A system and method for jointly producing marine natural gas hydrate, shallow gas and deep gas

Abstract

The present invention discloses a combined production system for marine natural gas hydrates, shallow gas, and deep gas, which includes a sea surface support system, a seabed support system, a natural gas production system, and a hydrate production system; the seabed support system includes a seabed dual-well suction pile, production tubing, large-diameter drill pipes, and coiled tubing; the natural gas production system includes downhole monitor I, downhole throttle I, and intelligent completion sliding sleeve I; the hydrate production system includes weighted drill pipe I, axial flow pump, hydraulic drive motor, and pressure-controlled jet fragmentation tool. The present invention can realize the combined production or separate production of different resources such as natural gas hydrates, shallow gas, and deep gas through a single wellbore and single wellhead underwater, and parameters such as natural gas flow rate and pressure during production can be monitored and controlled in real time; the production of shallow gas or deep gas can be regulated to assist in lifting the hydrate slurry, solving the problems of difficult return of the hydrate slurry during the separate production of natural gas hydrates, low recovery rate, and formation leakage, improving the production efficiency, and reducing the production cost.

Description

Technical Field

[0001] The present invention relates to the field of deep - sea oil and gas resource exploitation equipment, and particularly to a system and method for co - producing marine natural gas hydrate, shallow gas and deep gas. Background Art

[0002] Natural gas hydrate, also known as combustible ice, is a new energy source with great development potential, characterized by wide distribution, large geological reserves, high energy density and low environmental pollution. The research on the exploitation of natural gas hydrate in China started relatively late. In 2011 and 2016, researchers first conducted two on - land combustible ice test productions in the permafrost area of Qilian Mountains, with gas production for nearly 5 days and 23 days respectively. In 2017, the first offshore test production was carried out in China, with stable production for 60 days and gas production of 309,000 cubic meters. In 2020, the second test production was completed in the same sea area, testing the drilling technology of horizontal wells in soft submarine sediment, achieving stable production for 30 days and gas production of 861,400 cubic meters. So far, China is the country with the largest cumulative gas production from test production of combustible ice in the world. Although a key step has been taken in the development of marine natural gas hydrate, there are still huge challenges in basic theoretical research, exploitation methods, equipment, operation models, etc. The 12th World Conference on Natural Gas Hydrate Research and Development and the 284th China Engineering Science and Technology Forum of the Chinese Academy of Engineering were held at Southwest Petroleum University in October 2018. Many world - top experts in the field of natural gas hydrate research pointed out that "the co - production of natural gas hydrate, shallow gas and conventional gas" may be an effective way for humans to realize the commercial exploitation and utilization of natural gas hydrate in the early stage.

[0003] However, there is currently no set of systems and methods that can achieve the co - production of natural gas hydrate, shallow gas and deep gas. Therefore, in order to realize the early commercial exploitation and utilization of natural gas hydrate, the invented system for co - producing marine natural gas hydrate, shallow gas and deep gas needs to meet the following requirements, functions and characteristics:

[0004] 1. Realize the co - exploitation of natural gas hydrate, shallow gas and deep gas in the same system, and establish a single wellbore that can exploit the three resources, reduce the number of equipment, lower the operation cost and increase the production of the single wellbore.

[0005] 2. Have the function of stratified exploitation of shallow gas and deep gas, and monitoring and regulating environmental condition parameters such as gas production flow rate and pressure during the exploitation process, that is, realize the individual exploitation of each resource while realizing the simultaneous exploitation of the three resources.

[0006] 3. Can regulate the production of shallow gas and deep gas, and use the high - pressure characteristics of shallow gas and deep gas itself to realize gas lift assisted drainage of natural gas hydrate by shallow gas and deep gas, improve the production volume and production efficiency, and prevent problems such as non - return and leakage of natural gas hydrate.

[0007] Therefore, it is necessary to invent an integrated production system and method for marine natural gas hydrate, shallow gas, and deep gas, so as to achieve the combined or independent production of natural gas hydrate, shallow gas, and deep gas in a single underwater wellbore, and to monitor and control parameters such as the flow rate and pressure of the gas produced from different horizons in the wellbore, improve the production efficiency of natural gas hydrate, and meet the production volume, benefits, and economic requirements of commercial production of natural gas hydrate. Summary of the Invention

[0008] The object of the present invention is to propose an integrated production system and method for marine natural gas hydrate, shallow gas, and deep gas to solve the problems of low production volume of natural gas hydrate in a single wellbore, low production efficiency and non-return of natural gas hydrate, and combined or separate production of natural gas hydrate, shallow gas, and deep gas. The present invention simultaneously produces natural gas hydrate, shallow gas, and deep gas through a subsea support system, a natural gas production system, and a hydrate production system to increase the production volume of a single system; the self-high-pressure gas sources of shallow gas and deep gas are used to lift and assist in discharging the crushed natural gas hydrate slurry to improve the production efficiency of natural gas hydrate; a downhole throttle is used to control the pressure and adjust the production during the natural gas production process, and a downhole monitor is used to monitor the natural gas state in real time, so as to control the adjustment of the downhole throttle to natural gas.

[0009] The object of the present invention is achieved through the following technical solutions: An integrated production system for marine natural gas hydrate, shallow gas, and deep gas, comprising:

[0010] A sea surface support system; the sea surface support system includes a sea surface drilling and production vessel, a control device, a high-pressure pump set, a coiled tubing rig, a drilling rig derrick, and a surface circulation treatment system provided on the sea surface drilling and production vessel;

[0011] A subsea support system; the subsea support system includes a large-diameter drill pipe, a coiled tubing, a subsea dual-well suction pile, and a production tubing. The head end of the large-diameter drill pipe is installed on the sea surface drilling and production vessel, and the tail end is installed on the subsea dual-well suction pile. The coiled tubing is installed inside the large-diameter drill pipe, with the head end connected to the high-pressure pump set and the tail end connected to the hydrate production system. The subsea dual-well suction pile is installed at the subsea dual production wellhead, and the production tubing is installed in the natural gas wellbore and connected to the subsea dual-well suction pile;

[0012] Natural gas production system; the natural gas production system includes downhole monitor I, downhole throttle I, packer I, intelligent completion sliding sleeve I, downhole detector II, downhole throttle II, packer II, intelligent completion sliding sleeve II. The downhole monitor I is installed on the production tubing in the upper part of the shallow gas layer. The downhole throttle I is installed on the production tubing below the downhole monitor I. The packer I is anchored below the downhole throttle I. The intelligent completion sliding sleeve I is installed below the packer I. The downhole detector II is installed on the production tubing in the upper part of the deep gas layer. The downhole throttle II is installed on the production tubing below the downhole detector II. The packer II is anchored below the downhole throttle II. The intelligent completion sliding sleeve II is installed below the packer II;

[0013] Hydrate production system; the hydrate production system includes a coiled tubing adapter, weighted drill pipe I, pressure and video detection sub I, axial flow pump, hydraulic drive motor, weighted drill pipe II, pressure and video detection sub II, pressure-controlled jet fragmentation tool, high-pressure jet combination nozzle, downhole motor, hydrate bit. The above devices are preferably connected in sequence;

[0014] The head end of the coiled tubing adapter is connected to the coiled tubing, and the tail end is connected to the weighted drill pipe I;

[0015] The head end of the weighted drill pipe I is connected to the tail end of the coiled tubing adapter, and the tail end is connected to the pressure and video detection sub I;

[0016] The head end of the pressure and video detection sub I is connected to the tail end of the weighted drill pipe I, and the tail end is connected to the axial flow pump;

[0017] The head end of the axial flow pump is connected to the tail end of the pressure and video detection sub I, and the tail end is connected to the hydraulic drive motor;

[0018] The head end of the hydraulic drive motor is connected to the tail end of the axial flow pump, and the tail end is connected to the weighted drill pipe II;

[0019] The head end of the weighted drill pipe II is connected to the tail end of the hydraulic drive motor, and the tail end is connected to the pressure and video detection sub II;

[0020] The head end of the pressure and video detection sub II is connected to the tail end of the weighted drill pipe II, and the tail end is connected to the pressure-controlled jet fragmentation tool;

[0021] The head end of the pressure-controlled jet fragmentation tool is connected to the tail end of the pressure and video detection sub II, and the tail end is connected to the downhole motor;

[0022] The head end of the downhole motor is connected to the tail end of the pressure-controlled jet fragmentation tool, and the tail end is connected to the hydrate bit;

[0023] The hydrate bit is installed at the tail end of the downhole motor, and a jetting channel is provided along its axial direction;

[0024] The high-pressure jet combination nozzle is radially installed on the pressure-controlled jet fragmentation tool, and the high-pressure jet combination nozzle connects the inside of the pressure-controlled jet fragmentation tool with the external space of the hydrate production system.

[0025] Furthermore, the ground circulation treatment system in the sea surface support system is connected to the annulus space between the large-diameter drill pipe and the coiled tubing.

[0026] Furthermore, the subsea dual-well suction pile is internally provided with a left channel and a right channel. The left and right channels are connected, and a one-way valve is provided at the connection. The fluid can only flow from the left channel to the right channel. The left channel is connected to the production tubing, and the right channel is connected to the hydrate wellhead. A channel switch is provided at the right channel to connect and seal the annulus space between the right channel and the coiled tubing. The products produced by the dual wells are all transported to the sea surface through the right channel in the subsea dual-well suction pile.

[0027] Furthermore, the fragmented hydrate slurry is lifted through the hydrate production system and enters the ground circulation treatment system for treatment and storage through the annulus space between the hydrate production system and the cavity, the annulus space between the coiled tubing and the cavity, the annulus space between the coiled tubing and the right channel of the subsea dual-well suction pile, and the annulus space between the coiled tubing and the large-diameter drill pipe.

[0028] Furthermore, the natural gas enters the production tubing through the intelligent completion sliding sleeve I and the intelligent completion sliding sleeve II, passes through the production tubing, enters the right channel of the subsea dual-well suction pile through the left channel of the subsea dual-well suction pile, lifts and aids in discharging the fragmented hydrate slurry and is transported to the ground circulation treatment system together with the hydrate slurry.

[0029] Furthermore, when the pressure-controlled jet fragmentation tool is in the initial position, the connection between the inside of the pressure-controlled jet fragmentation tool and the high-pressure jet combination nozzle is closed.

[0030] Furthermore, the intelligent completion sliding sleeve I and the intelligent completion sliding sleeve II can be controlled by the control device on the offshore drilling and production ship to maintain and cut off the connection between the production tubing and the natural gas wellbore. The sliding sleeves are in the closed state when initially installed.

[0031] The present invention also provides a method for using a marine natural gas hydrate, shallow gas, and deep gas combined production system, which includes the following steps:

[0032] SⅠ. Joint exploitation of multiple resources, specifically including the following steps:

[0033] S1. Install the marine natural gas hydrate, shallow gas, and deep gas combined production system

[0034] After the operators make preparations before installation, they install the subsea support system, the natural gas production system, and the hydrate production system, and lower the hydrate production system to the hydrate layer;

[0035] S2. Hydrate production

[0036] When the hydrate production system is lowered into the hydrate layer and the drilling fluid flow rate is increased, due to the increase in the drilling fluid flow rate, the pressure-controlled jet fragmentation tool moves to the right. The pressure-controlled jet fragmentation tool blocks the communication channel with the downhole motor, and at the same time connects the inside of the pressure-controlled jet fragmentation tool with the high-pressure jet combination nozzle. At this time, the drilling fluid no longer passes through the downhole motor and is ejected from the hydrate bit. The drilling fluid is ejected through the high-pressure jet combination nozzle and breaks the natural gas hydrate. The hydrate production system is pulled back. The drilling fluid breaks the natural gas hydrate from the high-pressure jet combination nozzle. Since the drilling fluid passes through the hydraulic drive motor in the hydrate production system, the hydraulic drive motor drives the axial flow pump to lift the broken hydrate. The broken hydrate is lifted by the axial flow pump and enters the ground circulation treatment system for treatment and storage along the annulus space between the hydrate production system and the cavity, the annulus space between the coiled tubing and the cavity, the annulus space between the coiled tubing and the right channel of the subsea dual wellhead suction pile, and the annulus space between the coiled tubing and the large-size drill pipe;

[0037] S3. Natural gas assisted drainage

[0038] When starting to produce hydrates, open the intelligent completion sliding sleeve I or the intelligent completion sliding sleeve II or both at the same time. Natural gas enters the production tubing, passes through the production tubing and the left channel of the subsea dual wellhead suction pile and enters the right channel of the subsea dual wellhead suction pile to be mixed with the broken hydrate, reducing the density of the broken hydrate slurry, thereby helping to lift the broken hydrate. During this process, the state of the natural gas can be monitored through the downhole monitor I or the downhole detector II, and the pressure and flow rate of the natural gas can be regulated by controlling the downhole choke I or the downhole choke II, so that the natural gas reaches the pressure and flow rate required for gas-lifting the hydrate slurry;

[0039] S4. Changing the azimuth for production

[0040] When the natural gas hydrate production in one azimuth is completed, reduce the drilling fluid flow rate. The pressure-controlled jet fragmentation tool returns to its initial position. Close all intelligent completion sliding sleeves. Recover the hydrate production system to the main wellhead. Adjust the azimuth and lower the hydrate production system into the hydrate layer;

[0041] S5. Pull-back excavation, repeat steps S2 - S4 to complete the production in the second azimuth;

[0042] S6. Repeat the above process of changing the azimuth and pull-back excavation to complete the production of hydrates in a 360° azimuth at this point. At this time, while completing the production of hydrates, shallow gas and deep gas at multiple points in the longitudinal and horizontal directions of the hydrate layer are produced, enabling the multi-resource joint production effect of the marine natural gas hydrate, shallow gas, and deep gas co-production system, and improving the hydrate lifting efficiency.

[0043] When the hydrate is not fully exploited but the shallow gas and deep gas sources are insufficient to perform gas lift on the hydrate slurry, the marine natural gas hydrate, shallow gas, and deep gas co-production system can perform:

[0044] SⅡ and single hydrate exploitation, specifically including the following steps:

[0045] S7. Lower the tool

[0046] After the operator installs the marine natural gas hydrate, shallow gas, and deep gas co-production system, lower the hydrate exploitation system to the hydrate layer;

[0047] S8. Hydrate exploitation

[0048] When the hydrate exploitation system is lowered to the hydrate layer, increase the drilling fluid flow rate. Due to the increase in the drilling fluid flow rate, the pressure-controlled jet fragmentation tool moves to the right, blocking the communication channel with the power drill, and at the same time connecting the inside of the pressure-controlled jet fragmentation tool with the high-pressure jet combination nozzle. At this time, the drilling fluid no longer passes through the power drill and sprays out from the hydrate bit. The drilling fluid is sprayed out through the high-pressure jet combination nozzle and breaks the natural gas hydrate. Pull back the hydrate exploitation system. The drilling fluid breaks the natural gas hydrate from the high-pressure jet combination nozzle. Since the drilling fluid passes through the hydraulic drive motor in the hydrate exploitation system, the hydraulic drive motor drives the axial flow pump to lift the fragmented hydrate. The fragmented hydrate is lifted by the axial flow pump and enters the ground circulation treatment system through the annulus space between the hydrate exploitation system and the cavity, the annulus space between the coiled tubing and the cavity, the annulus space between the coiled tubing and the right channel of the subsea dual wellhead suction pile, and the annulus space between the coiled tubing and the large-diameter drill pipe for treatment and storage;

[0049] S9. Change the azimuth for exploitation

[0050] When the exploitation of natural gas hydrate in one azimuth is completed, reduce the drilling fluid flow rate, the pressure-controlled jet fragmentation tool returns to the initial position, close all intelligent completion sliding sleeves, recover the hydrate exploitation system to the main wellhead, adjust the azimuth and lower the hydrate exploitation system to the hydrate layer;

[0051] S10. Pull-back excavation

[0052] Repeat steps S8 - S9 to complete the exploitation in the second azimuth;

[0053] S11. Repeat the above process of changing the azimuth and pull-back excavation to complete the exploitation of the hydrate in a 360° azimuth at this point.

[0054] When the hydrate exploitation is completed and there are still shallow gas and deep gas sources at multiple points, the marine natural gas hydrate, shallow gas, and deep gas co-production system can also complete the separate exploitation of shallow gas and deep gas, specifically including the following steps:

[0055] SⅢ. Single shallow gas production, specifically including the following steps:

[0056] S12. Close the channel switch

[0057] Close the channel switch at the right channel of the subsea dual wellhead suction pile, and seal the annulus space between the right channel and the coiled tubing;

[0058] S13. Open the intelligent completion sliding sleeve

[0059] Open the intelligent completion sliding sleeve Ⅰ, and the natural gas permeating in the natural gas wellbore enters the production tubing through the intelligent completion sliding sleeve Ⅰ;

[0060] S14. Shallow gas production

[0061] When the intelligent completion sliding sleeve Ⅰ is opened, the natural gas enters the production tubing, and then the natural gas migrates upward, passing through the packer Ⅰ, downhole throttle Ⅰ, downhole monitor Ⅰ, left channel to right channel of the subsea dual wellhead suction pile, and the annulus space between the large-diameter drill pipe and the coiled tubing to the ground circulation treatment system;

[0062] S15. Close the intelligent completion sliding sleeve

[0063] When the shallow gas production is completed, control the intelligent completion sliding sleeve Ⅰ to cut off the connection between the production tubing and the wellbore;

[0064] SⅢ. Deep gas production, specifically including the following steps:

[0065] S16. Close the channel switch

[0066] Close the channel switch at the right channel of the subsea dual wellhead suction pile, and seal the annulus space between the right channel and the coiled tubing;

[0067] S17. Open the intelligent completion sliding sleeve

[0068] When the deep gas production is ready, open the intelligent completion sliding sleeve Ⅱ, and the natural gas permeating in the natural gas wellbore enters the production tubing through the intelligent completion sliding sleeve Ⅱ;

[0069] S18. Deep gas production

[0070] When the intelligent completion sliding sleeve Ⅱ is opened, the natural gas enters the production tubing, and then the natural gas migrates upward, passing through the packer Ⅱ, downhole throttle Ⅱ, downhole detector Ⅱ, intelligent completion sliding sleeve Ⅰ, packer Ⅰ, downhole throttle Ⅰ, downhole monitor Ⅰ, left channel to right channel of the subsea dual wellhead suction pile, and the annulus space between the large-diameter drill pipe and the coiled tubing to the ground circulation treatment system;

[0071] S19. Close the intelligent completion sliding sleeve

[0072] After the deep gas extraction is completed, control the intelligent completion sliding sleeve II to cut off the connection between the production tubing and the wellbore. Beneficial effects

[0073] Due to the adoption of the above technical solutions, the beneficial effects achieved by the present invention are as follows:

[0074] (1) Through the subsea support system, natural gas extraction system, and hydrate extraction system, the present invention can realize the joint extraction of multiple resources such as shallow gas, deep gas, and natural gas hydrate in a single wellbore underwater, and the real-time monitoring and control of the joint extraction and separate extraction processes of different types of resources, effectively reducing the cost of natural gas hydrate extraction.

[0075] (2) The present invention utilizes the high-pressure natural gas sources in the shallow gas reservoir and deep gas reservoir to realize the assisted drainage and lifting of the natural gas hydrate slurry, rationally utilizes the self-energy of the fluids in the shallow gas reservoir and deep gas reservoir, improves the extraction efficiency of natural gas hydrate, and realizes energy conservation and consumption reduction in the entire extraction process.

[0076] (3) The present invention uses downhole throttles to regulate the production volume and pressure of the shallow and deep produced natural gas, and at the same time uses downhole monitors to monitor the state of the natural gas in the wellbore in real time, which can effectively prevent the formation of hydrates in the wellbore from causing blockage and affecting the entire extraction process, and effectively guarantees the safety of production operations. Description of the drawings

[0077] Figure 1 It is a schematic diagram of the joint extraction of shallow gas, deep gas, and natural gas hydrate of the present invention;

[0078] Figure 2 It is Figure 1 The partial enlarged view of I;

[0079] Figure 3 It is a schematic diagram of the all-round extraction of natural gas hydrate of the present invention;

[0080] Figure 4 It is a schematic diagram of the separate extraction of natural gas hydrate of the present invention;

[0081] Figure 5 It is a schematic diagram of the separate extraction of shallow gas of the present invention;

[0082] Figure 6 It is a schematic diagram of the separate extraction of deep gas of the present invention;

[0083] Figure 7 It is a flow chart of the joint extraction of shallow gas, deep gas, and natural gas hydrate of the present invention;

[0084] In the figure, 1 - offshore drilling and production vessel, 2 - control device, 3 - high-pressure pump unit, 4 - coiled tubing drilling rig, 5 - drilling rig derrick, 6 - surface circulation treatment system, 7 - large-diameter drill pipe, 8 - coiled tubing, 9 - subsea dual-well suction pile, 10 - production tubing, 11 - downhole monitor I, 12 - downhole choke I, 13 - packer I, 14 - intelligent completion sliding sleeve I, 15 - downhole detector II, 16 - downhole choke II, 17 - packer II, 18 - intelligent completion sliding sleeve II, 19 - coiled tubing adapter, 20 - weighted drill pipe I, 21 - pressure and video detection sub-section I, 22 - axial flow pump, 23 - hydraulic drive motor, 24 - weighted drill pipe II, 25 - pressure and video detection sub-section II, 26 - pressure-controlled jet fragmentation tool, 27 - high-pressure jet combination nozzle, 28 - power drill, 29 - hydrate bit, 30 - drilling fluid migration direction, 31 - migrated direction of fragmented natural gas hydrate, 32 - natural gas migration direction, 33 - seawater, 34 - sediment cover layer, 35 - hydrate layer, 36 - formation, 37 - shallow gas layer, 38 - deep gas layer. Detailed implementation mode

[0085] The following further describes the present invention in conjunction with the accompanying drawings. The protection scope of the present invention is not limited to the following description:

[0086] As Figure 1 — Figure 7 shown, a co-production system for marine natural gas hydrate, shallow gas, and deep gas includes:

[0087] A sea surface support system; the sea surface support system includes an offshore drilling and production vessel 1, a control device 2, a high-pressure pump unit 3, a coiled tubing drilling rig 4, a drilling rig derrick 5, and a surface circulation treatment system 6 provided on the offshore drilling and production vessel 1;

[0088] A subsea support system; the subsea support system includes a large-diameter drill pipe 7, a coiled tubing 8, a subsea dual-well suction pile 9, and a production tubing 10. The head end of the large-diameter drill pipe 7 is installed on the offshore drilling and production vessel 1, and the tail end is installed on the subsea dual-well suction pile 9. The coiled tubing 8 is installed inside the large-diameter drill pipe 7, with the head end connected to the high-pressure pump unit 3 and the tail end connected to the hydrate production system. The subsea dual-well suction pile 9 is installed at the subsea production wellhead, and the production tubing 10 is installed in the natural gas wellbore and connected to the subsea dual-well suction pile 9;

[0089] Natural gas production system; the natural gas production system includes downhole monitor I 11, downhole throttle I 12, packer I 13, intelligent completion sliding sleeve I 14, downhole detector II 15, downhole throttle II 16, packer II 17, and intelligent completion sliding sleeve II 18. The downhole monitor I 11 is installed on the production tubing 10 above the shallow gas layer 37. The downhole throttle I 12 is installed on the production tubing 10 below the downhole monitor I 11. The packer I 13 is anchored below the downhole throttle I 12. The intelligent completion sliding sleeve I 14 is installed below the packer I 13. The downhole detector II 15 is installed on the production tubing 10 above the deep gas layer 38. The downhole throttle II 16 is installed on the production tubing 10 below the downhole detector II 15. The packer II 17 is anchored below the downhole throttle II 16. The intelligent completion sliding sleeve II 18 is installed below the packer II 17;

[0090] Hydrate production system; the hydrate production system includes a coiled tubing adapter 19, weighted drill pipe I 20, pressure and video detection sub I 21, axial flow pump 22, hydraulic drive motor 23, weighted drill pipe II 24, pressure and video detection sub II 25, pressure-controlled jet fragmentation tool 26, high-pressure jet combination nozzle 27, downhole motor 28, and hydrate bit 29.

[0091] Further, the head end of the coiled tubing adapter 19 is connected to the coiled tubing 8, and the tail end is connected to the weighted drill pipe I 20;

[0092] The head end of the weighted drill pipe I 20 is connected to the tail end of the coiled tubing adapter 19, and the tail end is connected to the pressure and video detection sub I 21;

[0093] The head end of the pressure and video detection sub I 21 is connected to the tail end of the weighted drill pipe I 20, and the tail end is connected to the axial flow pump 22;

[0094] The head end of the axial flow pump 22 is connected to the tail end of the pressure and video detection sub I 21, and the tail end is connected to the hydraulic drive motor 23;

[0095] The head end of the hydraulic drive motor 23 is connected to the tail end of the axial flow pump 22, and the tail end is connected to the weighted drill pipe II 24;

[0096] The head end of the weighted drill pipe II 24 is connected to the tail end of the hydraulic drive motor 23, and the tail end is connected to the pressure and video detection sub II 25;

[0097] The head end of the pressure and video detection sub II 25 is connected to the tail end of the weighted drill pipe II 24, and the tail end is connected to the pressure-controlled jet fragmentation tool 26;

[0098] The head end of the pressure-controlled jet fragmentation tool 26 is connected to the tail end of the pressure and video detection sub II 25, and the tail end is connected to the downhole motor 28;

[0099] The first end of the downhole motor 28 is connected to the end of the pressure-controlled jet fragmentation tool 26, and the end is connected to the hydrate bit 29.

[0100] The hydrate bit 29 is installed at the end of the downhole motor 28, and a jetting channel is provided along its axial direction.

[0101] The high-pressure jet combination nozzle 27 is radially installed on the pressure-controlled jet fragmentation tool 26, and the high-pressure jet combination nozzle 27 connects the inside of the pressure-controlled jet fragmentation tool 26 with the external space of the hydrate production system.

[0102] Further, the ground circulation treatment system 6 in the sea surface support system is connected to the annulus space between the large-diameter drill pipe 7 and the coiled tubing 8.

[0103] Further, the subsea dual-well suction pile 9 is internally provided with a left channel 903 and a right channel 904. The left and right channels are connected, and a check valve 901 is provided at the connection. The fluid can only flow from the left channel 903 to the right channel 904. The left channel 903 is connected to the production tubing 10, and the right channel 904 is connected to the hydrate wellhead. A channel switch 902 is provided at the right channel 904 to connect and seal the annulus space between the right channel 904 and the coiled tubing 8. The products produced by the dual wells are all transported to the sea surface through the right channel 904 in the subsea dual-well suction pile 9.

[0104] Further, the fragmented hydrate slurry is lifted by the hydrate production system and enters the ground circulation treatment system 6 for treatment and storage through the annulus space between the hydrate production system and the cavity, the annulus space between the coiled tubing 8 and the cavity, the annulus space between the coiled tubing 8 and the right channel 904 of the subsea dual-well suction pile 9, and the annulus space between the coiled tubing 8 and the large-diameter drill pipe 7.

[0105] Further, the natural gas enters the production tubing 10 through the intelligent completion sliding sleeve I 14 and the intelligent completion sliding sleeve II 18, passes through the production tubing 10, enters the right channel 904 of the subsea dual-well suction pile 9 through the left channel 903 of the subsea dual-well suction pile 9, lifts and assists in discharging the fragmented hydrate slurry and is transported to the ground circulation treatment system 6 together with the hydrate slurry.

[0106] Further, when the pressure-controlled jet fragmentation tool 26 is in the initial position, the connection between the inside of the pressure-controlled jet fragmentation tool 26 and the high-pressure jet combination nozzle 27 is closed.

[0107] Further, the intelligent completion sliding sleeve I 14 and the intelligent completion sliding sleeve II 18 can be controlled by the control device 2 on the offshore drilling and production ship 1 to maintain and cut off the connection between the production tubing 10 and the natural gas wellbore. The sliding sleeves are in the closed state when initially installed.

[0108] The present invention also provides a method for using a combined production system for marine natural gas hydrates, shallow gas, and deep gas, which includes the following steps:

[0109] SⅠ. Combined exploitation of multiple resources, specifically including the following steps:

[0110] S1. Install the combined production system for marine natural gas hydrates, shallow gas, and deep gas

[0111] After the operators complete the preparations before installation, install the subsea support system, natural gas production system, and hydrate production system, and lower the hydrate production system to the hydrate layer 35;

[0112] S2. Hydrate production

[0113] When the hydrate production system is lowered to the hydrate layer 35, increase the drilling fluid flow rate. Due to the increase in the drilling fluid flow rate, the pressure-controlled jet breaking tool 26 moves to the right. The pressure-controlled jet breaking tool 26 blocks the communication channel with the downhole motor 28, and at the same time connects the inside of the pressure-controlled jet breaking tool 26 with the high-pressure jet combination nozzle 27. At this time, the drilling fluid no longer sprays out from the hydrate bit 29 through the downhole motor 28. The drilling fluid is ejected through the high-pressure jet combination nozzle 27 and breaks the natural gas hydrate. Pull back the hydrate production system. The drilling fluid breaks the natural gas hydrate from the high-pressure jet combination nozzle 27. Since the drilling fluid passes through the hydraulic drive motor 23 in the hydrate production system, the hydraulic drive motor 23 drives the axial flow pump 22 to lift the broken hydrate. The broken hydrate is lifted by the axial flow pump 22 and enters the ground circulation treatment system 6 for treatment and storage along the annulus space between the hydrate production system and the cavity, the annulus space between the coiled tubing 8 and the cavity, the annulus space between the coiled tubing 8 and the right channel 904 of the subsea dual wellhead suction pile 9, and the annulus space between the coiled tubing 8 and the large-size drill pipe 7;

[0114] S3. Natural gas assisted drainage

[0115] When starting to produce hydrates, open the intelligent completion sliding sleeve Ⅰ 14 or the intelligent completion sliding sleeve Ⅱ 18 or both at the same time. Natural gas enters the production tubing 10, passes through the production tubing 10 and the left channel 903 of the subsea dual wellhead suction pile 9, and enters the right channel 904 of the subsea dual wellhead suction pile 9 to be mixed with the broken hydrate, reducing the density of the broken hydrate slurry, thereby helping to lift the broken hydrate. During this process, the state of the natural gas can be monitored through the downhole monitor Ⅰ 11 or the downhole detector Ⅱ 15, and the pressure and flow rate of the natural gas can be regulated by controlling the downhole throttle Ⅰ 12 or the downhole throttle Ⅱ 16, so that the natural gas reaches the pressure and flow rate required for gas-lifting the hydrate slurry;

[0116] S4. Production in a different direction

[0117] After the natural gas hydrate in one azimuth is mined out, reduce the flow rate of the drilling fluid. The pressure-controlled jet fragmentation tool 26 returns to its initial position, close all intelligent completion sleeves, recover the hydrate mining system to the main wellhead, adjust the azimuth and lower the hydrate mining system to the hydrate layer 35;

[0118] S5. Drag and extract

[0119] Repeat steps S2 - S4 to complete the mining in the second azimuth;

[0120] S6. Repeat the above processes of changing azimuth and drag and extract to complete the mining of natural gas hydrates in a 360° azimuth at this point. At this time, while completing the mining of natural gas hydrates, shallow gas and deep gas at multiple points in the vertical and horizontal directions of the hydrate layer are mined, enabling the multi-resource combined mining system of marine natural gas hydrates, shallow gas, and deep gas to achieve the effect of multi-resource combined mining and improving the lifting efficiency of hydrates.

[0121] When the natural gas hydrate is not completely mined but the gas sources of shallow gas and deep gas are insufficient and not enough to conduct gas lift on the hydrate slurry, the multi-resource combined mining system of marine natural gas hydrates, shallow gas, and deep gas:

[0122] SⅡ. Single hydrate mining, specifically including the following steps:

[0123] S7. Lower the tool

[0124] After the operator installs the multi-resource combined mining system of marine natural gas hydrates, shallow gas, and deep gas, lower the hydrate mining system to the hydrate layer 35;

[0125] S8. Hydrate mining

[0126] When the hydrate mining system is lowered to the hydrate layer 35, increase the flow rate of the drilling fluid. Due to the increase in the flow rate of the drilling fluid, the pressure-controlled jet fragmentation tool 26 moves to the right. The pressure-controlled jet fragmentation tool 26 blocks the communication channel with the downhole motor 28, and at the same time connects the inside of the pressure-controlled jet fragmentation tool 26 with the high-pressure jet combination nozzle 27. At this time, the drilling fluid no longer passes through the downhole motor 28 and sprays out from the hydrate bit 29. The drilling fluid is sprayed out through the high-pressure jet combination nozzle 27 and fragments the natural gas hydrate. Drag the hydrate mining system back. The drilling fluid fragments the natural gas hydrate from the high-pressure jet combination nozzle 27. Since the drilling fluid passes through the hydraulic drive motor 23 in the hydrate mining system, the hydraulic drive motor 23 drives the axial flow pump 22 to lift the fragmented hydrate. The fragmented hydrate is lifted by the axial flow pump 22 and enters the ground circulation treatment system 6 for treatment and storage along the annulus space between the hydrate mining system and the cavity, the annulus space between the coiled tubing 8 and the cavity, the annulus space of the right channel 904 between the coiled tubing 8 and the subsea dual-wellhead suction pile 9, and the annulus space between the coiled tubing 8 and the large-diameter drill pipe 7;

[0127] S9. Mining in a different azimuth

[0128] After the natural gas hydrate in one azimuth is mined out, reduce the flow rate of the drilling fluid. The pressure-controlled jet fragmentation tool 26 returns to the initial position, close all intelligent completion sliding sleeves, recover the hydrate production system to the main wellhead, adjust the azimuth and lower the hydrate production system to the hydrate layer 35;

[0129] S10. Pull-back and excavation

[0130] Repeat steps S8 - S9 to complete the mining in the second azimuth;

[0131] S11. Repeat the above process of changing azimuth and pulling-back and excavation to complete the mining of the hydrate in 360° azimuth at this point.

[0132] When the hydrate mining is completed and there are shallow gas and deep gas sources at multiple points, this marine natural gas hydrate, shallow gas, and deep gas combined production system can also complete the separate production of shallow gas and deep gas, specifically including the following steps:

[0133] SⅢ. Separate shallow gas production, specifically including the following steps:

[0134] S12. Close the channel switch

[0135] Close the channel switch 902 at the right channel 904 of the subsea double-wellhead suction pile 9 to seal the annulus space between the right channel 904 and the coiled tubing 8;

[0136] S13. Open the intelligent completion sliding sleeve

[0137] Open the intelligent completion sliding sleeve Ⅰ14, and the natural gas permeating in the natural gas wellbore enters the production tubing 10 through the intelligent completion sliding sleeve Ⅰ14;

[0138] S14. Shallow gas production

[0139] When the intelligent completion sliding sleeve Ⅰ14 is opened and the natural gas enters the production tubing 10, then the natural gas migrates upward, passing through the packer Ⅰ13, downhole choke Ⅰ12, downhole monitor Ⅰ11, left channel 903 of the subsea double-wellhead suction pile 9 to the right channel 904, and the annulus space between the large-diameter drill pipe 7 and the coiled tubing 8 to the surface circulation treatment system 6;

[0140] S15. Close the intelligent completion sliding sleeve

[0141] When the shallow gas production is completed, control the intelligent completion sliding sleeve Ⅰ14 to cut off the connection between the production tubing 10 and the wellbore;

[0142] SⅣ. Deep gas production, specifically including the following steps:

[0143] S16. Close the channel switch

[0144] Close the channel switch 902 at the right channel 904 of the subsea dual-wellhead suction pile 9 to seal the annulus space between the right channel 904 and the coiled tubing 8;

[0145] S17. Open the intelligent completion sliding sleeve

[0146] When the deep gas production is ready, open the intelligent completion sliding sleeve II 18, and the natural gas permeating in the natural gas wellbore enters the production tubing 10 through the intelligent completion sliding sleeve II 18;

[0147] S18. Deep gas production

[0148] When the intelligent completion sliding sleeve II 18 is opened, the natural gas enters the production tubing 10, and then the natural gas migrates upward, passing through the packer II 17, downhole throttle II 16, downhole detector II 15, intelligent completion sliding sleeve I 14, packer I 13, downhole throttle I 12, downhole monitor I 11, the left channel 903 to the right channel 904 of the subsea dual-wellhead suction pile 9, and the annulus space between the large-diameter drill pipe 7 and the coiled tubing 8 to the ground circulation treatment system 6;

[0149] S19. Close the intelligent completion sliding sleeve

[0150] When the deep gas production is completed, control the intelligent completion sliding sleeve II 18 to cut off the connection between the production tubing 10 and the wellbore;

[0151] Obviously, the above embodiments are only examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A combined production system for marine natural gas hydrate, shallow gas and deep gas, characterized in that: It includes a sea surface support system, a seabed support system, a natural gas production system, and a hydrate production system; The sea surface support system includes a sea surface drilling and production vessel (1), a control device (2), a high-pressure pump set (3), a coiled tubing drilling rig (4), a drilling rig derrick (5), and a surface circulation treatment system (6) arranged on the sea surface drilling and production vessel (1); The seabed support system includes a large-diameter drill pipe (7), a coiled tubing (8), a seabed dual-well suction pile (9), and a production tubing (10). The head end of the large-diameter drill pipe (7) is installed on the sea surface drilling and production vessel (1), and the tail end is installed on the seabed dual-well suction pile (9). The coiled tubing (8) is installed inside the large-diameter drill pipe (7), with the head end connected to the high-pressure pump set (3) and the tail end connected to the hydrate production system. The seabed dual-well suction pile (9) is installed at the seabed dual-production wellhead, and the production tubing (10) is installed in the natural gas wellbore and connected to the seabed dual-well suction pile (9); The natural gas production system includes a downhole monitor I (11), a downhole throttle I (12), a packer I (13), an intelligent completion sliding sleeve I (14), a downhole detector II (15), a downhole throttle II (16), a packer II (17), and an intelligent completion sliding sleeve II (18). The downhole monitor I (11) is installed on the production tubing (10) above the shallow gas layer (37). The downhole throttle I (12) is installed on the production tubing (10) below the downhole monitor I (11). The packer I (13) is anchored below the downhole throttle I (12). The intelligent completion sliding sleeve I (14) is installed below the packer I (13). The downhole detector II (15) is installed on the production tubing (10) above the deep gas layer (38). The downhole throttle II (16) is installed on the production tubing (10) below the downhole detector II (15). The packer II (17) is anchored below the downhole throttle II (16). The intelligent completion sliding sleeve II (18) is installed below the packer II (17).The hydrate production system includes a coiled tubing adapter (19), a weighted drill pipe I (20), a pressure and video detection sub I (21), an axial flow pump (22), a hydraulic drive motor (23), a weighted drill pipe II (24), a pressure and video detection sub II (25), a pressure-controlled jet fragmentation tool (26), a high-pressure jet combination nozzle (27), a downhole motor (28), and a hydrate bit (29). The head end of the coiled tubing adapter (19) is connected to the coiled tubing (8), and the tail end is connected to the weighted drill pipe I (20). The head end of the weighted drill pipe I (20) is connected to the tail end of the coiled tubing adapter (19), and the tail end is connected to the pressure and video detection sub I (21). The head end of the pressure and video detection sub I (21) is connected to the tail end of the weighted drill pipe I (20), and the tail end is connected to the axial flow pump (22). The head end of the axial flow pump (22) is connected to the tail end of the pressure and video detection sub I (21), and the tail end is connected to the hydraulic drive motor (23). The head end of the hydraulic drive motor (23) is connected to the tail end of the axial flow pump (22), and the tail end is connected to the weighted drill pipe II (24). The head end of the weighted drill pipe II (24) is connected to the tail end of the hydraulic drive motor (23), and the tail end is connected to the pressure and video detection sub II (25). The head end of the pressure and video detection sub II (25) is connected to the tail end of the weighted drill pipe II (24), and the tail end is connected to the pressure-controlled jet fragmentation tool (26). The head end of the pressure-controlled jet fragmentation tool (26) is connected to the tail end of the pressure and video detection sub II (25), and the tail end is connected to the downhole motor (28). The head end of the downhole motor (28) is connected to the tail end of the pressure-controlled jet fragmentation tool (26), and the tail end is connected to the hydrate bit (29). The hydrate bit (29) is installed at the tail end of the downhole motor (28), and a jetting channel is provided along its axial direction. The high-pressure jet combination nozzle (27) is radially installed on the pressure-controlled jet fragmentation tool (26), and the high-pressure jet combination nozzle (27) connects the inside of the pressure-controlled jet fragmentation tool (26) to the external space of the hydrate production system.

2. The combined production system for marine natural gas hydrate, shallow gas and deep gas according to claim 1, wherein, The surface circulation treatment system (6) in the sea surface support system is communicated with the annulus space between the large-diameter drill pipe (7) and the coiled tubing (8).

3. The combined production system for marine natural gas hydrate, shallow gas and deep gas according to claim 1, characterized in that The seabed dual-well suction pile (9) is internally provided with a left channel (903) and a right channel (904). The left and right channels are communicated, and a check valve (901) is provided at the communication part. The fluid can only flow from the left channel (903) to the right channel (904). The left channel (903) is connected to the production tubing (10), and the right channel (904) is connected to the hydrate wellhead. A channel switch (902) is provided at the right channel (904) to connect and seal the annulus space between the right channel (904) and the coiled tubing (8). The products produced by the dual wells are all transported to the sea surface through the right channel (904) inside the seabed dual-well suction pile (9).

4. A combined production system for marine natural gas hydrates, shallow gas, and deep gas according to claim 1, characterized in that, The broken hydrate slurry is lifted through the hydrate production system and enters the surface circulation treatment system (6) for treatment and storage through the annulus space between the hydrate production system and the cavity, the annulus space between the coiled tubing (8) and the cavity, the annulus space between the coiled tubing (8) and the right channel (904) of the seabed dual-well suction pile (9), and the annulus space between the coiled tubing (8) and the large-diameter drill pipe (7).

5. The combined production system for marine natural gas hydrates, shallow gas, and deep gas according to claim 1, characterized in that, The natural gas enters the production tubing (10) through the intelligent completion sliding sleeve I (14) and the intelligent completion sliding sleeve II (18), passes through the production tubing (10), enters the right channel (904) of the seabed dual-well suction pile (9) through the left channel (903) of the seabed dual-well suction pile (9), lifts and assists in discharging the broken hydrate slurry and is transported to the surface circulation treatment system (6) together with the hydrate slurry.

6. The co-production system for marine natural gas hydrates, shallow gas, and deep gas according to claim 1, wherein When the pressure-controlled jet fragmentation tool (26) is in the initial position, the communication between the inside of the pressure-controlled jet fragmentation tool (26) and the high-pressure jet combination nozzle (27) is closed.

7. The combined production system for marine natural gas hydrate, shallow gas and deep gas according to claim 1, characterized in that, The intelligent completion sliding sleeve I (14) and the intelligent completion sliding sleeve II (18) can be controlled by the control device (2) on the sea surface drilling and production vessel (1) to maintain and cut off the communication between the production tubing (10) and the natural gas wellbore. The intelligent completion sliding sleeve I (14) and the intelligent completion sliding sleeve II (18) are in the closed state when initially installed.

8. A method for using the marine natural gas hydrate, shallow gas, and deep gas combined production system according to any one of claims 1 to 7, characterized in that: It includes the following steps: SⅠ. Joint exploitation of multiple resources, specifically including the following steps: Sa. Install the combined exploitation system. After the operators complete the preparations before installation, install the subsea support system, natural gas exploitation system, and hydrate exploitation system, and lower the hydrate exploitation system to the hydrate layer (35); Sb. Hydrate exploitation. When the hydrate exploitation system is lowered to the hydrate layer (35), increase the drilling fluid flow rate. Due to the increase in the drilling fluid flow rate, the pressure-controlled jet fragmentation tool (26) moves to the right. The pressure-controlled jet fragmentation tool (26) blocks the communication channel with the downhole motor (28), and at the same time connects the inside of the pressure-controlled jet fragmentation tool (26) with the high-pressure jet combination nozzle (27). At this time, the drilling fluid no longer passes through the downhole motor (28) and sprays out from the hydrate bit (29). The drilling fluid is ejected through the high-pressure jet combination nozzle (27) and breaks the natural gas hydrate. Pull back the hydrate exploitation system. The drilling fluid breaks the natural gas hydrate from the high-pressure jet combination nozzle (27). Since the drilling fluid passes through the hydraulic drive motor (23) in the hydrate exploitation system, the hydraulic drive motor (23) drives the axial flow pump (22) to lift the broken hydrate. The broken hydrate is lifted by the axial flow pump (22) and enters the surface circulation treatment system (6) for treatment and storage along the annulus space between the hydrate exploitation system and the cavity, the annulus space between the coiled tubing (8) and the cavity, the annulus space between the coiled tubing (8) and the right channel (904) of the subsea dual wellhead suction pile (9), and the annulus space between the coiled tubing (8) and the large-diameter drill pipe (7); Sc. Natural gas assisted drainage. When starting to exploit the hydrate, open the intelligent completion sliding sleeve I (14) or the intelligent completion sliding sleeve II (18) or both at the same time. Natural gas enters the production tubing (10), passes through the production tubing (10) and the left channel (903) of the subsea dual wellhead suction pile (9) and enters the right channel (904) of the subsea dual wellhead suction pile (9) to be mixed with the broken hydrate, reducing the density of the broken hydrate slurry, thereby helping to lift the broken hydrate. During this process, the state of the natural gas can be monitored through the downhole monitor I (11) or the downhole detector II (15), and the pressure and flow rate of the natural gas can be regulated by controlling the downhole throttle valve I (12) or the downhole throttle valve II (16) so that the natural gas reaches the pressure and flow rate required for gas-lifting the hydrate slurry; Sd. Change the azimuth for exploitation. When the natural gas hydrate in one azimuth is exploited, reduce the drilling fluid flow rate. The pressure-controlled jet fragmentation tool (26) returns to the initial position. Close all intelligent completion sliding sleeves. Recover the hydrate exploitation system to the main wellhead. Adjust the azimuth and lower the hydrate exploitation system to the hydrate layer (35); Se. Pull back and excavate. Repeat steps Sb - Sd to complete the exploitation in the second azimuth; Sf. Repeat the above processes of changing the mining direction and dragging and mining, and complete the mining of hydrates in all 360° directions at this point. At this time, while completing the mining of hydrates, shallow gas and deep gas at multiple points in the vertical and horizontal directions of the hydrate layer are mined, enabling the multi-resource combined mining system for marine natural gas hydrates, shallow gas, and deep gas to achieve the effect of combined mining of multiple resources, and improving the lifting efficiency of hydrates; When the hydrates are not fully mined but the gas sources of shallow gas and deep gas are insufficient and not enough to conduct gas lift on the hydrate slurry, the multi-resource combined mining system for marine natural gas hydrates, shallow gas, and deep gas can perform the following: SⅡ. Single hydrate mining, which specifically includes the following steps: Sg. Lower the tool. After the operator installs the combined mining system, lower the hydrate mining system to the hydrate layer (35); Sh. Hydrate mining. When the hydrate mining system is lowered to the hydrate layer (35), increase the drilling fluid flow rate. Due to the increase in the drilling fluid flow rate, the pressure-controlled jet breaking tool (26) moves to the right, blocking the communication channel with the downhole motor (28), and at the same time connecting the inside of the pressure-controlled jet breaking tool (26) with the high-pressure jet combination nozzle (27). At this time, the drilling fluid no longer passes through the downhole motor (28) and sprays out from the hydrate bit (29). Instead, the drilling fluid is sprayed out through the high-pressure jet combination nozzle (27) to break the natural gas hydrates, and then drag the hydrate mining system back. The drilling fluid breaks the natural gas hydrates through the high-pressure jet combination nozzle (27). Since the drilling fluid passes through the hydraulic drive motor (23) in the hydrate mining system, the hydraulic drive motor (23) drives the axial flow pump (22) to lift the broken hydrates. The broken hydrates are lifted by the axial flow pump (22) and enter the surface circulation treatment system (6) for treatment and storage along the annulus between the hydrate mining system and the cavity, the annulus between the coiled tubing (8) and the cavity, the annulus between the coiled tubing (8) and the right channel (904) of the subsea dual-well suction pile (9), and the annulus between the coiled tubing (8) and the large-diameter drill pipe (7); Si. Change the mining direction. After the natural gas hydrates in one direction are fully mined, reduce the drilling fluid flow rate. The pressure-controlled jet breaking tool (26) returns to its initial position, close all intelligent completion sliding sleeves, recover the hydrate mining system to the main wellhead, adjust the direction, and lower the hydrate mining system to the hydrate layer (35); Sj. Drag and mine. Repeat steps Sh - Si to complete the mining in the second direction; Sk. Repeat the above processes of changing the mining direction and dragging and mining, and complete the mining of hydrates in all 360° directions at this point; When the hydrate mining is completed and there are still gas sources of shallow gas and deep gas at multiple points, the multi-resource combined mining system for marine natural gas hydrates, shallow gas, and deep gas can also complete the separate mining of shallow gas and deep gas, which specifically includes the following steps: SⅢ. Single shallow gas mining, which specifically includes the following steps: Sl. Close the channel switch. Close the channel switch (902) at the right channel (904) of the subsea dual-well suction pile (9) to seal the annulus between the right channel (904) and the coiled tubing (8); Sm. Open the intelligent completion sliding sleeve I (14), and the natural gas permeating in the natural gas wellbore enters the production tubing (10) through the intelligent completion sliding sleeve I (14). Sn. Shallow gas production. When the intelligent completion sliding sleeve I (14) is opened, the natural gas enters the production tubing (10). Subsequently, the natural gas migrates upward, passing through the packer I (13), downhole throttle I (12), downhole monitor I (11), the left channel (903) to the right channel (904) of the subsea dual-wellhead suction pile (9), the annulus space between the large-diameter drill pipe (7) and the coiled tubing (8) to the surface circulation treatment system (6). So. When the shallow gas production is completed, control the intelligent completion sliding sleeve I (14) to cut off the connection between the production tubing (10) and the wellbore. SⅣ. Deep gas production, specifically including the following steps: Sp. Close the channel switch. Close the channel switch (902) at the right channel (904) of the subsea dual-wellhead suction pile (9) to seal the annulus space between the right channel (904) and the coiled tubing (8). Sq. When the deep gas production is ready, open the intelligent completion sliding sleeve II (18), and the natural gas permeating in the natural gas wellbore enters the production tubing (10) through the intelligent completion sliding sleeve II (18). Sr. Deep gas production. When the intelligent completion sliding sleeve II (18) is opened, the natural gas enters the production tubing (10). Subsequently, the natural gas migrates upward, passing through the packer II (17), downhole throttle II (16), downhole detector II (15), intelligent completion sliding sleeve I (14), packer I (13), downhole throttle I (12), downhole monitor I (11), the left channel (903) to the right channel (904) of the subsea dual-wellhead suction pile (9), the annulus space between the large-diameter drill pipe (7) and the coiled tubing (8) to the surface circulation treatment system (6). Ss. When the deep gas production is completed, control the intelligent completion sliding sleeve II (18) to cut off the connection between the production tubing (10) and the wellbore.

Images