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CN220167919U - Three-horizontal well group structure for exploiting natural gas hydrate - Google Patents

Three-horizontal well group structure for exploiting natural gas hydrate Download PDF

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Publication number
CN220167919U
CN220167919U CN202321485654.9U CN202321485654U CN220167919U CN 220167919 U CN220167919 U CN 220167919U CN 202321485654 U CN202321485654 U CN 202321485654U CN 220167919 U CN220167919 U CN 220167919U
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well
horizontal section
natural gas
heat
heat insulation
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CN202321485654.9U
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陈雄
杨付林
蔡平雄
周雄
李岩
陈波
方丽萍
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Beibu Gulf University
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Beibu Gulf University
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Abstract

The utility model discloses a three-horizontal well group structure for exploiting natural gas hydrate, and belongs to the technical field of natural gas hydrate exploitation. The three-horizontal well group structure comprises a production well, a heat injection well and a sand discharge well which extend to a natural gas hydrate reservoir, each well comprises a vertical section and horizontal sections positioned in the natural gas hydrate reservoir, a plurality of heat insulation pipe groups are uniformly arranged on the well walls of each well horizontal section at intervals along the length direction, each heat insulation pipe group consists of a heat insulation pipe arranged on the production horizontal section, a heat insulation pipe arranged on the heat injection horizontal section and a heat insulation pipe arranged on the sand discharge horizontal section, and the heat insulation pipes in the same heat insulation pipe group are aligned up and down; and openings are formed in the parts of the well walls of the production horizontal section, the heat injection horizontal section and the sand discharge horizontal section, which are not provided with the heat insulation pipes. The well group structure can effectively discharge sand grains and water while providing required heat for decomposing natural gas hydrate, and prevent a reservoir from collapsing.

Description

Three-horizontal well group structure for exploiting natural gas hydrate
Technical Field
The utility model belongs to the technical field of natural gas hydrate exploitation, and particularly relates to a three-horizontal well group structure for exploiting natural gas hydrate.
Background
The natural gas hydrate (Natural GasHydrate) is a cage-type crystal substance generated by natural gas and water under specific temperature and pressure (low temperature and high pressure), is like ice and snow, and is commonly called as 'combustible ice' because of its ignitability. Natural gas hydrate is a clean and efficient new energy source, and has huge reserves. The total organic carbon reserves in natural gas hydrates on earth are about twice the sum of petroleum, natural gas and coal, wherein the natural gas hydrate resources in the ocean area account for 99% of the total resources. With the progressive and intensive research into natural gas hydrate production, commercial production is also becoming increasingly more likely.
The method for theoretically exploiting natural gas hydrate at present mainly comprises a depressurization method, a heat injection method and CO 2 Substitution method. Because the displacement method has the defects of long reaction period, slow speed, low efficiency and the like, the decompression method and the heat injection method are mostly adopted for exploitation in practical application. The depressurization method is economical, but the depressurization exploitation cannot be performed efficiently and continuously due to the characteristics of poor permeability, low heat and mass transfer efficiency and low diversion capability of the marine hydrate reservoirProceeding; on the other hand, in the depressurization production, the temperature of the reservoir is lowered due to the heat absorption of decomposition of the hydrate, and the passage is easily blocked in the vicinity of the decomposed layer.
The heat injection method is to pump hot fluid (such as steam, hot water, hot brine and other hot fluids) into a natural gas hydrate reservoir from the ground by using a high-pressure pump to raise the temperature of the hydrate reservoir, so as to achieve the aim of decomposing the natural gas hydrate. The heat injection method can effectively promote the decomposition of the hydrate, has wide application range, but has the defects of large heat transfer loss, low heat utilization efficiency, small heating area, uncontrollable heat transfer direction and the like, so that most of heat is used for heating pore gas liquid and depositing. The utility model patent with publication number of CN108005626A discloses a natural gas hydrate exploitation device based on a heat pipe technology, which comprises a plurality of exploitation wells and exploitation wells, wherein the exploitation wells extend to a natural gas hydrate reservoir, each exploitation well comprises a exploitation well vertical section and a exploitation well horizontal section positioned in the natural gas hydrate reservoir, a gas-liquid separator is connected at a well mouth of the exploitation well positioned in the exploitation well vertical section, and a plurality of heat pipes extending into the natural gas hydrate reservoir are radially and uniformly arranged on a well wall of the exploitation well horizontal section. The utility model uses the heat pipe to transfer the hot water heat in the exploitation well to the natural gas hydrate reservoir, and most of the heat damages the hydrate phase balance instead of heating pore gas liquid and sediment, thereby realizing the directional heat transfer, expanding the heating area, improving the heat utilization efficiency, and overcoming the defects of few heating areas and uncontrollable heat transfer direction in the traditional heat injection method.
Disclosure of Invention
The utility model aims to provide a three-horizontal well group structure for exploiting natural gas hydrate, which can effectively discharge sand grains and water and prevent reservoir collapse while providing heat required for decomposing the natural gas hydrate.
In order to solve the technical problems, the utility model adopts the following technical scheme:
a three horizontal well group structure for exploiting natural gas hydrate, comprising a production well, a heat injection well and a sand discharge well extending to a natural gas hydrate reservoir, wherein the production well, the heat injection well and the sand discharge well all comprise vertical sections and horizontal sections positioned in the natural gas hydrate reservoir, the production horizontal sections are close to an overburden layer, the sand discharge horizontal sections are close to an underburden layer, and the heat injection horizontal sections are positioned between the production horizontal sections and the sand discharge horizontal sections;
a plurality of heat insulation pipe groups are uniformly arranged on the well walls of the production horizontal section, the heat injection horizontal section and the sand discharge horizontal section at intervals along the length direction, each heat insulation pipe group consists of a heat insulation pipe arranged on the production horizontal section, a heat insulation pipe arranged on the heat injection horizontal section and a heat insulation pipe arranged on the sand discharge horizontal section, and the heat insulation pipes in the same heat insulation pipe group are aligned up and down;
and openings are formed in the parts of the production horizontal section, the heat injection horizontal section and the sand discharge horizontal section, which are not provided with the heat insulation pipes, on the well walls.
In the three-horizontal well group structure, the open holes are distributed on the well wall of the production horizontal section, the heat injection horizontal section or the sand discharge horizontal section at intervals along the length direction of the well wall, and are uniformly distributed along the circumferential direction of the well wall. Further, the caliber of the opening is preferably more than 2 times of the maximum sand radius in the natural gas hydrate reservoir.
Compared with the prior art, the utility model has the advantages that the sand discharging well is additionally arranged at the position close to the lower overburden layer, the heat insulation pipe group and the arrangement of the openings are combined, the thermal cavity which is communicated up and down is formed in the same vertical area corresponding to the opening position on the horizontal section of the three wells through thermal circulation, the water and sand generated by dissolution of the natural gas hydrate are discharged through the sand discharging well while the required heat is provided for the decomposition of the natural gas hydrate, the blockage of a shaft is effectively avoided, and meanwhile, the natural gas hydrate on the upper side and the lower side of the heat insulation pipe group is reserved as a supporting body, so that the natural gas leakage caused by the collapse of a reservoir is prevented.
Drawings
Fig. 1 shows an embodiment of a three horizontal well group structure for producing natural gas hydrate according to the present utility model.
Fig. 2 is a schematic cross-sectional view of the embodiment of fig. 1.
The reference numerals in the figures are:
1, a sand discharging well; 101 a sand discharge vertical section; 102, a sand discharge horizontal section; 2, a heat injection well; 201 heat injection vertical section; 202 heat injection horizontal segment; 3, a production well; 301 producing a vertical section; 302 producing a horizontal segment; 4 overburden formation; 5 a natural gas hydrate reservoir; 6, overburden layer under; 7 heat insulating pipes; 8, a thermal cavity; 9 holes are formed.
Detailed Description
The utility model relates to a three-horizontal well group structure for exploiting natural gas hydrate, which comprises a production well 3, a heat injection well 2 and a sand discharge well 1 which extend to a natural gas hydrate reservoir 5, wherein the production well 3, the heat injection well 2 and the sand discharge well 1 all comprise vertical sections and horizontal sections positioned in the natural gas hydrate reservoir 5, the production horizontal section 302 is close to an overburden 4, the sand discharge horizontal section 102 is close to an underburden 6, and the heat injection horizontal section 202 is positioned between the production horizontal section 302 and the sand discharge horizontal section 102;
a plurality of heat insulation pipe groups are uniformly arranged on the well walls of the production horizontal section 302, the heat injection horizontal section 202 and the sand discharge horizontal section 102 at intervals along the length direction, each heat insulation pipe group consists of a heat insulation pipe 7 arranged on the production horizontal section 302, a heat insulation pipe 7 arranged on the heat injection horizontal section 202 and a heat insulation pipe arranged on the sand discharge horizontal section 102, and the heat insulation pipes 7 in the same heat insulation pipe group are aligned up and down;
the production horizontal section 302, the heat injection horizontal section 202, and the sand discharge horizontal section 102 are provided with openings 9 at portions where the heat insulating pipes 7 are not provided on the walls of the wells.
In the three-horizontal well group structure, the arrangement of the production well 3, the heat injection well 2 and the sand discharge well 1, the arrangement of the heat insulation pipe 7 and the open hole 9 on the wall of each well, the well completion operation and the like are completed by adopting the prior conventional technology.
In the three-horizontal well group structure, the distance between two adjacent heat insulation pipe groups is determined according to the needs, and is preferably set to be 10-30 meters. The heat insulating pipes 7 are preferably equal in length. It is further preferable to wrap the heat insulating pipe 7 with a heat insulating material to insulate heat exchange between each well shaft and the natural gas hydrate reservoir 5, so that the natural gas hydrate at the upper and lower corresponding parts of the heat insulating pipe 7 is not mined, so as to be used for supporting the natural gas hydrate reservoir 5, thereby maintaining the stability of the natural gas hydrate reservoir 5.
The vertical alignment of the heat insulation pipes 7 in the same heat insulation pipe group means that the initial ends of the heat insulation pipes 7 on the production horizontal section 302, the heat insulation pipes 7 on the heat injection horizontal section 202 and the heat insulation pipes 7 on the sand discharge horizontal section 102 in the same heat insulation pipe group are aligned or the absolute value of the maximum distance of the vertical plane where the initial ends of the three are positioned is less than or equal to 2 meters.
In the above three-horizontal well group structure, the openings 9 are distributed on the well wall of the production horizontal section 302, the heat injection horizontal section 202 or the sand discharge horizontal section 102 at intervals along the length direction of the well wall, and are uniformly distributed along the circumferential direction of the well wall. The shape of the opening 9 may be a regular shape such as a circle, an ellipse, a rectangle, or a square, or may be an irregular shape. Further, the caliber of the opening 9 is preferably more than 2 times of the maximum sand radius in the natural gas hydrate reservoir 5. Furthermore, in order to be more favorable for forming the thermal cavity 8 which is communicated up and down in the same vertical area corresponding to the positions of the openings 9 on the horizontal sections of the three wells, the maximum distance between the initial ends of the first opening 9 on the horizontal production section 302, the initial opening 9 on the horizontal heat injection section 202 and the initial opening 9 on the horizontal sand discharge section 102 in the same vertical area is aligned or the initial ends of the three openings are located on the vertical plane of the three openings, and the absolute value of the maximum distance is less than or equal to 2 meters.
In order to better explain the technical scheme of the present utility model, the present utility model will be described in further detail with reference to the accompanying drawings and examples, but the embodiments of the present utility model are not limited thereto.
FIG. 1 shows an embodiment of a three horizontal well group structure for producing natural gas hydrate according to the present utility model. In fig. 1, a three-horizontal well group structure for exploiting natural gas hydrate comprises a production well 3, a heat injection well 2 and a sand discharge well 1, wherein the production well 3 comprises a production vertical section 301 and a production horizontal section 302, the heat injection well 2 comprises a heat injection vertical section 201 and a heat injection horizontal section 202, the sand discharge well 1 comprises a sand discharge vertical section 101 and a sand discharge horizontal section 102, and the production horizontal section 302, the heat injection horizontal section 202 and the sand discharge horizontal section 102 are all positioned in a natural gas hydrate reservoir 5, wherein the production horizontal section 302 is close to an overburden 4, the sand discharge horizontal section 102 is close to an underburden 6, and the running depth of the heat injection horizontal section 202 is positioned between the running depths of the production horizontal section 302 and the sand discharge horizontal section 102 (as shown in fig. 2); the production horizontal section 302, the heat injection horizontal section 202 and the sand discharge horizontal section 102 are provided with a plurality of heat insulation pipe groups at equal intervals along the length direction on the well wall, each heat insulation pipe group consists of a heat insulation pipe 7 arranged on the production horizontal section 302, a heat insulation pipe 7 arranged on the heat injection horizontal section 202 and a heat insulation pipe arranged on the sand discharge horizontal section 102, the lengths of the heat insulation pipes 7 are equal, each heat insulation pipe 7 is wrapped with a heat insulation material, and the starting ends of the heat insulation pipes 7 in the same heat insulation pipe group are aligned; the parts of the well walls of the production horizontal section 302, the heat injection horizontal section 202 and the sand discharge horizontal section 102, on which the heat insulation pipes 7 are not arranged, are provided with openings 9, and the openings 9 are rectangular, are distributed on the well walls of the production horizontal section 302, the heat injection horizontal section 202 or the sand discharge horizontal section 102 at intervals along the length direction of the well walls, and are uniformly distributed along the circumferential direction of the well walls; the absolute value of the maximum distance of the vertical plane of the initial ends of the first opening 9 on the production horizontal section 302, the first opening 9 on the heat injection horizontal section 202 and the first opening 9 on the sand discharge horizontal section 102 in the same vertical area is less than or equal to 2 meters.
The method for exploiting natural gas hydrate by utilizing the three-horizontal well group structure comprises the following steps:
1) After the well group structure arrangement and the well completion operation are completed, hot fluid is respectively injected into the production well 3, the heat injection well 2 and the sand discharge well 1, the heat circulation is carried out in the production well 3, the heat injection well 2 and the sand discharge well 1, the hot fluid is outwards diffused through the openings 9 on the production well 3, the heat injection well 2 and the sand discharge well 1, and a hot cavity 8 is formed near the openings 9 on the sand discharge horizontal section 102, the heat injection horizontal section 202 and the production horizontal section 302; by continuous thermal circulation, a thermal cavity 8 which is communicated up and down is formed in the same vertical area corresponding to the position of the opening 9 on the production horizontal section 302, the heat injection horizontal section 202 and the sand discharge horizontal section 102;
2) After the hot cavity 8 communicated up and down is formed, the injection of the hot fluid into the production well 3 and the sand discharging well 1 is stopped, the injection of the hot fluid into the heat injection well 2 is continued to dissolve natural gas hydrate, the natural gas hydrate is dissolved, the dissolved natural gas enters the production well 3 through the opening 9 on the production well 3 and is extracted from the production well 3, and water and sand grains generated after the natural gas hydrate is dissolved enter the sand discharging well 1 through the opening 9 on the sand discharging well 1 under the action of gravity and pressure and are discharged from the sand discharging well 1.
The hot fluid involved in the above method may be hot water, hot brine, or the like, which is commonly used in the art. By simultaneously performing thermal circulation in the production well 3, the heat injection well 2 and the sand discharge well 1, when three wells are subjected to pressure linkage at the same time (wherein one well is subjected to pressure change, and the other two wells are subjected to pressure linkage along with the pressure change), the thermal cavity 8 which is communicated up and down is considered to be formed. After the hot cavity 8 communicated up and down is formed, the flow ratio of the sand discharging well 1 to the heat injecting well 2 is controlled to be larger than or equal to 1, so that the sand discharging well 1 is prevented from air discharging (after the hot cavity 8 communicated up and down is formed, the production well 3 and the sand discharging well 1 stop injecting hot fluid, and the heat injecting well 2 continues injecting hot fluid, so that heat is prevented from being accumulated and absorbed in a reservoir to avoid energy waste, and the hot fluid cooled after heat release is discharged through the sand discharging well 1).
In the whole exploitation process, the flow of the output in the production well 3 and the volume and shape of the thermal cavity 8 after the exploitation of the natural gas hydrate are controlled by controlling the temperature and pressure of the hot fluid injected into the thermal injection well 2. In the exploitation process, when natural gas or steam is produced in the sand discharging well 1, the natural gas or steam is prevented from being produced in the sand discharging well 1 by stopping injecting hot fluid into the heat injecting well 2 or reducing the temperature and pressure of the hot fluid injected into the heat injecting well 2, and keeping the temperature difference between the hot fluid injected and the produced liquid within a required range. During production, the temperature of the output of the sand removal well 1 (including condensate water, natural gas hydrate water, sand in the reservoir, etc.) is preferably no more than 40 ℃ and no less than 0 ℃, and is regulated by controlling the temperature and pressure of the hot fluid injected into the injection well 2.

Claims (3)

1. A three horizontal well group structure for producing natural gas hydrate, comprising a production well (3), a heat injection well (2) and a sand discharge well (1) extending to a natural gas hydrate reservoir (5), wherein the production well (3), the heat injection well (2) and the sand discharge well (1) all comprise vertical sections and horizontal sections positioned in the natural gas hydrate reservoir (5), wherein the production horizontal section (302) is close to an overburden (4), the sand discharge horizontal section (102) is close to an underburden (6), and the heat injection horizontal section (202) is positioned between the production horizontal section (302) and the sand discharge horizontal section (102);
a plurality of heat insulation pipe groups are uniformly arranged on the well walls of the production horizontal section (302), the heat injection horizontal section (202) and the sand discharge horizontal section (102) at intervals along the length direction, each heat insulation pipe group consists of a heat insulation pipe (7) arranged on the production horizontal section (302), a heat insulation pipe (7) arranged on the heat injection horizontal section (202) and a heat insulation pipe (7) arranged on the sand discharge horizontal section (102), and the heat insulation pipes (7) in the same heat insulation pipe group are aligned up and down;
and openings (9) are formed in the parts, which are not provided with the heat insulation pipes (7), of the well walls of the production horizontal section (302), the heat injection horizontal section (202) and the sand discharge horizontal section (102).
2. The three horizontal well group structure for producing natural gas hydrate according to claim 1, wherein the openings (9) are distributed at intervals along the length direction of the well wall on the production horizontal section (302), the heat injection horizontal section (202) or the sand discharge horizontal section (102) and are uniformly distributed along the circumferential direction of the well wall.
3. The three horizontal well group structure for the production of natural gas hydrate according to claim 1 or 2, characterized in that the aperture of the opening (9) is more than 2 times the radius of the largest sand in the natural gas hydrate reservoir (5).
CN202321485654.9U 2023-06-12 2023-06-12 Three-horizontal well group structure for exploiting natural gas hydrate Active CN220167919U (en)

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Application Number Priority Date Filing Date Title
CN202321485654.9U CN220167919U (en) 2023-06-12 2023-06-12 Three-horizontal well group structure for exploiting natural gas hydrate

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Application Number Priority Date Filing Date Title
CN202321485654.9U CN220167919U (en) 2023-06-12 2023-06-12 Three-horizontal well group structure for exploiting natural gas hydrate

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CN220167919U true CN220167919U (en) 2023-12-12

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