Method, device and equipment for determining CO2 fracturing process of target reservoir

Abstract

The invention relates to the technical field of CO2 fracturing, in particular to a CO2 fracturing process determining method, device and equipment for a target reservoir, and the method comprises the steps that a first CO2 fracturing process is selected according to geological parameters of the target reservoir; performing pressure test on the target reservoir by using a first CO2 fracturing process to obtain a first fracturing parameter of the target reservoir; according to the first fracturing parameter of the target reservoir, a preset fracturing sand plugging judgment model is used for selecting a first fracture expansion model of the target reservoir; according to a first fracture expansion model of the target reservoir and the propping agent particle size corresponding to the first CO2 fracturing process, the corresponding sand plugging risk level when the target reservoir is fractured through the first CO2 fracturing process is judged; and if the sand plugging risk level is within the preset sand plugging risk level interval, determining that the first CO2 fracturing process is the CO2 fracturing process of the target reservoir.

Description

Technical Field

[0001] The embodiments of this specification relate to the field of CO2 fracturing technology, and specifically to a method, device and equipment for determining a CO2 fracturing process for a target reservoir. Background Art

[0002] The reservoir sensitivity and heterogeneity of the target block vary greatly, and the requirements for fracturing are different, making it difficult to select the right type. In addition, the artificial fractures formed by fracturing are narrow. When the proppant is carried into the artificial fracture to form a sand-filled fracture, the proppant will aggregate at the bottom of the well or in the fracture to form a blockage, causing the construction pressure to suddenly increase, which makes it difficult to carry out the fracturing construction. This phenomenon is called a sand plugging accident. The occurrence of sand plugging events can easily lead to the failure of fracturing construction and waste fracturing fluid and proppant. At the same time, in order to solve the sand plugging problem, it is necessary to carry out sand flushing and unblocking construction, thereby increasing additional construction costs and reducing the efficiency of fracturing construction. Therefore, in order to reduce the probability of sand plugging events in fracturing construction and improve the safety and efficiency of fracturing construction, it is necessary to predict the risk of sand plugging for the target fracturing construction reservoir and conduct real-time evaluation of the CO2 fracturing process selection based on the prediction results.

[0003] Existing sand plugging risk monitoring systems are all real-time warning systems for on-site construction, mainly including the following methods: relying on the naked eye to observe and analyze on-site construction data to determine the level of sand plugging risk; using real-time on-site construction data to establish a double logarithmic curve slope fracturing sand plugging risk warning model; using a large amount of downhole related event data to establish a risk prediction model based on Bayesian network.

[0004] The above existing methods only consider the relationship between fracturing construction parameters and sand plugging events, and carry out real-time assessment and early warning of sand plugging risks based on real-time on-site construction data. They lack comprehensive assessment and the accuracy of the assessment is unsatisfactory. In addition, the above methods cannot predict the risk of sand plugging before construction, and cannot evaluate and optimize the selection of CO2 fracturing technology in real time. Therefore, how to overcome the problems of one-sided evaluation and unsatisfactory evaluation accuracy in existing sand plugging risk monitoring methods, and propose a method for determining the CO2 fracturing technology of the target reservoir, so as to more comprehensively and accurately predict the risk of sand plugging before construction and conduct real-time evaluation and optimization of the selection of CO2 fracturing technology, is a key problem to be solved urgently. Summary of the invention

[0005] The purpose of the embodiments of this specification is to provide a method, device and equipment for determining the CO2 fracturing process of a target reservoir, so as to overcome the problems of one-sided assessment and unsatisfactory assessment accuracy in existing sand plugging risk monitoring methods, and to more comprehensively and accurately predict the sand plugging risk before construction and conduct real-time evaluation and optimization of CO2 fracturing process selection.

[0006] On the one hand, an embodiment of the present specification proposes a method for determining a CO2 fracturing process for a target reservoir, and the method for determining a CO2 fracturing process for a target reservoir includes: selecting a first CO2 fracturing process according to the geological parameters of the target reservoir; using the first CO2 fracturing process to test the target reservoir to obtain a first fracturing parameter of the target reservoir; according to the first fracturing parameter of the target reservoir, using a preset fracturing sand plugging determination model to select a first fracture extension model of the target reservoir; according to the first fracture extension model of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process, judging the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process; if the sand plugging risk level is within a preset sand plugging risk level range, determining that the first CO2 fracturing process is the CO2 fracturing process for the target reservoir.

[0007] On the other hand, a device for determining a CO2 fracturing process for a target reservoir comprises: a selection module for selecting a first CO2 fracturing process according to geological parameters of the target reservoir; an acquisition module for testing the target reservoir using the first CO2 fracturing process to obtain a first fracturing parameter of the target reservoir; a selection module for selecting a first fracture extension model of the target reservoir using a preset fracturing sand plugging judgment model according to the first fracturing parameter of the target reservoir; a judgment module for judging a corresponding sand plugging risk level when fracturing the target reservoir using the first CO2 fracturing process according to the first fracture extension model of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process; and a determination module for determining that the first CO2 fracturing process is the CO2 fracturing process for the target reservoir if the sand plugging risk level is within a preset sand plugging risk level interval.

[0008] On the other hand, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the CO2 fracturing process determination method for the target reservoir.

[0009] It can be seen from the technical solutions provided in the above embodiments of this specification that the embodiments of this specification can select a first CO2 fracturing process according to the geological parameters of the target reservoir; use the first CO2 fracturing process to test the target reservoir to obtain the first fracturing parameters of the target reservoir; select the first fracture extension model of the target reservoir using a preset fracturing sand plugging judgment model according to the first fracturing parameters of the target reservoir; judge the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process according to the first fracture extension model of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process; if the sand plugging risk level is within the preset sand plugging risk level range, determine that the first CO2 fracturing process is the CO2 fracturing process for the target reservoir. Compared with the existing methods, the embodiments of this specification can evaluate and optimize the CO2 fracturing process in real time based on the test pressure results of the CO2 fracturing process on the target reservoir, and thus can more comprehensively and accurately predict the risk of sand plugging before construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings required for use in the embodiments or the prior art description are briefly introduced below.

[0011] Figure 1 It is a flow chart of a method for determining a CO2 fracturing process for a target reservoir provided in an embodiment of this specification;

[0012] Figure 2 It is an overall logic flow chart of a method for determining a CO2 fracturing process for a target reservoir provided in an embodiment of this specification;

[0013] Figure 3 A schematic diagram of a process for real-time sand plugging risk assessment based on a CO2 fracturing process determination method for a target reservoir provided in an embodiment of this specification;

[0014] Figure 4 It is a schematic diagram of the conditional optimization fracturing process standard of the target reservoir of group A of the known well M provided in the embodiments of this specification;

[0015] Figure 5 This is a schematic diagram of the structure of a device for determining a CO2 fracturing process for a target reservoir provided in an embodiment of this specification;

[0016] Figure 6 It is a schematic diagram of the structural composition of a computer device provided in an embodiment of this specification. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this specification.

[0018] Figure 1 A flow chart of a method for determining a CO2 fracturing process for a target reservoir provided in an embodiment of this specification. Figure 2 This is an overall logical flow chart of a method for determining a CO2 fracturing process for a target reservoir provided in an embodiment of this specification. Figure 3 A schematic diagram of a flow chart of a method for determining a CO2 fracturing process for a target reservoir to conduct real-time sand plugging risk assessment based on an embodiment of this specification. In specific implementation, the method includes the following steps:

[0019] S101: Selecting a first CO2 fracturing process according to geological parameters of a target reservoir.

[0020] In some embodiments, a first CO2 fracturing process may be selected based on geological parameters of the target reservoir.

[0021] By selecting a suitable first CO2 fracturing process according to the geological parameters of the target reservoir, the first CO2 fracturing process can be used to test the target reservoir, and then the sand plugging risk level corresponding to the first CO2 fracturing process can be evaluated based on the pressure parameters obtained from the pressure test.

[0022] The geological parameters of the target reservoir may include clay content, burial depth, Young's modulus, and fracture development. Reservoirs with high clay content are more sensitive to fracturing fluid, so CO2 fracturing fluid (CO2 fracturing process) that is less harmful to clay can be selected. For reservoirs with low clay content, the selection of fracturing fluid can be relatively loose. However, the fluidity of CO2 fracturing fluid and the degree of damage to the reservoir still need to be considered. As the reservoir burial depth increases, the temperature and pressure will also increase accordingly. Therefore, CO2 fracturing fluid that can withstand high temperature and high pressure can be selected. For reservoirs with shallow burial depth, the temperature and pressure are relatively low, and the requirements for the high temperature and high pressure resistance of CO2 fracturing fluid are not high. However, the fluidity of CO2 fracturing fluid and the degree of damage to the reservoir still need to be considered. The rock of the reservoir with high Young's modulus is relatively hard, and CO2 fracturing fluid with strong rock breaking ability can be selected. For reservoirs with low Young's modulus, the rock is relatively soft, and the requirements for the rock breaking ability of CO2 fracturing fluid are relatively low. However, the fluidity of CO2 fracturing fluid and the degree of damage to the reservoir still need to be considered. Reservoirs with well-developed fractures already have natural fracture networks, and the selection of CO2 fracturing fluid can focus on improving the conductivity of fractures and maintaining the stability of fractures. For reservoirs with poor fracture development, it is necessary to select CO2 fracturing fluid that can form a complex fracture network. Therefore, according to multiple geological parameters such as clay content, burial depth, Young's modulus and fracture development of the target reservoir, a suitable CO2 fracturing process can be selected as the first CO2 fracturing process, and then the first CO2 fracturing process can be used to test the reservoir.

[0023] For example, for target reservoirs with low clay content, high burial depth, high Young's modulus and high degree of fracture development, the normal pressure quasi-dry method can be selected. The normal pressure quasi-dry method has the characteristics of no need for special closed sand mixing equipment, normal pressure sand mixing, and convenient preparation. The normal pressure quasi-dry method can form a complex fracture network and improve the permeability of the target reservoir by injecting CO2 fracturing fluid under high pressure. The normal pressure quasi-dry method is suitable for high temperature and high pressure environments, meets the needs of high burial depth reservoirs, and can make full use of natural fractures in the reservoir to form a complex fracture network and improve the recovery rate of the reservoir. Low clay content can indicate that the target reservoir is less sensitive to CO2 fracturing fluid, which is conducive to the flow and diffusion of CO2 fracturing fluid in the reservoir. In addition, low clay content means that the permeability of the target reservoir may be relatively high, which is conducive to the output of fluid after fracturing. The target reservoir at high burial depth may be accompanied by a high temperature and high pressure environment, which has certain requirements for the high temperature and high pressure resistance of CO2 fracturing fluid. The normal pressure quasi-dry fracturing technology can adapt to high temperature and high pressure environments to ensure the safety and effectiveness of fracturing operations. High Young's modulus indicates that the target reservoir rock is relatively hard, requiring fracturing technology with strong rock-breaking ability. Normal pressure quasi-dry fracturing technology can form a complex fracture network and improve the permeability of the reservoir by injecting CO2 fracturing fluid under high pressure. Well-developed fractures indicate that the target reservoir already has a natural fracture network, and fracturing operations should focus on improving the conductivity of the fractures and maintaining the stability of the fractures. Normal pressure quasi-dry fracturing technology can make full use of the natural fractures in the target reservoir to form a more complex fracture network and improve the recovery rate of the target reservoir.

[0024] S102: Performing a pressure test on a target reservoir using the first CO2 fracturing process to obtain a first fracturing parameter of the target reservoir.

[0025] In some embodiments, the first CO2 fracturing process may be used to perform a pressure test on a target reservoir to obtain a first fracturing parameter of the target reservoir.

[0026] By using the first CO2 fracturing process to test the target reservoir and obtain the first fracturing parameters of the target reservoir, a foundation is laid for selecting the first fracture propagation model of the target reservoir based on the first fracturing parameters.

[0027] Before the first CO2 fracturing process is used to formally fractur e the target reservoir, the first CO2 fracturing process can be used to test the target reservoir to evaluate the response of the target reservoir and the effect of the first CO2 fracturing process. According to the test pressure results corresponding to the first CO2 fracturing process, the first fracturing parameter of the target reservoir can be obtained. The first fracturing parameter may include data such as displacement, sand ratio, total sand delivery and total liquid volume. Displacement may refer to the volume of fracturing fluid passing through the fracturing pump per unit time. Large displacement helps to form, maintain and obtain higher conductivity of cracks. However, excessive displacement may increase friction loss in the pipeline, reduce effective pressure, and be limited by equipment capacity. Therefore, according to the permeability of the target reservoir, the development of cracks and the performance of the fracturing fluid corresponding to the first CO2 fracturing process, it can be judged whether the displacement in the first fracturing parameter during the pressure test is appropriate. The sand ratio may refer to the proportion of proppant (usually sand particles) in the fracturing fluid corresponding to the first CO2 fracturing process. A high sand ratio can increase the proppant concentration in the crack and improve the conductivity of the crack. However, too high a sand ratio may cause sand plugging and affect the fracturing effect. Therefore, according to the fracture width and conductivity requirements, it can be judged whether the sand ratio of the fracturing fluid corresponding to the first CO2 fracturing process during the pressure test is appropriate. The total amount of sand delivered can refer to the total amount of proppant injected during the entire fracturing process. The total amount of sand delivered directly affects the support effect and conductivity of the fracture. Therefore, according to the fracture development of the reservoir, the conductivity requirements and the proppant performance, it can be judged whether the total amount of sand delivered during the pressure test is appropriate. The total liquid volume can refer to the sum of the pre-fluid, sand-carrying fluid and displacement fluid during the fracturing construction process. The total liquid volume affects the length and width of the fracture, and thus affects the fracturing effect. Therefore, according to the permeability of the reservoir, the fracture development and the fracturing target, it can be judged whether the total liquid volume during the pressure test is appropriate.

[0028] S103: According to the first fracturing parameter of the target reservoir, a first fracture propagation model of the target reservoir is selected using a preset fracturing sand plugging determination model.

[0029] In some embodiments, based on the geological parameters of the target reservoir and the first fracturing parameters, a preset fracturing sand plugging determination model can be used to determine the sand plugging event level corresponding to when the target reservoir is fracturing using the first CO2 fracturing process; based on the sand plugging event level corresponding to when the target reservoir is fracturing using the first CO2 fracturing process, the first fracture extension model of the target reservoir can be selected.

[0030] By using a preset fracturing sand plugging determination model to determine the corresponding sand plugging event level when the target reservoir is fracturing using the first CO2 fracturing process, the first fracture extension model suitable for the target reservoir fracture extension can be selected based on the geological conditions of the target reservoir and the results of the pressure test using the first CO2 fracturing process.

[0031] The preset fracturing sand plugging judgment model can determine the geological parameters and fracturing parameters corresponding to sand plugging events of different sand plugging event levels based on historical fracturing data. According to the geological parameters and fracturing parameters of the sand plugging event, the crack extension characteristics corresponding to the sand plugging event level can be extracted. According to the crack extension characteristics corresponding to the sand plugging event level, a suitable crack extension model can be selected. Specifically, data such as clay content, burial depth, Young's modulus and crack development in geological parameters are closely related to the expansion of cracks and the formation of sand plugging. Different combinations of geological parameters may lead to sand plugging events of different levels. Similarly, data such as displacement, sand ratio, total sand delivery and total liquid volume in fracturing parameters can directly affect the crack expansion effect and the risk of sand plugging. Therefore, by comparing the geological parameters and fracturing parameters corresponding to different sand plugging event levels in historical fracturing data, the crack extension characteristics closely related to the sand plugging event level can be extracted. Therefore, according to the geological parameters of the target reservoir (including data such as clay content, burial depth, Young's modulus and fracture development) and the first fracturing parameters (including data such as displacement, sand ratio, total sand delivery and total liquid volume), the preset fracturing sand plugging determination model can be used to preliminarily determine the sand plugging event level corresponding to the fracturing of the target reservoir using the first CO2 fracturing process. According to the sand plugging event level corresponding to the fracturing of the target reservoir using the first CO2 fracturing process, the first fracture extension model of the target reservoir corresponding to the first CO2 fracturing process can be obtained.

[0032] In some embodiments, based on the historical fracturing parameters of multiple historical fracturing wells in a historical reservoir, a double logarithmic curve of the bottom hole net pressure and time corresponding to multiple historical fracturing wells in the historical reservoir can be generated; based on the slope of the double logarithmic curve of the bottom hole net pressure and time corresponding to the multiple historical fracturing wells, a fracturing sand plugging determination model can be constructed using expert experience.

[0033] During the fracturing process, if sand plugging occurs, the net bottom hole pressure will change, and this change will be reflected in the slope of the double logarithmic curve. By constructing double logarithmic curves of bottom hole net pressure and time corresponding to multiple historical fracturing wells, real-time monitoring and early warning of sand plugging can be achieved. Combined with expert experience, the fracture extension and sand plugging can be judged, which helps to improve the accuracy and reliability of the fracturing sand plugging judgment model.

[0034] The historical fracturing parameters of multiple historical fracturing wells collected in the historical reservoir can be combined with the wellbore fluid mechanics model to calculate the bottom hole net pressure of each fracturing well during the construction process. At the same time, the time information of each historical fracturing well during the construction process can be obtained to draw a double logarithmic curve of the bottom hole net pressure and time. The obtained bottom hole net pressure and the corresponding time data are sorted to form time series data. The time series data is double-logarithmically transformed, that is, the natural logarithm of the bottom hole net pressure and time is taken, and then plotted on the coordinate system to form a double logarithmic curve of the bottom hole net pressure and time. The slope of the bottom hole net pressure-time double logarithmic curve of each fracturing well can be calculated to obtain the slope value of each curve. The slope value reflects the rate at which the bottom hole net pressure changes with time, that is, the speed and efficiency of fracture extension. Different slope values ​​may correspond to different fracture extension modes and fracturing effects. Combined with the expert experience and knowledge in the field of fracturing, the correlation between different slope values ​​and fracturing sand plugging is analyzed. For example, a sudden increase in slope may mean the occurrence of sand plugging. Based on slope analysis and expert experience, a fracturing sand plugging determination model is constructed. The fracturing sand plugging determination model can be a simple threshold judgment model, that is, when the slope exceeds a certain threshold, it is considered that sand plugging has occurred, or it can be a more complex machine learning model that predicts the occurrence of sand plugging by training historical data, which will not be repeated here. For example, the slopes of the double logarithmic curves of net bottom pressure-time correspond to different levels of sand plugging events, which can be divided into three levels. Slope a corresponds to level I, slopes a~b correspond to level II, and slopes 0~b correspond to level III, where parameters a and b can be derived based on expert experience. Based on the divided sand plugging event levels, the historical fracturing parameters can be summarized, thereby obtaining the geological conditions and fracturing parameters of fracturing events of different levels, which will not be repeated here.

[0035] In some embodiments, based on the historical fracturing parameters, the bottom hole pressure of the historical fracturing well and the closing pressure of the historical reservoir fractures can be determined; based on the bottom hole pressure of the historical fracturing well and the closing pressure of the historical reservoir fractures, the bottom hole net pressure of the historical fracturing well can be calculated; based on the bottom hole net pressure of the historical fracturing well, a double logarithmic curve of the bottom hole net pressure and time can be generated.

[0036] Based on the bottom hole pressure of historical fracturing wells and historical reservoir fractures, the bottom hole net pressure can be calculated and a double logarithmic curve of bottom hole net pressure and time can be drawn. These rich historical data provide a solid foundation for building a fracturing sand plugging determination model. In addition, different historical fracturing wells may have different geological conditions, fracturing processes, etc. These factors will lead to differences in the slope of the bottom hole net pressure-time double logarithmic curve. This diversity of data helps to build a more comprehensive and accurate fracturing sand plugging determination model.

[0037] Based on the simulation and calculation of the flow of fracturing fluid in the wellbore and formation, the bottom hole pressure of the historical fracturing well during the construction process can be calculated by using the principles of fluid mechanics and the wellbore model, and combined with the historical fracturing parameters. The closing pressure of the historical reservoir fracture refers to the minimum pressure required to completely close the historical reservoir fracture. The closing pressure of the historical reservoir fracture can be estimated by analyzing the formation response after the historical reservoir fracturing (such as microseismic monitoring data) or using the geomechanical model, which will not be repeated here. The bottom hole net pressure of the historical fracturing well refers to the difference between the actual pressure at the bottom of the historical fracturing well and the closing pressure of the historical reservoir fracture closure. This value reflects the net driving force of the historical reservoir fracture during the fracturing process. The calculated bottom hole net pressure and the corresponding time data can be sorted to form time series data. The time series data can be double-logarithmic transformed, that is, the natural logarithm of the bottom hole net pressure and time is taken, and then plotted on the coordinate system. The curve obtained in this way is the double-logarithmic curve of the bottom hole net pressure and time. By analyzing the double logarithmic curves of bottom hole net pressure and time, we can understand the dynamic behavior of historical reservoir fractures during the fracturing process, and then build a fracturing sand plugging determination model.

[0038] S104: Determine, based on the first fracture propagation model of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process, a corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process.

[0039] In some embodiments, based on the geological parameters of the target reservoir and the first fracturing parameters, the first fracture extension model can be used to predict the fracture parameters of the target reservoir; based on the predicted fracture parameters of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process, the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process can be determined.

[0040] The fracture parameters of the target reservoir are predicted by the first fracture propagation model, which provides a basis for selecting the appropriate proppant particle size. Combining the proppant particle size and fracture parameters, the corresponding sand plugging risk level when fracturing the target reservoir using the first CO2 fracturing process can be more accurately evaluated.

[0041] The first fracture propagation model may be a PKN fracture propagation model or a KGD fracture propagation model. Based on the first fracture propagation model, fracture parameters of the target reservoir may be predicted. The fracture parameters of the target reservoir may include fracture length and fracture width.

[0042] For example, according to the PKN fracture propagation model, the following formula can be used to predict the fracture length and width of the target reservoir:

[0043]

[0044] Where: L is the total seam length (unit: m), w is the seam width (unit: mm), Q0 is the injection displacement (unit: m3 / min), C L is the filtration coefficient (unit: m / min 0.5 ), H is the seam height (unit: m), t is the injection time (unit: min), is the plane strain elastic modulus (unit: MPa), and μ is the fracturing fluid viscosity (unit: cP).

[0045] For example, according to the KGD fracture propagation model, the following formula can be used to predict the fracture length and width of the target reservoir:

[0046]

[0047] Where: L is the total fracture length (unit: m), w is the fracture width (unit: mm), Q0 is the injection displacement (unit: m3 / min), t is the injection time (unit: min), v is the Poisson's ratio, μ is the fracturing fluid viscosity (unit: cP), and G is the rock shear modulus.

[0048] According to the predicted fracture parameters of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process, the proppant bridging theory can be used to calculate the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process. Specifically, according to the proppant particle size corresponding to the first CO2 fracturing process, a critical fracture width for sand plugging can be set. According to the predicted fracture parameters of the target reservoir, the total fracture length and the fracture length of the portion of the fracture that is less than or equal to the critical fracture width for sand plugging can be determined. According to the total fracture length and the fracture length of the portion of the fracture that is less than or equal to the critical fracture width for sand plugging, the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process can be calculated.

[0049] In some embodiments, the first crack propagation model may be updated based on continuous machine learning.

[0050] By using machine learning to continue updating the first fracture propagation model, the prediction performance of the first fracture propagation model under different reservoir and fracturing conditions can be guaranteed, which helps to improve prediction accuracy, enhance model generalization ability and improve computational efficiency.

[0051] The first fracture extension model may be a model constructed based on a machine learning algorithm or a formulated model. For example, the first fracture extension model may be a model constructed based on a machine learning algorithm. Based on the PKN fracture extension model, the geological parameters and historical fracturing parameters corresponding to the historical reservoir may be used as input parameters of the first fracture extension model, and the first fracture extension model predicts and outputs the historical fracture parameters. The difference between the predicted historical fracture parameters and the real historical fracture parameters is minimized until the first fracture extension model converges. At every preset time interval, the first fracture extension model may be updated using the geological parameters, fracturing parameters, and fracture parameters of the target reservoir to ensure the generalization and robustness of the first fracture extension model. For example, the first fracture extension model may be a formulated model. A filter loss coefficient prediction model based on a machine learning algorithm may be constructed. Based on the PKN fracture extension model, the geological parameters and historical fracturing parameters corresponding to the historical reservoir may be used as inputs of the filter loss coefficient prediction model, and the filter loss coefficient prediction model predicts and outputs the filter loss coefficient corresponding to the historical reservoir. The difference between the predicted filter loss coefficient and the real filter loss coefficient is minimized until the filter loss coefficient prediction model converges. At preset time intervals, the geological parameters, fracturing parameters and fluid loss coefficient of the target reservoir may be used to update the fluid loss coefficient prediction model, thereby ensuring the generalization and robustness of the first fracture propagation model.

[0052] In some embodiments, the critical fracture width for sand plugging can be determined based on the proppant particle size corresponding to the first CO2 fracturing process; the total fracture length and the fracture length of the portion of the fracture that is less than or equal to the critical fracture width for sand plugging can be determined based on the predicted fracture parameters of the target reservoir; based on the total fracture length and the fracture length of the portion of the fracture that is less than or equal to the critical fracture width for sand plugging, the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process can be calculated.

[0053] Based on the total fracture length and the fracture length of the portion of the fracture that is less than or equal to the critical fracture width of sand plugging, the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process can be quickly and accurately calculated, which helps to optimize and adjust the CO2 fracturing process of the target reservoir based on the sand plugging risk level.

[0054] According to the proppant particle size corresponding to the first CO2 fracturing process, the critical crack width of sand plugging can be determined using the proppant bridging theory. For example, w=6a can be selected as the critical crack width of sand plugging, where a is the proppant particle size corresponding to the first CO2 fracturing process. According to the predicted fracture parameters of the target reservoir - the crack length and crack width, it can be determined that the length of the portion of the target reservoir crack width that is less than or equal to the critical crack width w of sand plugging is l. The total crack length of the target reservoir is L, so the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process is f=l / L%.

[0055] S105: If the sand plugging risk level is within a preset sand plugging risk level interval, determining the first CO2 fracturing process as the CO2 fracturing process for the target reservoir.

[0056] In some embodiments, based on historical fracturing parameters of multiple historical fracturing wells and historical CO2 fracturing processes of historical reservoirs, sand plugging risk level intervals corresponding to multiple sand plugging event levels can be determined; if the sand plugging risk level is within the sand plugging risk level interval, it can be determined that the first CO2 fracturing process is the CO2 fracturing process for the target reservoir.

[0057] By determining the sand plugging risk level intervals corresponding to multiple sand plugging event levels, a foundation is laid for realizing real-time evaluation of the first CO2 fracturing process based on the sand plugging risk level of the first CO2 fracturing process.

[0058] The slopes of the double logarithmic curves of net bottom pressure-time correspond to different levels of sand plugging events, which can be divided into three levels: slope a corresponds to level I, slope a~b corresponds to level II, and slope 0~b corresponds to level III, where parameters a and b can be obtained based on expert experience. Based on the divided sand plugging event levels, the historical fracturing parameters can be summarized, thereby obtaining the geological conditions and fracturing parameters of different levels of fracturing events, which will not be repeated here.

[0059] Based on the historical fracture parameters of multiple historical reservoirs and the proppant particle size corresponding to the historical CO2 fracturing process, the proppant bridging theory can be used to calculate the sand plugging risk level corresponding to different levels of fracturing events. Specifically, based on the proppant particle size corresponding to the historical CO2 fracturing process, the corresponding critical fracture width for sand plugging can be calculated. Based on the historical fracture parameters of the historical reservoir, the total fracture length of the historical fractures and the fracture length of the portion of the historical fractures that is less than or equal to the critical fracture width for sand plugging can be determined. Based on the total fracture length of the historical fractures and the fracture length of the portion of the historical fractures that is less than or equal to the critical fracture width for sand plugging, the sand plugging risk level corresponding to different levels of fracturing events can be calculated. For example, for sand plugging event levels I, II, and III, the corresponding sand plugging risk levels are f, respectively. Ⅰ 、f Ⅱ 、f Ⅲ The sand plugging risk levels of the three sand plugging event levels are f Ⅰ 、f Ⅱ 、f Ⅲ , three sand plugging risk level intervals can be determined, namely [f Ⅰ ,1]、[f Ⅱ ,f Ⅰ ),[f Ⅲ ,f Ⅱ ]. If the calculated sand plugging risk level of the target reservoir is in the interval [f Ⅲ ,f Ⅱ ] or interval [fⅡ ,f Ⅰ ), it can be determined that the first CO2 fracturing process is the CO2 fracturing process for the target reservoir. The calculated sand plugging risk level corresponding to the target reservoir is in the interval [f Ⅲ ,f Ⅱ ] indicates that under the current construction conditions, there is no risk of sand plugging when the first CO2 fracturing process is used to fractur e the target reservoir. The proppant particle size corresponding to the first CO2 fracturing process will not cause sand plugging events. Therefore, the first CO2 fracturing process can be used as the CO2 fracturing process for the target reservoir. The calculated sand plugging risk level corresponding to the target reservoir is in the interval [f Ⅱ ,f Ⅰ ) indicates that under the current construction conditions, there is a risk of low sand plugging when using the first CO2 fracturing process to fracture the target reservoir. The first CO2 fracturing process can be used as the CO2 fracturing process for the target reservoir and the construction parameters can be monitored and optimized in real time during the construction process.

[0060] In some embodiments, if the sand plugging risk level is outside a preset sand plugging risk level interval, the second CO2 fracturing process can be selected as a new first CO2 fracturing process based on the geological parameters of the target reservoir and the first CO2 fracturing process; the steps of obtaining the first fracturing parameters, selecting the first fracture propagation model, judging the sand plugging risk level, and selecting the second CO2 fracturing process as the new first CO2 fracturing process can be iteratively performed until the sand plugging risk level corresponding to the new first CO2 fracturing process is within the preset sand plugging risk level interval; the new first CO2 fracturing process can be determined as the CO2 fracturing process for the target reservoir.

[0061] By selecting the second CO2 fracturing process as the new first CO2 fracturing process according to the geological parameters of the target reservoir and the first CO2 fracturing process when the sand plugging risk level is outside the preset sand plugging risk level range, the CO2 fracturing process of the target reservoir can be dynamically selected and adjusted according to the sand plugging risk level to ensure the safety of the fracturing operation of the target reservoir.

[0062] If the sand plugging risk level is outside the preset sand plugging risk level range, it means that the first CO2 fracturing process currently used is not the optimal choice and the sand plugging risk is too high. For example, for sand plugging event levels Ⅰ, Ⅱ, and Ⅲ, the corresponding three sand plugging risk level ranges are [f Ⅰ ,1]、[f Ⅱ ,f Ⅰ ),[f Ⅲ ,f Ⅱ ]. If the calculated sand plugging risk level of the target reservoir is not within the interval [f Ⅲ ,f Ⅱ ] and the interval [fⅡ ,f Ⅰ ), that is, the sand plugging risk level corresponding to the target reservoir is within the interval [f Ⅰ ,1], indicating that there is a high risk of sand plugging when the first CO2 fracturing process is used to fractur e the target reservoir under the current construction conditions, and a new first CO2 fracturing process needs to be selected. If the sand plugging risk level is outside the preset sand plugging risk level interval, the second CO2 fracturing process can be selected as the new first CO2 fracturing process according to the geological parameters of the target reservoir and the first CO2 fracturing process. Specifically, according to the geological parameters of the target reservoir, several usable CO2 fracturing processes can be pre-set to construct an optional CO2 fracturing process set. For all usable CO2 fracturing processes in the CO2 fracturing process set, the correlation between the two CO2 fracturing processes is determined according to the similarity of the method steps of the two CO2 fracturing processes. If the first CO2 fracturing process is not suitable as the CO2 fracturing process for the target reservoir, the first CO2 fracturing process can be removed from the CO2 fracturing process set, and the CO2 fracturing process with the highest correlation with the first CO2 fracturing process can be selected from the CO2 fracturing process set as the second CO2 fracturing process. Iteratively execute the steps of obtaining the first fracturing parameters, selecting the first fracture propagation model, determining the sand plugging risk level, and selecting the second CO2 fracturing process as the new first CO2 fracturing process until the sand plugging risk level corresponding to the new first CO2 fracturing process is within a preset sand plugging risk level interval. The new first CO2 fracturing process with a sand plugging risk level within the preset sand plugging risk level interval is determined as the CO2 fracturing process for the target reservoir.

[0063] A specific embodiment of this specification is provided below:

[0064] 1. Based on the fracturing design plan of Group A of Well M, the target reservoir is 4593.0-4604.0m, and the lithology is tuffaceous breccia and brecciated tuff. The rock mechanical characteristics of the target reservoir are: Young's modulus average 2.9×104MPa; Poisson's ratio is about 0.23; the minimum horizontal principal stress is 65MPa. The formation permeability of this well is 0.06mD, and the porosity is 7.3%. The design displacement of the main sand addition stage is 7.0-9.0m3 / min, the fracturing fluid viscosity is 0.1cP, the highest sand ratio is 17% (sand concentration is 300kg / m3), the average sand ratio is 13.0%, and 40 / 70 mesh ceramsite is used.

[0065] 2. Figure 4 It is the optimal fracturing process standard for the target reservoir conditions of group A in well M. Figure 3First, select the closed pure dry method for pressure testing. A total of 22 fracturing construction data from the early stage of the reservoir are selected, and the double logarithmic curves of the bottom-hole net pressure and time for each well are plotted respectively. After comprehensive evaluation by experts, the critical slopes a and b of the bottom-hole net pressure-time double logarithmic curve are determined to be 0.20 and 0.45 respectively. Thus, it can be divided into three grades. The slope greater than or equal to 0.45 corresponds to Grade I, the slope between 0.20 and 0.45 corresponds to Grade II, and the slope between 0 and 0.20 corresponds to Grade III.

[0066] 3. According to the analysis results, the geological conditions and fracturing parameters of the fracturing events corresponding to critical Grade I and critical Grade II are known. Using the PKN fracture propagation model considering fluid loss, the fracture propagation characteristics of the corresponding grade sand plugging events are inverted, and the variation process of fracture length-fracture width is obtained. The sand plugging risk levels of critical Grade I and critical Grade II are 7.8%, f Ⅱ is 3.0%, f Ⅲ is 0%.

[0067] 4. The geological conditions of the target reservoir are known: the average Young's modulus is 2.9×104 MPa, the Poisson's ratio is about 0.23, the permeability is 0.05 mD, and the porosity is 7.3%; the designed fracturing parameters are: the minimum displacement is 7 m3 / min, the viscosity of the fracturing fluid is 0.1 cP, the highest sand ratio is 17% (sand concentration 300 kg / m3), the average sand ratio is 13.0%, and the proppant particle size is 40 / 70 mesh. It is calculated that the sand plugging risk level during fracturing of the target reservoir under the designed fracturing parameters is 4.2%. Since f0 = 4.2%. Since 3.0% < f0 < 7.8%, it is predicted that the sand plugging risk grade of the target reservoir during fracturing under the current fracturing parameters is II, and real-time monitoring is required to prevent sand plugging.

[0068] Based on the above method for determining the CO2 fracturing process of the target reservoir, this specification also presents an embodiment of the device for determining the CO2 fracturing process of the target reservoir. As Figure 5 shown, the device 400 for determining the CO2 fracturing process of the target reservoir may specifically include the following modules:

[0069] A selection module 501, which can be used to select the first CO2 fracturing process according to the geological parameters of the target reservoir.

[0070] An acquisition module 502, which can be used to conduct pressure testing on the target reservoir using the first CO2 fracturing process to obtain the first fracturing parameters of the target reservoir.

[0071] A selection module 503, which can be used to select the first fracture propagation model of the target reservoir using a preset fracturing sand plugging judgment model according to the first fracturing parameters of the target reservoir.

[0072] The judgment module 504 may be used to judge the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process according to the first fracture propagation model of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process.

[0073] The determination module 505 may be configured to determine that the first CO2 fracturing process is the CO2 fracturing process for the target reservoir if the sand plugging risk level is within a preset sand plugging risk level interval.

[0074] In some embodiments, the above-mentioned selection module 503 can be specifically used to determine the sand plugging event level corresponding to when the target reservoir is fracturing using the first CO2 fracturing process based on the geological parameters and the first fracturing parameters of the target reservoir, using a preset fracturing sand plugging determination model; and select the first fracture extension model of the target reservoir based on the sand plugging event level corresponding to when the target reservoir is fracturing using the first CO2 fracturing process.

[0075] In some embodiments, the above-mentioned selection module 503 can also be specifically used to generate a double logarithmic curve of bottom hole net pressure and time corresponding to multiple historical fracturing wells in a historical reservoir based on the historical fracturing parameters of multiple historical fracturing wells in the historical reservoir; and use expert experience to construct a fracturing sand plugging determination model based on the slope of the double logarithmic curve of bottom hole net pressure and time corresponding to the multiple historical fracturing wells.

[0076] In some embodiments, the above-mentioned selection module 503 can also be specifically used to determine the bottom hole pressure of the historical fracturing well and the closing pressure of the historical reservoir fractures according to the historical fracturing parameters; calculate the bottom hole net pressure of the historical fracturing well according to the bottom hole pressure of the historical fracturing well and the closing pressure of the historical reservoir fractures; generate a double logarithmic curve of the bottom hole net pressure and time according to the bottom hole net pressure of the historical fracturing well.

[0077] In some embodiments, the above-mentioned judgment module 504 can be specifically used to predict the fracture parameters of the target reservoir using the first fracture extension model based on the geological parameters of the target reservoir and the first fracturing parameters; and to judge the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process based on the predicted fracture parameters of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process.

[0078] In some embodiments, the above-mentioned judgment module 504 can also be specifically used to determine the critical fracture width of sand plugging according to the proppant particle size corresponding to the first CO2 fracturing process; determine the total fracture length of the fracture and the fracture length of the portion of the fracture that is less than or equal to the critical fracture width of sand plugging according to the predicted fracture parameters of the target reservoir; and calculate the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process according to the total fracture length of the fracture and the fracture length of the portion of the fracture that is less than or equal to the critical fracture width of sand plugging.

[0079] In some embodiments, the above-mentioned determination module 505 can be specifically used to determine the sand plugging risk level intervals corresponding to multiple sand plugging event levels based on historical fracturing parameters of multiple historical fracturing wells of historical reservoirs and historical CO2 fracturing processes; if the sand plugging risk level is within the sand plugging risk level interval, determine that the first CO2 fracturing process is the CO2 fracturing process for the target reservoir.

[0080] In some embodiments, the above-mentioned determination module 505 can also be specifically used to select the second CO2 fracturing process as the new first CO2 fracturing process according to the geological parameters of the target reservoir and the first CO2 fracturing process if the sand plugging risk level is outside the preset sand plugging risk level interval; iteratively execute the steps of obtaining the first fracturing parameters, selecting the first fracture propagation model, judging the sand plugging risk level, and selecting the second CO2 fracturing process as the new first CO2 fracturing process until the sand plugging risk level corresponding to the new first CO2 fracturing process is within the preset sand plugging risk level interval; and determine the new first CO2 fracturing process as the CO2 fracturing process for the target reservoir.

[0081] As can be seen from the above, based on the CO2 fracturing process determination device for the target reservoir provided in the embodiment of this specification, the first CO2 fracturing process can be selected according to the geological parameters of the target reservoir; the target reservoir can be pressure tested using the first CO2 fracturing process to obtain the first fracturing parameters of the target reservoir; according to the first fracturing parameters of the target reservoir, the first fracture extension model of the target reservoir is selected using a preset fracturing sand plugging determination model; according to the first fracture extension model of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process, the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process is judged; if the sand plugging risk level is within the preset sand plugging risk level range, the first CO2 fracturing process is determined to be the CO2 fracturing process for the target reservoir. Compared with the existing methods, the CO2 fracturing process can be evaluated and optimized in real time based on the pressure test results of the CO2 fracturing process on the target reservoir, so that the sand plugging risk prediction before construction can be carried out more comprehensively and accurately.

[0082] It should be noted that the units, devices or modules described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. For the convenience of description, the above devices are described separately by functions divided into various modules. Of course, when implementing this specification, the functions of each module can be implemented in the same or more software and / or hardware, or the modules that implement the same function can be implemented by a combination of multiple sub-modules or sub-units. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0083] The embodiments of the present specification also provide a computer device for a method of determining a CO2 fracturing process for a target reservoir, comprising a processor and a memory for storing instructions executable by the processor, wherein the processor can perform the following steps according to the instructions when implemented: selecting a first CO2 fracturing process according to geological parameters of the target reservoir; performing a pressure test on the target reservoir using the first CO2 fracturing process to obtain a first fracturing parameter of the target reservoir; selecting a first fracture extension model of the target reservoir using a preset fracturing sand plugging determination model according to the first fracturing parameter of the target reservoir; judging a corresponding sand plugging risk level when fracturing the target reservoir using the first CO2 fracturing process according to the first fracture extension model of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process; and determining that the first CO2 fracturing process is the CO2 fracturing process for the target reservoir if the sand plugging risk level is within a preset sand plugging risk level interval.

[0084] In order to complete the above instructions more accurately, refer to Figure 6 As shown, the embodiment of this specification also provides another specific computer device 600, wherein the computer device 600 includes a network communication port 601, a processor 602 and a memory 603, and the above structures are connected through internal cables so that each structure can perform specific data interaction.

[0085] The processor 602 can be specifically used to select a first CO2 fracturing process according to the geological parameters of the target reservoir; use the first CO2 fracturing process to test the target reservoir to obtain the first fracturing parameters of the target reservoir; select the first fracture extension model of the target reservoir according to the first fracturing parameters of the target reservoir using a preset fracturing sand plugging judgment model; judge the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process according to the first fracture extension model of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process; if the sand plugging risk level is within the preset sand plugging risk level range, determine that the first CO2 fracturing process is the CO2 fracturing process for the target reservoir.

[0086] The memory 603 may be specifically used to store corresponding instruction programs.

[0087] In this embodiment, the network communication port 601 can be a virtual port that is bound to different communication protocols so that different data can be sent or received. For example, the network communication port can be a port responsible for web data communication, a port responsible for FTP data communication, or a port responsible for email data communication. In addition, the network communication port can also be a physical communication interface or communication chip. For example, it can be a wireless mobile network communication chip, such as GSM, CDMA, etc.; it can also be a Wifi chip; it can also be a Bluetooth chip.

[0088] In this embodiment, the processor 602 may be implemented in any appropriate manner. For example, the processor may take the form of a microprocessor or processor and a computer-readable medium storing a computer-readable program code (such as software or firmware) executable by the (micro)processor, a logic gate, a switch, an application specific integrated circuit (ASIC), a programmable logic controller, and an embedded microcontroller, etc. This specification does not limit this.

[0089] In this embodiment, the memory 603 includes a volatile memory and a non-volatile memory. The memory 603 may include multiple levels. In a digital system, anything that can store binary data can be a memory; in an integrated circuit, a circuit with a storage function without a physical form is also called a memory, such as RAM, FIFO, etc.; in a system, a storage device with a physical form is also called a memory, such as a memory stick, TF card, etc.

[0090] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0091] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0092] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0093] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0094] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for determining a CO2 fracturing process for a target reservoir, characterized in that: The method comprises: Select the first CO2 fracturing process according to the geological parameters of the target reservoir; Performing a pressure test on the target reservoir using the first CO2 fracturing process to obtain a first fracturing parameter of the target reservoir; According to the first fracturing parameter of the target reservoir, a first fracture propagation model of the target reservoir is selected using a preset fracturing sand plugging determination model; According to the first fracture propagation model of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process, determining the corresponding sand plugging risk level when the target reservoir is fractured using the first CO2 fracturing process; If the sand plugging risk level is within a preset sand plugging risk level interval, the first CO2 fracturing process is determined to be the CO2 fracturing process for the target reservoir.

2. The method according to claim 1, characterized in that: The method of selecting a first fracture propagation model of the target reservoir using a preset fracturing sand plugging determination model according to the first fracturing parameter of the target reservoir includes: According to the geological parameters of the target reservoir and the first fracturing parameters, a preset fracturing sand plugging determination model is used to determine the corresponding sand plugging event level when the target reservoir is fractured using the first CO2 fracturing process; A first fracture propagation model of the target reservoir is selected according to a corresponding sand plugging event level when the target reservoir is fracturing using the first CO2 fracturing process.

3. The method according to claim 1, characterized in that: The method for constructing the fracturing sand plugging determination model includes: Generate a double logarithmic curve of bottom hole net pressure and time corresponding to the multiple historical fracturing wells in the historical reservoir according to the historical fracturing parameters of the multiple historical fracturing wells in the historical reservoir; According to the slopes of the double logarithmic curves of bottom hole net pressure and time corresponding to the plurality of historical fracturing wells, a fracturing sand plugging determination model is constructed using expert experience.

4. The method according to claim 3, characterized in that: The method of generating a double logarithmic curve of bottom hole net pressure and time corresponding to multiple historical fracturing wells in the historical reservoir according to the historical fracturing parameters of multiple historical fracturing wells in the historical reservoir comprises: Determining the bottom hole pressure of the historical fracturing well and the closing pressure of the historical reservoir fracture according to the historical fracturing parameters; Calculating the net bottom hole pressure of the historical fracturing well according to the bottom hole pressure of the historical fracturing well and the closing pressure of the historical reservoir fracture; A double logarithmic curve of bottom hole net pressure and time is generated according to the bottom hole net pressure of the historical fracturing well.

5. The method according to claim 1, characterized in that: The step of judging the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process according to the first fracture propagation model of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process includes: Predicting fracture parameters of the target reservoir using a first fracture propagation model according to the geological parameters of the target reservoir and the first fracturing parameters; According to the predicted fracture parameters of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process, the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process is determined.

6. The method according to claim 5, characterized in that: The step of judging the corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process according to the predicted fracture parameters of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process includes: Determine the critical seam width of sand plugging according to the proppant particle size corresponding to the first CO2 fracturing process; According to the predicted fracture parameters of the target reservoir, the total fracture length and the fracture length of the portion of the fracture that is less than or equal to the critical fracture width of sand plugging are determined; The corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process is calculated according to the total fracture length and the fracture length of the portion of the fracture that is less than or equal to the critical fracture width of sand plugging.

7. The method according to claim 1, characterized in that: If the sand plugging risk level is within a preset sand plugging risk level interval, determining the first CO2 fracturing process as the CO2 fracturing process for the target reservoir includes: Based on the historical fracturing parameters of multiple historical fracturing wells in the historical reservoir and the historical CO2 fracturing technology, the sand plugging risk level intervals corresponding to multiple sand plugging event levels are determined; If the sand plugging risk level is within the sand plugging risk level interval, the first CO2 fracturing process is determined to be the CO2 fracturing process for the target reservoir.

8. The method according to claim 1, characterized in that: The method further comprises: If the sand plugging risk level is outside the preset sand plugging risk level interval, the second CO2 fracturing process is selected as the new first CO2 fracturing process according to the geological parameters of the target reservoir and the first CO2 fracturing process; Iteratively executing the steps of obtaining the first fracturing parameter, selecting the first fracture propagation model, determining the sand plugging risk level, and selecting the second CO2 fracturing process as the new first CO2 fracturing process, until the sand plugging risk level corresponding to the new first CO2 fracturing process is within a preset sand plugging risk level interval; A new first CO2 fracturing process is determined as the CO2 fracturing process for the target reservoir.

9. A device for determining a CO2 fracturing process for a target reservoir, characterized in that: The device comprises: A selection module, used to select a first CO2 fracturing process according to geological parameters of a target reservoir; An acquisition module, configured to perform a pressure test on a target reservoir using the first CO2 fracturing process to obtain a first fracturing parameter of the target reservoir; A selection module, configured to select a first fracture propagation model of the target reservoir using a preset fracturing sand plugging determination model according to a first fracturing parameter of the target reservoir; A judgment module, configured to judge a corresponding sand plugging risk level when the target reservoir is fracturing using the first CO2 fracturing process according to the first fracture propagation model of the target reservoir and the proppant particle size corresponding to the first CO2 fracturing process; A determination module is configured to determine that the first CO2 fracturing process is the CO2 fracturing process for the target reservoir if the sand plugging risk level is within a preset sand plugging risk level interval.

10. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 8 is implemented.

Images