Method and device for realizing staged fracturing of horizontal well by adopting knot type temporary plugging agent

Abstract

The embodiment of the invention provides a method and device for achieving staged fracturing of a horizontal well through a knot type temporary plugging agent, and belongs to the field of oil and gas field engineering. The method comprises the following steps: acquiring multi-cluster perforation parameters of a target well section; on the basis of the multi-cluster perforation parameters, a weighted graph representing the communication relation between the perforations is constructed, and all the perforations are divided into a plurality of fracturing clusters through a spectral clustering algorithm; for each perforation, generating matched knot type temporary plugging agent structure parameters according to the aperture, the hole direction and the resistance parameters of the corresponding perforation, and performing corresponding knot type temporary plugging agent configuration; and the prepared knot type temporary plugging agent is sequentially fed into a shaft according to the sequence of the fracturing clusters, and staged fracturing operation is completed. According to the scheme, the accuracy and stability of inter-section packing are improved, the energy fluid channeling risk is reduced, and the overall efficiency and adaptability of staged fracturing are improved.

Description

Technical Field

[0001] The present invention relates to the field of oil and gas field engineering, and particularly to a method for realizing staged fracturing of horizontal wells by using a knot-type temporary plugging agent and a device for realizing staged fracturing of horizontal wells by using a knot-type temporary plugging agent. Background Art

[0002] In the development process of unconventional oil and gas reservoirs, the multi-cluster perforation staged fracturing technology for horizontal wells has become an important means to improve production capacity. In order to achieve effective staging, the conventional method usually uses bridge plugs or soluble particle-type temporary plugging agents to temporarily seal the well sections. Bridge plug-type tools have problems such as complex downhole operations, high risk of setting failure, and the need for drilling and milling for flowback, and are particularly difficult to apply in working conditions such as wellbore deformation or refracturing. In contrast, although soluble particle-type or fiber composite temporary plugging agents can complete the temporary plugging operation by pumping, there are still technical shortcomings such as high uncertainty in plugging, difficult control of the plugging position, and low success rate of temporary plugging.

[0003] Currently, the general particle-type temporary plugging technology adopts the "large accumulation" method, relying on particles to form an interception structure near the perforations. However, the fluid path in the wellbore is complex, the spatial distribution of perforations varies greatly, the aperture, direction, and flow resistance of different perforations are different, and it is difficult for a temporary plugging agent with a single particle size or structure to effectively match each hole, often resulting in problems such as plugging off-target, energy cross-flow between segments, and fracturing failure. In addition, most of the existing temporary plugging agents lack the "structural adaptability" to match the specific perforation characteristics, and cannot achieve automatic recognition and customized configuration before staged fracturing, affecting the operation efficiency and plugging accuracy. Therefore, there is an urgent need for a temporary plugging solution with precise adaptation ability to improve the temporary plugging stability and fracturing isolation quality in the multi-cluster perforation environment of horizontal wells. Summary of the Invention

[0004] The purpose of the embodiment of the present invention is to provide a method and device for realizing staged fracturing of horizontal wells by using a knot-type temporary plugging agent, so as to at least solve the problems of uncontrollable plugging position and poor structural adaptability of the temporary plugging agent in the prior art.

[0005] To achieve the above purpose, in the first aspect of the present invention, a method for realizing staged fracturing of horizontal wells by using a knot-type temporary plugging agent is provided. The method includes: obtaining multi-cluster perforation parameters of a target well section; based on the multi-cluster perforation parameters, constructing a weighted graph representing the connectivity relationship between perforations, and using a spectral clustering algorithm to divide all perforations into multiple fracturing clusters; for each perforation, generating matching knot-type temporary plugging agent structure parameters according to the aperture, hole direction, and resistance parameters of the corresponding perforation, and performing corresponding knot-type temporary plugging agent configuration; and sequentially injecting the configured knot-type temporary plugging agent into the wellbore in the order of the fracturing clusters to complete the staged fracturing operation.

[0006] Optionally, the multi-cluster perforation parameters include any one or more of the spatial position of perforations, aperture size, hole direction angle, and estimated value of flow resistance; the multi-cluster perforation parameters are acquired based on a multi-arm acoustic imaging logging tool; the radial image output by the multi-arm acoustic imaging logging tool is parsed into a three-dimensional coordinate system of perforation space, and combined with well trajectory information to obtain the perforation azimuth and wellbore offset angle; the aperture size is calculated by an imaging inversion fitting method and normalized to a preset size grade; the estimated value of flow resistance is obtained by calculating the wellbore roughness, the angle between the perforation direction and the wellbore axis, and the local flow velocity disturbance coefficient.

[0007] Optionally, in the process of constructing a weighted graph representing the connectivity relationship between perforations, the method further includes: the weight of each edge of the weighted graph includes the Euclidean distance between perforations, the cosine value of the hole direction angle, and the flow-through possibility factor; the weights of all edges are standardized, and non-primary paths are trimmed using a threshold value; the k-th eigenvector of the Laplacian matrix is used as the benchmark for the embedding space in spectral clustering, and the number of clusters is set according to the principle of the maximum eigenvalue difference.

[0008] Optionally, the structural parameters of the knot-type temporary plugging agent include any one or more of the knot body diameter, knot body morphology type, effective length of the rope body, number of rope ends, and material grade; the structural parameters are generated by a fuzzy logic algorithm, where the input variables of the fuzzy logic algorithm are the perforation aperture grade, perforation dip angle grade, and resistance grade, and the output variable of the fuzzy logic algorithm is a preset structural grade label; each preset structural grade label corresponds to a specific structural configuration, including any one or more of the material type, manufacturing batch number, and adapted dissolution time parameter.

[0009] Optionally, in the process of configuring the corresponding knot-type temporary plugging agent, the method further includes: after the knot-type temporary plugging agent is configured on the ground, it is encapsulated in a degradable shell, and the shell is molded by a thermoplastic polymer or wax-based material; an identifiable identifier, including a radio frequency tag or a QR code, is embedded on the surface of each shell for calibrating its matching perforation number and delivery order; after the shell enters the manifold system, it is cracked or dissolved by the action of a shear valve or a variable diameter device, so as to release the knot body into the position of the perforation cluster.

[0010] Optionally, in the process of sequentially delivering the configured knot-type temporary plugging agent into the wellbore in the order of the fracturing clusters, the method further includes: after each stage of fracturing is completed, the pump injection is paused, and the knot-type temporary plugging agent delivered in the previous stage is kept under pressure and statically placed in the wellbore to stably plug near the target perforation; before the fracturing operation continues, it is determined whether the placement effect of the temporary plugging agent is effective in establishing a seal through the initial fracturing displacement / pressure ratio; if it is detected that the fracturing fluid leakage indication exceeds the preset threshold, additional knot-type temporary plugging agents in the same stage are added and the pressure is kept until the seal is established.

[0011] In a second aspect of the present invention, a knot-type temporary plugging agent device for realizing staged fracturing of horizontal wells is provided. The device includes: an acquisition unit for obtaining multi-cluster perforation parameters of a target well section; a processing unit for constructing a weighted graph representing the connectivity relationship between perforations based on the multi-cluster perforation parameters, and using a spectral clustering algorithm to divide all perforations into multiple fracturing clusters; a configuration unit for generating matching structural parameters of the knot-type temporary plugging agent for each perforation according to the aperture, hole direction and resistance parameters of the corresponding perforation, and performing corresponding configuration of the knot-type temporary plugging agent; and an execution unit for sequentially injecting the configured knot-type temporary plugging agent into the wellbore in the order of the fracturing clusters to complete the staged fracturing operation.

[0012] Optionally, the knot body of the knot-type temporary plugging agent is formed by tying multiple strands of high-molecular braided ropes. The diameter of the knot body is larger than the aperture of the perforation it fits. The rope end of the knot-type temporary plugging agent is at least four single-strand end ropes, and there is a winding reinforcement section between the rope body and the rope end of the knot-type temporary plugging agent. The knot body shape of the knot-type temporary plugging agent is a ball knot, a double hitch knot or a multiple intertwined knot, generated according to the ratio setting. Each knot-type temporary plugging agent is made by an integral molding process and is provided with a unique structural coding label.

[0013] Optionally, the knot-type temporary plugging agent is encapsulated in a soluble outer shell. The thickness of the soluble outer shell is less than 2 mm. The soluble outer shell is prepared by a wax injection or molding process. The material of the soluble outer shell is polylactic acid, a degradable polyester or a natural wax-based composite material. The two halves of the soluble outer shell are heat-sealed and clamped. A limiting fitting groove structure is formed between the inner surface of the shell and the knot body. An optical or radio frequency identification mark is set on the surface of the soluble outer shell for identifying the order and positioning number in the manifold.

[0014] On the other hand, the present invention provides a computer-readable storage medium, on which instructions are stored, and when the instructions are run on a computer, the computer is caused to execute the method for realizing staged fracturing of horizontal wells by using a knot-type temporary plugging agent as described above.

[0015] Through the above technical solutions, the solution of the present invention obtains multi-cluster perforation parameters of a target well section, constructs a weighted graph based on the spatial position relationship, hole direction angle and flow characteristics between perforations, and uses a spectral clustering algorithm to realize automatic segmentation of perforations, which can effectively identify the optimal fracturing cluster division strategy in the well section. Combining the aperture, direction and resistance characteristics of each perforation, matching structural parameters of the knot-type temporary plugging agent are further generated to realize customized configuration of one knot for one hole. By sequentially injecting the configured temporary plugging agent in the order of clusters, precise plugging is formed at the corresponding perforations, thereby improving the accuracy and stability of inter-stage sealing, reducing the risk of energy crossflow, and improving the overall efficiency and adaptability of staged fracturing.

[0016] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent specific embodiment part. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation to the embodiments of the present invention. In the drawings: Figure 1 is a flowchart of the steps of a method for realizing staged fracturing of a horizontal well by using a knot-type temporary plugging agent provided by an embodiment of the present invention; Figure 2 is a schematic diagram for comparing fracturing curves provided by an embodiment of the present invention; Figure 3 is a structural diagram of a device for realizing staged fracturing of a horizontal well by using a knot-type temporary plugging agent provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The following will describe in detail the specific embodiments of the present invention with reference to the drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0019] Figure 1 is a flowchart of the steps of a method for realizing staged fracturing of a horizontal well by using a knot-type temporary plugging agent provided by an embodiment of the present invention. As Figure 1 shown, an embodiment of the present invention provides a method for realizing staged fracturing of a horizontal well by using a knot-type temporary plugging agent, and the method includes: Step S10: Obtain multi-cluster perforation parameters of a target well section.

[0020] Specifically, the multi-cluster perforation parameters include any one or more of the spatial position of perforation, aperture size, hole direction angle, and estimated value of flow resistance; the multi-cluster perforation parameters are collected based on a multi-arm acoustic imaging logging tool; the radial image output by the multi-arm acoustic imaging logging tool is parsed into a three-dimensional coordinate system of perforation space, and combined with well trajectory information to obtain the perforation azimuth and wellbore offset angle; the aperture size is calculated by an imaging inversion fitting method and normalized to a preset size level; the estimated value of flow resistance is obtained by calculating the wellbore roughness, the angle between the perforation direction and the wellbore axis, and the local flow velocity disturbance coefficient.

[0021] In the embodiments of the present invention, in order to achieve intelligent identification and precise adaptation of multiple clusters of perforations in a well section, it is first necessary to obtain the key parameter information of each cluster of perforations and construct a comprehensive and quantifiable perforation database. The parameters of the multiple clusters of perforations include, but are not limited to, any one or more of the spatial position of the perforation, the aperture size, the hole direction angle, and the estimated value of the flow resistance. These parameters are collected by a multi-arm acoustic imaging logging tool deployed in the wellbore. The radial acoustic imaging data obtained during the logging process reflects the integrity of the wellbore wall surface and the structural morphology of each perforation.

[0022] The image data output by the logging tool is a radial grayscale image of the inner wall of the wellbore unfolded 360°. The perforation boundary contour is extracted through image recognition and edge enhancement algorithms. Further, based on the depth calibration of the tool and the wellbore trajectory data, the coordinate information of each perforation in three-dimensional space is reconstructed, thereby constructing a complete perforation spatial position model. In this model, the geometric center of the perforation is represented as three-dimensional coordinates , and its direction is described by the hole direction angle and the angle with the wellbore axis .

[0023] Furthermore, for the aperture size of each perforation, an imaging inversion fitting method is used to estimate its equivalent diameter. The measured actual aperture data is normalized and divided into multiple discrete levels. For example, the normalization is performed through the following formula: where is the measured aperture of the current perforation, and are the minimum and maximum apertures in the same well section respectively. The estimated value of the flow resistance of the perforation is comprehensively calculated by combining multiple factors, including the roughness of the wellbore wall, the angle between the perforation azimuth and the main axis of the wellbore, and the degree of disturbance of the expected fracturing fluid in the local area. The flow resistance can be expressed as: where is the roughness factor near the perforation, is the perforation tilt angle, represents the local disturbance velocity change amount, and is the empirical weight coefficient. Through the above method, a high-dimensional and structured multi-cluster perforation characteristic parameter library can be established, providing a data basis for subsequent map construction, intelligent clustering and segmentation, and the structural matching of knot-type temporary plugging agents, ensuring the target accuracy and adaptability of subsequent plugging operations.

[0024] Step S20: Based on the parameters of the multiple clusters of perforations, construct a weighted graph representing the connection relationship between the perforations, and use the spectral clustering algorithm to divide all the perforations into multiple fracturing clusters.

[0025] Specifically, in the process of constructing a weighted graph representing the connectivity relationship between perforations, the method further includes: the weight of each edge of the weighted graph includes the Euclidean distance between perforations, the cosine value of the hole direction angle, and the flow possibility factor; standardize the weights of all edges, and use a threshold to clip non-main paths; in the spectral clustering, use the k-th eigenvector of the Laplacian matrix as the embedding space benchmark, and set the number of clusters according to the principle of the largest eigenvalue difference.

[0026] In the embodiments of the present invention, based on the obtained multi-cluster perforation parameters, in order to achieve intelligent staged fracturing, it is necessary to construct a connectivity model that can reflect the geometric relationship and flow interference characteristics between perforations. For this purpose, a structure modeling method based on graph theory is proposed, by constructing a weighted undirected graph , where the node set V represents all perforation points, the edge set E represents the connectivity relationship between two points, and the weight matrix W reflects the physical association strength of each edge. Specifically, the edge weight between every two perforations is jointly determined by the following three types of parameters: 1) The Euclidean space distance between perforations , representing geometric proximity.

[0027] 2) The cosine similarity of the hole direction angles , representing direction consistency.

[0028] 3) The flow possibility factor , used to evaluate the possible interconnection degree between two holes in the fracturing fluid flow field.

[0029] The weight is defined as follows: where, is the distance attenuation factor, ensuring that the influence of distant nodes on the result is weakened. This composite weight reflects the comprehensive degree of both geometric proximity, direction consistency, and flow coupling between perforations.

[0030] Furthermore, after forming a complete weighted graph, to improve the clustering quality, standardize the weights of all edges, and set a lower threshold to clip the edges below the threshold to avoid weak connectivity paths interfering with the clustering structure. The threshold can be adaptively set according to the edge weight distribution, such as set as a certain percentile of the mean of all edge weights. After the graph is constructed, use the spectral clustering algorithm to divide the nodes in the graph into fracturing clusters. The specific method is: construct the symmetric normalized Laplacian matrix of the graph , extract the eigenvectors corresponding to the first k smallest eigenvalues, form an eigen-subspace, and perform k-means clustering. The number of clusters k is determined based on the difference (eigengap) between the eigenvalues of the Laplacian matrix, and the k value corresponding to the point with the largest difference is taken as the optimal number of clusters.

[0031] Based on the solution of the present invention, the automatic identification of the best fracturing clusters is realized, the accuracy of the isolation between fracturing sections is improved, and the risk of energy crossflow is reduced, which is especially applicable to the horizontal well conditions with uneven perforation distribution, scattered directions or complex wellbore trajectories.

[0032] Step S30: For each perforation, generate the structural parameters of the knot-type temporary plugging agent that match the perforation diameter, perforation direction and resistance parameters of the corresponding perforation, and configure the corresponding knot-type temporary plugging agent.

[0033] Specifically, the structural parameters of the knot-type temporary plugging agent include any one or more of the following: the diameter of the knot body, the type of the knot body shape, the effective length of the rope body, the number of rope ends, and the material grade; the structural parameters are generated by a fuzzy logic algorithm, where the input variables of the fuzzy logic algorithm are the perforation diameter grade, the perforation inclination grade and the resistance grade, and the output variable of the fuzzy logic algorithm is a preset structural grade label; each preset structural grade label corresponds to a specific structural configuration, including any one or more of the material type, the manufacturing batch number and the adapted dissolution time parameter.

[0034] In the embodiment of the present invention, after realizing the automatic multi-cluster perforation segmentation, in order to ensure that each perforation can be effectively plugged, it is further necessary to generate the structural parameters of the knot-type temporary plugging agent corresponding to each perforation according to the structural characteristics and fluid characteristics of each perforation, so as to realize "perforation-level matching plugging". In this embodiment, a structure adaptation method based on a fuzzy logic algorithm is adopted to generate a corresponding temporary plugging agent structure configuration model for the characteristic parameters of each perforation, and it is used as the basis for subsequent ground temporary plugging agent customization and batching.

[0035] The input parameters of each perforation include, but are not limited to, the normalized feature quantities in three dimensions: the aperture grade (SizeLevel), the hole direction inclination grade (Angle Level), and the flow resistance grade (Resistance Level). These features come from the output after the data normalization process in the previous stage. To express the fuzzy input vector, it can be expressed as: Among them, is the aperture grade of the i-th perforation, is the inclination grade, Let \(R\) be the resistance level, and all three are mapped to the closed interval \([0, 1]\). The above input vector is fed into fuzzy logic reasoning and undergoes fuzzy mapping using a set of preset three-dimensional fuzzy rule bases. The rule bases are constructed from the experience of domain experts and data from historical plugging cases. For example: 1) If \(S\) is large, \(A\) is steep, and \(R\) is high, the output structure grade is L3 (large knot body + reinforcing rope body + slow-release material).

[0036] 2) If \(S\) is small, \(A\) is gentle, and \(R\) is medium, the output structure grade is L1 (compact knot body + short rope end).

[0037] Output a structure grade tag (such as L1, L2, L3, etc.) to call the corresponding structure configuration template. Each tag is mapped to a set of structural parameter combinations, including but not limited to: 1) Knot body diameter (such as 10mm, 15mm, 20mm, etc.).

[0038] 2) Knot body morphology type (single-ball knot, double-loop knot, multiple braids).

[0039] 3) Effective length of the rope body (such as 50mm, 70mm, 90mm).

[0040] 4) Number of rope ends (4, 6, 8).

[0041] 5) Material grade (such as fast-dissolving / medium-dissolving / slow-dissolving type PGA / PLA composite filament).

[0042] 6) Additional information such as manufacturing batch number, material ratio coding, and matching bottom hole temperature range.

[0043] This hierarchical structure configuration can be stored in a preset structural parameter database in a standardized manner. The fuzzy output result will directly index this database to generate manufacturing orders or deployment instructions for surface delivery. This structure matching method based on multi-parameter fuzzy mapping significantly improves the adaptability and plugging stability of the temporary plugging agent under complex perforation conditions. Especially in working conditions where the perforation distribution directions are diverse, the hole diameter changes greatly, and the wellbore disturbance is strong, it can avoid problems such as "failure of the general plugging agent structure to plug" or "plugging off-target", ensuring that each delivered rope knot type temporary plugging agent can fully fit the target hole.

[0044] In a possible implementation, rope knot temporary plugging agents of different sizes (such as 18 - 22mm and 14 - 16mm) exhibit different characteristics in terms of plugging effect. The rope knot size has a significant impact on the adaptability to the plugged hole, pressure response, and fluid resistance. Therefore, selecting the appropriate rope knot size is crucial for the fracturing effect.

[0045] 1) 18 - 22 mm knots: Suitable for plugging larger holes. Knots of this size have a higher plugging capacity and can effectively seal larger pores during pressure tests. Such knots have a relatively stable plugging effect in high - pressure environments, can maintain airtightness for a long time, and are suitable for inter - layer segmentation and post - fracturing sealing.

[0046] 2) 14 - 16 mm knots: Suitable for plugging smaller holes. Although its plugging capacity is slightly inferior to that of 18 - 22 mm knots, it still shows a good plugging effect when dealing with smaller holes or areas with lower pressure requirements. Especially when dealing with smaller cracks or pores, 14 - 16 mm knots can provide good plugging stability.

[0047] Such as Figure 2 , when using knot temporary plugging agents for plugging, the size of the knots has a significant impact on the pressure response. For example, the total sand addition in the 6th stage is 80.6 tons, and the total sand addition in the 9th stage is 120.3 tons. After the total sand addition increases, the plugging capacity of the knots decreases. When 18 - 22 mm knots are used, the initial pressure rises significantly (such as 16 MPa), while 14 - 16 mm knots usually show a lower initial pressure rise. During use, larger - sized knots can quickly and effectively seal the holes and produce an obvious pressure response. This feature has been verified in the construction of multiple well sections. In areas with higher porosity, choosing smaller - sized knots (such as 14 - 16 mm) helps to improve the plugging efficiency because smaller knots can fill more pores and increase airtightness. In areas with lower porosity or larger holes, larger - sized knots (such as 18 - 22 mm) can better meet the plugging requirements and avoid incomplete plugging due to too - small size.

[0048] In another possible implementation, in this embodiment, in order to achieve the structural adaptation relationship between the knot - type temporary plugging agent and each perforation hole, instead of using a fuzzy logic algorithm, a fast matching method based on "structural level template + static matching index" is introduced. Specifically, first, the perforations in the well section are divided into several typical working condition combinations according to the preset aperture range, inclination angle interval, and resistance grading rules, and each combination is preset with a corresponding structural template number, such as types A, B, C, etc.

[0049] During the construction preparation stage, according to the wellbore logging data and the results of perforation parameter acquisition, the parameters of each perforation are compared with the structural template table, and the corresponding structural type is quickly located according to the range of the interval it belongs to. For example, perforations with a small aperture + medium inclination angle + high resistance will be matched to "structural type C", while perforations with a large aperture + small inclination angle + low resistance will be matched to "structural type A". Each structural type corresponds to a set of standardized manufacturing parameters, including the shape of the knot body, size, length of the rope body, and configuration of the rope end.

[0050] In the factory manufacturing process, all structural types of knotted temporary plugging agents are prefabricated according to the template number and coded for identification. Based on the matching result of perforation and the structural template, the corresponding type of knotted agent is called from the temporary plugging agent storage unit during surface batching. The delivery sequence corresponds one-to-one with the perforation sequence to ensure the compatibility between each temporary plugging agent structure and its target perforation parameters. This method eliminates the online calculation and dynamic reasoning processes and is applicable to the fracturing engineering of well sections with relatively concentrated perforation type distributions. It has the advantages of fast structural configuration response speed and convenient on-site batch operation. Through the fast index mapping relationship between the structural template and the perforation template, the "fixed-type matching" plugging strategy under simplified conditions is realized, which can also ensure the temporary plugging accuracy and the inter-stage isolation effect.

[0051] Specifically, in a possible implementation, for the combined fracturing of 10 sections in the casing deformation section, the first to the tenth sections are designed to use coiled tubing perforation. There are 12 clusters per single section, with a perforation density of 3 holes per cluster, and a total of 36 holes. The tenth section has 5 clusters, with a perforation density of 8 holes per cluster and a total of 40 holes. In actuality, the first section is perforated with 12 clusters and 36 holes, and the second to the fourth sections are perforated with 14 clusters and 42 holes. The first four sections are perforated with a total of 162 holes. For the construction of each section, it is necessary to adjust the dosage of the temporary plugging agent according to the geological characteristics, hole size, and quantity of different sections. For example: For the first to the fourth sections: Since the holes in these sections are relatively uniform and the hole diameters are small, it is designed to use 165 knotted temporary plugging agents with a size of 18 - 22 mm for plugging. Each section is divided into two deliveries to ensure that the perforation holes in each section can be effectively plugged.

[0052] For the fifth to the tenth sections: The holes in these sections are larger or there are certain deformed sections, so the number of knotted temporary plugging agents designed to be used gradually increases. The specific dosage is adjusted according to the actual construction situation. For example, 80 knotted agents with a size of 18 - 22 mm are used in the fifth section, and 94 knotted agents with a size of 18 - 22 mm are used in the sixth section. According to the difficulties in sand addition and pressure changes during construction, the quantity of the temporary plugging agent is increased in real time.

[0053] At the initial stage of the construction of each section, knotted agents with a smaller particle size (14 - 16 mm) are selected for delivery to first seal the smaller holes and improve the initial sealing performance. Subsequently, knotted agents with a size of 18 - 22 mm are used for supplementation to ensure the integrity and effectiveness of plugging the holes.

[0054] When pressure fluctuations or difficulties in sand addition are encountered, the quantity of the temporary plugging agent delivered is increased. Especially for areas with larger hole diameters or developed fractures, the number of knotted agents with a size of 18 - 22 mm is increased to improve the plugging stability.

[0055] Specifically, during the implementation process, the placement of the knot temporary plugging agent is operated through a dedicated injection device to ensure that the temporary plugging agent for each section can be accurately placed at the target position. After each placement, pressure monitoring and microseismic monitoring are required to confirm the arrival of the knot temporary plugging agent. The placement amount and particle size distribution of the temporary plugging agent for the subsequent sections are adjusted according to the real-time monitoring data to ensure effective sealing between sections. During the placement process of each stage, the pumping program needs to be precisely controlled. Before construction, by setting an appropriate liquid pumping displacement (such as 16 m³ / min), ensure the smooth placement of the knot temporary plugging agent to the bottom of the well. Especially in the subsequent stages, control the pumping flow rate and pressure to avoid excessive pressure fluctuations or uneven distribution of the temporary plugging agent. To ensure the plugging effect, a batch placement method is usually adopted. For example, each section is divided into 2 to 4 additions to avoid construction difficulties and pressure risks caused by excessive one-time placement.

[0056] Step S40: Sequentially feed the configured knot-type temporary plugging agent into the wellbore according to the order of the fracturing clusters to complete the staged fracturing operation.

[0057] Specifically, during the process of sequentially feeding the configured knot-type temporary plugging agent into the wellbore according to the order of the fracturing clusters, the method further includes: after the fracturing of each section is completed, suspend the pumping, and keep the knot-type temporary plugging agent fed in the previous section under pressure and static in the wellbore to make it stably plug at the position adjacent to the target perforation; before the continuation of the fracturing operation, determine whether an effective plug is established by the initial fracturing displacement / pressure ratio of the temporary plugging agent; if it is detected that the indication of fracturing fluid leakage exceeds the preset threshold, add the knot-type temporary plugging agent of the same section and repressurize until the plugging is established.

[0058] In the embodiment of the present invention, after the configuration of the knot-type temporary plugging agent structure is completed, to achieve efficient and reliable staged fracturing operation, the configured knot-type temporary plugging agent needs to be fed into the wellbore section by section according to the order of the pre-divided fracturing clusters, and closely cooperate with the actual fracturing process to ensure effective plugging of the target perforation clusters before each stage of fracturing. This implementation method adopts an intermittent feeding and real-time plugging verification mechanism to achieve the unity of the accuracy and safety of the temporary plugging operation.

[0059] Specifically, after the injection operation of the current fracturing section is completed, the on-site fracturing pump injection operation is suspended. While keeping the wellbore pressure stable, the knot-type temporary plugging agent corresponding to the next fracturing cluster is injected into the high-pressure manifold through ground agent delivery, and it is pushed into the wellbore by the displacement fluid. To avoid the drift or accumulation of the temporary plugging agent in the pipe, the quantity of each delivery is determined according to the number of corresponding perforations, and the "one knot per hole" or "cluster matching" method is used for proportioning.

[0060] When the knotted temporary plugging agent descends to the vicinity of the target section, the pumping is stopped and the pressure is maintained in the wellbore for a period of time (such as 3 to 5 minutes) to allow the knot structure to unfold in the fluid environment, its knot part is wedged into the perforation channel, and the rope end is attached to the periphery of the hole edge to form an effective plugging. This static process is particularly important for the knotted structure, which helps it to fully fit the complex hole wall in a non-rigid state and improve the plugging stability. Before entering the next stage of fracturing operation, the initial fracturing displacement and pressure change rate are monitored in real time to determine whether the current section has been successfully plugged. If it is found that the initial pressure rises slowly, the displacement increases abnormally, or a rapid pressure drop occurs during the injection process, it can be determined that the temporary plugging effect is not good, and there may be incomplete plugging or dislocation of the knot. At this time, the injection is immediately stopped, and the same type of knotted temporary plugging agent is added, and the "delivery-pressure maintenance-observation" process is repeated until the wellhead pressure response meets the preset standard (for example: the initial fracturing pressure is more than 10% higher than the stable pressure of the previous section, or the displacement fluctuation value is within the tolerance range).

[0061] The scheme of the present invention improves the robustness of the plugging operation through the combination of delivery-stationary-feedback judgment-dynamic adjustment, ensuring that each stage of fracturing is under controllable and highly isolated operating conditions before operation. It is particularly suitable for operating environments with complex perforation structures, large differences in temporary plugging agent configurations, or obvious differences in well sections.

[0062] In one possible implementation, during fracturing, the difficulty of adding sand is usually manifested as abnormal pressure increase or excessive filtration loss, resulting in the inability to effectively carry sand or excessive pumping pressure. During the sand adding process, as the pressure gradually increases, some sections of the well experience abnormal pressure increases, especially when the filter layer is uneven or the crack expansion is hindered, the pressure will rise sharply. Due to excessive filtration loss or poor cracking, the migration and distribution of sand particles become difficult, resulting in uneven sand concentration, which affects the effective support and crack expansion of the crack.

[0063] In the process of repeating "delivery-maintaining pressure-observation", when adding sand is difficult, the solution of the present invention uses a knot temporary plugging agent to block certain unsmooth cracks or holes to avoid sand loss or blockage. The knot temporary plugging agent can effectively isolate the fractured area and reduce the pressure fluctuation during the sand addition process. In the section where adding sand is difficult, use 18-22mm knot temporary plugging agent for plugging to ensure that the cracks in the high-pressure area can be properly closed, thereby reducing the pressure fluctuation of the subsequent fracturing section. By releasing the knot temporary plugging agent in batches (for example, 2 to 4 times per section), it is ensured that the pressure can be stabilized after each release to avoid the impact of sudden pressure changes on the construction.

[0064] Adjust the pumping flow rate and pressure according to real-time pressure monitoring data to avoid equipment failures or fracture ruptures caused by excessive pumping pressure. At this time, reduce the pumping flow rate (for example, from 4.0 m³ / min to 2.0 m³ / min) to maintain a stable construction progress. For sections with difficult sand addition and large pressure fluctuations, use crosslinked fluid to expand the fractures and improve the fracture acceptability, thereby reducing the rate and frequency of pressure increase. During the sand addition process, add sand using a low-concentration fine sand slug to avoid a sharp increase in pressure caused by a high-concentration sand slug. The low-concentration fine sand slug can better distribute the sand grains, ensure uniform transportation of the sand grains, and avoid the occurrence of pressure peaks.

[0065] Furthermore, during the sand addition process, real-time pressure monitoring is crucial. By using microseismic monitoring and pressure monitoring equipment, the construction team can obtain the pressure state of the construction section in real time and adjust the strategy in a timely manner. For example, during the sand addition process in Sections 5 and 6, if a sharp increase in pressure or difficult sand addition is detected, the pumping pressure can be immediately reduced, the quantity of the knotted temporary plugging agent put in can be adjusted, or the liquid ratio can be changed.

[0066] Figure 3 It is the device structure diagram of the device for realizing staged fracturing of horizontal wells using a knotted temporary plugging agent provided by an embodiment of the present invention. As Figure 3 shown, an embodiment of the present invention provides a device for realizing staged fracturing of horizontal wells using a knotted temporary plugging agent. The device includes: an acquisition unit for obtaining multi-cluster perforation parameters of a target well section; a processing unit for constructing a weighted graph representing the connectivity relationship between perforations based on the multi-cluster perforation parameters and dividing all perforations into multiple fracturing clusters using a spectral clustering algorithm; a configuration unit for generating matching structural parameters of the knotted temporary plugging agent for each perforation according to the aperture, hole direction, and resistance parameters of the corresponding perforation and performing the configuration of the corresponding knotted temporary plugging agent; and an execution unit for sequentially injecting the configured knotted temporary plugging agent into the wellbore in the order of the fracturing clusters to complete the staged fracturing operation.

[0067] Preferably, the knot body of the knotted temporary plugging agent is formed by knotting multi-strand high-molecular braided ropes. The diameter of the knot body is larger than the aperture of the perforation it fits. The rope end of the knotted temporary plugging agent is at least four single-strand end ropes. There is a winding reinforcement section between the rope body and the rope end of the knotted temporary plugging agent. The knot body shape of the knotted temporary plugging agent is a ball knot, a double hitch knot, or a multiple interwoven knot, generated according to the ratio setting. Each knotted temporary plugging agent is made by an integral molding process and is provided with a unique structure coding label.

[0068] In the embodiments of the present invention, the structural design of the knot-type temporary plugging agent fully considers the physical characteristics of downhole perforation channels and the fluid forces during the fracturing process. Using multi-strand polymer braided ropes as raw materials, a stable-structured knot body is constructed through a specific knotting method. The knot body is the core plugging part of the temporary plugging agent, and its diameter is designed to be larger than the corresponding perforation diameter, so that it can produce a wedging effect after being pumped to the perforation position, ensuring the stability and impact resistance of the plugging position.

[0069] Preferably, the knot body is formed by multi-strand ropes through a mechanized knotting process, with a good balance of flexibility and a certain rigidity. In terms of shape, it can adopt a ball knot type, a double knot type or a multi-layer intertwined type according to different perforation types. The ball knot type has a compact structure and is suitable for small-diameter perforations; the double knot adds a reinforcing structure on the outside to improve its plugging stability; the multi-layer intertwined structure is suitable for high-inclination or irregular hole types and has a stronger ability to deform and fit.

[0070] The rope body of the knot-type temporary plugging agent is the middle section connecting the knot body and the end rope strands, and its length is adjustable according to preset parameters. At least four single-strand end ropes are provided at the end of the rope body as the rope end part. These rope ends are radially unfolded in the fluid environment, covering the periphery of the hole opening, which helps to increase the contact area, fill the gaps, and further limit the displacement of the knot body in the perforation. To enhance the structural stability, a winding reinforcement section is provided between the rope body and the rope end. This section is processed by densified braiding or local cementing technology to improve the local tensile and torsional resistance, preventing structural separation or fracture under complex downhole stress conditions.

[0071] Each knot-type temporary plugging agent is prepared by an integral molding process, avoiding the structural weaknesses caused by segmented splicing and ensuring the continuity and stability of the overall strength. In order to achieve surface identification and downhole tracking, each temporary plugging agent is given a unique structural coding label during the manufacturing process. This label can be attached to the surface of the rope body or inside the outer shell in the form of an RFID electronic chip, two-dimensional code printing or hot stamping, for identifying its type, structural parameters, adapted section number and dissolution time number.

[0072] Preferably, the knot-type temporary plugging agent is encapsulated in a soluble outer shell; the thickness of the soluble outer shell is less than 2 mm; the soluble outer shell is prepared by a wax injection or molding process, and the material of the soluble outer shell is polylactic acid, biodegradable polyester or natural wax-based composite material; the two halves of the soluble outer shell are heat-sealed and clamped, and a limiting and fitting groove structure is formed between the inner surface of the shell and the knot body; optical or radio frequency identification marks are set on the surface of the soluble outer shell for identifying the order and positioning number in the pipe string.

[0073] In the embodiments of the present invention, to improve the pumping stability and directional release accuracy of the knot-type temporary plugging agent in a high-pressure fluid system, the knot-type temporary plugging agent is encapsulated in a soluble shell. This shell provides physical protection to the knot body, keeping its shape compact and attitude stable during transportation, storage, and pumping, and preventing entanglement, overlap, or deformation between multiple temporary plugging agents. At the same time, the soluble shell also has a controllable release function, which can quickly dissolve or rupture after entering the wellbore to achieve the immediate release and accurate deployment of the knot structure.

[0074] The thickness of the shell of the soluble shell is preferably less than 2 mm, which reduces the influence of the shell on the outer diameter while ensuring the structural strength, facilitating the smooth passage through pipe manifold elbows and variable-diameter sections. The shell can be manufactured using a wax injection molding process or a compression molding process. The wax injection process is suitable for scenarios with high precision requirements and strong batch consistency, while the compression molding process is more suitable for the rapid production of shaped materials such as polyester shells.

[0075] In terms of the shell material, it is preferably made of polylactic acid (PLA), biodegradable polyester, or natural wax-based composite materials, which have good processability, controllable dissolution performance under bottom-hole temperature conditions, and environmental protection characteristics of being pollution-free to fracturing fluid and having no toxic by-products. The two halves of the shell are joined by a heat-sealed edge-closing die process to ensure the formed shell has reliable sealing and overall strength, while also facilitating natural detachment during dissolution in a shearing device or wellbore fluid.

[0076] To improve the identification efficiency and delivery sequence control accuracy of the knot-type temporary plugging agent in the surface agent delivery system, an optical or radio frequency identification mark is provided on the outer surface of the soluble shell. The optical mark can be achieved by means of two-dimensional code, bar code spraying, or laser etching, and is suitable for an automatic loading module read by a vision system. The radio frequency mark uses a miniature RFID tag embedded in the shell material, which can be identified by a wireless scanning device after encapsulation, and is used to read the matching perforation number, structure type, and the sequence number of the fracturing cluster to which the temporary plugging agent belongs. This identification mechanism can be linked with the pipe manifold control system to ensure that each temporary plugging agent is delivered in sequence according to the established procedure.

[0077] The embodiments of the present invention also provide a computer-readable storage medium, which stores instructions that, when run on a computer, cause the computer to execute the method for implementing staged fracturing of horizontal wells using a knot-type temporary plugging agent as described above.

[0078] Those skilled in the art can understand that all or part of the steps in the methods of the above embodiments can be completed by instructing relevant hardware through a program, which is stored in a storage medium and includes several instructions to enable a single-chip microcomputer, a chip or a processor to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs.

[0079] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention. Additionally, it should be noted that, in the above specific embodiments, the various specific technical features described can be combined in any appropriate manner without conflict. To avoid unnecessary repetition, the embodiments of the present invention will not separately describe various possible combination methods.

[0080] In addition, any combination can be made between various different embodiments of the present invention as long as it does not violate the idea of the embodiments of the present invention, and it should also be regarded as the content disclosed by the embodiments of the present invention.

Claims

1. A method for realizing staged fracturing of horizontal wells by using knot-type temporary plugging agents, characterized in that, The method includes: Obtaining multi-cluster perforation parameters of a target well section; Based on the multi-cluster perforation parameters, constructing a weighted graph representing the connectivity relationship between perforations, and using a spectral clustering algorithm to divide all perforations into multiple fracturing clusters; For each perforation, according to the aperture, hole direction, and resistance parameters of the corresponding perforation, generating matching knot-type temporary plugging agent structure parameters, and performing corresponding knot-type temporary plugging agent configuration; Sequentially injecting the configured knot-type temporary plugging agent into the wellbore in the order of the fracturing clusters to complete the staged fracturing operation.

2. The method according to claim 1, characterized in that, The multi-cluster perforation parameters include: Any one or more of the spatial position, aperture size, hole direction angle, and estimated value of flow resistance of the perforations; The multi-cluster perforation parameters are collected based on a multi-arm acoustic imaging logging tool; The radial image output by the multi-arm acoustic imaging logging tool is parsed into a three-dimensional coordinate system of perforation space, and combined with well trajectory information to obtain the perforation azimuth and wellbore deviation angle; The aperture size is calculated by an imaging inversion fitting method and normalized to a preset size grade; The estimated value of flow resistance is obtained by calculating the wellbore roughness, the angle between the perforation direction and the wellbore axis, and the local flow velocity perturbation coefficient.

3. The method according to claim 1, wherein In the process of constructing a weighted graph representing the connectivity relationship between perforations, the method further includes: The weight of each edge of the weighted graph includes the Euclidean distance between perforations, the cosine value of the hole direction angle, and the flow possibility factor; Normalizing the weights of all edges, and using a threshold value to cut off non-main paths; In the spectral clustering algorithm, the k-th eigenvector of the Laplacian matrix is used as the embedding space reference, and the number of clusters is set according to the principle of the maximum eigenvalue difference.

4. The method according to claim 1, characterized in that The structure parameters of the knot-type temporary plugging agent include: Any one or more of the knot body diameter, knot body morphology type, effective length of the rope body, number of rope ends, and material grade; The structure parameters are generated by a fuzzy logic algorithm, where the input variables of the fuzzy logic algorithm are the perforation aperture grade, perforation dip angle grade, and resistance grade, and the output variable of the fuzzy logic algorithm is a preset structure grade label; Each preset structure grade label corresponds to a specific structure configuration, including any one or more of the material type, manufacturing batch number, and adapted dissolution time parameter.

5. The method according to claim 1, wherein In the process of performing the corresponding knot-type temporary plugging agent configuration, the method further includes: After the knot-type temporary plugging agent is configured on the ground, it is encapsulated in a degradable shell, and the shell is molded by a thermoplastic polymer or a wax-based material; An identifiable identifier, including a radio frequency tag or a two-dimensional code, is embedded on the surface of each shell for calibrating its matching perforation number and delivery order; After the shell enters the pipe manifold system, it is cracked or dissolved under the action of a shear valve or a variable diameter device, so as to release the knot body into the position of the perforation cluster.

6. The method according to claim 1, wherein In the process of sequentially injecting the configured knot-type temporary plugging agent into the wellbore in the order of the fracturing clusters, the method further includes: After each stage of fracturing is completed, the pump injection is paused, and the knot-type temporary plugging agent injected in the previous stage is kept under pressure and static in the wellbore to stably plug it in the vicinity of the target perforation; Before the fracturing operation continues, the placement effect of the temporary plugging agent is judged by the ratio of the initial fracturing displacement / pressure to determine whether a plugging is effectively established. If the indication of fracturing fluid leakage is detected to exceed the preset threshold, additional knot-type temporary plugging agents in the same section shall be added and the pressure shall be maintained again until the plugging is successful.

7. An apparatus for realizing staged fracturing of horizontal wells by using a knot-type temporary plugging agent, characterized in that, The device includes: An acquisition unit, configured to obtain multi-cluster perforation parameters of a target well section; A processing unit, configured to construct a weighted graph representing the connectivity relationship between perforations based on the multi-cluster perforation parameters, and use a spectral clustering algorithm to divide all perforations into multiple fracturing clusters; A configuration unit, configured to generate matching structural parameters of the knot-type temporary plugging agent for each perforation according to the aperture, hole direction and resistance parameters of the corresponding perforation, and configure the corresponding knot-type temporary plugging agent; An execution unit, configured to sequentially inject the configured knot-type temporary plugging agents into the wellbore in the order of the fracturing clusters to complete the staged fracturing operation.

8. The device according to claim 7, characterized in that, The knot body of the knot-type temporary plugging agent is formed by tying multiple strands of high-molecular braided ropes. The diameter of the knot body is larger than the aperture of the perforation it fits. The rope end of the knot-type temporary plugging agent is at least four single-strand end ropes, and there is a winding reinforcement section between the rope body and the rope end of the knot-type temporary plugging agent; The knot body shape of the knot-type temporary plugging agent is a ball knot, a double half hitch or a multiple intertwined knot, generated according to the ratio setting; Each knot-type temporary plugging agent is made by an integral molding process and is provided with a unique structural coding label.

9. The device according to claim 8, characterized in that, The knot-type temporary plugging agent is encapsulated in a soluble outer shell; The thickness of the soluble outer shell is less than 2 mm; The soluble outer shell is prepared by a wax injection or molding process, and the material of the soluble outer shell is polylactic acid, biodegradable polyester or natural wax-based composite material; The two halves of the soluble outer shell are heat-sealed and clamped together, and a limit fitting groove structure is formed between the inner surface of the shell and the knot body; An optical or radio frequency identification mark is provided on the surface of the soluble outer shell for identifying the sequence and positioning number in the manifold.

10. A computer-readable storage medium, characterized in that, Instructions are stored on the computer-readable storage medium, which, when running on a computer, cause the computer to execute the method for realizing staged fracturing of a horizontal well using a knot-type temporary plugging agent according to any one of claims 1-6.

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