Downhole natural gas hydrate coupling separation desilting tool

Abstract

The invention relates to an underground natural gas hydrate coupling separation desilting tool which comprises a spiral-rotational flow coupling separation tool, a rotational flow suction coarse separation device and a jet flow desilting device which are sequentially connected from bottom to top. The lower end of the jet flow sand discharging device is used for being connected with a power drilling tool, and the upper end of the spiral-rotational flow coupling separation tool is used for being connected with a jet flow breaking spray head, so that the high-sand-content natural gas hydrate enters the spiral-rotational flow coupling separation tool and the rotational flow suction coarse separation device in sequence; and mud and sand in the high-sand-content natural gas hydrate are discharged to the sea through the jet flow sand discharging device. The device can effectively decompose hydrates, mud and sand and water, and can realize effective separation of micron-sized superfine mud and sand solid-phase particles with cross-scale particle sizes in multi-phase mixed slurry, so that the purity of natural gas hydrates returned in the development process is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of natural gas hydrate development, and in particular to an underground natural gas hydrate coupling separation and sand removal tool. Background Art

[0002] Natural gas hydrate, also known as "combustible ice", is a high-density, high-calorific value, unconventional clean alternative energy source. In the deep seabed, natural gas hydrates mainly exist in sandstone type, sandstone fissure type, fine-grained fissure type and dispersed type. Among them, fine-grained fissure type and dispersed natural gas hydrates account for the vast majority, but this type of natural gas hydrate is shallowly buried and has weak cementation, which can easily cause geological and environmental disasters during mining. Existing mining methods such as solid fluidization method have the bottleneck problem of large sand output, which seriously hinders the development of natural gas hydrate mining process and technology.

[0003] The patent application number is 201920013263.4, and the patent application date is January 4, 2019. The patent application number is 201920013263.4. The patent application date is January 4, 2019. The patent application number is 201811412136.8. The patent application number is November 25, 2018. The patent application number is "An offset symmetrical parallel type seabed shallow natural gas hydrate in-situ separation device", respectively puts traditional cyclone or spiral separators into the pipeline and then arranges them in parallel. However, the flow channel setting is complicated, and mud and sand are prone to accumulation and blockage of the flow channel. It is not suitable for the integrated operation process of efficient recovery, separation, debonding and backfilling of natural gas hydrates. Moreover, no special mud and sand discharge mechanism is set, and efficient mud and sand removal and backfilling cannot be achieved.

[0004] In summary, there is an urgent need for a downhole natural gas hydrate coupled separation and sand removal tool. Summary of the invention

[0005] The present invention provides an underground natural gas hydrate coupled separation and sand removal tool, which realizes the integrated functions of recovery, separation and backfilling such as efficient cyclone suction of natural gas hydrate mixed slurry in the crushing cavity, in-situ separation of mud and sand underground, rupture of weak cementation bonds of slurry, and removal and backfilling of mud and sand, thereby improving the recovery efficiency, reducing the overall operating cost, and reducing the risk of collapse of the crushing cavity.

[0006] The present invention provides a downhole natural gas hydrate coupled separation and sand removal tool, comprising a spiral-cyclone coupled separation tool, a cyclone suction coarse separation device and a jet sand removal device. The spiral-cyclone coupled separation tool, the cyclone suction coarse separation device and the jet sand removal device are sequentially connected from top to bottom, the lower end of the jet sand removal device is used to be connected to a power drill, and the upper end of the spiral-cyclone coupled separation tool is used to be connected to a jet crushing nozzle, so that after high-sand-content natural gas hydrate enters the spiral-cyclone coupled separation tool and the cyclone suction coarse separation device in sequence, the mud and sand in the high-sand-content natural gas hydrate are discharged into the sea through the jet sand removal device.

[0007] The downhole natural gas hydrate coupled separation and sand removal tool, preferably, the spiral-cyclone coupled separation tool includes a cyclone suction outer tube and a spiral-cyclone separation tool shell, the outer side of the cyclone suction outer tube is provided with the spiral-cyclone separation tool shell, the cyclone suction outer tube is a double-layer tube structure, the inner layer tube of the cyclone suction outer tube is used to provide a hydrate recovery channel, the inner layer tube of the cyclone suction outer tube is provided with a power fluid pipe, and the bottom end of the power fluid pipe is assembled on the jet sand removal device, the outer layer tube of the cyclone suction outer tube is provided with a first cyclone auxiliary flow channel and a second cyclone auxiliary flow channel and a circumferentially distributed vortex groove, the first cyclone auxiliary flow channel and the second cyclone auxiliary flow channel are provided below the vortex groove, the cyclone suction coarse separation device and the jet sand removal device are arranged in sequence from top to bottom below the cyclone suction outer tube, and the cyclone suction coarse separation device is located in the spiral-cyclone separation tool shell, and the jet sand removal device is connected to the lower end of the spiral-cyclone separation tool shell.

[0008] The downhole natural gas hydrate coupled separation and sand removal tool, preferably, the swirl suction coarse separation device includes a plurality of swirl flow stabilizing baffles and a conical swirl generator, the bottom of the conical swirl generator is provided with a plurality of the swirl flow stabilizing baffles, and a labyrinth seal is provided at the lower end of the swirl flow stabilizing baffle, the swirl flow stabilizing baffle is made of rubber material to achieve radial deformation when under pressure, and there is a gap between the conical swirl generator and the inner wall of the spiral-swirl separation tool housing, and the gap enables a large mass of mud and sand to enter the jet sand removal device.

[0009] The downhole natural gas hydrate coupled separation and sand removal tool, preferably, the conical vortex generator includes a conical body and a cylindrical channel, a plurality of vortex stabilizing baffles are provided at the bottom of the conical body, the gap is formed between the outer diameter of the conical body and the outer shell of the spiral-vortex separation tool, and the cylindrical channel is arranged on the central axis of the conical body.

[0010] The downhole natural gas hydrate coupled separation and sand removal tool, preferably, the jet sand removal device includes a sand removal spray barrel, a first spring, a sand removal sleeve, a second spring and a spring cover plate, the sand removal spray barrel is connected to the spiral-cyclone separation tool housing, the first spring is assembled at the lower end of the sand removal sleeve, the second spring is assembled at the upper end of the sand removal sleeve and is fixed in the sand removal spray barrel through the spring cover plate to form a whole, and the bottom end of the power fluid pipe is assembled at the pipeline sealing ring groove of the sand removal spray barrel.

[0011] The beneficial effects are:

[0012] The present application adopts a vortex groove structure, so that the natural gas hydrate generates a circumferential velocity after being sucked in, thereby separating mud and sand from the natural gas hydrate. The suction port has a simple structure and does not need to set up a complex flow channel, which can avoid the accumulation and blockage of mud and sand.

[0013] The jet sand removal device uses high-pressure power fluid to directly backfill the separated mud and sand into the goaf, reducing the riser delivery volume, reducing the consumption of pumping mud and sand, improving recovery efficiency, greatly reducing mining costs, and avoiding erosion, wear and blockage of wellbores, equipment, etc. by mud and sand.

[0014] The present application utilizes the special structure of a cyclone suction coarse separation device and a sand discharge mechanism to realize integrated recovery and separation of natural gas hydrates, and can be used for the continuous exploitation of natural gas hydrate strata with high sand content, thereby reducing the cost of natural gas hydrate exploitation and the number of operations, thereby realizing efficient exploitation of natural gas hydrates.

[0015] The natural gas hydrate of the present application can effectively decompose hydrate, mud, sand and water in the flow field formed by the cyclone suction coarse separation device and the spiral-cyclone coupling separation tool, and can achieve effective separation of cross-scale particle sizes and micron-level ultra-fine mud and sand solid phase particles in the multiphase mixed slurry, thereby ensuring the purity of the returned natural gas hydrate during the development process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the present invention;

[0017] Figure 2a yes Figure 1 Schematic diagram of the AA surface structure;

[0018] Figure 2b yes Figure 1 Schematic diagram of the structure of the middle BB surface;

[0019] Figure 2c yes Figure 2a Schematic diagram of the structure of the middle CC surface;

[0020] Figure 3 is a three-dimensional cross-sectional view of the spiral-cyclone coupling separation tool;

[0021] Figure 4a It is a top view of the sandblasting barrel;

[0022] Figure 4b yes Figure 4a Schematic diagram of the AA surface structure;

[0023] Figure 5a It is a three-dimensional diagram of the cyclone suction rough separation device;

[0024] Figure 5b is a side view of the cyclone suction coarse separation device;

[0025] Figure 5c It is a top view of the cyclone suction coarse separation device.

[0026] 1. Sand discharge spray gun; 1-1. Flat thread; 1-2: Sand discharge hole; 1-3 Spring placement groove;

[0027] 1-4, concave cone surface; 1-5, male taper thread;

[0028] 2. First spring; 3. Sand discharge sleeve; 4. Second spring; 5. Spring cover;

[0029] 6. Swirl flow stabilizing baffle; 601. Labyrinth seal;

[0030] 7. Conical swirl generator; 701. Cylindrical channel; 702. Conical body;

[0031] 8. Spiral-cyclone coupling separation tool; 801. vortex groove; 802. cyclone suction outer tube;

[0032] 803, first swirl auxiliary flow channel; 804, second swirl auxiliary flow channel; 805, hydrate recovery channel;

[0033] 806. circumferential spline keyway; 807. spiral-cyclone separation tool housing; 808. drill pipe flat thread; 9. outer layer tube of cyclone suction outer tube; 11. power fluid tube. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner" and "outer" indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the system or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" and other words are used to define components only for the convenience of distinguishing the above components. If not otherwise stated, the above terms have no special meanings and cannot be understood as indicating or implying relative importance.

[0036] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "setting" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] The present invention provides a downhole natural gas hydrate coupled separation and sand removal tool, comprising a spiral-cyclone coupled separation tool, a cyclone suction coarse separation device and a jet sand removal device, wherein the spiral-cyclone coupled separation tool, the cyclone suction coarse separation device and the jet sand removal device are sequentially connected from top to bottom, the lower end of the jet sand removal device is used to be connected to a power drill, and the upper end of the spiral-cyclone coupled separation tool is used to be connected to a jet crushing nozzle, so that after the high-sand natural gas hydrate enters the spiral-cyclone coupled separation tool and the cyclone suction coarse separation device in sequence, the mud and sand in the high-sand natural gas hydrate are discharged into the sea through the jet sand removal device. The natural gas hydrate of the present invention can effectively decompose hydrate, mud, sand and water in the flow field formed by the cyclone suction coarse separation device and the spiral-cyclone coupled separation tool, and can realize the effective separation of cross-scale particle sizes and micron-level ultra-fine mud and sand solid phase particles in the multi-phase mixed slurry, thereby ensuring the purity of the returned natural gas hydrate during the development process.

[0038] The entire technical process is described in detail below using an underground natural gas hydrate coupled separation and sand removal tool as an example.

[0039] Reference Figure 1 , Figure 2a , Figure 2b and Figure 2cA downhole natural gas hydrate coupled separation and sand removal tool is shown, comprising a cyclone suction coarse separation device, a jet sand removal device, and a spiral-cyclone coupled separation tool 8, wherein the jet sand removal device is located at the lowest end of the entire device, the upper end of the jet sand removal device is connected to the cyclone suction coarse separation device by threads, and the cyclone suction coarse separation device is connected to the lower end of the spiral-cyclone coupled separation tool 8 by threads, the spiral-cyclone coupled separation tool 8 is a double-layer tube structure, and the innermost layer of the spiral-cyclone coupled separation tool 8 is a power fluid pipe 11, wherein the power fluid pipe 11 is a thin tube arranged in the axial direction. The lower end of the jet sand removal device is connected to a power drill, and the upper end of the spiral-cyclone coupled separation tool is connected to a jet crushing nozzle.

[0040] Reference Figure 3 As shown, the spiral-cyclone coupling separation tool 8 includes a cyclone suction outer tube 802 and a spiral-cyclone separation tool housing 807. The outer side of the cyclone suction outer tube 802 is provided with a spiral-cyclone separation tool housing 807. The cyclone suction outer tube 802 is a double-layer tube structure. The inner tube of the cyclone suction outer tube is used as a recovery channel 805 for providing hydrates. The inner tube of the cyclone suction outer tube is provided with a power fluid pipe 11, and the bottom end of the power fluid pipe 11 is assembled on the jet sand discharge device. The outer tube 9 of the cyclone suction outer tube is provided with a power fluid pipe 11. There are a first swirl auxiliary flow channel 803 and a second swirl auxiliary flow channel 804 and a circumferentially distributed vortex groove 801. The first swirl auxiliary flow channel 803 and the second swirl auxiliary flow channel 804 are arranged below the vortex groove 801. The swirl suction coarse separation device and the jet sand removal device are arranged from top to bottom below the swirl suction outer pipe 802, and the swirl suction coarse separation device is located in the spiral-swirl separation tool housing 807, and the jet sand removal device is connected to the lower end of the spiral-swirl separation tool housing 807.

[0041] Reference Figure 1 and Figure 3 As shown, a circumferential spline keyway 806 is further provided in the spiral-cyclone separation tool housing 807 , and two cavities are circumferentially distributed in the circumferential spline keyway 806 . The circumferential spline keyway 806 connects and fixes the cyclone flow stabilizing baffle 6 to the power fluid pipe 11 .

[0042] Reference Figure 5a , Figure 5b and Figure 5c As shown, the swirl suction coarse separation device includes a plurality of swirl flow stabilizing baffles 6 and a conical swirl generator 7. A plurality of swirl flow stabilizing baffles 6 are provided at the bottom of the conical swirl generator 7, and a labyrinth seal 601 is provided at the lower end of the swirl flow stabilizing baffle 6. The swirl flow stabilizing baffle 6 is made of rubber material so as to achieve radial deformation when under pressure. There is a gap between the conical swirl generator 7 and the inner wall of the swirl suction outer tube 802, and the gap enables a large mass of mud and sand to enter the jet sand discharge device.

[0043] The swirl suction outer tube has a circumferential vortex groove on its upper part. The vortex groove is characterized by being circumferentially distributed on the swirl suction outer tube, and the fluid flows in from the vortex groove to generate circumferential velocity.

[0044] The conical swirl generator 7 includes a conical body 702 and a cylindrical channel 701. A plurality of swirl stabilizing baffles 6 are provided at the bottom of the conical body 702. The gap is formed between the outer diameter of the conical body 702 and the spiral-swirl separation tool housing 807. The cylindrical channel 701 is arranged on the central axis of the conical body 702.

[0045] Refer to Figure 2 and Figure 4a , Figure 4b As shown, the jet sand removal device includes a sand removal spray barrel 1, a first spring 2, a sand removal sleeve 3, a second spring 4 and a spring cover plate 5. The sand removal spray barrel 1 is connected to the spiral-cyclone separation tool housing 807. The first spring 2 is assembled at the lower end of the sand removal sleeve 3. The second spring 4 is assembled at the upper end of the sand removal sleeve 3 and is fixed in the sand removal spray barrel 1 through the spring cover plate 5 to form a whole. The sand removal sleeve 3 can slide up and down, and the bottom end 11 of the power fluid pipe is assembled at the pipeline sealing ring groove of the sand removal spray barrel 1.

[0046] Among them, the upper end of the sand-removing spray barrel 1 is a flat thread 1-1, which is connected to the thread of the spiral-cyclone separation tool housing 807. The lower end of the sand-removing spray barrel 1 is a male tapered thread 1-5, which has sand-removing holes 1-2 in its circumference, and the internal annulus is a spring placement groove 1-3. The second spring 4 is placed at the upper end of the spring placement groove 1-3, and the first spring 2 is placed at the lower end, and the concave cone surface 1-4 is next to the groove.

[0047] The sandblasting sleeve 3 is inside the spring placement groove 1-3. A second spring 4 is arranged at the upper end of the sandblasting sleeve 3 and a first spring 2 is arranged at the lower end. When the second spring 4 or the first spring 2 is acted upon by force, the sandblasting sleeve 3 is driven to slide up and down.

[0048] The high-sand-content natural gas hydrate enters the interior of the spiral-swirl coupling separation tool 8 from the vortex groove 801 on the upper part of the swirl suction outer tube. The high-sand-content natural gas hydrate flows through the first swirl auxiliary flow channel 803 and the second swirl auxiliary flow channel 804 in the swirl suction rough separation device. Due to the centrifugal principle, the mud and sand move outward to the wall of the separation cylinder, while the light natural gas hydrate in the center of the fluid is blocked by the conical swirl generator 7 to produce an upward swirl. At the same time, due to the "particle revolution" characteristics of natural gas hydrate in the spiral-swirl coupling separation tool, it can achieve effective separation of cross-scale particle sizes and micron-level ultra-fine mud and sand solid phase particles in the multi-phase mixed slurry, thereby ensuring the high purity of the returned natural gas hydrate during the development process. The mud and sand separated to the wall settle downward due to its own gravity, and the mud and sand pass through the gap between the conical swirl generator 7 and the spiral-swirl coupling separation tool 8 and accumulate on the conical body 702 of the swirl steady flow baffle 6. When the mud and sand accumulated on the rubber cone surface 601 reaches a certain weight, the conical body 702 is squeezed and deformed, and the mud and sand fall into the sand discharge sleeve 3. When the mud and sand in the sand discharge sleeve 3 accumulate to a certain amount, the gravity of the mud and sand pushes the sand discharge sleeve 3 to slide downward. The mud and sand in the sand discharge sleeve 3 are discharged into the sea together with the power fluid. The downhole hydrate separation and sand discharge tool is a double-layer pipe structure, and the innermost layer is the hydrate recovery channel 805.

[0049] The downhole hydrate separation and sand removal tool is connected to the natural gas water and production tool pipe string, the lower end of which is connected to the power drill, and the upper end is connected to the jet crushing nozzle.

[0050] The working process of the present invention is as follows:

[0051] The present invention is a recovery and separation part of a natural gas hydrate production tool pipe string, and the drill pipe flat thread 808 is connected to the natural gas hydrate production jet breaking sleeve. The present invention is lowered into the seabed together with the natural gas hydrate production tool pipe string, and is suitable for solid fluidization production method. First, drill the tool pipe string into the natural gas hydrate ore layer, and then pull the tool pipe string back. At this time, the jet crushing sleeve at the upper end of the tool pipe string crushes the natural gas hydrate. The crushed high-pressure sand-containing natural gas hydrate enters the vortex suction coarse separation device through the vortex groove 801. Due to the action of the vortex groove 801, the sand-containing natural gas hydrate generates a tangential velocity. Further, the first vortex auxiliary flow channel 803 and the second vortex auxiliary flow channel 804 assist the fluid to form a tangential velocity flow. Due to the centrifugal force, solid particles such as mud and sand with larger mass approach the inner wall of the spiral-vortex coupling separation tool 8, and the fluid flows downward in a spiral as a whole. Due to the obstruction of the conical vortex generator 7, the mud and sand with larger mass flow in the outer ring through the gap between the inner wall of the spiral-vortex coupling separation tool 8 and the conical vortex generator 7 into the sand discharge sleeve 3, and the smaller mass encounters the vortex steady flow baffle 6 and flows upward. When the mud and sand on the sand discharge sleeve 3 accumulates to a certain weight, the gravity of the mud and sand is greater than the elastic force of the first spring 2 , the sand discharge sleeve 3 slides downward, and the mud and sand rushes out of the sand discharge nozzle 1 .

[0052] Finally, it should be noted that the above 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 with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A downhole natural gas hydrate coupled separation and sand removal tool, characterized in that: It comprises a spiral-cyclone coupling separation tool, a cyclone suction coarse separation device and a jet sand discharge device, wherein the spiral-cyclone coupling separation tool, the cyclone suction coarse separation device and the jet sand discharge device are sequentially connected from top to bottom, the lower end of the jet sand discharge device is used to be connected to a power drill, and the upper end of the spiral-cyclone coupling separation tool is used to be connected to a jet crushing nozzle, so that after high-sand-content natural gas hydrate enters the spiral-cyclone coupling separation tool and the cyclone suction coarse separation device in sequence, the mud and sand in the high-sand-content natural gas hydrate are discharged into the sea through the jet sand discharge device.

2. The downhole natural gas hydrate coupled separation and sand removal tool according to claim 1, characterized in that: The spiral-cyclone coupling separation tool includes a cyclone suction outer tube and a spiral-cyclone separation tool shell, the spiral-cyclone separation tool shell is provided on the outer side of the cyclone suction outer tube, the cyclone suction outer tube is a double-layer tube structure, the inner tube of the cyclone suction outer tube is used to provide a hydrate recovery channel, a power fluid pipe is provided in the inner tube of the cyclone suction outer tube, and the bottom end of the power fluid pipe is assembled on the jet sand removal device, the outer tube of the cyclone suction outer tube is provided with a first cyclone auxiliary flow channel and a second cyclone auxiliary flow channel and a circumferentially distributed vortex groove, the first cyclone auxiliary flow channel and the second cyclone auxiliary flow channel are provided below the vortex groove, the cyclone suction coarse separation device and the jet sand removal device are arranged in sequence from top to bottom below the cyclone suction outer tube, and the cyclone suction coarse separation device is located in the spiral-cyclone separation tool shell, and the jet sand removal device is connected to the lower end of the spiral-cyclone separation tool shell.

3. The downhole natural gas hydrate coupled separation and sand removal tool according to claim 2, characterized in that: The swirl suction rough separation device includes a plurality of swirl flow stabilizing baffles and a conical swirl generator. The bottom of the conical swirl generator is provided with a plurality of swirl flow stabilizing baffles, and a labyrinth seal is provided at the lower end of the swirl flow stabilizing baffle. The swirl flow stabilizing baffle is made of rubber material so as to achieve radial deformation when under pressure. There is a gap between the conical swirl generator and the inner wall of the spiral-swirl separation tool housing, and the gap enables a large mass of mud and sand to enter the jet sand discharge device.

4. The downhole natural gas hydrate coupled separation and sand removal tool according to claim 3, characterized in that: The conical swirl generator includes a conical body and a cylindrical channel. A plurality of swirl stabilizing baffles are provided at the bottom of the conical body. The gap is formed between the outer diameter of the conical body and the housing of the spiral-swirl separation tool. The cylindrical channel is arranged on the central axis of the conical body.

5. The downhole natural gas hydrate coupled separation and sand removal tool according to claim 4, characterized in that: The jet sand removal device includes a sand removal nozzle, a first spring, a sand removal sleeve, a second spring and a spring cover plate. The sand removal nozzle is connected to the housing of the spiral-cyclone separation tool. The first spring is assembled at the lower end of the sand removal sleeve, the second spring is assembled at the upper end of the sand removal sleeve and is fixed in the sand removal nozzle through the spring cover plate to form a whole. The bottom end of the power fluid pipe is assembled at the pipeline sealing ring groove of the sand removal nozzle.

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