阅读说明：本技术 一种天然气水合物储层多级防砂方式及装置 (Multistage sand prevention mode and device for natural gas hydrate reservoir ) 是由 闫传梁 董磊峰 程远方 任旭 田万顷 李振琦 姜传祥 于 2019-09-18 设计创作，主要内容包括：本发明涉及一种天然气水合物储层多级防砂方式及装置。其技术方案是包括以下过程：(1)先采用大尺寸钻头钻至目的层形成主井眼,再用小尺寸钻头在目的层钻取多个分支井眼；(2)将单体式金属棉滤砂管下放到分支井眼中,将其放置在井内生产层段处；(3)将绕丝筛管下入井内防砂层段处,用流体携带地面选好的砾石,充填于管和储层之间,以阻止储层砂粒流入井内；(4)流入井筒的气、水、砂混合物通过气液固分离器,对固相颗粒进行分离,分离出的砂粒被收集到储砂装置内；待盛满砂粒之后提出井筒,在地面清理干净后再次下放到井底,依次往复进行；其有益效果是：通过多级过滤降低由储层进入井筒的砂量,有效控制储层出砂,提高水合物的产能。(The invention relates to a natural gas hydrate reservoir multi-stage sand prevention method and device. The technical scheme comprises the following processes: (1) firstly, a large-size drill bit is adopted to drill a target layer to form a main borehole, and then a small-size drill bit is adopted to drill a plurality of branch boreholes in the target layer; (2) placing the single-body metal cotton sand screen into the branch well bore, and placing the single-body metal cotton sand screen at the production interval section in the well; (3) lowering the wire-wrapped screen pipe into the sand prevention interval section in the well, filling fluid carrying gravel well selected from the ground between the pipe and the reservoir to prevent sand grains in the reservoir from flowing into the well; (4) the gas, water and sand mixture flowing into the shaft passes through a gas-liquid-solid separator to separate solid-phase particles, and the separated sand grains are collected into a sand storage device; after sand grains are filled, the shaft is lifted out, and the shaft is put down to the bottom of the well again after the ground is cleaned up, and the operation is carried out in sequence; the beneficial effects are as follows: the sand amount entering a shaft from a reservoir is reduced through multi-stage filtration, the sand production of the reservoir is effectively controlled, and the hydrate production capacity is improved.)

1. A multistage sand control mode for a natural gas hydrate reservoir is characterized by comprising the following steps:

(1) firstly, a large-size drill bit is adopted to drill a target layer to form a main borehole, and then a small-size drill bit is adopted to drill a plurality of branch boreholes in the target layer;

(2) putting the single-body metal cotton sand screen into the branch well bore, and putting the single-body metal cotton sand screen at a production interval section in the well through an auxiliary tool;

(3) lowering the wire-wound sieve tube into a sand prevention interval in the well, filling gravel with certain granularity selected from the ground by using fluid with certain mass between the tube and the reservoir to form a gravel layer with certain thickness so as to prevent sand grains in the reservoir from flowing into the well;

(4) the gas, water and sand mixture flowing into the shaft passes through a gas-liquid-solid separator to separate solid-phase particles, and the separated sand grains are collected into a sand storage device; after sand grains are filled, the shaft is lifted out, and the shaft is put down to the bottom of the well again after the ground is cleaned up, and the operation is carried out in sequence;

(5) sand in the stratum flows out of the stratum along with the exploitation of the hydrate and enters a shaft, firstly enters a single metal cotton sand filtering pipe in a branch well, and passes through a stainless steel metal cotton wire in the pipe and a first-stage coarse sand control of a porous cover to block the sand with large particle size in a reservoir, and the sand with the particle size of less than medium particle size enters the branch well along with gas and water generated by the decomposition of the hydrate; the sand grains enter a gravel filling sand prevention layer of the main well bore, and the fluid with the extremely fine sand grains sequentially flows through the gravel filling layer and the wire-wound sieve tube to perform secondary fine sand prevention, so that the sand grains with medium grain sizes can be blocked outside the sand prevention layer; finally, a part of fine sand entering the main well bore is separated out through a solid-liquid separator and is settled in a sand storage device at the bottom of the well.

2. The multi-stage sand control mode for the natural gas hydrate reservoir as claimed in claim 1, which is characterized in that: the single metal cotton sand filtering pipe (12) is composed of a porous cover (13), stainless steel metal cotton wires (14), a pressing plate (15) and a base pipe (16), a plurality of groups of sand filtering holes are distributed on the outer wall of the base pipe (16), the porous cover (13), the stainless steel metal cotton wires (14) and the pressing plate (15) are sequentially arranged in each group of sand filtering holes from outside to inside, and welding seams are arranged on the outer sides of the stainless steel metal cotton wires (14).

3. The multi-stage sand control mode for the natural gas hydrate reservoir as claimed in claim 1, which is characterized in that: the wire-wrapped screen pipe is mainly composed of stainless steel wires, a central pipe with holes, longitudinal ribs and a coupling, the wire-wrapped screen pipe is placed at a sand prevention section in a well, fluid is used for carrying gravel well selected from the ground and filling the gravel between the pipe and a reservoir stratum, a gravel layer with a certain thickness is formed, and reservoir stratum sand grains are prevented from flowing into the well.

4. The utility model provides a multistage sand control device of natural gas hydrate reservoir stratum which characterized by: comprises a production casing (1), a separator (2), a reservoir (3), a branch well bore (4), a cement sheath (5), a wire-wrapped screen pipe (6), gravels (7), a main well bore (8), a solid-gas-liquid three-phase separator (9) and a single metal cotton sand screen pipe (12), a plurality of branch well bores (4) are arranged at the middle lower part of the main well bore (8), a single metal cotton sand filtering pipe (12) is arranged in each branch well bore (4), a production casing (1), a separator (2) and a wire-wrapped screen pipe (6) are arranged in a main borehole (8), the reservoir (3) is separated by a separator (2), gravel (7) is put into an annular space between the wire-wrapped screen pipe (6) and the cement sheath (5), the upper end of the wire-wrapped screen pipe (6) is connected with a production casing pipe (1), the lower end of the production casing (1) is provided with a solid-gas-liquid three-phase separator (9).

5. The multistage sand control device of a natural gas hydrate reservoir as claimed in claim 4, wherein: a sand storage device (10) is arranged at the lower part of the main well hole (8), and a lifting device (11) is arranged at the upper part of the sand storage device (10).

6. The multistage sand control device of a natural gas hydrate reservoir as claimed in claim 4, wherein: the single metal cotton sand filtering pipe (12) is composed of a porous cover (13), stainless steel metal cotton wires (14), a pressing plate (15) and a base pipe (16), a plurality of groups of sand filtering holes are distributed on the outer wall of the base pipe (16), the porous cover (13), the stainless steel metal cotton wires (14) and the pressing plate (15) are sequentially arranged in each group of sand filtering holes from outside to inside, and welding seams are arranged on the outer sides of the stainless steel metal cotton wires (14).

Technical Field

The invention relates to a sand prevention technology for exploiting natural gas hydrates, in particular to a multistage sand prevention method and device for a natural gas hydrate reservoir.

Background

The natural gas hydrate is an ice-like crystalline substance formed by methane and other gases and water molecules under the conditions of high pressure and low temperature, has high resource density, is widely distributed in the world and has extremely high resource value. Is the most ideal potential oil and gas alternative energy in the world nowadays, and is increasingly attracting high attention of all countries in the world. Natural gas hydrates are present in onshore permafrost zones and shallow deep sea sediments. In recent years, multiple hydrate trial production operations are implemented at home and abroad, and almost all failed natural gas hydrate trial production is forced to be terminated in advance due to serious sand production. Therefore, the problem of reservoir sand production when producing hydrates has been a major factor affecting the continued efficient production of hydrates.

The multistage sand control of hydrate exploitation mainly focuses on the ingenious cooperation of multiple sand control modes, and the influence of the multistage sand control on hydrate exploitation is reduced before produced sand of a stratum returns on produced liquid, so that the purpose of safe and stable production is achieved.

Disclosure of Invention

The invention aims to provide a multistage sand control mode for a natural gas hydrate reservoir, which aims at the problem of sand control at different positions in the hydrate exploitation process respectively and reduces the influence of reservoir sand production on exploitation as much as possible through multistage sand control, thereby improving the hydrate productivity.

The invention provides a multistage sand control mode for a natural gas hydrate reservoir, which comprises the following processes:

(1) firstly, a large-size drill bit is adopted to drill a target layer to form a main borehole, and then a small-size drill bit is adopted to drill a plurality of branch boreholes in the target layer;

(2) putting the single-body metal cotton sand screen into the branch well bore, and putting the single-body metal cotton sand screen at a production interval section in the well through an auxiliary tool;

(3) lowering the wire-wound sieve tube into a sand prevention interval in the well, filling gravel with certain granularity selected from the ground by using fluid with certain mass between the tube and the reservoir to form a gravel layer with certain thickness so as to prevent sand grains in the reservoir from flowing into the well;

(4) the gas, water and sand mixture flowing into the shaft passes through a gas-liquid-solid separator to separate solid-phase particles, and the separated sand grains are collected into a sand storage device; after sand grains are filled, the shaft is lifted out, and the shaft is put down to the bottom of the well again after the ground is cleaned up, and the operation is carried out in sequence;

(5) sand in the stratum flows out of the stratum along with the exploitation of the hydrate and enters a shaft, firstly enters a single metal cotton sand filtering pipe in a branch well, and passes through a stainless steel metal cotton wire in the pipe and a first-stage coarse sand control of a porous cover to block the sand with large particle size in a reservoir, and the sand with the particle size of less than medium particle size enters the branch well along with gas and water generated by the decomposition of the hydrate; the sand grains enter a gravel filling sand prevention layer of the main well bore, and the fluid with the extremely fine sand grains sequentially flows through the gravel filling layer and the wire-wound sieve tube to perform secondary fine sand prevention, so that the sand grains with medium grain sizes can be blocked outside the sand prevention layer; finally, a part of fine sand entering the main well bore is separated out through a solid-liquid separator and is settled in a sand storage device at the bottom of the well.

Preferably, go up monomer formula metal wool sand screen (12) and constitute by porous lid (13), stainless steel metal wool (14), clamp plate (15) and parent tube (16), the outer wall of parent tube (16) has laid multiunit sand filtration hole, and every group sand filtration is downthehole from outer to interior porous lid (13), stainless steel metal wool (14) and clamp plate (15) of being equipped with in proper order, and the outside of stainless steel metal wool (14) is equipped with the welding seam.

Preferably, the wire-wrapped screen pipe is mainly composed of stainless steel wires, a central pipe with holes, longitudinal ribs and a coupling, the wire-wrapped screen pipe is lowered into the sand prevention section of the well, fluid is used for carrying gravel well selected from the ground and filling the gravel between the pipe and the reservoir to form a gravel layer with a certain thickness, and sand of the reservoir is prevented from flowing into the well.

The invention provides a multistage sand control device for a natural gas hydrate reservoir, which has the technical scheme that: comprises a production casing (1), a separator (2), a reservoir (3), a branch well bore (4), a cement sheath (5), a wire-wrapped screen pipe (6), gravels (7), a main well bore (8), a solid-gas-liquid three-phase separator (9) and a single metal cotton sand screen pipe (12), a plurality of branch well bores (4) are arranged at the middle lower part of the main well bore (8), a single metal cotton sand filtering pipe (12) is arranged in each branch well bore (4), a production casing (1), a separator (2) and a wire-wrapped screen pipe (6) are arranged in a main borehole (8), the reservoir (3) is separated by a separator (2), gravel (7) is put into an annular space between the wire-wrapped screen pipe (6) and the cement sheath (5), the upper end of the wire-wrapped screen pipe (6) is connected with a production casing pipe (1), the lower end of the production casing (1) is provided with a solid-gas-liquid three-phase separator (9).

A sand storage device (10) is arranged at the lower part of the main well hole (8), and a lifting device (11) is arranged at the upper part of the sand storage device (10).

Preferably, the single metal cotton sand filtering pipe (12) consists of a porous cover (13), stainless steel metal cotton wires (14), a pressing plate (15) and a base pipe (16), wherein multiple groups of sand filtering holes are distributed on the outer wall of the base pipe (16), the porous cover (13), the stainless steel metal cotton wires (14) and the pressing plate (15) are sequentially arranged in each group of sand filtering holes from outside to inside, and welding seams are arranged on the outer sides of the stainless steel metal cotton wires (14).

Compared with the prior art, the invention has the beneficial effects that:

(1) in the oil and gas exploitation process, a single sand control mode is mostly adopted to control the sand production amount of the production interval. The technology adopts different sand prevention modes at different sand production positions in the well, reduces the sand amount entering the shaft from the reservoir through multi-stage filtration, effectively controls the sand production of the reservoir and improves the productivity of the hydrate;

(2) according to the technology, the main well bore is drilled firstly, and then the horizontal well bore is drilled, so that the mining contact area is increased, the well pattern structure is optimized, and the hydrate productivity is improved;

(3) the size of the gap of the metal cotton material adopted in the branch well is related to the compactness of fiber accumulation, and the sand prevention requirement of sand grains of different reservoirs can be met by controlling the compaction degree of the fibers;

(4) the metal cotton has certain self-cleaning and self-repairing functions and can be well suitable for hydrate exploitation. If the metal wool in the sand filter pipe is blocked, the aim of unblocking can be achieved by injecting gas into the well reversely;

(5) in the process of oil and gas development, the control of the sand production amount of a reservoir is generally emphasized, the treatment of sand grains entering a shaft is neglected, and the problem that the safety and the stability of the exploitation of the hydrate are influenced by the sand setting at the bottom of the shaft is effectively solved by the technology.

Drawings

FIG. 1 is a schematic illustration of a main wellbore screen and gravel pack sand control in accordance with the present invention;

FIG. 2 is a schematic cross-sectional view of a production well;

FIG. 3 is a schematic top view of a lateral well;

FIG. 4 is a schematic diagram of sand control of a metal wool sand screen in a branch well;

FIG. 5 is a schematic view of a one-piece metal wool sand screen;

in the upper diagram: the production method comprises the following steps of production casing 1, a separator 2, a reservoir 3, a branch well 4, a cement sheath 5, a wire-wrapped screen 6, gravels 7, a main well 8, a solid-gas-liquid three-phase separator 9, a sand storage device 10, a lifting device 11, a single metal cotton sand filtering pipe 12, a porous cover 13, stainless steel metal cotton wires 14, a pressure plate 15 and a base pipe 16.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.