Sand consolidation construction method for temporary plugging without flowback after fracturing

Abstract

The invention relates to the technical field of oil development and fracturing well completion, in particular to a sand consolidation construction method for temporary plugging without flowback after fracturing. The method comprises the steps that a target fractured well is determined, a fractured layer section is selected in the determined target fractured well, fracturing construction is conducted on the selected fractured layer section through fracturing construction equipment, alternative extrusion is conducted on the fractured layer section through fracturing fluid, and a rope knot fiber temporary plugging agent is put into the determined target fractured well through a temporary plugging agent manifold. The rope knot fiber temporary plugging agent plugs a slotting shot hole of a fractured interval, an oil pressure boosting curve of the fractured interval is monitored in real time, fracturing construction and shutdown are continued for no more than one minute when the oil pressure boosting curve rises, a casing pressure drop curve of a target fractured well is monitored, and when the casing pressure after fracturing is lower than the casing pressure before fracturing, a fracturing pipe column is pulled up, and the casing pressure drop curve of the target fractured well is stopped; and if no overflow or small overflow exists in the process of moving the pipe column, well completion is carried out. According to the method provided by the invention, the purposes of sand consolidation, blowout prevention and efficiency improvement of the fracturing construction well can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum development and fracturing completion, and in particular to a sand consolidation construction method for temporary plugging without flowback after fracturing. Background Art

[0002] As the scale of fracturing transformation increases year by year, the sand stuck caused by sand production after fracturing is becoming more and more serious. Conventional fracturing construction technology is widely used in oil fields as the main process for tapping the potential of residual oil. In recent years, with the deterioration of oil layer physical properties and connectivity conditions, the scale of fracturing transformation has increased year by year. The formation pressure after fracturing is high, which makes it difficult to pump, and the self-flowing production affects the initial effect; sand is produced after fracturing, and frequent pump inspections increase operating costs; the diffusion time is long, and the waiting time of the team affects the construction efficiency and other problems.

[0003] Specifically, after fracturing, the suction pressure and the production pressure differential generated by flowback during string lifting affect the stability of the seam, which can easily cause fracturing sand to spit back into the wellbore, resulting in sand jamming or sand burying the string and oil layer, causing pump inspections during the warranty period. After injecting a large amount of fracturing fluid into the formation during fracturing, the pressure in the oil pipe and near-wellbore formation is high. In the absence of sufficient diffusion time, the string can cause a large amount of overflow or string lifting after the string is opened, affecting the normal pumping operation. In order to meet the initial setting requirements of chemical sand consolidation, the diffusion time after fracturing needs to diffuse for 24 hours before the pump can be lowered, resulting in long waiting times for the operation team and affecting the operation team's construction efficiency. Therefore, to address the above shortcomings, a sand consolidation construction method without flowback after fracturing is proposed. Summary of the Invention

[0004] (1) Technical issues to be solved

[0005] The present invention provides a post-fracture sand consolidation construction method for temporary plugging without flowback, so as to overcome the limitations of existing conventional fracturing construction technology in improving completion quality, sand consolidation effect and construction efficiency, as well as the inadaptability of existing conventional fracturing construction technology in post-fracture well completion.

[0006] (2) Technical solution

[0007] In order to solve the above problems, the present invention provides a sand consolidation construction method for temporary plugging without flowback after fracturing, comprising:

[0008] Step S1: determining a target fracturing well and selecting one or more fracturing intervals in the determined target fracturing well;

[0009] Step S2: performing fracturing construction on the fracturing layer selected in step S1 by means of fracturing construction equipment, and displacing the fracturing layer by means of fracturing fluid;

[0010] Step S3: injecting a knotted fiber temporary plugging agent into the target fracturing well determined in step S1 through a temporary plugging agent manifold, the knotted fiber temporary plugging agent plugging the slotted blastholes of the fracturing layer, and monitoring the oil pressure rise curve of the fracturing layer in real time;

[0011] Step S4: Observing that the oil pressure rise curve of step S3 shows an upward trend, continue the fracturing operation for no more than one minute and stop the fracturing operation equipment;

[0012] Step S5: If multiple fracturing intervals are selected in step S1, repeat steps S2 to S4 to complete the fracturing equipment shutdown in step S4 and monitor the casing pressure drop curve of the target fracturing well in real time;

[0013] Step S6: Observe the casing pressure drop curve of step S5. When the casing pressure after fracturing is lower than the casing pressure before fracturing, start the fracturing string. If there is no overflow or the overflow is small during the string movement, complete the well.

[0014] Preferably, in step S2, the fracturing construction equipment includes a sand tank truck, a liquid tank truck, a fracturing truck, a sand mixing truck and an instrument truck. The sand tank truck transports quartz sand, the liquid tank truck transports fracturing fluid, the sand mixing truck mixes quartz sand and fracturing fluid, and the fracturing truck is equipped with multiple plunger pumps inside. The fracturing truck transports sand-containing fracturing fluid through the plunger pumps. The instrument truck monitors the mixed sand concentration of the sand mixing truck, and the instrument truck monitors the pumping displacement of the fracturing truck.

[0015] Preferably, in step S3, the temporary plugging agent manifold is a wax ball manifold, and the cross-sectional diameter of the temporary plugging agent manifold is larger than the cross-sectional diameter of the knotted fiber temporary plugging agent.

[0016] Preferably, in step S3, the knotted fiber temporary plugging agent comprises a knot structure and a tail wing structure, and the knotted fiber temporary plugging agent is embedded to plug the blasthole.

[0017] Preferably, the cross-sectional diameter of the knotted fiber temporary plugging agent is adapted to the cross-sectional diameter of the blasthole.

[0018] Preferably, the quantity of the knotted fiber temporary plugging agent is adapted to the quantity of the blast holes.

[0019] Preferably, the knotted fiber temporary plugging agent automatically degrades within a preset time, and the preset time range of the knotted fiber temporary plugging agent is 24-48 hours.

[0020] Preferably, factors influencing the amount of the knotted fiber temporary plugging agent include the number of cracks opened in the fracturing layer and the effective thickness of the fracturing layer.

[0021] Preferably, in step S5, the number of the fracturing segments is adapted to the number of repeated operations.

[0022] (3) Beneficial effects

[0023] The present invention provides a sand consolidation construction method for temporary plugging without backflow after fracturing. Professional fracturing construction equipment is used to put a knotted fiber temporary plugging agent into the well. The knotted fiber temporary plugging agent enters the slotted blasthole along with the fracturing fluid and is tightly embedded to form a temporary plug. By using the knotted fiber temporary plugging agent, not only can direct well completion without backflow be achieved, and there is no sand stuck rework problem after production, but also the purposes of sand consolidation, blowout prevention and efficiency improvement of the fracturing construction well can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of a sand consolidation construction method for temporary plugging without flowback after fracturing according to an embodiment of the present invention;

[0025] Figure 2 Schematic diagram of a device for a sand consolidation construction method for temporary plugging without flowback after fracturing according to an embodiment of the present invention;

[0026] Figure 3 This is a curve chart of the casing pressure change of Example L9-342 of the present invention. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Figure 1 Flowchart of the sand consolidation construction method for temporary plugging without flowback after fracturing according to an embodiment of the present invention. Figure 1 As shown, the present invention provides a sand consolidation construction method for temporary plugging without flowback after fracturing, which specifically includes:

[0029] Step S1: determining a target fracturing well and selecting one or more fracturing intervals in the determined target fracturing well;

[0030] Step S2: performing fracturing construction on the fracturing layer selected in step S1 by means of fracturing construction equipment, and displacing the fracturing layer by means of fracturing fluid;

[0031] Step S3: injecting a knotted fiber temporary plugging agent into the target fracturing well determined in step S1 through a temporary plugging agent manifold, the knotted fiber temporary plugging agent plugging the slotted blastholes of the fracturing layer, and monitoring the oil pressure rise curve of the fracturing layer in real time;

[0032] Step S4: Observing that the oil pressure rise curve of step S3 shows an upward trend, continue the fracturing operation for no more than one minute and stop the fracturing operation equipment;

[0033] Step S5: If multiple fracturing intervals are selected in step S1, repeat steps S2 to S4 to complete the fracturing equipment shutdown in step S4 and monitor the casing pressure drop curve of the target fracturing well in real time;

[0034] Step S6: Observe the casing pressure drop curve of step S5. When the casing pressure after fracturing is lower than the casing pressure before fracturing, start the fracturing string. If there is no overflow or the overflow is small during the string movement, complete the well.

[0035] Figure 2 Schematic diagram of the device of the sand consolidation construction method for temporary plugging without flowback after fracturing according to the embodiment of the present invention. Figure 2 As shown, in step S2, the fracturing construction equipment includes a sand tank truck, a liquid tank truck, a fracturing truck, a sand mixing truck and an instrument truck. The sand tank truck transports quartz sand, the liquid tank truck transports fracturing fluid, the sand mixing truck mixes quartz sand and fracturing fluid, and the fracturing truck is equipped with multiple plunger pumps inside. The fracturing truck transports sand-containing fracturing fluid through the plunger pumps. The instrument truck monitors the mixed sand concentration of the sand mixing truck, and the instrument truck monitors the pumping displacement of the fracturing truck.

[0036] In actual applications, quartz sand is used as a proppant for fracturing. The sand mixing truck mixes the proppant and fracturing fluid into sand-containing fracturing fluid. The fracturing truck is also called a fracturing pump truck. Multiple plunger pumps constitute a plunger pump group. The fracturing truck injects the mixed sand-containing fracturing fluid into the internal equipment of the target fracturing well through the plunger pump group. The instrument truck is responsible for controlling the sand mixing truck and the fracturing pump truck, controlling parameters such as the mixed sand concentration and pumping displacement. After passing through the fracturing pump truck, the sand-containing fracturing fluid passes through the temporary plugging agent manifold and is injected into the fracturing well.

[0037] In this construction method, in step S3, the temporary plugging agent manifold is a wax ball manifold, which is used to inject wax balls in conventional fracturing and is used to inject temporary plugging agents in this process. The cross-sectional diameter of the temporary plugging agent manifold is larger than the cross-sectional diameter of the knotted fiber temporary plugging agent.

[0038] In actual application, in step S3, the knotted fiber temporary plugging agent includes a knot structure and a tail wing structure, the knotted fiber temporary plugging agent is embedded in the blasthole to block the blasthole, the cross-sectional diameter of the knotted fiber temporary plugging agent is adapted to the cross-sectional diameter of the blasthole, the number of the knotted fiber temporary plugging agent is adapted to the number of the blastholes, the knotted fiber temporary plugging agent automatically degrades within a preset time, the preset time range of the knotted fiber temporary plugging agent is 24-48 hours, and the factors affecting the number of the knotted fiber temporary plugging agent include the number of cracks opened in the fracturing layer and the effective thickness of the fracturing layer.

[0039] It should be noted that the blasthole refers to the cavity left after the casing is shot open by the plugging gun, which connects the inside of the casing and the formation; displacement is achieved by injecting fracturing fluid that does not contain quartz sand, so that all the previous sand-containing fracturing fluid is injected into the formation, preventing the presence of quartz sand in the pipe string from the pump truck outlet to the ground pipeline to the well, which may cause engineering accidents such as pipe string sticking.

[0040] Regarding the plugging principle of knotted fiber temporary plugging agents, they are used to temporarily plug fracturing openings. The temporary plugging agent utilizes a knot-and-tail structure. Optimized structure and density significantly enhance its penetration efficiency and ability to block erosion and expansion holes, creating an embedded plug. The size of the knotted fiber temporary plugging agent is selected to match the blasthole size, and a sizing design template has been developed. Table 1 shows the sizing design template for the knotted fiber temporary plugging agent. As shown in Table 1, after fracturing, the temporary plugging agent degrades and returns to the formation within a predetermined time.

[0041] Table 1 Design template for size of knotted fiber temporary plugging agent

[0042] Hole diameter (mm) Temporary plugging agent size (mm) 10.4-11.0 13 12.2-13.8 15

[0043] Regarding the optimization of the dosage of knotted fiber temporary plugging agents, the dosage of knotted fiber temporary plugging agents for each layer is determined according to the number of cracks opened and the effective thickness of the fracturing layer. Table 2 is a design template for the dosage of knotted fiber temporary plugging agents. As shown in Table 2, it can achieve the predetermined bearing pressure and seal the high-permeability holes after fracturing. It should be noted that with the help of downhole television imaging simulation, the number of fracturing and sanding holes in a crack in the stuck section is 3-5.

[0044] Table 2 Design template for dosage of knotted fiber temporary plugging agent

[0045]

[0046] It should be noted that the unit of knot temporary plugging agent is , which is calculated based on the number of blastholes, and one knot plugs one blasthole.

[0047] Regarding the temporary plugging of knotted fiber-based plugging agents, they are deployed after the fracturing and displacement operation. Depending on the size and type of the temporary plugging agent, wax balls are deployed through the surface pipeline and into the blasthole along with the fracturing fluid to prevent the fracturing truck from being evacuated.

[0048] In actual application, by observing the oil pressure rise curve, it is found that the oil pressure when the knotted fiber temporary plugging agent is added after fracturing is higher than the oil pressure of the same displacement during displacement, which can prove the temporary plugging effect; after the knotted fiber temporary plugging agent is added, the oil pressure shows an upward trend and continues to maintain the construction displacement of no more than one minute. The fracturing pump truck is stopped and the casing pressure drop curve is continuously monitored. When the casing pressure after fracturing is lower than the casing pressure before fracturing, the fracturing string is started and the overflow is observed during the movement of the string. There is no overflow or the overflow is small, and no fracturing fluid or fracturing sand is found in the overflow, which further proves the good temporary plugging effect.

[0049] In this construction method, in step S5, the number of fracturing layers is adapted to the number of times the operation is repeated.

[0050] The present invention provides a method for temporary plugging and sand consolidation after fracturing without backflow. The temporary plugging and sand consolidation construction method can effectively temporarily plug the open blasthole, temporarily separate the fracturing sand and the wellbore, improve the sand consolidation effect, temporarily seal the high pressure in the formation and slowly diffuse it, and carry out completion operations under conditions of no backflow. There is no need to consider the diffusion time. The operation time is determined according to the casing pressure change and the backflow fluid volume, effectively shortening the diffusion time.

[0051] To address the issues of difficulty in pumping, sand production, and long diffusion time after fracturing, a post-fracturing, no-flowback temporary plugging sand consolidation construction method has been proposed. By applying a high-strength soluble temporary plugging agent to seal the fracture openings, the stability of the fractures during the completion operation is improved without flowback, thereby improving the sand consolidation effect. The following describes in detail the working principle of this post-fracturing, no-flowback temporary plugging sand consolidation construction method:

[0052] Step 1: determine a target fracturing well and select one or more fracturing intervals in the determined target fracturing well;

[0053] Step 2: Fracturing the selected fracturing layer segment using fracturing equipment and displacing the fracturing layer segment using fracturing fluid;

[0054] Step 3: injecting a knotted fiber temporary plugging agent into the target fracturing well through the temporary plugging agent manifold to plug the slotted blastholes of the fracturing layer with the knotted fiber temporary plugging agent, and monitoring the oil pressure rise curve of the fracturing layer in real time;

[0055] Step 4: If an upward trend is observed on the oil pressure rise curve, continue the fracturing operation for no more than one minute and stop the fracturing equipment;

[0056] Step 5: If multiple fracturing intervals are selected, repeat steps 2 to 4 to complete the shutdown of the fracturing equipment and monitor the casing pressure drop curve of the target fracturing well in real time;

[0057] Step 6: Observe the casing pressure drop curve. When the casing pressure after fracturing is lower than the casing pressure before fracturing, start the fracturing string. If there is no overflow or the overflow is small during the movement of the string, complete the well.

[0058] In this embodiment, fracturing construction is first carried out on the fracturing layer section, and fracturing fluid is used as a replacement agent. The knotted fiber temporary plugging agent is put into the pipeline from the wax ball manifold and pumped into the formation by a pump truck. After the knotted fiber temporary plugging agent reaches the fracturing layer, it seals the open blasthole and is tightly embedded in it. The construction curve is observed to judge the temporary plugging effect.

[0059] It should be noted that the fracturing layer section is selected by the reservoir department, which will comprehensively consider the distribution of remaining oil in the reservoir. The process of injecting sand-containing fracturing fluid into the formation through a fracturing pump truck is fracturing.

[0060] In actual application, if the above construction steps are repeated for fracturing multiple sections, the operation should be stopped after the pressure stabilizes, and the pressure drop curve and overflow situation should be measured to observe the temporary plugging effect. If the casing pressure after fracturing is lower than the casing pressure before fracturing, the well can be completed directly without waiting for the diffusion time. It should be noted that the degradation rate of the knotted fiber temporary plugging agent is greater than 90% after 48 hours after fracturing, and the production layer is released to resume normal production.

[0061] Table 3 Fracturing process table

[0062] cycle Trial squeeze fracture Add sand Alternatives Add knotted fiber temporary plugging agent Well Completion

[0063] In this embodiment, Table 3 is a fracturing process table. As shown in Table 3, L9-324 is the target fracturing well determined in this embodiment. Two layers of L9-324 are selected for fracturing. Table 4 is a design table for the dosage of the temporary plugging agent for L9-324. As shown in Table 4, based on the blasthole diameter of 12.2 mm, the knotted fiber temporary plugging agent size of 15 mm is selected.

[0064] Table 4 L9-324 Temporary Plugging Agent Dosage Design Table

[0065]

[0066] In actual application, knotted fiber temporary plugging agent was added according to the construction process, and the fracturing curve was observed. Compared with the oil pressure at the same displacement during displacement, the pressure of Sa II 10+11 increased by 3.4MPa and that of Sa II 9 increased by 3.6MPa. Figure 3 This is a curve diagram of casing pressure change of Example L9-342 of the present invention, as shown in FIG. Figure 3 As shown in the figure, after the construction was completed, the casing pressure was observed and recorded for comparison. The casing pressure was 4.2MPa before compression and 1.8MPa after 4 hours of diffusion, and gradually decreased. The casing pressure after compression decreased significantly compared with the pressure of the movable open pipe string.

[0067] In this embodiment, the fracturing vehicle group is 0.7m 3 / min low displacement into knotted fiber temporary plugging agent, after 5 minutes of injection, gradually increase the displacement to 2.4m 3 / min, maintain the construction displacement for 1 minute, and stop the operation after the knotted fiber temporary plugging agent is fully deformed and embedded in the blasthole.

[0068] In actual application, the active string was lifted with a load of 15 tons, the packer was released without obstruction, and the casing pressure was 0.4 MPa. Observation of the overflow revealed only oil and gas, with no fracturing fluid or fracturing sand, and the overflow volume was small, indicating that the temporary plugging agent effectively sealed the seam openings. In this example, the casing pressure remained below 1 MPa throughout the completion process. After 46 hours of applying the knotted fiber temporary plugging agent, the overflow gradually increased. By the time the original well string was lowered after 72 hours, the estimated self-flowing fluid volume in the liquid tank reached 95 tons / day, and the casing pressure reached 5 MPa, indicating that the temporary plugging agent had degraded and production capacity had been restored.

[0069] In addition, compared with conventional fracturing construction, in terms of sand consolidation, the average sand stuck rework rate of conventional fracturing wells in Lamadian Oilfield is 9%. As of now, the well has been put into production for 3 months without sand stuck. In terms of blowout prevention, there is no overflow after fracturing the well, and the construction of the well was successfully completed without backflow. The knotted fiber temporary plugging agent can withstand a pressure of up to 25MPa, and the temporary plugging agent has a stable platform period of 24 hours. The degradation rate reaches more than 90% within 48 hours at formation temperature. In terms of efficiency improvement, the diffusion time is shortened from 24 hours to 4 hours, which improves the construction efficiency of the operation team.

[0070] The present invention provides a sand consolidation construction method for temporary plugging without backflow after fracturing. Professional fracturing construction equipment is used to put a knotted fiber temporary plugging agent into the well. The knotted fiber temporary plugging agent enters the slotted blasthole along with the fracturing fluid and is tightly embedded to form a temporary plug. By using the knotted fiber temporary plugging agent, not only can direct well completion without backflow be achieved, and there is no sand stuck rework problem after production, but also the purposes of sand consolidation, blowout prevention and efficiency improvement of the fracturing construction well can be achieved.

[0071] The above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. Ordinary technicians in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the scope of patent protection of the present invention should be defined by the claims.

Claims

1. A sand consolidation construction method for temporary plugging without flowback after fracturing, characterized in that: include: Step S1: determining a target fracturing well and selecting one or more fracturing intervals in the determined target fracturing well; Step S2: performing fracturing construction on the fracturing layer selected in step S1 by means of fracturing construction equipment, and displacing the fracturing layer by means of fracturing fluid; Step S3: injecting a knotted fiber temporary plugging agent into the target fracturing well determined in step S1 through a temporary plugging agent manifold, the knotted fiber temporary plugging agent plugging the slotted blastholes of the fracturing layer, and monitoring the oil pressure rise curve of the fracturing layer in real time; Step S4: Observing that the oil pressure rise curve of step S3 shows an upward trend, continue the fracturing operation for no more than one minute and stop the fracturing operation equipment; Step S5: If multiple fracturing intervals are selected in step S1, repeat steps S2 to S4 to complete the fracturing equipment shutdown in step S4 and monitor the casing pressure drop curve of the target fracturing well in real time; Step S6: Observe the casing pressure drop curve of step S5. When the casing pressure after fracturing is lower than the casing pressure before fracturing, start the fracturing string. If there is no overflow or the overflow is small during the string movement, complete the well.

2. The sand consolidation construction method for temporary plugging without flowback after fracturing according to claim 1, characterized in that: In step S2, the fracturing construction equipment includes a sand tank truck, a liquid tank truck, a fracturing truck, a sand mixing truck and an instrument truck. The sand tank truck transports quartz sand, the liquid tank truck transports fracturing fluid, the sand mixing truck mixes quartz sand and fracturing fluid, and the fracturing truck is equipped with multiple plunger pumps inside. The fracturing truck transports sand-containing fracturing fluid through the plunger pumps. The instrument truck monitors the mixed sand concentration of the sand mixing truck, and the instrument truck monitors the pumping displacement of the fracturing truck.

3. The sand consolidation construction method for temporary plugging without flowback after fracturing according to claim 1, characterized in that: In step S3, the temporary plugging agent manifold is a wax ball manifold, and the cross-sectional diameter of the temporary plugging agent manifold is larger than the cross-sectional diameter of the knotted fiber temporary plugging agent.

4. The sand consolidation construction method for temporary plugging without flowback after fracturing according to claim 1, characterized in that: In step S3, the knotted fiber temporary plugging agent includes a knot structure and a tail wing structure, and the knotted fiber temporary plugging agent is embedded to plug the blasthole.

5. The sand consolidation construction method for temporary plugging without flowback after fracturing according to claim 4, characterized in that: The cross-sectional diameter of the knotted fiber temporary plugging agent is adapted to the cross-sectional diameter of the blasthole.

6. The sand consolidation construction method for temporary plugging without flowback after fracturing according to claim 4, characterized in that: The quantity of the knotted fiber temporary plugging agent is adapted to the quantity of the blast holes.

7. The sand consolidation construction method for temporary plugging without flowback after fracturing according to claim 1, characterized in that: The knotted fiber temporary plugging agent automatically degrades within a preset time, and the preset time range of the knotted fiber temporary plugging agent is 24-48 hours.

8. The sand consolidation construction method for temporary plugging without flowback after fracturing according to claim 6, characterized in that: Factors influencing the amount of the knotted fiber temporary plugging agent include the number of cracks opened in the fracturing layer and the effective thickness of the fracturing layer.

9. The sand consolidation construction method for temporary plugging without flowback after fracturing according to claim 1, characterized in that: In the step S5, the number of the fracturing layers is adapted to the number of repeated operations.

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