Releasing type sealing-uniflow tool and oil layer anti-pollution mechanical protection method

Abstract

The invention relates to a releasing type sealing-uniflow tool and an oil layer anti-pollution mechanical protection method, the releasing type sealing-uniflow tool comprises a packing mechanism and a uniflow mechanism, and the bottom of the packing mechanism is in threaded connection with the top of the uniflow mechanism. According to the releasing type sealing-uniflow tool and the oil layer anti-pollution mechanical protection method, through the design of the releasing type sealing-uniflow tool, one-way flow control over wellbore fluid is achieved, well killing fluid is prevented from leaking out of a stratum, and the purpose of reservoir protection is achieved; a nitrogen or nitrogen foam well washing method is provided, so that the working condition of the tool can be kept stable, and the reliability of unblocking and pulling-out operation of the underground tool is improved; the mechanical protection method provided by the invention is not only suitable for the oil production well, but also suitable for the gas production well, and the process application range is widened.

Description

Technical Field

[0001] The present application relates to the field of oil and gas field development, and in particular to a hands-free seal-single-flow tool and an oil layer anti-pollution mechanical protection method. Background Art

[0002] In the development of oil and gas fields, in order to prevent overflow, well completion, water injection, production enhancement measures, and well repair operations, it is necessary to continuously inject well-killing fluid into the well, which can easily cause solid particles, water sensitivity, water lock, poor compatibility, organic damage, etc. to the reservoir, especially to high-permeability layers, low-pressure layers, and deep wells, affecting oil well production, so improvements are needed.

[0003] The main research directions of existing technologies are operating processes and reservoir protection agents, such as perforation-production integrated processes and anti-swelling agents. However, such processes cannot fundamentally prevent operating fluids from entering the reservoir and can only protect the reservoir to a certain extent.

[0004] There are also mechanical protection processes. For example, in the patent document CNIO5221113A, the anti-pollution pipe string is lowered into the oil well to fish out the production plug, and the soluble ball is put in for well washing. After the well washing operation is completed, the annulus is pressurized, the upper pipe string is pulled out, and the soluble ball and ball seat are left in the well to prevent pollution. The upper pipe string is lowered, and the submersible electric pump unit is turned on to produce the oil well. However, after the operation of this process is completed once, the production plug needs to be frequently fished out and the soluble ball is put in, which cannot achieve the purpose of one-time operation and multiple operations for storage and protection. Summary of the invention

[0005] In order to solve the above technical problems or at least partially solve the above technical problems, the present application provides a hands-free seal-single-flow tool and an oil layer anti-pollution mechanical protection method.

[0006] In a first aspect, the present application provides a hands-free sealing-single-flow tool, comprising: a sealing mechanism and a single-flow mechanism,

[0007] Wherein, the bottom of the isolation mechanism is threadedly connected to the top of the single-flow mechanism.

[0008] Preferably, the isolation mechanism comprises: a release joint, a packer, a short circuit and a sealing ball seat, wherein the top end of the packer is connected to the release joint and the bottom end is connected to the top end of the short circuit, and the bottom end of the short circuit is connected to the top end of the sealing ball seat.

[0009] Preferably, the single-flow mechanism comprises: a single-flow valve, a sand settling tube and a threaded plug, wherein the top end of the sand settling tube is connected to the bottom end of the single-flow valve and the bottom end is connected to the top end of the threaded plug, and the top end of the single-flow valve is threadedly connected to the isolation mechanism.

[0010] Preferably, the check valve comprises: a body, the top end of the body is threadedly connected to the isolation mechanism, and the bottom end of the body is threadedly connected to the top end of the sand trapping tube.

[0011] Preferably, a cavity is provided inside the body, and the cavity connects the isolation mechanism and the sand trap.

[0012] Preferably, a valve seat is provided at the bottom of the cavity.

[0013] Preferably, a valve cover is provided at the top of the cavity.

[0014] Preferably, a side wall of the body is provided with a suction port, and the suction port is connected to the cavity.

[0015] Preferably, a valve ball is arranged in the suction port.

[0016] In a second aspect, the present application provides a method for mechanical protection of oil layer pollution prevention, the method comprising the steps of:

[0017] Lower the hands-free seal-single-flow tool through the oil pipe to the predetermined working position in the wellbore;

[0018] Sealing the isolation mechanism of the drop-type seal-single flow tool;

[0019] Lift the pipe column to release the release seal-single flow mechanism;

[0020] Run the production pipe string for mining;

[0021] Wherein, the hands-free seal-single-flow tool comprises the hands-free seal-single-flow tool as described in any one of claims 1-9.

[0022] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0023] The present application provides a hands-free seal-single-flow tool and a mechanical protection method for oil layer pollution prevention, which realizes unidirectional flow control of wellbore fluid through the design of the hands-free seal-single-flow tool, prevents the well-killing fluid from leaking into the formation, and achieves the purpose of reservoir protection; provides a nitrogen or nitrogen foam well washing method, which helps to maintain the stability of the tool working condition and improves the reliability of the downhole tool unsealing and lifting operations; the mechanical protection method provided by the present invention is not only applicable to oil wells, but also to gas wells, which improves the scope of application of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0026] Figure 1 It is a structural schematic diagram of a hands-free seal-single flow tool provided by an embodiment of the present invention;

[0027] Figure 2 It is a structural schematic diagram of a single-flow valve in a hands-free seal-single-flow tool provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0029] Figure 1 A schematic structural diagram of a hands-free seal-single flow tool provided in an embodiment of the present application.

[0030] The present application provides a hands-free sealing-single-flow tool, comprising: a sealing mechanism and a single-flow mechanism, wherein the bottom of the sealing mechanism is threadedly connected to the top of the single-flow mechanism.

[0031] Specifically, the isolation mechanism is used to seal the wellbore, and effective sealing and isolation between the single-flow tool and the casing annulus is achieved. After the sealing is completed, the tubing is lifted to a force of 10-15t to separate the single-flow tool from the tubing, and the tool is released. The single-flow mechanism controls the wellbore fluid to flow from bottom to top and prevents it from flowing from top to bottom, thereby preventing foreign fluids, impurities and organic matter from leaking into the reservoir during operation to cause pollution, thereby protecting the reservoir and oil well production capacity.

[0032] In an embodiment of the present application, the isolation mechanism includes: a release joint, a packer, a short circuit and a sealing ball seat, wherein the top end of the packer is connected to the release joint and the bottom end is connected to the top end of the short circuit, and the bottom end of the short circuit is connected to the top end of the sealing ball seat.

[0033] Specifically, the packing structure is composed of a release joint 1, a packer 2, a short circuit 3, and a sealing ball seat 4. The sealing ball adopts a soluble ball, which dissolves after the sealing is completed to ensure smooth one-way flow. The sealing structure adopts a permanent packer. If it cannot be unsealed after a long period of work, the downhole tool can be removed by milling.

[0034] In an embodiment of the present application, the single-flow mechanism includes: a single-flow valve, a sand settling tube and a threaded plug, wherein the top end of the sand settling tube is connected to the bottom end of the single-flow valve and the bottom end is connected to the top end of the threaded plug, and the top end of the single-flow valve is threadedly connected to the isolation mechanism.

[0035] Specifically, the one-way valve 5, the sand settling tube 6, and the threaded plug 7 are threadedly connected in sequence to form a one-way mechanism. The one-way mechanism uses the one-way valve 5 to prevent sand from burying the valve and uses the sand settling tube to achieve effective sand settling. The wellbore liquid flows through the one-way valve 5, and the larger particle size sand is deposited in the sand settling tube. The small particle size enters the upper part of the tool with the wellbore production fluid and is produced to the ground through the production tubing, thereby achieving effective sand prevention and protection of the one-way mechanism and the production tubing.

[0036] In the embodiment of the present application, the one-flow valve includes: a main body, the top end of the main body is threadedly connected to the isolation mechanism, the bottom end of the main body is threadedly connected to the top end of the sand settling tube, a cavity is provided inside the main body, the cavity connects the isolation mechanism and the sand settling tube, a valve seat is provided at the bottom of the cavity, a valve cover is provided at the top of the cavity, a suction port is provided on the side wall of the main body, the suction port is connected to the cavity, and a valve ball is provided in the suction port.

[0037] Specifically, the check valve 5 is mainly composed of a body 501, a valve cover 502, a valve ball 503, a valve seat 504 and a suction port 505. The upper part of the body 501 is threadedly connected to the isolation mechanism, and the lower part is threadedly connected to the sand settling tube 6; the side wall is designed with a suction port 505, and two sets of fixed valves are installed in sequence to ensure the sealing stability. The valve cover 502 adopts a two-side liquid outlet structure design, and the upper sand and gravel are mainly deposited on the upper part of the valve cover and in the bottom sand settling tube 6 to prevent sand from burying the valve and sand from blocking the valve, thereby ensuring the stability of the single-flow mechanism.

[0038] In a second aspect, the present application provides a method for mechanical protection of oil layer pollution prevention, the method comprising the steps of:

[0039] Lower the hands-free seal-single-flow tool through the oil pipe to the predetermined working position in the wellbore;

[0040] Sealing the isolation mechanism of the drop-type seal-single flow tool;

[0041] Lift the pipe column to release the release seal-single flow mechanism;

[0042] Run the production pipe string for mining;

[0043] Wherein, the hands-free seal-single-flow tool comprises the hands-free seal-single-flow tool as described in any one of claims 1-9.

[0044] Specifically, the release seal-single flow tool is lowered to the predetermined working position in the wellbore through the oil pipe, and the packer mechanism is sealed by dropping the ball and pressing. The release seal-single flow mechanism is released by lifting the pipe string, and then the production pipe string is lowered for production. During the production process of the oil well, the oil flow is controlled to flow in one direction upward by the single flow mechanism. When the production well is switched to pumping or the well needs to be killed, the well fluid cannot reach below the release mechanism, thereby achieving the purpose and effect of reservoir protection. In new wells, wells with a history of sand production, and wells where the distance between the bottom of the artificial well and the reservoir is less than 50m, the working position of the release seal-single flow tool is designed to be 100-150m above the reservoir; in old wells, wells with no history of sand production, and wells where the distance between the bottom of the artificial well and the reservoir is greater than 50m, the working position of the release seal-single flow tool is designed to be 50-100m above the reservoir. When operating again, use nitrogen or nitrogen foam as the medium to wash the well, flush out possible sand on the top of the throw-away seal-single-flow tool to ensure smooth unsealing and lifting operations; for wells that have been working continuously for more than 3 years, use the characteristics of nitrogen or nitrogen foam to reduce back pressure and increase displacement to implement instantaneous large-volume drainage for more than 2 weeks, completely remove the sand and organic matter in the single-flow mechanism, and carry them out of the wellhead to ensure smooth passage of the single-flow mechanism.

[0045] The present application provides a hands-free seal-single-flow tool and a mechanical protection method for oil layer pollution prevention, which realizes unidirectional flow control of wellbore fluid through the design of the hands-free seal-single-flow tool, prevents the well-killing fluid from leaking into the formation, and achieves the purpose of reservoir protection; provides a nitrogen or nitrogen foam well washing method, which helps to maintain the stability of the tool working condition and improves the reliability of the downhole tool unsealing and lifting operations; the mechanical protection method provided by the present invention is not only applicable to oil wells, but also to gas wells, which improves the scope of application of the process.

[0046] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0047] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A hands-free seal-single flow tool, characterized in that: include: A sealing mechanism and a single-flow mechanism, wherein the bottom of the sealing mechanism is threadedly connected to the top of the single-flow mechanism.

2. The hands-free seal-single flow tool according to claim 1, characterized in that: The packing mechanism comprises: a release joint, a packer, a short circuit and a sealing ball seat, wherein the top end of the packer is connected to the release joint and the bottom end is connected to the top end of the short circuit, and the bottom end of the short circuit is connected to the top end of the sealing ball seat.

3. The hands-free seal-single flow tool according to claim 1, characterized in that: The single-flow mechanism includes: a single-flow valve, a sand settling tube and a threaded plug, wherein the top end of the sand settling tube is connected to the bottom end of the single-flow valve and the bottom end is connected to the top end of the threaded plug, and the top end of the single-flow valve is threadedly connected to the isolation mechanism.

4. The hands-free seal-single flow tool according to claim 3, characterized in that: The check valve comprises a body, the top end of which is threadedly connected to the isolation mechanism, and the bottom end of which is threadedly connected to the top end of the sand trapping tube.

5. The hands-free seal-single flow tool according to claim 4, characterized in that: A cavity is arranged inside the body, and the cavity connects the isolation mechanism and the sand settling tube.

6. The hands-free seal-single flow tool according to claim 5, characterized in that: A valve seat is arranged at the bottom of the cavity.

7. The hands-free seal-single flow tool according to claim 5, characterized in that: A valve cover is arranged at the top of the cavity.

8. The hands-free seal-single flow tool according to claim 5, characterized in that: The side wall of the body is provided with a suction port, and the suction port is connected to the cavity.

9. The hands-free seal-single flow tool according to claim 8, characterized in that: A valve ball is arranged in the suction port.

10. A mechanical protection method for oil layer pollution prevention, characterized in that: The method comprises the steps of: Lower the hands-free seal-single-flow tool through the oil pipe to the predetermined working position in the wellbore; A sealing mechanism for sealing the hands-free seal-single flow tool; Lift the pipe column to release the release seal-single flow mechanism; Run the production pipe string for mining; Wherein, the hands-free seal-single-flow tool comprises the hands-free seal-single-flow tool as described in any one of claims 1-9.

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