Integrated system and method for deep-sea natural gas hydrate exploitation and carbon dioxide storage

Abstract

The present invention discloses an integrated system for deep-sea natural gas hydrate exploitation and carbon dioxide storage, which includes an ocean platform injection and production master control system, an underwater pipe collection and transportation and wellhead system, a formation drilling and injection system, and a real-time monitoring system for seabed leakage. The formation drilling and injection system includes an all-round whipstock, a double-layer expansion packer, a replaceable core double-nozzle jet pump, a jet cavity fracturing and injection multifunctional tool, and a hydrate drill bit. The present invention realizes the exploitation of deep-sea natural gas hydrates by combining multiple methods such as solid fluidization method, depressurization method, and displacement method, effectively utilizing the advantages of each method and improving the exploitation efficiency and output; supercritical carbon dioxide fracturing is used to increase the contact area between carbon dioxide and hydrate ore body, and improve the efficiency and safety of exploitation and carbon fixation; carbon dioxide is fixed in the form of hydrate, which has higher stability; at the same time, real-time monitoring of the exploitation and carbon fixation areas is realized, effectively improving the safety of operations.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas hydrate exploitation and carbon dioxide storage, and in particular to a deep-sea natural gas hydrate exploitation and carbon dioxide storage integrated system and method. Background Art

[0002] Natural gas hydrate is one of the unconventional natural gas resources with the greatest potential that has not yet been developed. Compared with traditional oil and gas reservoirs, safe and efficient development is a huge challenge. Nowadays, the exploitation of natural gas hydrate resources is mainly achieved by breaking the phase equilibrium of natural gas hydrates. Based on this principle, the main technical methods for the development of natural gas hydrates that have been proposed are: pressure reduction method, thermal shock method, chemical potential difference drive method (including injection and carbon dioxide replacement, etc.); in addition, scholars have also proposed a solid fluidization mining method based on the characteristics of natural gas hydrates in my country's marine environment, such as weak cementation and no dense caprock.

[0003] Deep-sea carbon dioxide hydrate carbon sequestration technology refers to the technology of storing carbon dioxide in the deep sea in the form of solid hydrates. This technology usually involves injecting carbon dioxide into seabed sediments to form stable solid hydrates under specific temperature and pressure conditions, thereby achieving long-term carbon sequestration. The principle of deep-sea carbon dioxide hydrate carbon sequestration technology is similar to the formation mechanism of natural gas hydrates. In the deep-sea environment, gases such as methane can combine with water molecules to form hydrates. This process is called hydration. Similarly, carbon dioxide can also form hydrates with water molecules under specific conditions. These hydrates are relatively stable in the deep-sea environment and can store carbon dioxide for a long time.

[0004] At present, various methods of natural gas hydrate extraction are still in the research stage, and only five countries in the world have conducted trial extraction of natural gas hydrates, which is still a long way from commercial extraction. Although some progress has been made in the research and development of deep-sea carbon dioxide hydrate carbon fixation technology, countries are still in the research stage of deep-sea carbon dioxide hydrate carbon fixation technology and lack relevant experience. In the implementation of specific projects, they still face a series of challenges, including technical difficulties and economic costs. In short, natural gas extraction and deep-sea carbon dioxide hydrate carbon fixation technology methods have their own shortcomings, and there are many problems that need to be solved urgently, as follows:

[0005] (1) The current single method of natural gas hydrate extraction has some problems, resulting in low efficiency, high cost, and short gas production cycle, which is difficult to meet the requirements of large-scale and commercial extraction. For example, the extraction of natural gas hydrate by carbon dioxide displacement has a long displacement time, a small displacement contact area, and low efficiency; the extraction of natural gas hydrate by pressure reduction method, because the decomposition of natural gas hydrate absorbs heat, natural gas hydrate will be regenerated or cause formation water to freeze, resulting in a decrease in the permeability of the natural gas hydrate reservoir, and the pressure drop propagates slowly in the formation, affecting the decomposition and gas production rate of natural gas hydrate; the single output in the process of solid fluidization extraction of natural gas hydrate is small and the economic benefits are low.

[0006] (2) During the gas hydrate exploitation process, the decomposition and extraction of hydrates will reduce the strength of the gas hydrate reservoir, increasing the risk of reservoir instability during the gas hydrate exploitation process. In addition, the decomposition and extraction of gas hydrates will also cause changes in the mechanical properties of the formation, leading to well wall instability, formation collapse, submarine landslides, and even tsunamis and other engineering and geological problems.

[0007] (3) The cost of deep-sea carbon dioxide hydrate fixation mainly comes from the construction and maintenance of dedicated facilities. In addition, site selection, drilling, injection and storage also require a large amount of capital investment. According to relevant research, the cost of these engineering practices is so high that it is difficult to achieve commercialization in the short term.

[0008] (4) After carbon sequestration, deep-sea carbon dioxide hydrates face the problem of carbon dioxide leakage. Carbon dioxide leakage may cause ocean acidification and ecosystem damage, reduce the effect of carbon sequestration, and may pose a threat to human health and marine resources.

[0009] Therefore, it is necessary to invent an integrated system and method for deep-sea natural gas hydrate exploitation and carbon dioxide storage, which can combine the existing various natural gas hydrate exploitation methods to improve the efficiency and output of natural gas hydrate exploitation; increase the contact area between carbon dioxide and natural gas hydrate and the carbon dioxide storage space, increase the structural strength of the natural gas hydrate reservoir, and improve the safety of the exploitation process; prevent seabed geological disasters caused by natural gas hydrate exploitation; improve the durability and safety of carbon dioxide storage, and reduce the engineering practice cost of carbon storage. Summary of the invention

[0010] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an integrated system and method for deep-sea natural gas hydrate exploitation and carbon dioxide storage, which realizes the exploitation of deep-sea natural gas hydrates by combining multiple methods such as solid fluidization method, pressure reduction method, replacement method, etc., effectively utilizes the advantages of each method, and improves the exploitation efficiency and output; adopts supercritical carbon dioxide jet cavity making and fracturing, increases the contact area between carbon dioxide and hydrate ore body, improves the efficiency and safety of exploitation and carbon fixation; realizes carbon fixation in the form of carbon dioxide hydrate, which has higher stability; realizes real-time monitoring of exploitation and carbon fixation areas, and effectively improves the safety of operations.

[0011] The object of the present invention is achieved through the following technical solutions: a deep-sea natural gas hydrate exploitation and carbon dioxide storage integrated system, characterized in that it includes an offshore platform injection and production master control system, an underwater pipe string gathering and transportation and wellhead system, a formation drilling and injection system, and a seabed leakage real-time monitoring system;

[0012] The offshore platform injection and production master control system includes a floating injection and production platform floating on the sea surface, an injection and production operation control terminal arranged on the floating injection and production platform, an injection and production high-pressure pump group, a hydrate pretreatment and storage device, a double-layer pipe complete operation device, a multifunctional derrick, a double-layer pipe injection head, a high-pressure carbon dioxide compressor group, and a carbon dioxide treatment and storage device;

[0013] The underwater pipe string gathering and wellhead system includes a double-layer pipe, a watertight pipe, a subsea blowout preventer group, and an open-hole packer installed on the mud cap layer. The head end of the watertight pipe is installed on the floating injection and production platform, and the tail end is installed on the subsea blowout preventer group. The subsea blowout preventer group is installed on the seabed wellhead. The double-layer pipe is installed in the watertight pipe, and the head end is installed on the double-layer pipe complete set of operating devices. The inner layer channel is connected to the hydrate pretreatment and storage device, the outer layer channel is connected to the injection and production high-pressure pump group, and the tail end is connected to the formation drilling and injection system. The open-hole packer is anchored on the casing under the subsea blowout preventer group.

[0014] The formation drilling and injection system is composed of a double-layer pipe adapter, an all-round whipstock, a double-layer pipe safety joint, a double-layer pipe hydraulic anchor, a double-layer expansion packer, a downhole temperature and pressure and visual monitoring short section, a replaceable core double-nozzle jet pump, a jet cavity fracturing and injection multifunctional tool, a horizontal well downhole tractor, a bent screw power drill, a near-drill bit geological steering tool, and a hydrate drill bit connection. The inner layer channel of the double-layer pipe adapter is connected to the inner layer channel of the double-layer pipe, the outer layer channel is connected to the outer layer channel of the double-layer pipe, and the head end of the double-layer pipe safety joint is connected to the double-layer pipe adapter. The head of the multifunctional tool for jet cavitation fracturing and injection is connected to the replaceable core double-nozzle jet pump, and the end is connected to the downhole tractor of the horizontal well. The head end of the bent screw power drilling tool is connected to the downhole tractor of the horizontal well, and the end is connected to the near-drill-bit geological guidance tool, and the hydrate drill bit is connected to the near-drill-bit geological guidance tool.

[0015] The real-time monitoring system for seabed leakage includes distributed optical fiber pressure and temperature sensors, seabed pH sensors, hydrate leakage detection devices, power supply devices, data acquisition and wireless communication devices. The distributed optical fiber pressure and temperature sensors are installed in the formation drilling and injection system and are lowered along with the tool string. The seabed pH sensors and hydrate leakage detection devices are installed in the mud cap layer. The data acquisition and wireless communication devices are connected and transmit monitoring information in real time. The power supply device provides power guarantee for the equipment installed on the seabed.

[0016] The replaceable core double nozzle jet pump includes a throat, a jet nozzle and a diverter nozzle. The throat of the replaceable core double nozzle jet pump is connected to the inner layer channel of the downhole temperature and pressure and visual monitoring short section, and the diverter nozzle is connected to the inside of the jet cavity fracturing and injection multifunctional tool. The replaceable core double nozzle jet pump can replace the double nozzle structure with a single jet nozzle structure by unlocking the pump core. The injection and production high pressure pump group in the offshore platform injection and production master control system is connected to the annular space between the water-proof pipe and the double-layer pipe. The double-layer pipe hydraulic anchor and double-layer expansion packer have inner and outer double channels, which can be set and unsealed by changing the size of seawater flow, and can be anchored and isolated in the horizontal open hole section. The omnidirectional whipstock is lowered into the well through the drill pipe, and is positioned in the hydrate reservoir to guide the hydrate drill bit to perform directional drilling according to a predetermined trajectory. The seabed pH sensor and hydrate leakage detection device are arranged at multiple points in the sediment cap layer and form a monitoring network on the seabed to achieve coverage monitoring of the storage area.

[0017] The method for natural gas hydrate exploitation and carbon dioxide storage in the deep-sea natural gas hydrate exploitation and carbon dioxide storage integrated system is characterized in that it comprises the following steps:

[0018] SⅠ, drilling, solid fluidized mining, specifically including the following steps:

[0019] Sa. Running tools: The omnidirectional whipstock is run into the well through the drill pipe, and after positioning in the hydrate reservoir, the double-layer pipe, riser, formation drilling and injection system are lowered to the hydrate reservoir together through the multifunctional derrick and double-layer pipe injection head;

[0020] Sb. Horizontal section drilling: The injection and production high-pressure pump group is controlled by the injection and production operation control terminal. The injection and production high-pressure pump group pumps seawater into the outer channel of the double-layer pipe. The pressurized seawater passes through the double-layer pipe adapter, double-layer pipe safety joint, double-layer pipe hydraulic anchor, double-layer expansion packer, downhole temperature and pressure and visual monitoring short section, and enters the outer channel of the replaceable core double-nozzle jet pump in sequence, and then enters its jet nozzle and diversion nozzle respectively. The seawater after the diversion nozzle enters the horizontal well downhole tractor, bent screw power drilling tool, and near-drill bit geological steering tool through the jet cavity fracturing and injection multifunctional tool, and then drives the hydrate drill bit to rotate. The hydrate drill bit drills horizontally in the hydrate reservoir to the predetermined mining position, and the seawater ejected through the jet nozzle sucks the hydrate slurry at the throat of the replaceable core double-nozzle jet pump through the double-layer pipe to enter the floating injection and production platform;

[0021] Sc. Solid fluidized production: The injection and production high-pressure pump group is controlled by the injection and production operation control terminal to increase the seawater flow rate. The injection and production high-pressure pump group pumps seawater into the outer channel of the double-layer pipe. The large flow of seawater passes through the double-layer pipe adapter, double-layer pipe safety joint, double-layer pipe hydraulic anchor, double-layer expansion packer, downhole temperature and pressure and visual monitoring short section, and the outer channel of the replaceable core double-nozzle jet pump in sequence. The seawater after passing through the diverter nozzle reaches the jet cavity fracturing and injection multifunctional tool. The jet cavity fracturing and injection multifunctional tool is switched to the radial injection state. High-pressure seawater is ejected to the hydrate reservoir through the jet nozzle to crush the hydrate. The seawater ejected by the jet nozzle is sucked by the throat to suck the crushed hydrate slurry through the inner channel of the double-layer pipe into the hydrate pretreatment and storage device, and at the same time, the seabed drilling and injection system is towed back to complete the solid fluidized cavity operation of the natural gas hydrate reservoir.

[0022] SⅡ, the first depressurization mining, specifically includes the following steps:

[0023] Sd. Replace the pump core of the replaceable double-nozzle jet pump: After the solid fluidization cavity making operation is completed, seawater is injected from the inner tube of the double-layer tube through the injection and production operation control terminal to unlock the pump core in the replaceable double-nozzle jet pump; after the pump core is unlocked, seawater is injected from the outer tube of the double-layer tube, and the unlocked double-nozzle pump core is transported to the floating injection and production platform. After it is taken out from the wellhead, the single jet nozzle pump core is put in, and seawater is injected from the inner tube of the double-layer tube, transported to the replaceable double-nozzle jet pump and locked. At this time, the replaceable double-nozzle jet pump does not have a diversion effect, and the double-nozzle jet pump becomes a conventional jet pump.

[0024] Se. The first depressurization production of hydrates: seawater is injected from the outer layer of the double-layer tube, and the depressurization production of natural gas hydrates is carried out through a replaceable core double-nozzle jet pump.

[0025] SⅢ, natural gas hydrate reservoir fracturing, specifically includes the following steps:

[0026] Sf. Hydrate reservoir fracturing: After the depressurization production is completed, the supercritical carbon dioxide is controlled by the injection and production operation control terminal to pass through the carbon dioxide treatment and storage device and the high-pressure carbon dioxide compressor unit to add sand to form a supercritical carbon dioxide fracturing medium, which is injected from the inner and outer pipes of the double-layer pipe; the supercritical carbon dioxide fracturing medium is ejected from the replaceable core double-nozzle jet pump into the natural gas hydrate cavity to form a high-pressure environment. At the same time, due to the internal and external pressure difference, the double-layer pipe hydraulic anchor is anchored and the double-layer expansion packer is sealed, so that the hydrate reservoir is fractured and transformed to form a fracture network. In addition, carbon dioxide can replace natural gas hydrates to a certain extent, and carbon dioxide hydrates are formed to solidify the natural gas hydrate cavity.

[0027] SIV. Secondary pressure reduction and production after fracturing, specifically including the following steps:

[0028] Sg. Second depressurization and production: After the fracturing is completed, the injection medium is replaced by seawater from the supercritical carbon dioxide fracturing medium through the injection and production operation control terminal, and the seawater is injected from the outer layer of the double-layer tube. The seawater is depressurized and produced through a replaceable core double-nozzle jet pump. At the same time, the displaced natural gas is pumped into the hydrate pretreatment and storage device through the double-layer tube.

[0029] SⅤ, post-fracture replacement mining, specifically including the following steps:

[0030] Sh. Injection replacement: After the post-fracture depressurization production is completed, supercritical carbon dioxide is injected from the inner and outer pipes of the double-layer pipe through the carbon dioxide processing and storage device and the high-pressure carbon dioxide compressor unit through the injection and production operation control terminal. The supercritical carbon dioxide is ejected through the replaceable core double-nozzle jet pump and injected into the hydrate cavity after fracturing, and the well is shut down for a period of time;

[0031] Si. Replacement lifting: After the natural gas replacement is completed, seawater is injected from the outer layer of the double-layer tube, and the replaced natural gas and carbon dioxide mixture is sucked out through a replaceable core double-nozzle jet pump.

[0032] SVI, carbon dioxide storage, specifically including the following steps:

[0033] Sj. Injection and storage: After the carbon dioxide replacement method is completed, supercritical carbon dioxide is injected from the inner and outer pipes of the double-layer pipe through the carbon dioxide treatment and storage device and the high-pressure carbon dioxide compressor unit. The supercritical carbon dioxide is ejected by a replaceable core double-nozzle jet pump and injected into the natural gas hydrate goaf to form carbon dioxide hydrate, thus realizing permanent geological storage of carbon dioxide.

[0034] SVII. Comprehensive hydrate mining and carbon fixation, specifically including the following steps:

[0035] Sk, when hydrate production and carbon fixation in one direction are completed, the double-layer pipe hydraulic anchor and double-layer expansion packer are unsealed, the formation drilling and injection system is recovered to the wellhead, and the omnidirectional whipstock position is adjusted;

[0036] S1, repeat the above steps Sa-Sk to complete the full range of hydrate extraction and carbon fixation at the corresponding points;

[0037] SⅧ, carbon dioxide and hydrate leakage monitoring, specifically including the following steps:

[0038] Sm, leakage monitoring: After completing the comprehensive hydrate extraction and carbon fixation operations at the corresponding points, the autonomous underwater robot is released via the floating injection and production platform. The autonomous underwater robot carries the seabed pH sensor, hydrate leakage detection device, power supply device, data acquisition and wireless communication device to the predetermined location on the seabed to install the leakage monitoring equipment. After installation and commissioning, long-term monitoring is carried out.

[0039] The beneficial effects of the present invention are:

[0040] (1) Compared with the previous single natural gas hydrate extraction method, a combination of multiple natural gas hydrate extraction methods is proposed, which improves the extraction efficiency of natural gas hydrate and increases the output;

[0041] (2) Using supercritical carbon dioxide for fracturing to form a fracture network, increase the contact area and carbon dioxide storage space, and use supercritical carbon dioxide to replace surface methane to form carbon dioxide hydrates, thereby improving the structural strength of the natural gas hydrate reservoir;

[0042] (3) Combining the exploitation of natural gas hydrates with carbon sequestration, storing carbon dioxide in the form of solid hydrates has the dual advantages of large storage capacity and high safety, reducing the engineering practice cost of carbon sequestration, and at the same time preventing geological disasters such as submarine landslides and collapses after the exploitation of natural gas hydrates.

[0043] (4) Long-term monitoring of CO2 storage areas improves the durability and safety of CO2 storage and prevents damage to the seabed ecosystem caused by CO2 leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a general schematic diagram of the scheme of the present invention;

[0045] Figure 2 This is a schematic diagram of the solid-state fluidization and cavity-making structure of the present invention;

[0046] Figure 3 This is a schematic diagram of the fracturing structure of the present invention;

[0047] Figure 4 for Figure 1 A partial enlarged view of part I;

[0048] Figure 5 for Figure 2 A partial enlarged view of part II;

[0049] Figure 6 This is a schematic diagram of the all-round hydrate mining and carbon fixation of the present invention;

[0050] Figure 7The present invention is a flow chart of an integrated system and method for deep-sea natural gas hydrate exploitation and carbon dioxide storage; in the figure, 1-floating injection and production platform, 2-injection and production operation control terminal, 3-injection and production high-pressure pump group, 4-hydrate pretreatment and storage device, 5-double-layer pipe complete operation device, 6-multifunctional derrick, 7-double-layer pipe injection head, 8-high-pressure carbon dioxide compressor group, 9-carbon dioxide treatment and storage device, 10-double-layer pipe, 11-underwater blowout preventer group, 12-open hole packer, 13-seawater, 14-silt cap layer, 15-hydrate reservoir, 16-double-layer pipe adapter, 17-omnidirectional whipstock, 18-double-layer pipe safety joint, 19-double-layer pipe hydraulic anchor, 20-double-layer expansion packer, 2 1- Downhole temperature and pressure and visual monitoring pup joint, 22- Replaceable core double nozzle jet pump, 2201- Throat, 2202- Jet nozzle, 2203- Diverter nozzle, 2204- Single jet nozzle, 23- Jet cavity fracturing and injection multifunctional tool, 2301- Jet nozzle, 24- Downhole tractor for horizontal wells, 25- Bent screw power drilling tool, 26- Near-drill bit geological guidance tool, 27- Hydrate drill bit, 28- Subsea pH sensor, 29- Hydrate leakage detection device, 30- Power supply device, 31- Data acquisition and wireless communication device, 32- Autonomous underwater robot, 33- Solid fluidization cavity, 34- Fracturing network, 35- Riser, 36- Distributed optical fiber pressure and temperature sensor. DETAILED DESCRIPTION

[0051] The present invention is further described below in conjunction with the accompanying drawings, and the protection scope of the present invention is not limited to the following:

[0052] like Figures 1 to 6 As shown, a deep-sea natural gas hydrate exploitation and carbon dioxide storage integrated system is characterized in that it includes an offshore platform injection and production master control system, an underwater pipe collection and transportation and wellhead system, a formation drilling and injection system, and a seabed leakage real-time monitoring system;

[0053] The offshore platform injection and production master control system comprises a floating injection and production platform 1 floating on the sea surface, an injection and production operation control terminal 2, an injection and production high-pressure pump group 3, a hydrate pretreatment and storage device 4, a double-layer pipe complete operation device 5, a multifunctional derrick 6, a double-layer pipe injection head 7, a high-pressure carbon dioxide compressor group 8, and a carbon dioxide treatment and storage device 9 arranged on the floating injection and production platform;

[0054] The underwater pipe string gathering and wellhead system includes a double-layer pipe 10, a watertight pipe 35, a subsea blowout preventer group 11, and an open hole packer 12 installed on a silt cap layer 14. The head end of the watertight pipe 35 is installed on a floating injection and production platform 1, and the tail end is installed on the subsea blowout preventer group 11. The subsea blowout preventer group 11 is installed on a seabed wellhead. The double-layer pipe 10 is installed in the watertight pipe 35, and the head end is installed on a double-layer pipe complete set of operating devices 5. The inner layer channel is connected to a hydrate pretreatment and storage device 4, the outer layer channel is connected to an injection and production high-pressure pump group 3, and the tail end is connected to a formation drilling and injection system. The open hole packer 12 is anchored on a casing under the subsea blowout preventer group 11.

[0055] The formation drilling and injection system is sequentially connected and composed of a double-layer pipe adapter 16, an omnidirectional whipstock 17, a double-layer pipe safety joint 18, a double-layer pipe hydraulic anchor 19, a double-layer expansion packer 20, a downhole temperature and pressure and visual monitoring short section 21, a replaceable core double-nozzle jet pump 22, a jet cavity fracturing and injection multifunctional tool 23, a horizontal well downhole tractor 24, a bent screw power drill 25, a near-drill bit geological steering tool 26, and a hydrate drill bit 27. The inner layer channel of the double-layer pipe adapter 16 is connected to the inner layer channel of the double-layer pipe 10, and the outer layer channel is connected to the outer layer channel of the double-layer pipe 10. The head end of the double-layer pipe safety joint 18 is connected to the double-layer pipe adapter 16. The first end of the downhole temperature, pressure and visualization monitoring short section 21 is connected to the double-layer expansion packer 20, and the last section is connected to the replaceable core double-nozzle jet pump 22. The first end of the jet cavity fracturing and injection multifunctional tool 23 is connected to the replaceable core double-nozzle jet pump 22, and the last section is connected to the horizontal well downhole tractor 24. The first end of the bent screw power drilling tool 25 is connected to the horizontal well downhole tractor 24, and the last section is connected to the near-drill-bit geological steering tool 26. The hydrate drill bit 27 is connected to the near-drill-bit geological steering tool 26.

[0056] The real-time monitoring system for seabed leakage includes a distributed optical fiber pressure and temperature sensor 36, a seabed pH sensor 28, a hydrate leakage detection device 29, a power supply device 30, and a data acquisition and wireless communication device 31. The distributed optical fiber pressure and temperature sensor 36 is installed in the formation drilling and injection system and is lowered along with the tool string. The seabed pH sensor 28 and the hydrate leakage detection device 29 are installed in the sediment cover layer 14. The data acquisition and wireless communication device 31 is connected to transmit monitoring information in real time. The power supply device 30 provides power guarantee for the equipment installed on the seabed.

[0057] The replaceable core double nozzle jet pump 22 includes a throat 2201, a jet nozzle 2202 and a diverter nozzle 2203. The throat 2201 of the replaceable core double nozzle jet pump 22 is connected to the inner channel of the downhole temperature and pressure and visual monitoring short section 21, and the diverter nozzle 2203 is connected to the inside of the jet cavity fracturing and injection multifunctional tool 23. The replaceable core double nozzle jet pump 22 can replace the double nozzle structure with a single jet nozzle 2204 structure by unlocking the pump core. The injection and production high pressure pump group 3 in the offshore platform injection and production master control system is connected to the annular space between the watertight pipe 35 and the double-layer pipe 10. The double-layer pipe hydraulic anchor 19 and the double-layer expansion packer 20 have inner and outer double channels, which can be set and unsealed by changing the flow rate of seawater 13, and can achieve anchoring and isolation in the horizontal open hole section. The omnidirectional whipstock 17 is lowered into the well through a drill pipe and positioned in the hydrate reservoir 15 to guide the hydrate drill bit 27 to perform directional drilling according to a predetermined trajectory. The seabed pH sensor 28 and the hydrate leakage detection device 29 are arranged at multiple points in the sediment cap layer 14 and form a monitoring network on the seabed to achieve coverage monitoring of the storage area.

[0058] The method for deep-sea natural gas hydrate exploitation and carbon dioxide storage is characterized in that it comprises the following steps:

[0059] SⅠ, drilling, solid fluidized mining, specifically including the following steps:

[0060] Sa. Running tools: The omnidirectional whipstock 17 is run into the well through the drill pipe, and after the hydrate reservoir 15 is located at an appropriate depth, the double-layer pipe 10, the riser 35, the formation drilling and injection system are lowered to the hydrate reservoir 15 via the multifunctional derrick 6 and the double-layer pipe injection head 7;

[0061] Sb. Horizontal section drilling: The injection and production high-pressure pump group 3 is controlled by the injection and production operation control terminal 2. The injection and production high-pressure pump group 3 pumps seawater 13 into the outer channel of the double-layer pipe 10. The pressurized seawater 13 passes through the double-layer pipe adapter 16, the double-layer pipe safety joint 18, the double-layer pipe hydraulic anchor 19, the double-layer expansion packer 20, the downhole temperature and pressure and visual monitoring short section 21, and enters the outer channel of the replaceable core double-nozzle jet pump 22, and then enters its jet nozzle 2202 and the diverter nozzle 2203 respectively. The seawater 13 after the nozzle 2203 enters the horizontal well downhole tractor 24, the bent screw power drill 25, and the near-drill-bit geological steering tool 26 through the jet cavity fracturing and injection multifunctional tool 23, and then drives the hydrate drill bit 27 to rotate. The hydrate drill bit 27 drills horizontally in the hydrate reservoir 15 to the predetermined mining position, and the seawater 13 ejected through the jet nozzle 2202 sucks the hydrate slurry at the throat 2201 of the replaceable core double-nozzle jet pump 22 through the double-layer pipe 10 and enters the floating injection and production platform 1;

[0062] Sc. Solid fluidized mining: The injection and production operation control terminal 2 controls the injection and production high-pressure pump group 3 to increase the seawater flow rate. The injection and production high-pressure pump group 3 pumps seawater 13 into the outer channel of the double-layer pipe 10, such as Figure 2 As shown by the solid arrow flow direction, the large flow seawater 13 passes through the double-layer pipe adapter 16, the double-layer pipe safety joint 18, the double-layer pipe hydraulic anchor 19, the double-layer expansion packer 20, the downhole temperature and pressure and visualization monitoring short section 21, and the outer channel of the replaceable core double-nozzle jet pump 22 in sequence, wherein the seawater 13 after passing through the diverter nozzle 2203 reaches the jet cavity fracturing and injection multifunctional tool 23, and the jet cavity fracturing and injection multifunctional tool 23 switches to the radial injection state, and the high-pressure seawater 13 is ejected to the hydrate reservoir 15 through the jet nozzle 2301 for hydrate crushing, wherein the seawater 13 ejected by the jet nozzle 2202 is as shown in FIG. Figure 4 As shown by the hollow arrow, the crushed hydrate slurry is sucked through the throat 2201 as shown in FIG. Figure 4 As shown by the regular hexagon, the gas enters the hydrate pretreatment and storage device 4 through the inner channel of the double-layer pipe 10, and at the same time, it is towed back to the seabed drilling and injection system to complete the solid fluidization cavity making 33 operation of the natural gas hydrate reservoir.

[0063] SⅡ, the first depressurization mining, specifically includes the following steps:

[0064] Sd. Replace the pump core of the replaceable core double-nozzle jet pump: After the solid fluidization cavity making operation 33 is completed, the seawater 13 is injected from the inner tube of the double-layer tube 10 through the injection and production operation control terminal 2 to unlock the pump core in the replaceable core double-nozzle jet pump 22; after the pump core is unlocked, the seawater 13 is injected from the outer tube of the double-layer tube 10, and the unlocked double-nozzle pump core is transported to the floating injection and production platform 1. After it is taken out from the wellhead, the single jet nozzle 2204 pump core is put in, and the seawater 13 is injected from the inner tube of the double-layer tube 10, and it is transported to the replaceable core double-nozzle jet pump 22 and locked. At this time, the replaceable core double-nozzle jet pump 22 does not have a diversion effect, and the double-nozzle jet pump becomes a conventional jet pump.

[0065] Se. First depressurization exploitation of hydrates: inject seawater 13 from the outer tube of the double-layer tube 10, and depressurize and exploit the natural gas hydrates through the replaceable core double-nozzle jet pump 22.

[0066] SⅢ, natural gas hydrate reservoir fracturing, specifically includes the following steps:

[0067] Sf. Hydrate reservoir fracturing: After the depressurization is completed, the supercritical carbon dioxide is controlled by the injection and production operation control terminal 2 to pass through the carbon dioxide processing and storage device 9 and the high-pressure carbon dioxide compressor unit 8 to add sand to form a supercritical carbon dioxide fracturing medium, which is injected from the inner and outer pipes of the double-layer pipe 10; Figure 3As indicated by the solid arrow, the supercritical carbon dioxide fracturing medium is ejected from the replaceable core double nozzle jet pump 22 into the natural gas hydrate cavity to form a high pressure environment. At the same time, due to the internal and external pressure difference, the double-layer tubular hydraulic anchor 19 is anchored and the double-layer expansion packer 20 is set, so as to perform fracturing transformation on the hydrate reservoir 15, as shown in FIG. Figure 5 As shown, a fracture network 34 is formed, and carbon dioxide can replace natural gas hydrate to a certain extent, and carbon dioxide hydrate solidifies the natural gas hydrate cavity.

[0068] SIV. Secondary pressure reduction and production after fracturing, specifically including the following steps:

[0069] Sg. Second depressurization production: After the fracturing is completed, the injection medium is replaced by seawater 13 from the supercritical carbon dioxide fracturing medium through the injection and production operation control terminal 2, and the seawater 13 is injected from the outer tube of the double-layer tube 10. The seawater 13 is depressurized and produced through the replaceable core double-nozzle jet pump 22. At the same time, the displaced natural gas is pumped into the hydrate pretreatment and storage device 4 through the double-layer tube 10.

[0070] SⅤ, post-fracture replacement mining, specifically including the following steps:

[0071] Sh. Injection replacement: After the post-fracture decompression production is completed, the supercritical carbon dioxide is injected from the inner and outer pipes of the double-layer pipe 10 through the carbon dioxide processing and storage device 9 and the high-pressure carbon dioxide compressor unit 8 through the injection and production operation control terminal 2. The supercritical carbon dioxide is ejected through the replaceable core double-nozzle jet pump 22 and injected into the hydrate cavity after fracturing, and the well is shut down for a period of time;

[0072] Si. Replacement lifting: After the natural gas replacement is completed, seawater 13 is injected from the outer layer of the double-layer pipe 10, and the replaced natural gas and carbon dioxide mixed gas are sucked out by the replaceable core double-nozzle jet pump 22.

[0073] SVI, carbon dioxide storage, specifically including the following steps:

[0074] Sj. Injection and storage: After the carbon dioxide replacement method is completed, supercritical carbon dioxide is injected from the inner and outer pipes of the double-layer pipe 10 through the carbon dioxide processing and storage device 9 and the high-pressure carbon dioxide compressor unit 8. The supercritical carbon dioxide is ejected by the replaceable core double-nozzle jet pump 22 and injected into the natural gas hydrate goaf to form carbon dioxide hydrate, thereby realizing permanent geological storage of carbon dioxide.

[0075] SVII. Comprehensive hydrate mining and carbon fixation, specifically including the following steps:

[0076] Sk, when the hydrate production and carbon fixation in one position are completed, the double-layer pipe hydraulic anchor 19 and the double-layer expansion packer 20 are unsealed, the formation drilling and injection system is recovered to the wellhead, and the position of the omnidirectional whipstock 17 is adjusted;

[0077] S1, repeat the above steps Sa-Sk, such as Figure 6 As shown, the full range of hydrate extraction and carbon fixation at the corresponding points are completed;

[0078] SⅧ, carbon dioxide and hydrate leakage monitoring, specifically including the following steps:

[0079] Sm, leakage monitoring: After completing the comprehensive hydrate extraction and carbon fixation operations at the corresponding points, such as Figure 1 As shown, an autonomous underwater robot 32 is released via the floating injection and production platform 1. The autonomous underwater robot 32 carries a seabed pH sensor 28, a hydrate leakage detection device 29, a power supply device 30, and a data acquisition and wireless communication device 31 to a predetermined position on the seabed to install the leakage monitoring equipment. After the installation and debugging are completed, long-term monitoring is carried out.

[0080] Obviously, the described embodiments are only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0081] In the description of the present invention, it should be noted that the directions or positional relationships indicated by "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are directions or positional relationships based on the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device 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, "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0082] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, "installation", "connection" 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 indirectly connected 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.

[0083] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0084] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. An integrated system for deep-sea natural gas hydrate extraction and carbon dioxide storage, characterized by: It includes the offshore platform injection and production control system, underwater pipe collection and transportation and wellhead system, formation drilling and injection system, and submarine leakage real-time monitoring system; The offshore platform injection and production master control system comprises a floating injection and production platform (1) floating on the sea surface, an injection and production operation control terminal (2) arranged on the floating injection and production platform, an injection and production high-pressure pump group (3), a hydrate pretreatment and storage device (4), a double-layer pipe complete operation device (5), a multifunctional derrick (6), a double-layer pipe injection head (7), a high-pressure carbon dioxide compressor group (8), and a carbon dioxide treatment and storage device (9); The underwater pipe string gathering and wellhead system comprises a double-layer pipe (10), a watertight pipe (35), a subsea blowout preventer group (11), and an open-hole packer (12) installed on a sediment cap layer (14); the head end of the watertight pipe (35) is installed on a floating injection and production platform (1), and the tail end is installed on the subsea blowout preventer group (11); the subsea blowout preventer group (11) is installed on a seabed wellhead; the double-layer pipe (10) is installed in the watertight pipe (35), the head end is installed on a double-layer pipe complete set of operating devices (5); the inner layer channel is connected to a hydrate pretreatment and storage device (4), the outer layer channel is connected to an injection and production high-pressure pump group (3), and the tail end is connected to a formation drilling and injection system; the open-hole packer (12) is anchored on a casing under the subsea blowout preventer group (11); The formation drilling and injection system is sequentially connected and composed of a double-layer pipe adapter (16), an all-round whipstock (17), a double-layer pipe safety joint (18), a double-layer pipe hydraulic anchor (19), a double-layer expansion packer (20), a downhole temperature and pressure and visual monitoring short section (21), a replaceable core double-nozzle jet pump (22), a jet cavity fracturing and injection multifunctional tool (23), a horizontal well downhole tractor (24), a bent screw power drill (25), a near-bit geological steering tool (26), and a hydrate drill bit (27). The inner layer channel of the double-layer pipe adapter (16) is connected to the inner layer channel of the double-layer pipe (10), and the outer layer channel is connected to the outer layer channel of the double-layer pipe (10). The head end of the double-layer pipe safety joint (18) is connected to the double-layer pipe. The adapter (16) is connected to the double-layered hydraulic anchor (19), the double-layered hydraulic anchor (19) is connected to the double-layered expansion packer (20), the downhole temperature and pressure and visualization monitoring short section (21) is connected to the double-layered expansion packer (20), the end is connected to the replaceable core double-nozzle jet pump (22), the jet cavity fracturing and injection multifunctional tool (23) is connected to the replaceable core double-nozzle jet pump (22) at the head end, and is connected to the horizontal well downhole tractor (24) at the end end, the bent screw power drilling tool (25) is connected to the horizontal well downhole tractor (24) at the head end, and is connected to the near-drill-bit geological steering tool (26), and the hydrate drill bit (27) is connected to the near-drill-bit geological steering tool (26); The seabed leakage real-time monitoring system comprises a distributed optical fiber pressure and temperature sensor (36), a seabed pH sensor (28), a hydrate leakage detection device (29), a power supply device (30), and a data acquisition and wireless communication device (31). The distributed optical fiber pressure and temperature sensor (36) is installed in the formation drilling and injection system and is lowered along with the tool string. The seabed pH sensor (28) and the hydrate leakage detection device (29) are installed in the sediment cover layer (14). The data acquisition and wireless communication device (31) is connected to transmit monitoring information in real time. The power supply device (30) provides power guarantee for the equipment installed on the seabed.

2. The integrated system for deep-sea natural gas hydrate extraction and carbon dioxide storage according to claim 1, characterized in that: The replaceable core double-nozzle jet pump (22) comprises a throat (2201), a jet nozzle (2202) and a diverter nozzle (2203); the throat (2201) of the replaceable core double-nozzle jet pump (22) is connected to the inner channel of the downhole temperature, pressure and visual monitoring short section (21); the diverter nozzle (2203) is connected to the inside of the jet cavity fracturing and injection multifunctional tool (23); the replaceable core double-nozzle jet pump (22) can replace the double-nozzle structure with a single jet nozzle (2204) structure by unlocking the pump core.

3. The integrated system for deep-sea natural gas hydrate extraction and carbon dioxide storage according to claim 1, characterized in that: The injection and production high-pressure pump group (3) in the offshore platform injection and production master control system is in communication with the annular space between the riser (35) and the double-layer pipe (10).

4. The integrated system for deep-sea natural gas hydrate extraction and carbon dioxide storage according to claim 1, characterized in that: The double-layer hydraulic anchor (19) and the double-layer expansion packer (20) have inner and outer double channels, can be set and released by changing the flow rate of seawater (13), and can realize anchoring and outer annular space isolation in the horizontal open hole section.

5. The integrated system for deep-sea natural gas hydrate extraction and carbon dioxide storage according to claim 1, characterized in that: The omnidirectional whipstock (17) is lowered into the well through the drill pipe and positioned in the hydrate reservoir (15), guiding the hydrate drill bit (27) to perform directional drilling according to a predetermined trajectory and can achieve steering within a range of 360 degrees.

6. The integrated system for deep-sea natural gas hydrate extraction and carbon dioxide storage according to claim 1, characterized in that: The seabed pH sensors (28) and hydrate leakage detection devices (29) are arranged at multiple points in the sediment cover layer (14) and form a monitoring network on the seabed to achieve coverage monitoring of the sealed area.

7. The method for integrating deep-sea natural gas hydrate extraction and carbon dioxide storage according to claim 2, characterized in that: It includes the following steps: SⅠ, drilling, solid fluidized mining, specifically includes the following steps: Sa. Running tools: An omnidirectional whipstock (17) is run into the well through a drill pipe, and after positioning in the hydrate reservoir (15), a double-layer pipe (10), a water-relief pipe (35), a formation drilling and injection system are lowered together into the hydrate reservoir (15) via a multifunctional derrick (6) and a double-layer pipe injection head (7); Sb. Horizontal section drilling: The injection and production high pressure pump group (3) is controlled by the injection and production operation control terminal (2). The injection and production high pressure pump group (3) pumps seawater (13) into the outer channel of the double-layer pipe (10). The pressurized seawater (13) passes through the double-layer pipe adapter (16), the double-layer pipe safety joint (18), the double-layer pipe hydraulic anchor (19), the double-layer expansion packer (20), the downhole temperature and pressure and visual monitoring short section (21), and enters the outer channel of the replaceable core double nozzle jet pump (22). Then, the seawater enters the jet nozzle (2202) and the diverter nozzle (2203) thereof, and passes through the diverter nozzle. The seawater (13) after (2203) enters the horizontal well downhole tractor (24), the bent screw power drill (25), and the near-drill-bit geological steering tool (26) through the jet cavity fracturing and injection multifunctional tool (23), and then drives the hydrate drill bit (27) to rotate. The hydrate drill bit (27) drills horizontally in the hydrate reservoir (15) to the predetermined mining position, and the seawater (13) ejected through the jet nozzle (2202) sucks the hydrate slurry at the throat (2201) of the replaceable core double-nozzle jet pump (22) through the double-layer pipe (10) and enters the floating injection and production platform (1); Sc, solid fluidized mining: The injection and production operation control terminal (2) controls the injection and production high-pressure pump group (3) to increase the seawater flow rate, and the injection and production high-pressure pump group (3) pumps the seawater (13) into the outer channel of the double-layer pipe (10). The large flow of seawater (13) passes through the double-layer pipe adapter (16), the double-layer pipe safety joint (18), the double-layer pipe hydraulic anchor (19), the double-layer expansion packer (20), the downhole temperature and pressure and visual monitoring short section (21), and the outer channel of the replaceable core double-nozzle jet pump (22). The seawater (13) after passing through the diversion nozzle (2203) reaches the jet The multifunctional tool (23) for cavitation fracturing and injection is switched to a radial injection state, and high-pressure seawater (13) is injected into the hydrate reservoir (15) through the jet nozzle (2301) to crush the hydrate, wherein the seawater (13) ejected from the jet nozzle (2202) is sucked through the throat (2201) to suck the crushed hydrate slurry into the hydrate pretreatment and storage device (4) through the inner channel of the double-layer pipe (10), and at the same time, the seabed drilling and injection system is pulled back to complete the solid fluidization cavitation (33) operation of the natural gas hydrate reservoir; SⅡ, the first pressure reduction mining, specifically includes the following steps: Sd. Replace the pump core of the replaceable core double-nozzle jet pump (22): After the solid fluidization cavity making (33) operation is completed, seawater (13) is injected from the inner tube of the double-layer tube (10) through the injection and production operation control terminal (2), unlocking the pump core in the replaceable core double-nozzle jet pump (22); after the pump core is unlocked, seawater (13) is injected from the outer tube of the double-layer tube (10), and the unlocked double-nozzle pump core is transported to the floating injection and production platform (1). After being taken out from the wellhead, the single jet nozzle (2204) pump core is put in, and seawater (13) is injected from the inner tube of the double-layer tube (10), transported to the replaceable core double-nozzle jet pump (22) and locked. At this time, the replaceable core double-nozzle jet pump (22) does not have a diversion effect, and its function is the same as that of a conventional jet pump; Se, hydrate first decompression mining: inject seawater (13) from the outer tube of the double-layer tube (10), and decompression mining of natural gas hydrate is carried out through the replaceable core double nozzle jet pump (22); SⅢ, natural gas hydrate reservoir fracturing, specifically includes the following steps: Sf, hydrate reservoir fracturing: after the depressurization and mining are completed, the supercritical carbon dioxide is controlled by the injection and mining operation control terminal (2) to pass through the carbon dioxide processing and storage device (9) and the high-pressure carbon dioxide compressor unit (8) to add sand to form a supercritical carbon dioxide fracturing medium, which is injected from the inner and outer pipes of the double-layer pipe (10); the supercritical carbon dioxide fracturing medium is ejected from the replaceable core double-nozzle jet pump (22) into the natural gas hydrate cavity to form a high-pressure environment, and at the same time, due to the internal and external pressure difference, the double-layer pipe hydraulic anchor (19) is anchored and the double-layer expansion packer (20) is set, so that the hydrate reservoir (15) is fracturing and reformed to form a fracture network (34), and the carbon dioxide can replace the natural gas hydrate to a certain extent, and form carbon dioxide hydrate to solidify the natural gas hydrate cavity; SIV, the second depressurization mining after fracturing, specifically includes the following steps: Sg. Second decompression production: After the fracturing is completed, the injection medium is replaced by seawater (13) from the supercritical carbon dioxide fracturing medium through the injection and production operation control terminal (2), and the seawater (13) is injected from the outer tube of the double-layer tube (10). The seawater (13) is decompressed and produced through the replaceable core double-nozzle jet pump (22), and the displaced natural gas is pumped into the hydrate pretreatment and storage device (4) through the double-layer tube (10); SⅤ, post-fracture replacement mining, specifically including the following steps: Sh, injection replacement: After the post-fracture decompression production is completed, supercritical carbon dioxide is injected from the inner and outer pipes of the double-layer pipe (10) through the carbon dioxide processing and storage device (9) and the high-pressure carbon dioxide compressor unit (8) under the control of the injection and production operation control terminal (2). The supercritical carbon dioxide is ejected through the replaceable core double-nozzle jet pump (22) and injected into the hydrate cavity after the fracturing, and the well is shut down for a period of time; Si. Replacement lifting: After the natural gas replacement is completed, seawater (13) is injected from the outer layer of the double-layer pipe (10), and the replaced natural gas and carbon dioxide mixture is sucked out through the replaceable core double-nozzle jet pump (22); SVI, CO2 storage, specifically includes the following steps: Sj, injection and storage: After the carbon dioxide replacement method is completed, supercritical carbon dioxide is injected from the inner and outer pipes of the double-layer pipe (10) through the carbon dioxide processing and storage device (9) and the high-pressure carbon dioxide compressor unit (8). The supercritical carbon dioxide is ejected by the replaceable core double-nozzle jet pump (22) and injected into the natural gas hydrate goaf to form carbon dioxide hydrate, thereby realizing permanent geological storage of carbon dioxide; SVII. Comprehensive hydrate mining and carbon sequestration, specifically including the following steps: Sk, when hydrate extraction and carbon fixation in one direction are completed, the double-layered tubular hydraulic anchor (19) and the double-layered expandable packer (20) are unsealed, the formation drilling and injection system is recovered to the wellhead, and the orientation of the omnidirectional whipstock (17) is adjusted; S1. Repeat the above steps Sa-Sk to complete the comprehensive hydrate extraction and carbon sequestration at the corresponding points; SⅧ, carbon dioxide and hydrate leakage monitoring, specifically including the following steps: Sm, leakage monitoring: After completing the full range of hydrate mining and carbon fixation operations at the corresponding points, the autonomous underwater robot (32) is released via the floating injection and production platform (1). The autonomous underwater robot (32) carries a seabed pH sensor (28), a hydrate leakage detection device (29), a power supply device (30), and a data acquisition and wireless communication device (31) to a predetermined location on the seabed to install the leakage monitoring equipment. After installation and commissioning, long-term monitoring is carried out.

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