Offshore shale oil slim-hole high-pressure well completion double-safety-barrier tubular column

Abstract

The invention relates to the technical field of oil field well completion and oil production processes, and provides an offshore shale oil slim-hole high-pressure well completion double-safety-barrier pipe column which comprises an upper pipe column body, a middle pipe column body and a lower pipe column body which are sequentially installed on a production oil pipe from top to bottom. Before oil and gas production, an oil pipe is tripped into the lower pipe column to form a first safety production barrier, then the middle pipe column is tripped into the upper portion of the lower pipe column to form a second safety production barrier, and finally the upper pipe column is tripped into the upper portion of the middle pipe column. During oil and gas production, the switch tool in the upper pipe column is activated through internal pressurization of an oil pipe, the switch tool descends to open the middle pipe column, pressurization continues to open the lower pipe column, the lower pipe column, the middle pipe column and the upper pipe column are communicated, and oil and gas production is achieved. A one-trip tubular column structure is adopted, self-spraying production in a high-productivity stage can be achieved, and pumping production in a low-productivity stage can also be achieved; and meanwhile, a plurality of production barriers are arranged, so that the safety problem in the well completion stage is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield completion and oil production technology, and in particular to an offshore shale oil small-hole high-pressure completion double safety barrier pipe string. Background Art

[0002] As conventional oil and gas production continues to decline worldwide, exploration concepts are gradually changing and innovating, and unconventional oil and gas such as shale oil resources have become an important part of the resource ladder.

[0003] In order to meet the requirements of fracturing, shale oil reservoirs usually use 51 / 2 small-size casing completion. The reservoir pressure after fracturing is high, the production capacity changes greatly, and the completion requirements for production barriers and high pressure of the reservoir after fracturing are high. At present, conventional completion technology and completion tools cannot meet the needs of high-pressure completion development of offshore shale oil. Summary of the invention

[0004] The object of the present invention is to solve at least one technical problem in the background technology and to provide a double safety barrier string for high pressure completion of offshore shale oil small wells.

[0005] To achieve the above object, the present invention provides an offshore shale oil small hole high pressure completion double safety barrier string, comprising:

[0006] The upper tubing string, the middle tubing string and the lower tubing string are sequentially installed on the production tubing from top to bottom;

[0007] Before oil and gas production, the oil pipe is lowered into the lower pipe string to form the first safety production barrier, and then the middle pipe string is lowered above the lower pipe string to form the second safety production barrier, and finally the upper pipe string is lowered above the middle pipe string;

[0008] During oil and gas production, the switch tool in the upper tubing string is activated by pressurizing the inside of the oil pipe. The switch tool moves downward to open the middle tubing string, and continues to pressurize to open the lower tubing string, connecting the lower tubing string, the middle tubing string and the upper tubing string to achieve oil and gas production.

[0009] According to one aspect of the present invention, the upper tubular string includes a safety valve, a cable packer, a production sleeve, an electric pump system and a mechanical intubation sleeve switching tool which are sequentially connected from top to bottom.

[0010] According to one aspect of the present invention, the safety valve is connected to a surface hydraulic control pipeline and is used for emergency well shut-in when an abnormality occurs at the bottom of the well.

[0011] According to one aspect of the present invention, the cable packer is a top-suspended packer for sealing an annulus, and the cable packer suspends a lower production sleeve, an electric pump system and a mechanical cannulation sleeve switching tool;

[0012] The top of the cable packer is provided with a cable passing hole, through which a cable can pass to control the start and stop of the electric pump system.

[0013] According to one aspect of the present invention, the production sleeve connects the oil pipe and the casing, and the connection and closing of the oil pipe and the casing are controlled by wire operation.

[0014] According to one aspect of the present invention, the middle pipe string includes a first permanent packer and a mechanical insertion sleeve which are sequentially connected from top to bottom.

[0015] According to one aspect of the present invention, the mechanical insertion sleeve switching tool is a sleeve connected to the mechanical insertion sleeve. After the upper tubular column is lowered into place, the mechanical insertion sleeve switching tool is activated by pressurizing the inside of the oil pipe, so that the mechanical insertion sleeve switching tool is downwardly inserted into the mechanical insertion sleeve. The positioning step on the mechanical insertion sleeve switching tool cooperates with the core shaft positioning step inside the mechanical insertion sleeve. Under the action of pressure, the core shaft in the mechanical insertion sleeve moves downward, so that the hole on the core shaft is aligned with the hole on the outer shell of the mechanical insertion sleeve, and the communication channel is opened, thereby realizing the connection between the upper tubular column and the middle tubular column.

[0016] According to one aspect of the present invention, the lower tubular string comprises a second permanent packer and a shear ball seat which are sequentially connected from top to bottom.

[0017] According to one aspect of the present invention, after the mechanical insertion sleeve switching tool is downwardly inserted into the mechanical insertion sleeve to open the mechanical insertion sleeve, the inside of the oil pipe continues to be pressurized, and the copper pin on the shear ball seat is sheared off under the action of pressure to open the shear ball seat, so that the upper tubing string, the middle tubing string and the lower tubing string are connected.

[0018] According to one solution of the present invention, a double safety barrier pipe string for high pressure completion of small boreholes of offshore shale oil includes: an upper pipe string, a middle pipe string and a lower pipe string which are sequentially installed on the production tubing from top to bottom; before oil and gas production, the tubing is lowered into the lower pipe string to form the first safety production barrier (sealing the tubing annulus and the formation high pressure), and then the middle pipe string is lowered above the lower pipe string to form the second safety production barrier (sealing the tubing annulus and the formation high pressure), and finally the upper pipe string is lowered above the middle pipe string; during oil and gas production, the switch tool in the upper pipe string is activated by pressurizing the inside of the tubing, the switch tool is lowered to open the middle pipe string, and the lower pipe string, the middle pipe string and the upper pipe string are connected to realize oil and gas production. With such a configuration, the present invention can be provided with multiple safety production barriers, which effectively solves the structural design problem of the small-size casing high pressure completion pipe string after fracturing and the safety problem of the completion stage.

[0019] According to one solution of the present invention, the upper tubular column includes a safety valve, a cable packer, a production sleeve, an electric pump system and a mechanical insertion sleeve switch tool connected in sequence from top to bottom. With such a configuration, after the upper tubular column is lowered into place, the mechanical insertion sleeve switch tool can be hydraulically activated, the mechanical insertion sleeve switch tool can be moved downward to open the mechanical insertion sleeve, connect the oil sleeve, and achieve the purpose of oil and gas production; the mechanical insertion sleeve switch tool can be moved upward to close the mechanical insertion sleeve, and stop oil and gas production.

[0020] According to one solution of the present invention, the middle pipe string includes a first permanent packer and a mechanical insertion sleeve connected in sequence from top to bottom. With such a configuration, the middle pipe string can be used as a second safety barrier for oil and gas production, which can not only protect the lowering and completion of the upper pipe string, but also connect the upper and lower pipe strings to achieve oil and gas production.

[0021] According to one solution of the present invention, the lower tubular string includes a second permanent packer and a shear ball seat connected in sequence from top to bottom. With such an arrangement, the lower tubular string can be used as the first safety barrier for oil and gas production, which not only protects the middle tubular string and the upper tubular string from being lowered and completed, but also enables the lower tubular string to be connected with the middle tubular string.

[0022] According to the solution of the present invention, the present invention provides a small-bore high-pressure completion double safety barrier self-flowing and pumping integrated tubing. The present invention adopts a one-trip tubing structure, which can realize self-flowing production in the high-capacity stage and pumping production in the low-capacity stage; at the same time, it has multiple production barriers, which effectively solves the safety problem in the completion stage.

[0023] According to the solution of the present invention, the present invention adopts the above-mentioned tubing solution, sets up multiple production safety barriers, and solves the safety problem of small-size casing high-pressure completion tubing after fracturing. The mechanical insertion sleeve switch tool is activated by pressurizing the inside of the oil pipe, and the mechanical insertion sleeve switch tool is moved downward to open the mechanical insertion sleeve, and the shear ball seat is opened by continuing to pressurize to achieve oil and gas production; in the high-capacity stage, production can be carried out through the production sleeve, and in the low-capacity stage, suction production can be carried out through the electric pump system, reducing the number of later replacement of tubing strings, improving recovery rate, and saving production costs.

[0024] According to the scheme of the present invention, the present invention can be used for offshore small-bore cased wells. Due to the limited size of the casing, conventional offshore completion tools and completion processes cannot meet the working conditions of high reservoir pressure and large production capacity changes in such completions. Therefore, the present invention proposes the above-mentioned high-pressure completion string suitable for offshore small-bore cased wells; the string provides multiple production barriers, which increases the protection of offshore completion work; using this string, high-pressure completion self-flowing and pumping integration are realized, without the need to replace the string midway, which improves the recovery efficiency and reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A cross-sectional view schematically shows the structural arrangement of a double safety barrier string for offshore shale oil small-hole high-pressure completion according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present invention will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are only to enable those skilled in the art to better understand and thus implement the present invention, rather than implying any limitation on the scope of the present invention.

[0027] As used herein, the term “including” and variations thereof are to be interpreted as open-ended terms meaning “including, but not limited to.” The term “based on” is to be interpreted as “based, at least in part, on.” The terms “one embodiment” and “an embodiment” are to be interpreted as “at least one embodiment.”

[0028] Figure 1 A schematic cross-sectional view of the structure arrangement of a double safety barrier string for offshore shale oil small hole high pressure completion according to an embodiment of the present invention is shown. Figure 1 As shown, in this embodiment, the offshore shale oil small hole high pressure completion double safety barrier string includes:

[0029] The upper tubing string, the middle tubing string and the lower tubing string are sequentially installed on the production tubing from top to bottom;

[0030] Before oil and gas production, the oil pipe is lowered into the lower pipe string to form the first safety production barrier (to isolate the annulus of the oil pipe and the high pressure of the formation), and then the middle pipe string is lowered above the lower pipe string to form the second safety production barrier (to isolate the annulus of the oil pipe and the high pressure of the formation), and finally the upper pipe string is lowered above the middle pipe string;

[0031] During oil and gas production, the switch tool in the upper pipe string is activated by pressurizing the inside of the oil pipe, the switch tool moves downward to open the middle pipe string, and continues to pressurize to open the lower pipe string, connecting the lower pipe string, the middle pipe string and the upper pipe string to achieve oil and gas production. This arrangement allows the present invention to have multiple safety production barriers, effectively solving the structural design problem of the small-size casing high-pressure completion pipe string after fracturing and the safety problem of the completion stage.

[0032] Further, according to one embodiment of the present invention, Figure 1As shown, the upper tubular column includes a safety valve 1, a cable packer 2, a production sleeve 3, an electric pump system 4 and a mechanical insertion sleeve switch tool 5 connected in sequence from top to bottom. With such an arrangement, after the upper tubular column is lowered into place, the mechanical insertion sleeve switch tool 5 is hydraulically activated, the mechanical insertion sleeve switch tool 5 is moved downward to open the mechanical insertion sleeve, and the oil pipe and casing are connected to achieve the purpose of oil and gas production; the mechanical insertion sleeve switch tool 5 moves upward to close the mechanical insertion sleeve, and oil and gas production is stopped.

[0033] Furthermore, in this embodiment, the safety valve 1 is connected to the surface hydraulic control pipeline for emergency well shut-in when an abnormality occurs at the bottom of the well.

[0034] Further, in this embodiment, the cable packer 2 is a top-suspended packer for sealing the annulus, and the cable packer 2 suspends a lower production sleeve 3, an electric pump system 4 and a mechanical intubation sleeve switch tool 5;

[0035] The top of the cable packer 2 is provided with a cable passing hole, through which a cable can pass to control the start and stop of the electric pump system 4.

[0036] Furthermore, in this embodiment, the production sleeve 3 connects the oil pipe and the casing, and the connection and closing of the oil pipe and the casing are controlled by wire operation.

[0037] In this embodiment, during the high-capacity completion stage, self-flowing production can be performed through the production sleeve 3; during the low-capacity completion stage, pumping production can be performed through the electric pump system 4.

[0038] Further, according to one embodiment of the present invention, Figure 1 As shown, the middle pipe string includes a first permanent packer 6 and a mechanical insertion sleeve 7 connected in sequence from top to bottom. With such an arrangement, the middle pipe string can be used as a second safety barrier for oil and gas production, which can not only protect the upper pipe string from being lowered and completed, but also connect the upper and lower pipe strings to achieve oil and gas production.

[0039] Furthermore, in the present embodiment, the mechanical insertion sleeve switch tool 5 is a sleeve connected to the mechanical insertion sleeve 7. After the upper tubular column is lowered into place, the mechanical insertion sleeve switch tool 5 is activated by pressurizing the inside of the oil pipe, so that the mechanical insertion sleeve switch tool 5 is downwardly inserted into the mechanical insertion sleeve 7. The positioning step on the mechanical insertion sleeve switch tool 5 cooperates with the core shaft positioning step inside the mechanical insertion sleeve 7. Under the action of pressure, the core shaft inside the mechanical insertion sleeve 7 moves downward, so that the hole on the core shaft is aligned with the hole on the outer shell of the mechanical insertion sleeve 7, and the communication channel is opened, thereby realizing the connection between the upper tubular column and the middle tubular column.

[0040] Further, according to one embodiment of the present invention, Figure 1As shown, the lower pipe string includes a second permanent packer 8 and a shear ball seat 9 connected in sequence from top to bottom. With such an arrangement, the lower pipe string can be used as the first safety barrier for oil and gas production, which not only protects the middle pipe string and the upper pipe string from being lowered and completed, but also enables the lower and middle pipe strings to be connected.

[0041] Furthermore, in this embodiment, after the mechanical insertion sleeve switching tool 5 is downwardly inserted into the mechanical insertion sleeve 7 to open the mechanical insertion sleeve 7, the inside of the oil pipe continues to be pressurized, and the copper pin on the shear ball seat is cut off under the action of pressure to open the shear ball seat, so that the upper pipe string, the middle pipe string and the lower pipe string are connected.

[0042] According to the above scheme of the present invention, the present invention provides a small-bore high-pressure completion double safety barrier self-flowing and pumping integrated tubing string. The present invention adopts a one-trip tubing string structure, which can realize self-flowing production in the high-capacity stage and pumping production in the low-capacity stage; at the same time, it has multiple production barriers to effectively solve the safety problem in the completion stage.

[0043] According to the above scheme of the present invention, the present invention adopts the above pipe string scheme, sets up multiple production safety barriers, and solves the safety problem of small-size casing high-pressure completion pipe string after fracturing. The mechanical insertion sleeve switch tool is activated by pressurizing the inside of the oil pipe, and the mechanical insertion sleeve switch tool is moved downward to open the mechanical insertion sleeve, and the shear ball seat is opened by continuing to pressurize to realize oil and gas production; in the high-capacity stage, production can be carried out through the production sleeve, and in the low-capacity stage, suction production can be carried out through the electric pump system, reducing the number of pipe string replacements in the later stage, improving the recovery rate, and saving production costs.

[0044] According to the above scheme of the present invention, the present invention can be used for offshore small-bore cased wells. Due to the limited size of the casing, conventional offshore completion tools and completion processes cannot meet the working conditions of high reservoir pressure and large production capacity changes in such completions. Therefore, the present invention proposes the above-mentioned high-pressure completion string suitable for offshore small-bore cased wells; the string provides multiple production barriers, which increases the protection of offshore completion work; using this string, high-pressure completion self-flowing and pumping integration are realized, without the need to replace the string midway, which improves the recovery efficiency and reduces the production cost.

[0045] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. Offshore shale oil small hole high pressure completion double safety barrier string, characterized by: include: The upper tubing string, the middle tubing string and the lower tubing string are sequentially installed on the production tubing from top to bottom; Before oil and gas production, the oil pipe is lowered into the lower pipe string to form the first safety production barrier, and then the middle pipe string is lowered above the lower pipe string to form the second safety production barrier, and finally the upper pipe string is lowered above the middle pipe string; During oil and gas production, the switch tool in the upper tubing string is activated by pressurizing the inside of the oil pipe. The switch tool moves downward to open the middle tubing string, and continues to pressurize to open the lower tubing string, connecting the lower tubing string, the middle tubing string and the upper tubing string to achieve oil and gas production.

2. The offshore shale oil small hole high pressure completion double safety barrier string according to claim 1, characterized in that: The upper tubular column comprises a safety valve, a cable packer, a production sleeve, an electric pump system and a mechanical insertion sleeve switch tool which are sequentially connected from top to bottom.

3. The offshore shale oil small hole high pressure completion double safety barrier string according to claim 2 is characterized in that: The safety valve is connected to the surface hydraulic control pipeline and is used for emergency well shut-in when an abnormality occurs at the bottom of the well.

4. The offshore shale oil small hole high pressure completion double safety barrier string according to claim 2, characterized in that: The cable packer is a top-suspended packer for sealing the annulus, and the cable packer suspends the lower production sleeve, the electric pump system and the mechanical intubation sleeve switching tool; The top of the cable packer is provided with a cable passing hole, through which a cable can pass to control the start and stop of the electric pump system.

5. The offshore shale oil small hole high pressure completion double safety barrier string according to claim 2, characterized in that: The production sleeve connects the oil pipe and the casing, and controls the connection and closing of the oil pipe and the casing through wire operation.

6. The offshore shale oil small hole high pressure completion double safety barrier string according to claim 2, characterized in that: The middle pipe string comprises a first permanent packer and a mechanical insertion sleeve which are sequentially connected from top to bottom.

7. The offshore shale oil small hole high pressure completion double safety barrier string according to claim 6, characterized in that: The mechanical insertion sleeve switching tool is a sleeve connected to the mechanical insertion sleeve. After the upper tubular column is lowered into place, the mechanical insertion sleeve switching tool is activated by pressurizing the inside of the oil pipe, so that the mechanical insertion sleeve switching tool is downwardly inserted into the mechanical insertion sleeve. The positioning step on the mechanical insertion sleeve switching tool cooperates with the core shaft positioning step inside the mechanical insertion sleeve. Under the action of pressure, the core shaft in the mechanical insertion sleeve moves downward, so that the hole on the core shaft is aligned with the hole on the outer shell of the mechanical insertion sleeve, and the communication channel is opened, thereby realizing the connection between the upper tubular column and the middle tubular column.

8. The offshore shale oil small hole high pressure completion double safety barrier string according to claim 2, characterized in that: The lower tubular string comprises a second permanent packer and a shear ball seat which are sequentially connected from top to bottom.

9. The offshore shale oil small hole high pressure completion double safety barrier string according to claim 8, characterized in that: After the mechanical insertion sleeve switch tool is inserted downward into the mechanical insertion sleeve to open the mechanical insertion sleeve, the inside of the oil pipe continues to be pressurized, and the copper pin on the shear ball seat is cut off under the action of pressure to open the shear ball seat, so that the upper pipe string, the middle pipe string and the lower pipe string are connected.

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