A method for preventing fracturing interference from adjacent well

Abstract

The application discloses a method for preventing fracturing interference of adjacent wells, which comprises the following steps: setting an upper packer of a drainage string in the oil and gas well at the upper part of a production layer section and setting a lower packer at the lower part of the production layer section; removing a sucker rod and a flange on the wellhead of the oil and gas well when the adjacent well is about to be fractured; connecting a press hose line with the upper end of the oil pipe, and connecting the other end of the press hose line with a hydraulic source; operating the hydraulic source to press the oil pipe via the press hose line so as to set the upper packer and the lower packer, seal the annulus corresponding to the production layer section, and keep the space between the upper packer and the lower packer at a predetermined pressure. The method avoids lifting the pipe string when the adjacent well is fractured, greatly shortens the influence time on the production well, is simple in construction method, saves the production cost, and greatly reduces the risk of sand burying the pipe string in the fracturing process of the adjacent well.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well development technology, and more specifically to a method for preventing interference from fracturing adjacent wells. Background Technology

[0002] Fracturing refers to the process of injecting a liquid with a certain viscosity into an oil-bearing formation using hydraulic force, exceeding the formation's absorption capacity. This gradually increases the wellbore pressure until it exceeds the pressure required to fracture the formation, resulting in one or more horizontal or vertical fractures. Fracturing is a technique that artificially creates fractures in the formation to improve the underground flow environment of crude oil, increase well production, and improve the flow conditions of crude oil at the bottom of the well.

[0003] As the density of oil and gas well deployments increases year by year, and the scale of fracturing gradually expands, the phenomenon of well perforation is also becoming more frequent. Wells that have been perforated exhibit a significant drop in gas production and require major workovers due to sand burial, incurring high operating costs. In some cases, even after normal fluid production, there is no gas production. In some wells where production tubing has been retrieved, the sand column height reaches 500-800 meters, making sand removal extremely difficult, and in some cases, it is impossible to remove the sand and the well is simply abandoned.

[0004] Generally, before fracturing an adjacent well, the production tubing of surrounding wells needs to be retrieved and the wellhead sealed. The production tubing is then lowered back in after fracturing is complete, resulting in a prolonged impact on the production of surrounding wells and incurring significant operational costs. In recent years, with the gradual adoption of L-shaped horizontal wells, the number of adjacent wells has increased dramatically. Furthermore, fracturing operations are now conducted on a large scale with high displacement, gradually increasing the probability of well cross-contamination. This necessitates retrieving even more tubing from surrounding wells, severely limiting production.

[0005] Methods to prevent interference from fracturing in adjacent wells need to be studied to reduce the impact time of fracturing in adjacent wells and prevent sand from burying the tubing string. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preventing interference from fracturing adjacent wells in order to solve at least one of the above-mentioned problems existing in the prior art.

[0007] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0008] According to one aspect of the present invention, a method for preventing interference from fracturing operations of adjacent wells is provided, comprising the following steps:

[0009] Step S1: Place the upper packer of the production tubing string in this oil and gas well at the upper part of the production zone and place the lower packer at the lower part of the production zone;

[0010] Step S2: When the adjacent well is about to be fractured, remove the sucker rod and the flange at the wellhead of this oil and gas well;

[0011] Step S3: Connect the pressure hose to the upper end of the oil pipe, and connect the other end of the pressure hose to the hydraulic power source;

[0012] Step S4: Operate the hydraulic source to pressurize the oil pipe via the pressurization hose to set the upper packer and the lower packer, seal the annulus corresponding to the production section, and maintain the space between the upper packer and the lower packer at a predetermined pressure.

[0013] According to one embodiment of the present invention, in step S1, the upper part of the production layer includes a range within 3-5 meters above the production layer, and the lower part of the production layer includes a range within 3-5 meters below the production layer.

[0014] According to one embodiment of the present invention, in step S1, the upper packer and the lower packer are rubber tube packers.

[0015] According to one embodiment of the present invention, in step S2, the distance between the adjacent well and the present oil and gas well does not exceed 500 meters.

[0016] According to one embodiment of the present invention, in step S2, the fracturing of the adjacent well includes 1-2 hours before the injection of fracturing fluid into the adjacent well.

[0017] According to one embodiment of the present invention, in step S2, removing the sucker rods at the wellhead of the oil and gas well includes removing the first sucker rod closest to the wellhead and lowering the remaining sucker rods into the tubing.

[0018] According to one embodiment of the present invention, in step S3, the pressure hose is connected to the oil pipe by a threaded connection, and a pressure gauge is provided on the pressure hose.

[0019] According to one embodiment of the present invention, in step S3, the hydraulic source is a cement pump truck.

[0020] According to one embodiment of the present invention, in step S4, when the pressure of the pressure gauge meets a predetermined value, the hydraulic source is operated to stop pressurizing.

[0021] According to one embodiment of the present invention, in step S4, the predetermined pressure is determined based on the pressure required for packer setting.

[0022] According to one embodiment of the present invention, after the fracturing of the adjacent well is completed, the wellhead pressure of the oil and gas well is unloaded, the upper packer and the lower packer are unsealed, the pressurization pipeline is removed, and the wellhead upper flange and the sucker rod are installed.

[0023] By adopting the above technical solutions, the method for preventing interference from fracturing in adjacent wells provided by this invention has the following advantages compared with the prior art: This method solves the problem of affecting gas production caused by fracturing in adjacent wells, eliminates the need to retrieve the tubing string from the production well and seal the wellhead, reduces the impact time, and prevents the tubing string from being buried by sand; moreover, this method does not require extensive adjustments and changes to the structure of the production well, and its workload and investment costs are low, significantly improving production efficiency and reducing development costs. This process has been applied in the field test in the coalbed methane block of the North China Oilfield in the Qinshui Basin, avoiding the occurrence of tubing string burial in adjacent wells caused by fracturing, with significant results. Attached Figure Description

[0024] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0025] Figure 1 A schematic diagram of the production tubing string used in the method for preventing fracturing interference from adjacent wells according to the present invention during normal production;

[0026] Figure 2 A schematic diagram of the production tubing string when implementing the method for preventing fracturing interference from adjacent wells according to the present invention;

[0027] Figure 3 This is a flowchart of a method for preventing interference from fracturing adjacent wells according to the present invention.

[0028] List of reference numerals in the attached diagram:

[0029] 10 Casing, 20 Pumping Unit, 21 Tubing, 22 Upper Packer, 23 Lower Packer, 24 Pumping Pump, 25 Tailpipe, 26 Sucker Rod, 30 Wellhead Control Unit, 31 Wellhead Gate Valve, 32 Upper Flange, 33 Lower Flange, 34 Pipeline, 40 Pressure Testing Hose Line, S Production Section. Detailed Implementation

[0030] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0031] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0032] Figure 1 A schematic diagram of the production tubing used in the method for preventing fracturing interference from adjacent wells according to the present invention is shown during normal production. (See diagram below.) Figure 1 As shown, the production and drainage string includes casing 10, pumping unit 20, and wellhead control unit 30.

[0033] The casing 10 is installed inside the coalbed methane well, and the end of the casing 10 closest to the wellhead is connected to the wellhead control device 30. The casing 10 includes at least one perforation located on the casing 10 at a position corresponding to the coalbed methane reservoir. The at least one perforation is used to allow coalbed methane to enter the casing 10 through the at least one perforation located on the casing 10 at a position corresponding to the coalbed methane reservoir.

[0034] The oil pumping unit 20 generally includes, from top to bottom, an oil pipe 21, an upper packer 22, a lower packer 23, a pumping pump 24, a tailpipe 25, and a sucker rod 26 installed inside the oil pipe.

[0035] The tubing 21 is housed within the hollow casing 10, with its upper end extending to the outside of the wellhead. An annular space exists between the tubing 21 and the casing 10. An upper packer 22 and a lower packer 23 are mounted on the tubing 21 and deform upon pressurization to seal the annular space between the tubing 21 and the casing 10. The upper packer 22 and the lower packer 23 can be rubber sleeve type packers.

[0036] The sucker rod 26 extends from the top to the bottom of the tubing 21, and the lower end of the sucker rod 26 is connected to the pumping pump 24. The sucker rod 26 can be a single-stage rod or a double-stage rod. Optionally, in some embodiments, a centralizer (not shown) may be fitted on the sucker rod 26 to reduce friction between the sucker rod 26 and the tubing 21.

[0037] The extraction pump 24 can be a rod pump or a plunger pump. The extraction pump 24 is lowered into the tubing 21 through the sucker rod 26 connected to it and is fixedly connected to the tubing 21 through a fixing device.

[0038] A wellhead control device 30 is provided above the wellhead. The wellhead control device 30 may include: a wellhead gate 31, an upper flange 32, a lower flange 33, and a pipeline 34 for discharging coalbed methane and water.

[0039] Wellhead gate 31 may include, for example, but not limited to, a tubing gate and / or a casing gate. The tubing gate is connected to the tubing 21 and is used to control the closing and opening of the tubing. The casing gate is connected to the casing 10 and is used to control the closing and opening of the casing 10.

[0040] During normal production, such as Figure 1As shown, the sucker rod 26 of the production tubing extends above the wellhead and is connected to an external power unit. Driven by the external power unit, it performs reciprocating cycles of upward and downward thrusting to extract oil and gas.

[0041] When implementing the method for preventing fracturing interference from adjacent wells according to the present invention, such as Figure 2 As shown, the upper packer 22 of the production tubing string in this oil and gas well is placed at the upper part of the production zone S, and the lower packer 23 is placed at the lower part of the production zone S. When a neighboring well is about to be fractured, the sucker rod 26 and the upper flange 32 at the wellhead of this oil and gas well are removed, the casing gate valve is closed, and the pressure hose 40 is connected to the upper end of the tubing 21 via, for example, a threaded connection. The other end of the pressure hose 40 is connected to a hydraulic power source, for example, a cement pump truck. The pressure hose is equipped with a pressure gauge and a pressure relief valve. The hydraulic power source is operated to pressurize the tubing 21 via the pressure hose 40 to set the upper packer 22 and the lower packer 23, sealing the annulus corresponding to the production zone S and maintaining a predetermined pressure in the space between the upper packer 22 and the lower packer 23. This pressure can prevent fracturing fluid or sand from the neighboring well from flowing into the wellbore.

[0042] Optionally, in some embodiments, the upper part of the production layer S includes a range within 3-5 meters above the production layer S, and the lower part of the production layer S includes a range within 3-5 meters below the production layer S.

[0043] Optionally, in some embodiments, the distance between adjacent wells and the current oil and gas well does not exceed 500 meters. Wells that are relatively close together may experience fracturing interference, while if the fracturing operation of a well is far from the current oil and gas well, its impact on the current well is minimal, and such temporary plugging is unnecessary. The length of the fracturing fracture is typically no more than 500 meters; therefore, interference between wells spaced greater than 500 meters is minimal.

[0044] Optionally, in some embodiments, the imminent fracturing of the adjacent well includes 1-2 hours prior to the injection of fracturing fluid into the adjacent well.

[0045] Optionally, in some embodiments, removing the sucker rod 26 from the wellhead of the oil and gas well includes removing the first sucker rod closest to the wellhead and lowering the remaining sucker rods into the tubing 21.

[0046] Optionally, in some embodiments, when the pressure gauge of the pressurized hose line meets a predetermined value, such as the pressure value for setting the upper packer 22 and the lower packer 23, the hydraulic source is operated to stop pressurizing.

[0047] Optionally, in some embodiments, after the fracturing of the adjacent well is completed, the wellhead pressure of this oil and gas well is unloaded, the upper packer 22 and the lower packer 23 are unsealed, the pressurization pipeline 40 is removed, the wellhead upper flange 32 and the sucker rod 26 are installed, and production is resumed.

[0048] The method of the present invention will be further explained in detail below using a coalbed methane well Z125-5 as an example. This well produces 1,500 cubic meters of gas per day, and the production zone is buried at a depth of 725m-728m. Due to fracturing of an adjacent well, well Z125-5 needs to take measures to prevent sand burial and to reduce the time that gas production is affected.

[0049] During normal production, the tubing string structure of this well, from top to bottom, is: D73mm flat tubing + K344 upper packer × depth 721m + D73mm flat tubing × 1 piece + K344 lower packer × depth 730m + D32mm tubing pump + tailpipe × 1 piece. During normal production, the packer is in the closed position. When fracturing an adjacent well, the following procedures are followed:

[0050] A. Wellhead removal: Upside down to remove the first sucker rod at the top of the wellhead, remove the upper flange of the wellhead, and close the casing gate valve;

[0051] B. Connecting the high-pressure hose: One end of the high-pressure hose is connected to the wellhead tubing, and the other end is connected to the cement pump truck. A pressure gauge and a pressure relief valve are installed on the pipeline to control the pipeline pressure.

[0052] C. Pressure setting: Calculate the pumping pressure of the cement pump truck based on the packer setting pressure, pressurize according to the predetermined pressure, set the packer, monitor pressure changes, and ensure that the packer is always in the setting state;

[0053] D. Depressurization and Unsealing: After the fracturing of the adjacent well is completed, monitor the wellhead pressure of the adjacent well. After the pressure of the adjacent well drops to 0, open the pressure relief valve to release the pressure and unseal the packer.

[0054] E. Install the wellhead: Install the upper flange of the wellhead, lower the sucker rod, connect the threads, and then re-drain after pumping.

[0055] The method has the following advantages: (1) By using this method, the fracturing of adjacent wells and the start-up of the tubing string are avoided, and the time of impact on the production well is greatly shortened; (2) The construction method is simple, saves production costs, and greatly reduces the risk of sand burying the tubing string during the fracturing of adjacent wells.

[0056] The packers in the device are made of ordinary steel and rubber cylinders, both of which are commonly used products in the petroleum industry. These components and parts are available on the market.

[0057] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0058] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0059] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preventing interference from fracturing operations of adjacent wells, characterized in that, Includes the following steps: Step S1: Place the upper packer of the production tubing string in this oil and gas well at the upper part of the production zone and place the lower packer at the lower part of the production zone; Step S2: When the adjacent well is about to be fractured, remove the sucker rod and the flange at the wellhead of this oil and gas well; Step S3: Connect the pressure hose to the upper end of the oil pipe, and connect the other end of the pressure hose to the hydraulic power source; Step S4: Operate the hydraulic source to pressurize the oil pipe via the pressurization hose to set the upper packer and the lower packer, seal the annulus corresponding to the production section, and maintain the space between the upper packer and the lower packer at a predetermined pressure; After the fracturing of the adjacent well is completed, the wellhead pressure of this oil and gas well is unloaded, the upper packer and the lower packer are unsealed, the pressure hose is removed, and the wellhead flange and the sucker rod are installed.

2. The method according to claim 1, characterized in that, In step S1, the upper part of the production layer includes a range of 3-5 meters above the production layer, and the lower part of the production layer includes a range of 3-5 meters below the production layer.

3. The method according to claim 1, characterized in that, In step S1, the upper packer and the lower packer are rubber tube packers.

4. The method according to claim 1, characterized in that, In step S2, the distance between the adjacent well and the current oil and gas well shall not exceed 500 meters.

5. The method according to claim 1, characterized in that, In step S2, the adjacent well is about to be fracturing, which includes 1-2 hours before the fracturing fluid is injected into the adjacent well.

6. The method according to claim 1, characterized in that, In step S2, removing the sucker rods from the wellhead of the oil and gas well includes removing the first sucker rod closest to the wellhead and lowering the remaining sucker rods into the tubing.

7. The method according to claim 1, characterized in that, In step S3, the pressure hose is connected to the oil pipe by a threaded connection, and a pressure gauge is installed on the pressure hose.

8. The method according to claim 1, characterized in that, In step S3, the hydraulic source is a cement pump truck.

9. The method according to claim 7, characterized in that, In step S4, when the pressure of the pressure gauge meets the predetermined value, the hydraulic source is operated to reach the predetermined pressure and then the pressurization is stopped.

10. The method according to claim 1, characterized in that, In step S4, the predetermined pressure is determined based on the pressure required for the packer to set.

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