Method for preventing adjacent well fracturing interference

Abstract

The invention discloses a method for preventing fracturing interference of an adjacent well, which comprises the following steps of: arranging an upper packer of a drainage pipe column in an oil-gas well at the upper part of a production layer section, and arranging a lower packer at the lower part of the production layer section; when the adjacent well is about to be fractured, a sucker rod at the wellhead of the oil-gas well and an upper flange at the wellhead are detached; a pressing hose is connected with the upper end of the oil pipe, and the other end of the pressing hose is connected with a hydraulic source; the hydraulic source is operated, the oil pipe is pressed through the pressing hose so that the upper packer and the lower packer can be set, the annulus corresponding to the production interval can be sealed, and the space between the upper packer and the lower packer can be kept at the preset pressure. According to the method, the pipe column is prevented from being pulled out when the adjacent well is fractured, the influence time on the production well is greatly shortened, the construction method is simple, the production cost is saved, and the risk of sand burying of the pipe column in the fracturing process of the adjacent well is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas well exploitation, and more specifically to a method for preventing adjacent well fracturing interference. Background Art

[0002] Fracturing refers to the process of injecting a liquid with a certain viscosity into the oil layer with a capacity greater than that of the oil layer during oil or gas production by hydraulic force, so that the wellbore pressure gradually increases. When the pressure increases to a level greater than the pressure required for the oil layer to rupture, one or several horizontal or vertical cracks will form in the oil layer. Fracturing is a process of artificially creating cracks in the formation, improving the flow environment of crude oil underground, increasing oil well production, and improving the flow conditions of crude oil at the bottom of the oil well.

[0003] As the density of oil and gas wells increases year by year and the scale of fracturing gradually increases, the phenomenon of well penetration is also increasing. The wells that are penetrated show a significant drop in gas volume and sand burial, which requires major repairs. The overhaul costs a lot of operating costs, and there is even no gas production after normal liquid production. In some wells where the production string is pulled out, the sand column height reaches 500-800 meters, and it is extremely difficult to clean the sand, or even cannot be cleaned and directly scrapped.

[0004] Generally, before fracturing adjacent wells, production tubings of adjacent wells need to be pulled out and the wellheads closed. Production tubings are then lowered after fracturing is completed, which affects the production of adjacent wells for a long time and generates a large amount of operating costs. In recent years, with the gradual promotion of L-type horizontal wells, the number of adjacent wells has increased dramatically, and fracturing has been carried out on a large scale and with large displacement. The probability of fracturing adjacent wells has gradually increased, and more tubings of surrounding wells need to be pulled out, which seriously limits production.

[0005] It is necessary to study methods to prevent interference from adjacent well fracturing in order to reduce the impact time of adjacent well fracturing and prevent sand burying the tubing string. Summary of the invention

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

[0007] In order to achieve the above 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 fracturing interference in adjacent wells is provided, comprising the following steps:

[0009] Step S1: setting an upper packer of the production and drainage pipe string in the oil and gas well at the upper part of the production layer section, and setting a lower packer at the lower part of the production layer section;

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

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

[0012] Step S4: operate the hydraulic source to pressurize the oil pipe via the pressurizing hose line to seal the upper packer and the lower packer, seal the annulus corresponding to the production layer section and maintain a predetermined pressure in the space between the upper packer and the lower packer.

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

[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 oil and gas well does not exceed 500 meters.

[0016] According to one embodiment of the present invention, in step S2, the adjacent well is about to be fractured including 1-2 hours before the adjacent well is injected with fracturing fluid.

[0017] According to an 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 oil pipe.

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

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

[0020] According to an 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 setting the packer.

[0022] According to one embodiment of the present invention, the process further includes unloading the wellhead pressure of the oil and gas well after the adjacent well fracturing is completely completed, unsealing the upper packer and the lower packer, removing the pressure-fracturing pipeline, and installing the wellhead upper flange and the sucker rod.

[0023] Due to the adoption of the above technical scheme, the method for preventing interference from adjacent well fracturing provided by the present invention has the following beneficial effects compared with the prior art: the method solves the problem of affecting gas production caused by adjacent well fracturing, and there is no need to pull out the tubing in the production well and seal the wellhead, which reduces the impact time and can prevent the occurrence of sand-buried tubing; moreover, the method does not require a large number of adjustments and changes to the structure of the production well, and the required workload and investment cost are low, which significantly improves production efficiency and reduces development costs. The process has been tested in the field application of the coalbed methane block of the North China Oilfield in the Qinshui Basin, avoiding the occurrence of sand-buried tubing in adjacent wells caused by fracturing, with significant results. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 A schematic diagram of the structure of a production and drainage pipe string used in the method for preventing interference from adjacent well fracturing according to the present invention during normal production;

[0026] Figure 2 It is a schematic diagram of the structure of the production and drainage string when implementing the method for preventing fracturing interference of adjacent wells according to the present invention;

[0027] Figure 3 The figure is a flow chart of the method for preventing fracturing interference of adjacent wells according to the present invention.

[0028] List of reference numerals:

[0029] 10 casing, 20 pumping unit, 21 tubing, 22 upper packer, 23 lower packer, 24 extraction pump, 25 tail pipe, 26 sucker rod, 30 wellhead control device, 31 wellhead gate, 32 upper flange, 33 lower flange, 34 pipeline, 40 pressure hose line, S production layer section. DETAILED DESCRIPTION

[0030] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

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

[0032] Figure 1 The schematic diagram of the structure of the production and drainage string used in the method for preventing adjacent well fracturing interference according to the present invention during normal production is shown. Figure 1 As shown, the production and drainage string includes a casing 10 , an oil pumping device 20 and a wellhead control device 30 .

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

[0034] The pumping device 20 generally includes an oil pipe 21, an upper packer 22, a lower packer 23, a pumping pump 24, a tail pipe 25 and a sucker rod 26 arranged in the oil pipe, which are arranged in sequence from top to bottom.

[0035] The oil pipe 21 is arranged in the hollow casing 10 and its upper end extends to the outside of the wellhead. There is an annular space between the oil pipe 21 and the casing 10. The upper packer 22 and the lower packer 23 are installed on the oil pipe 21, which are deformed during pressure injection to close the annular space between the oil pipe 21 and the casing 10. The upper packer 22 and the lower packer 23 can be rubber-type packers.

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

[0037] The extraction pump 24 may be a rod pump or a plunger pump. The extraction pump 24 is lowered into the oil pipe 21 through a sucker rod 26 connected thereto and is fixedly connected to the oil pipe 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] The wellhead gate 31 may include, for example but not limited to, a tubing gate and / or a casing gate. The tubing gate is communicated with the tubing 21 and is used to control the closing and opening of the tubing. The casing gate is communicated with the casing 10 and is used to control the closing and opening of the casing 10.

[0040] In normal production, Figure 1As shown, the sucker rod 26 of the production and drainage pipe string extends to the top of the wellhead and is connected to an external power device, and performs a reciprocating cycle of upstroke and downstroke under the drive of the external power device to produce oil and gas.

[0041] When the method for preventing adjacent well fracturing interference according to the present invention is to be implemented, Figure 2 As shown, the upper packer 22 of the production string in the oil and gas well is set at the upper part of the production layer section S, and the lower packer 23 is set at the lower part of the production layer section S. When the adjacent well is about to be fractured, the sucker rod 26 and the upper flange 32 of the wellhead of the oil and gas well are removed, the casing gate is closed, and then the pressure hose line 40 is connected to the upper end of the oil pipe 21 through, for example, a thread, and the other end of the pressure hose line 40 is connected to a hydraulic source such as a cement pump truck. The pressure hose line is provided with a pressure gauge and a pressure relief gate. The hydraulic source is operated to pressurize the oil pipe 21 through the pressure hose line 40 to seal the upper packer 22 and the lower packer 23, seal the annulus corresponding to the production layer section S, and keep the space between the upper packer 22 and the lower packer 23 at a predetermined pressure, which can prevent the fracturing fluid or sand of the adjacent well from flowing into the wellbore.

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

[0043] Optionally, in some embodiments, the distance between the adjacent well and the oil and gas well does not exceed 500 meters. There will be fracturing interference between wells that are relatively close, and if the well to be fractured is far away from the oil and gas well, its fracturing operation has little impact on the oil and gas well, and there is no need to use such temporary plugging operation. The length of the fractured crack is usually no more than 500 meters, so the interference between two wells with a distance greater than 500 meters is small.

[0044] Optionally, in some embodiments, the adjacent well is about to be fractured including 1-2 hours before the adjacent well is injected with fracturing fluid.

[0045] Optionally, in some embodiments, removing the sucker rods 26 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 oil pipe 21 .

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

[0047] Optionally, in some embodiments, when the fracturing of the adjacent well is completely completed, the wellhead pressure of the oil and gas well is unloaded, the upper packer 22 and the lower packer 23 are unsealed, the pressure 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 is further described below by taking a coalbed methane well Z125-5 as an example. The well produces 1500 cubic meters of gas per day, and the production layer is buried at a depth of 725m-728m. Due to fracturing of adjacent wells, Z125-5 well needs to take sand prevention measures and reduce the time of gas volume impact.

[0049] The pipe string structure of the well during normal production is as follows from top to bottom: D73mm flat tubing + K344 upper packer × depth 721m + D73mm flat tubing × 1 piece + K344 lower packer × depth 730m + D32mm tubular pump + tail pipe × 1 piece. The packer is in a closed state during normal production. When the adjacent well is fracturing, the following operations are adopted:

[0050] A. Dismantle the wellhead: remove the first sucker rod on the top of the wellhead by turning it upside down, remove the flange on the wellhead, and close the casing gate;

[0051] B. Connect the high-pressure hose: one end of the high-pressure hose is connected to the wellhead oil pipe, and the other end is connected to the cement pump truck. A pressure gauge and a pressure relief gate are installed on the pipeline to control the pipeline pressure;

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

[0053] D. Pressure relief and unsealing: After the adjacent well fracturing is completed, monitor the wellhead pressure of the adjacent well. When 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 flange on the wellhead, lower the sucker rod, connect it with the screws, and then pump out the oil again.

[0055] This method has the following advantages: (1) By using this method, the pipe string pulling during fracturing of adjacent wells is avoided, and the impact time 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 pipe string during fracturing of adjacent wells.

[0056] The packers in the device are made of ordinary steel and rubber cartridges, which are commonly used products, components and spare parts in the petroleum field and are available on the market.

[0057] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to 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 further describe various possible combinations.

[0059] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preventing interference from adjacent well fracturing, characterized in that: The following steps are involved: Step S1: setting an upper packer of the production and drainage pipe string in the oil and gas well at the upper part of the production layer section, and setting a lower packer at the lower part of the production layer section; Step S2: When the adjacent well is about to be fractured, the sucker rod and the wellhead flange of the oil and gas well are removed; Step S3: connecting the pressure hose line to the upper end of the oil pipe, and connecting the other end of the pressure hose line to the hydraulic source; Step S4: operate the hydraulic source to pressurize the oil pipe via the pressurizing hose line to seal the upper packer and the lower packer, seal the annulus corresponding to the production layer section and maintain a predetermined pressure in the space between the upper packer and the lower packer.

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

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 oil and gas well is no more than 500 meters.

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

6. The method according to claim 1, characterized in that 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 oil pipe.

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

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 a predetermined value, the hydraulic source is operated to reach a predetermined pressure and then the pressure 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 setting the packer.

11. The method according to claim 1, characterized in that: It also includes unloading the wellhead pressure of the oil and gas well after the adjacent well fracturing is completely completed, unsealing the upper packer and the lower packer, removing the pressure-fracturing pipeline, and installing the wellhead upper flange and the sucker rod.

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