perforation clusters; The cumulative sum of the shadow contribution of the same perforation cluster and all other perforation clusters is recorded as the shadow intensity value of the same perforation cluster; 3. The wellbore fracture control method for oil perforating operations of claim 1, wherein, The perforation cluster with the maximum shadow intensity value is recorded as the standard perforation cluster. The specific method for obtaining the closed pressure increment of the standard perforation cluster comprises the following steps:

4. The wellbore fracture control method for oil well perforating operations of claim 1, wherein, The micro-fracturing experiment is performed on the standard perforation cluster, the instantaneous shut-in pressure response after the pump is stopped is obtained, and the closed pressure increment of the standard perforation cluster is obtained by using a G function. The specific method for obtaining the net pressure compensation amount of the perforation cluster comprises the following steps:

5. The wellbore fracture control method for oil well perforating operations of claim 1, wherein, The ratio of the closed pressure increment of the standard perforation cluster to the shadow intensity value is recorded as a standard ratio, and the product of the shadow intensity value of the perforation cluster and the standard ratio is recorded as the net pressure compensation amount of the perforation cluster. The specific method for determining the order of sequentially fracturing each perforation cluster according to the value of the net pressure compensation amount of the perforation cluster and screening the high compensation cluster from the perforation cluster comprises the following steps: Each perforation cluster is sequentially fractured in the order from large to small according to the net pressure compensation amount of the perforation cluster; 6. The wellbore fracture control method for oil well perforating operations of claim 1, wherein, The upward integer value of 20% of the number of all perforation clusters of the oil perforation operation is recorded as a first value, and the first value of the perforation cluster with the maximum net pressure compensation amount is recorded as the high compensation cluster. The specific process of fracturing comprises the following steps:

7. The wellbore fracture control method for oil perforating operations of claim 4, wherein, The wellbore integrity is confirmed, all the preflush is pumped in, each high compensation cluster is divided into a short-time high-displacement pulse window, the sand slurry is pumped into the pulse window, the transition section is arranged, the high compensation cluster is compensated, the remaining fracture fracturing is completed, and the displacement fluid is pumped in. The specific method for obtaining the volume of the temporary plugging agent comprises the following steps: The temporary plugging agent is pumped into the layer segment which has been fractured but not fractured yet with a preset design discharge, and the bottom hole pressure is collected in real time until the temporary plugging agent reaches the perforation hole, the volume of the temporary plugging agent pumped at this time is recorded as a first volume, the difference between the bottom hole pressure at this time and the bottom hole pressure when the temporary plugging agent is started to be pumped is recorded as a bottom hole pressure difference, the ratio of the first volume to the bottom hole pressure difference is recorded as a first ratio, and the product of the net pressure compensation amount of the perforation cluster and the first ratio is recorded as the volume of the temporary plugging agent pumped into the perforation cluster.

8. The wellbore fracture control method for oil well perforating operations of claim 1, wherein, The specific steps for determining whether the high compensation cluster is activated include: According to the average pump pressure, when a continuous rising part with a time length greater than one third of the pulse window and a rising amplitude greater than or equal to one half of the net pressure compensation amount of the pulse window appears, it is determined that the compensation is successful, which is recorded as the first criterion being established; According to the average backflow particle concentration before the fracturing pump is stopped, the relative proportion of the peak area of the cluster to the total amount of backflow sand is recorded as a first proportion of the cluster, when the backflow particle concentration of the cluster corresponding to the tracer particle diameter segment or the fluorescence channel is greater than or equal to twice the average backflow particle concentration, and the first proportion of the cluster is greater than the sum of the average value of the first proportions of other clusters and the standard deviation of the first proportions of all clusters, it is determined that the cluster has sucked in the proppant and participated in the flow conduction, which is recorded as the second criterion being established; The microseismic events are located, the microseismic cloud map along the wellbore is obtained, and it is determined whether the fracture is started, the event density per 100 meters of the whole segment is taken as a background value, if the number of microseismic events in the range of ± 25 meters near the target well segment is more than 1 times the background density, and at the same time, the event with the maximum magnitude appears in the magnitude distribution of the region, it is determined that the fracture is started, which is recorded as the third criterion being established; When at least two criteria are established, it is determined that the high compensation cluster is activated.

9. The wellbore fracture control method for oil well perforating operations of claim 7, wherein, The specific steps for updating the calibration coefficient in reverse include: The calibration coefficient includes a standard ratio and a first ratio; The standard ratio of the high compensation cluster corresponding to the determination of the compensation success is improved; The first ratio of the high compensation cluster corresponding to the determination of the cluster having sucked in the proppant and participated in the flow conduction is improved.

10. A wellbore fracture control system for use in oil perforating operations, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, The processor implements the steps of the method of any one of claims 1-9 when executing the computer program.

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