Segmented cavity construction method and device for single-well horizontal cavity

Abstract

The invention provides a single well horizontal cavity sectional cavity construction method and device. The method comprises the steps that S1, a vertical well section and a horizontal well section with the first end connected with the top end of the vertical well section are constructed; and S2, from the second end, away from the vertical well section, of the horizontal well section to the first end of the horizontal well section, finally, cavities are sequentially constructed in a segmented mode at the bottom end of the vertical well section to form communicated horizontal cavities. According to the invention, the cavity construction efficiency and the cavity construction scale can be improved, so that the volume of the gas storage is increased, the storage construction advantage of underground layered rock salt resources is fully utilized, and the utilization rate of each device required by well drilling and cavity construction is improved.

Description

Technical Field

[0001] The invention relates to the field of gas storage construction engineering, and in particular to a single well horizontal cavity segmented cavity making method and device. Background Art

[0002] Salt cavern gas storage is the main type of underground gas storage, accounting for about 10% of the world's gas storage. Existing salt cavern gas storage is mainly constructed by single-well single-cavity vertical well water-soluble cavity construction. Only one cavity is built in each well as a gas storage. This method of building underground gas storage often places the equipment required for drilling and storage construction on the ground of each well, which will greatly occupy the ground space. In addition, only a single cavity is built in each single well as a gas storage, resulting in low cavity construction efficiency and small scale, resulting in a small volume of gas storage.

[0003] For example, the Chinese invention patent with announcement number CN110005468A discloses a horizontal cavity salt cavern gas storage, which includes: a first ground wellhead device, a first vertical well, a deflection well, an inclined horizontal well, a horizontal cavity, a vertical cavity, a second vertical well, and a second ground wellhead device; the first ground wellhead device is connected to the first vertical well on the ground, the first vertical well is connected to the inclined horizontal well through the deflection well, the shallower end of the inclined horizontal well is connected to the deflection well, the top of the vertical cavity is connected to the bottom of the second vertical well, and the top of the second vertical well is connected to the second ground wellhead device on the ground; the bottom of the horizontal cavity is connected to the inclined horizontal well, and the horizontal cavity is formed by dissolving salt rock in the inclined horizontal well. Although the horizontal cavity salt cavern gas storage of this scheme can increase the volume of the gas storage, since only one horizontal cavity is built as the gas storage, the increased volume of the gas storage is limited, and the overall scale of the cavity is very small, resulting in a small volume of the gas storage.

[0004] Existing salt cavern gas storages mainly adopt a single-well single-cavity construction method. This gas storage construction method has the disadvantages of occupying a large ground space, low cavity construction efficiency and small cavity construction scale. Therefore, a single-well multi-stage horizontal cavity salt cavern gas storage construction method is urgently needed to improve the above disadvantages. Summary of the invention

[0005] One object of the present invention is to propose a single-well horizontal cavity segmented cavity making method and device, so as to carry out segmented cavity making from the second end of the horizontal well section away from the vertical well section to the vertical well section in batches through hydraulic circulation, so as to form interconnected cavities in the horizontal well section and the vertical well section for use as a gas storage, thereby improving the cavity making efficiency and cavity making scale, thereby increasing the volume of the gas storage, making full use of the advantages of underground layered rock salt resources in building a reservoir, and improving the utilization rate of various equipment required for drilling and cavity making.

[0006] According to the present invention, a method for constructing a single-well horizontal cavity in sections is provided, comprising: S1, constructing a vertical well section and a horizontal well section whose first end is connected to the top of the vertical well section; S2, constructing cavities in sections from the second end of the horizontal well section away from the vertical well section to the first end of the horizontal well section, and finally at the bottom of the vertical well section to form a connected horizontal cavity.

[0007] In a preferred embodiment, step S1 includes: S11, drilling a vertical wellbore to the inside of the rock formation, and lowering a completion production casing into the vertical wellbore; S12, lowering a drill bit into the vertical wellbore and drilling inside the rock formation to construct the vertical well section; S13, lowering a drill bit into the vertical wellbore again, and drilling laterally inside the rock formation from the end of the vertical well section to complete the horizontal well section.

[0008] In a preferred embodiment, step S2 includes: S21, lowering the outer tube for cavity making and the inner tube arranged inside the outer tube to the second end of the horizontal well section away from the vertical well section, and forming a first cavity through hydraulic circulation; S22, lowering the outer tube part for cavity making and the inner tube arranged inside the outer tube part to a position close to or in contact with the first cavity and away from the second end of the horizontal well section, and forming a second cavity connected to the first cavity through hydraulic circulation; and so on, completing the construction of the nth cavity one by one, wherein the nth cavity is close to or located at the first end of the horizontal well section; S23, lowering the outer pipe for cavity making and the inner pipe arranged inside the outer pipe to the bottom of the vertical well section, and forming a cavity through hydraulic circulation to form the n+1th cavity connected to the nth cavity.

[0009] In a preferred embodiment, before S21, one or more centralizers are spaced apart on the outer wall of a portion of the inner tube.

[0010] In a preferred embodiment, step S21 specifically includes: lowering the outer tube and the inner tube together into the completion production casing, and then allowing the outer tube and the inner tube to enter the vertical wellbore, and enter the horizontal well section laterally from the top of the vertical well section, and extend laterally to the second end of the horizontal well section. After the outer tube and the inner tube reach the second end of the horizontal well section, a cavity is created by hydraulic circulation to form the first cavity.

[0011] In a preferred embodiment, step S22 specifically includes: lowering the outer tube portion and the inner tube portion together into the completion production casing, and then allowing the outer tube portion and the inner tube portion to enter the vertical wellbore, and enter the horizontal well section laterally from the top of the vertical well section, and extend laterally to the position where the ends of the outer tube portion and the inner tube portion are close to or in contact with the first cavity and away from the second end of the horizontal well section, and forming a cavity through hydraulic circulation to form the second cavity connected to the first cavity.

[0012] In a preferred embodiment, step S23 specifically includes: lowering the outer pipe and the inner pipe together into the completion production casing, and then allowing the outer pipe portion and the inner pipe portion to enter the vertical wellbore and directly enter the bottom end of the vertical well section, and form the n+1th cavity connected to the nth cavity through hydraulic circulation.

[0013] The present invention also provides a single-well horizontal cavity segmented cavity making device, comprising an outer tube and an inner tube arranged inside the outer tube, wherein parts of the outer tube and the inner tube are located inside the production casing and the remaining parts of the outer tube and the inner tube can enter the horizontal well section and the vertical well section for cavity making.

[0014] In a preferred embodiment, one or more centralizers are arranged at intervals on the outer wall of the inner pipe extending in the horizontal well section.

[0015] In a preferred embodiment, the centralizer is made of metal material.

[0016] The present invention constructs a vertical well section and a horizontal well section whose first end is connected to the top of the vertical well section; from the second end of the horizontal well section away from the vertical well section to the first end of the horizontal well section, and finally at the bottom of the vertical well section, cavity building is sequentially performed in sections to form a connected horizontal cavity. After the vertical well section and the horizontal well section connected to the top of the vertical well section are constructed, cavity building is performed in sections from the second end of the horizontal well section away from the vertical well section to the vertical well section by hydraulic circulation in batches, and after the cavity building is completed, all cavities can be connected, so that interconnected cavities can be formed in the horizontal well section and the vertical well section to be used as a gas storage reservoir. Compared with the method of only building a single cavity in a single well as a gas storage reservoir, the cavity building efficiency and cavity building scale can be improved, thereby increasing the volume of the gas storage reservoir, and making full use of the advantages of underground layered rock salt resources in building a reservoir. Since the present scheme only requires a set of drilling and cavity building equipment on the ground outside the well to realize the construction of a large-volume gas storage reservoir, the space occupied by the ground drilling and cavity building equipment can be reduced, and the utilization rate of each equipment required for drilling and cavity building can be improved.

[0017] The present invention arranges one or more centralizers at intervals on the outer wall of the inner tube extending in the horizontal well section, so that the inner tube is in the center of the outer tube, thereby improving stability in the subsequent cavity dissolution process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The flowchart of the method for creating a single-well horizontal cavity by segmentation is schematically shown according to the present invention;

[0019] Figure 2 A schematic diagram of step S1 of the method for creating a single-well horizontal cavity by segmentation according to the present invention is schematically shown;

[0020] Figure 3 The schematic diagram of step S2 of the method for creating a single-well horizontal cavity by segmentation according to the present invention is schematically shown;

[0021] Figure 4 Another schematic diagram of step S2 of the method for creating a single-well horizontal cavity by segmentation is schematically shown according to the present invention;

[0022] Figure 5 Another schematic diagram of step S2 of the segmented cavity making method for a single well horizontal cavity according to the present invention is schematically shown.

[0023] In the present application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn according to the actual scale. DETAILED DESCRIPTION

[0024] like Figure 1 As shown, the single well horizontal cavity segmented cavity making method 100 of the present invention comprises:

[0025] S1, constructing a vertical well section 2 and a horizontal well section 3 whose first end is connected to the top of the vertical well section 2;

[0026] S2, from the second end of the horizontal well section 3 away from the vertical well section 2 to the first end of the horizontal well section 3, and finally at the bottom end of the vertical well section 2, cavity building is carried out in sections to form a connected horizontal cavity.

[0027] Specifically, in the present invention, a vertical well section 2 is first constructed inside the rock formation 5, the vertical well section 2 is vertically arranged and has a top end and a bottom end, wherein the top end of the vertical well section 2 is close to the ground surface, and the bottom end of the vertical well section 2 is away from the ground surface relative to the top end of the vertical well section 2. Then, a horizontal well section 3 is constructed in the rock formation 5 at the top end of the vertical well section 2 along a horizontal direction perpendicular to the vertical well section 2, and a first end of the horizontal well section 3 is connected to the top end of the vertical well section 2 to form a whole single well in the rock formation 5.

[0028] Specifically, after the construction of a single well is completed, segmented cavity making is adopted in the horizontal well section 3 and the vertical well section 2 in turn, and each segment of the cavity is interconnected to form an entire interconnected cavity. In the process of cavity making in the horizontal well section 3, the cavity is made in sections from right to left, that is, the cavity is made in sections from the second end of the horizontal well section 3 away from the vertical well section 2 to the first end of the horizontal well section 3. Finally, in the process of cavity making in the vertical well section 2, a cavity is made at the bottom end of the vertical well section 2 to form a horizontal cavity connected with the cavity near or located at the first end of the horizontal well section 3.

[0029] The present invention constructs a vertical well section 2 and a horizontal well section 3 whose first end is connected to the top of the vertical well section 2; from the second end of the horizontal well section 3 away from the vertical well section 2 to the first end of the horizontal well section 3, and finally at the bottom of the vertical well section 2, cavity building is sequentially performed in sections to form a connected horizontal cavity. After the vertical well section 2 and the horizontal well section 3 connected to the top of the vertical well section 2 are constructed, cavity building is performed in sections from the second end of the horizontal well section 3 away from the vertical well section 2 to the vertical well section 2 by hydraulic circulation in batches, and after the cavity building is completed, all The cavities can be connected, so that interconnected cavities can be formed in the horizontal well section 3 and the vertical well section 2 to be used as gas storage. Compared with the method of only making a single cavity in a single well as a gas storage, the cavity making efficiency and scale can be improved, thereby increasing the volume of the gas storage and making full use of the advantages of underground layered rock salt resources in building a gas storage. Since this scheme only requires a set of drilling and cavity making equipment on the ground outside the well to realize the construction of a large-volume gas storage, the space occupied by the ground drilling and cavity making equipment can be reduced, and the utilization rate of each equipment required for drilling and cavity making can be improved.

[0030] like Figure 2 As shown, in one or more embodiments, step S1 includes:

[0031] S11, drilling a vertical wellbore to the inside of the rock formation 5, and running a completion production casing 1 into the vertical wellbore;

[0032] S12, lowering a drill bit into the vertical wellbore and drilling in the rock formation 5 along the vertical direction to construct a vertical well section 2;

[0033] S13, lowering the drill bit into the vertical wellbore again, and drilling laterally inside the rock formation from the end of the vertical well section 2 to complete the horizontal well section 3.

[0034] Specifically, in step S11, a vertical wellbore is drilled to the inside of the rock formation 5, and a completion production casing 1 is lowered into the vertical wellbore for cementing, completion and dissolution during the production process. By drilling a vertical wellbore to the inside of the rock formation 5, it is convenient to lower the completion production casing 1 into the vertical wellbore. Optionally, the diameter of the completion production casing 1 lowered into the vertical wellbore is above 244.5 mm. By lowering the completion production casing 1 into the vertical wellbore, completion production can be performed. The rock formation 5 may be a layered salt rock layer, and the rock formation 5 is located between interlayers 4 composed of mudstone and the like.

[0035] Specifically, in step S12, a drill bit is lowered into the vertical wellbore, and optionally, the diameter of the drill bit is greater than 215.9 mm, and then the drill bit is used to drill in the vertical direction inside the rock formation 5 to construct the vertical well section 2 for subsequent construction. The vertical well section 2 is arranged in the rock formation 5 in the vertical direction and has a top end and a bottom end, wherein the top end of the vertical well section 2 is close to the ground surface, and the bottom end of the vertical well section 2 is away from the ground surface relative to the top end of the vertical well section 2.

[0036] Specifically, in step S13, after the construction of the vertical well section 2 is completed, a drill bit is lowered into the vertical well bore again. Optionally, the diameter of the drill bit is greater than 215.9 mm. The drill bit is used to drill laterally inside the rock formation 5 from the top of the vertical well section 2 to complete the horizontal well section 3. The angle between the horizontal well section 3 and the vertical well section 2 is close to 90°. Through steps S11-S13, the vertical well section 2 and the horizontal well section 3 can be completed, and subsequently used to complete the cavity construction in the vertical well section 2 and the horizontal well section 3.

[0037] like Figures 3 to 5 As shown, in one or more embodiments, step S2 includes:

[0038] S21, lowering the outer tube 101 for cavity making and the inner tube 102 arranged inside the outer tube 101 to the second end of the horizontal well section 3 away from the vertical well section 2, and forming a cavity by hydraulic circulation to form a first cavity 104; before step S21, centralizers 103 are arranged at intervals on the outer wall of part of the inner tube 102;

[0039] S22, lower the outer tube part 201 used for cavity making and the inner tube part 202 arranged inside the outer tube part 201 to a position in contact with the first cavity 104 and away from the second end of the horizontal well section 3, and form a cavity by hydraulic circulation to form a second cavity 203 connected to the first cavity 104; and so on, successively complete the construction of the nth cavity 304, wherein the nth cavity 304 is close to or located at the first end of the horizontal well section 3; before step S22, a centralizer 103 is arranged at intervals on the outer wall of a part of the inner tube part 202;

[0040] S23, lowering the outer pipe 301 used for cavity formation and the inner pipe 302 arranged inside the outer pipe 301 to the bottom end of the vertical well section 2, and forming a cavity through hydraulic circulation to form the n+1th cavity 303 connected to the nth cavity 304.

[0041] Specifically, in step S21, the outer tube 101 used for cavity making and the inner tube 102 arranged inside the outer tube 101 are lowered into the completion production casing 1 together, and then the outer tube 101 and the inner tube 102 enter the vertical wellbore, and enter the horizontal well section 3 from the top of the vertical well section 2 along the side, and extend all the way to the second end of the horizontal well section 3 along the side, and one or more centralizers 103 are arranged at intervals on the outer wall of the inner tube 102 extending from the horizontal well section 3, so as to make the inner tube 102 in the outer tube 101 in the center position, and the centralizer 103 is made of metal material and has rigidity. The second end of the horizontal well section 3 is far away from the top of the vertical well section 2. After the outer tube 101 and the inner tube 102 reach the second end, the cavity is made by hydraulic circulation to form a first cavity 104, and the bottom of the first cavity 104 is deposited with sediment 105. After the first cavity 104 is completed, the outer tube 101 and the inner tube 102 are recovered from outside the well. Optionally, the diameter of the outer tube 101 may be 177.8 mm, and the diameter of the inner tube 102 may be 114.3 mm.

[0042] Specifically, in step S22, the outer tube 201 used for cavity making and the inner tube 202 arranged inside the outer tube 201 are lowered into the completion production casing 1 together, and then the outer tube 201 and the inner tube 202 enter the vertical wellbore, and enter the horizontal well section 3 from the top of the vertical well section 2 along the side, and extend along the side to the position where the ends of the outer tube 201 and the inner tube 202 are close to or in contact with the first cavity 104 and away from the second end of the horizontal well section 3, and one or more centralizers 103 are arranged at intervals on the outer wall of the inner tube 202 extending from the horizontal well section 3, so as to make the inner tube 202 in the outer tube 201 in the center position, and the centralizer 103 is made of metal material and has rigidity. After the outer tube 101 and the inner tube 102 reach the above position, the cavity is made by hydraulic circulation to form a second cavity 203 connected to the first cavity 104, and the bottom of the second cavity 203 is deposited with sediment 204. After the second cavity 203 is constructed, the outer tube 201 and the inner tube 202 are recovered from outside the well. Optionally, the diameter of the outer tube 201 can be 177.8 mm, and the diameter of the inner tube 202 can be 114.3 mm. By analogy, the construction of the nth cavity 304 is completed one by one (n is a natural number greater than 2), wherein the nth cavity 304 is close to or located at the first end of the horizontal well section 3. After the construction of the nth cavity 304 is completed, the cavity construction for the horizontal well section 3 is completed.

[0043] Specifically, in step S23, after the cavity making for the horizontal well section 3 is completed, the outer pipe 301 used for cavity making and the inner pipe 302 arranged inside the outer pipe 301 are lowered into the completion production casing 1 together, and then the outer pipe part 201 and the inner pipe part 202 enter the vertical wellbore and directly enter the bottom end of the vertical well section 2. After the outer pipe 101 and the inner pipe 102 reach the bottom end of the vertical well section 2, the cavity is made by hydraulic circulation to form the n+1th cavity 303 connected to the nth cavity 304. After the n+1th cavity 303 is completed, the outer pipe 301 and the inner pipe 302 are recovered from outside the well. Optionally, the diameter of the outer pipe 301 can be 177.8 mm, and the diameter of the inner pipe 302 can be 114.3 mm. After the n+1th cavity 303 is completed, the segmented cavity making of the entire single well horizontal cavity is completed, all cavities are connected together, and can be used as an underground gas storage.

[0044] Based on the above-mentioned single-well horizontal cavity segmented cavity making method, the present invention also provides a single-well horizontal cavity segmented cavity making device, including an outer tube 101 and an inner tube 102 arranged inside the outer tube 101, part of the outer tube 101 and the inner tube 102 are located inside the production casing 1 and the remaining parts of the outer tube 101 and the inner tube 102 can enter the horizontal well section 3 and the vertical well section 2 for cavity making.

[0045] In one or more embodiments, one or more centralizers 103 are spaced apart on the outer wall of the inner tube 102 extending in the horizontal well section 3 .

[0046] In the present invention, one or more centralizers 103 are arranged at intervals on the outer wall of the inner tube 102 extending from the horizontal well section 3, so that the inner tube 102 is centered in the outer tube 101, thereby improving stability in the subsequent cavity dissolution process.

[0047] The present invention constructs a vertical well section 2 and a horizontal well section 3 whose first end is connected to the top of the vertical well section 2; from the second end of the horizontal well section 3 away from the vertical well section 2 to the first end of the horizontal well section 3, and finally at the bottom of the vertical well section 2, cavity building is sequentially performed in sections to form a connected horizontal cavity. After the vertical well section 2 and the horizontal well section 3 connected to the top of the vertical well section 2 are constructed, cavity building is performed in sections from the second end of the horizontal well section 3 away from the vertical well section 2 to the vertical well section 2 by hydraulic circulation in batches, and after the cavity building is completed, all The cavities can be connected, so that interconnected cavities can be formed in the horizontal well section 3 and the vertical well section 2 to be used as gas storage. Compared with the method of only making a single cavity in a single well as a gas storage, the cavity making efficiency and scale can be improved, thereby increasing the volume of the gas storage and making full use of the advantages of underground layered rock salt resources in building a gas storage. Since this scheme only requires a set of drilling and cavity making equipment on the ground outside the well to realize the construction of a large-volume gas storage, the space occupied by the ground drilling and cavity making equipment can be reduced, and the utilization rate of each equipment required for drilling and cavity making can be improved.

[0048] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for creating a single well horizontal cavity by segmentation, comprising: S1, constructing a vertical well section and a horizontal well section whose first end is connected to the top of the vertical well section; S2, from the second end of the horizontal well section away from the vertical well section to the first end of the horizontal well section, and finally at the bottom end of the vertical well section, cavity building is carried out in sections to form a connected horizontal cavity.

2. The single well horizontal cavity segmented cavity making method according to claim 1 is characterized in that: Step S1 includes: S11, drilling a vertical wellbore to the inside of the rock formation, and running a completion production casing into the vertical wellbore; S12, lowering a drill bit into the vertical wellbore and drilling inside the rock formation to construct the vertical well section; S13, lowering the drill bit into the vertical wellbore again, and drilling laterally inside the rock formation from the end of the vertical well section to complete the horizontal well section.

3. The method for constructing a single well horizontal cavity by segmentation according to claim 2, characterized in that: Step S2 includes: S21, lowering an outer tube for cavity formation and an inner tube disposed inside the outer tube to a second end of the horizontal well section away from the vertical well section, and forming a cavity through hydraulic circulation to form a first cavity; S22, lowering the outer tube for cavity construction and the inner tube disposed inside the outer tube to a position close to or in contact with the first cavity and away from the second end of the horizontal well section, and forming a cavity by hydraulic circulation to form a second cavity connected to the first cavity; and so on, completing the construction of the nth cavity one by one, wherein the nth cavity is close to or located at the first end of the horizontal well section; S23, lowering an outer pipe used for cavity formation and an inner pipe arranged inside the outer pipe to the bottom end of the vertical well section, and forming a cavity through hydraulic circulation to form an (n+1)th cavity connected to the nth cavity.

4. The method for constructing a single well horizontal cavity by sections according to claim 3, characterized in that: Before S21, one or more centralizers are spaced apart on the outer wall of a portion of the inner tube.

5. The method for constructing a single well horizontal cavity by sections according to claim 3, characterized in that: Step S21 specifically includes: lowering the outer tube and the inner tube together into the completion production casing, and then allowing the outer tube and the inner tube to enter the vertical wellbore, and enter the horizontal well section laterally from the top of the vertical well section, and extend laterally to the second end of the horizontal well section. After the outer tube and the inner tube reach the second end of the horizontal well section, a cavity is created by hydraulic circulation to form the first cavity.

6. The method for constructing a single well horizontal cavity by sections according to claim 3, characterized in that: Step S22 specifically includes: lowering the outer tube portion and the inner tube portion together into the completion production casing, and then allowing the outer tube portion and the inner tube portion to enter the vertical wellbore, and enter the horizontal well section laterally from the top of the vertical well section, and extend laterally to a position where the ends of the outer tube portion and the inner tube portion are close to or in contact with the first cavity and away from the second end of the horizontal well section, and forming a cavity through hydraulic circulation to form the second cavity connected to the first cavity.

7. The method for constructing a single well horizontal cavity by sections according to claim 3, characterized in that: Step S23 specifically includes: lowering the outer pipe and the inner pipe together into the completion production casing, and then allowing the outer pipe part and the inner pipe part to enter the vertical wellbore and directly enter the bottom end of the vertical well section, and form the n+1th cavity connected to the nth cavity through hydraulic circulation.

8. A single well horizontal cavity segmented cavity making device, characterized in that: It comprises an outer pipe and an inner pipe arranged inside the outer pipe, parts of the outer pipe and the inner pipe are located inside the production casing and the rest of the outer pipe and the inner pipe can enter the horizontal well section and the vertical well section for cavity creation.

9. The method for constructing a single well horizontal cavity by sections according to claim 8, characterized in that: One or more centralizers are arranged at intervals on the outer wall of the inner pipe extending in the horizontal well section.

10. The method for constructing a single well horizontal cavity by sections according to claim 9, characterized in that: The centralizer is made of metal material.

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