CN115012883B - Device and method for rapidly mining natural gas hydrate by gas flooding - Google Patents
Device and method for rapidly mining natural gas hydrate by gas flooding Download PDFInfo
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- CN115012883B CN115012883B CN202210880918.4A CN202210880918A CN115012883B CN 115012883 B CN115012883 B CN 115012883B CN 202210880918 A CN202210880918 A CN 202210880918A CN 115012883 B CN115012883 B CN 115012883B
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/01—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells specially adapted for obtaining from underwater installations
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/166—Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium
- E21B43/168—Injecting a gaseous medium
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
- Y02P90/70—Combining sequestration of CO2 and exploitation of hydrocarbons by injecting CO2 or carbonated water in oil wells
Abstract
The invention discloses a device and a method for rapidly opening natural gas hydrate by gas drive, which relate to the technical field of drilling, wherein the lower end of a gas supply mechanism is connected with the upper end of a double-wall drill rod, the lower end of the double-wall drill rod is connected with one end of a gas-water mixer, the other end of the gas-water mixer is connected with the upper end of a single-wall drill rod, the lower end of the single-wall drill rod stretches into a conduit assembly and stretches into a hydrate layer together with the lower end of the conduit assembly, the single-wall drill rod and the conduit assembly can be communicated with the hydrate layer, the upper end of the conduit assembly is connected with a remote control blowout preventer, the gas supply mechanism is used for introducing high-pressure gas into the gas-water mixer through an annular gap of the double-wall drill rod, the gas-water mixer is used for introducing the high-pressure gas into an inner barrel of the double-wall drill rod, enabling fluid in the hydrate layer to flow into the single-wall drill rod, decomposing the hydrate and mixing the high-pressure gas with the high-pressure gas, and then rising to a drilling ship through the inner barrel of the double-wall drill rod. The invention can reduce the working difficulty and simplify the working flow.
Description
Technical Field
The invention relates to the technical field of drilling, in particular to a device and a method for rapidly mining natural gas hydrate by gas flooding.
Background
For the trial production of natural gas hydrate, large-scale equipment such as drilling platforms or large-scale drilling vessels (more than 3 ten thousand tons) is currently used, the design of the equipment is originally intended for offshore oil drilling, the pressure grade and the weight of the equipment are large, and the natural gas hydrate is exploited to form super-distribution, so that certain waste is caused.
The existing exploitation methods are that a blowout preventer (BOP) and a water isolation pipe with the diameter of 21 inches are arranged at a wellhead after drilling, the well is connected to a drilling platform all the way from the sea bottom, then an electric submersible pump is arranged in the water isolation pipe to a drill hole, and the electric submersible pump is used for pumping water to form pressure drop so as to promote the decomposition of natural gas hydrate. This approach also has certain drawbacks: 1. the weight of the marine riser and the blowout preventer is large, the time consumed in the running-in process is long, and the marine riser and the blowout preventer are not easy to release when encountering extreme weather; even if disengaged, the tie-back again takes a lot of time. 2. The electric submersible pump depressurization mode needs the drilling platform to provide power supply, control signals, monitoring signals and the like for the electric submersible pump depressurization mode, and the electric submersible pump depressurization mode needs to be realized by carrying a winch on the drilling platform, so that the construction complexity is increased; on the other hand, the electric submersible pump is extremely high in manufacturing cost, and is unfavorable for cost reduction and efficiency improvement.
Disclosure of Invention
The invention aims to provide a device and a method for rapidly mining natural gas hydrate by gas flooding, which are used for solving the problems of the prior art, reducing the working difficulty and simplifying the working flow.
In order to achieve the above object, the present invention provides the following solutions:
the invention provides a device for rapidly mining natural gas hydrate by gas drive, which comprises a gas supply mechanism, a double-wall drill rod, a gas-water mixer, a single-wall drill rod, a remote control blowout preventer and a conduit assembly, wherein the gas supply mechanism is arranged on a drilling ship, the lower end of the gas supply mechanism is connected with the upper end of the double-wall drill rod, the lower end of the double-wall drill rod is connected with one end of the gas-water mixer, the other end of the gas-water mixer is connected with the upper end of the single-wall drill rod, the lower end of the single-wall drill rod extends into the conduit assembly and extends into a hydrate layer together with the lower end of the conduit assembly, the single-wall drill rod and the conduit assembly can be communicated with the hydrate layer, the upper end of the conduit assembly is connected with the remote control blowout preventer, and the gas supply mechanism is used for introducing high-pressure gas into the gas-water mixer through an annular gap of the double-wall drill rod, and enabling fluid in the hydrate layer to flow inwards through the inner cylinder of the double-wall drill rod and the high-pressure gas to enter into the high-pressure gas mixture on the drilling ship after the high-pressure gas and the high-pressure gas is mixed with the drilling gas.
Preferably, the air supply mechanism comprises a nitrogen making machine, an air compressor, an injection pipe and an air box, wherein the nitrogen making machine is connected with the air compressor, the air compressor is connected with the air box through the injection pipe, the air box is connected with the upper end of the double-wall drill rod, the air compressor is used for compressing nitrogen produced by the nitrogen making machine and then introducing the nitrogen into the air box through the injection pipe, and the air box is used for introducing high-pressure nitrogen into the annular gap.
Preferably, the device further comprises a slurry outlet pipe, a three-phase separator, a gas collecting pipe and a storage tank, wherein the slurry outlet pipe, the three-phase separator, the gas collecting pipe and the storage tank are arranged on the drilling ship, one end of the slurry outlet pipe is connected and communicated with the inner cylinder of the double-wall drill pipe, the other end of the slurry outlet pipe is connected and communicated with the three-phase separator, the slurry outlet pipe is used for guiding out a mixture in the inner cylinder of the double-wall drill pipe, the three-phase separator is used for separating the mixture guided out through the slurry outlet pipe, and the separated natural gas is led into the storage tank through the gas collecting pipe to be collected.
Preferably, the remote control blowout preventer comprises a hydraulic connector, a blowout preventer stack, a high-pressure accumulator, a valve island and an acoustic controller, wherein the hydraulic connector is positioned at a low-pressure wellhead at the upper end of the conduit assembly, the hydraulic connector can seal the low-pressure wellhead at the upper end of the conduit assembly, the blowout preventer stack is positioned below the double-wall drill rod and above the conduit assembly and at the periphery of the single-wall drill rod, the high-pressure accumulator, the valve island and the acoustic controller are all installed at the upper end of the conduit assembly, the acoustic controller is used for receiving acoustic information sent out by a drilling ship and controlling the valve island to open and close, and when the valve island is opened, high-pressure liquid in the high-pressure accumulator can enter a driving cavity of the blowout preventer stack and drive the blowout preventer stack to be attached to the periphery of the single-wall drill rod.
Preferably, the catheter assembly comprises a surface casing, a production casing and a connecting element, wherein the upper end of the production casing extends into the lower end of the surface casing and is limited in the surface casing through the connecting element, the upper end of the surface casing is connected with the remote control blowout preventer, the lower end of the production casing extends into the hydrate layer, the lower end of the single-wall drill rod can penetrate through the surface casing and extends into the production casing, and a plurality of through holes are formed in the lower end of the outer wall of the production casing.
Preferably, the periphery of the surface layer sleeve is also provided with a bearing base plate, and the bearing base plate is used for being supported on a seabed mud line.
The invention also discloses a method for rapidly mining the natural gas hydrate by gas flooding, which adopts any one of the technical schemes, and comprises the following steps:
s1: calculating the pressure of a hydrate layer in a drilled area according to the early geological data, selecting parameters of a conduit assembly according to the pressure of the hydrate layer, adopting the conduit assembly in a jet drilling mode, and standing for 5 hours after the jet process is finished;
s2: drilling, namely drilling a hydrate layer, and forming a dust and sand pocket downwards exceeding 20 meters below the hydrate layer, wherein the dust and sand pocket is used for precipitating drill cuttings and producing dust and sand;
s3: providing an in-well drilling tool in S1 and S2, lowering a production sleeve, a single-wall drilling rod and a double-wall drilling rod, enabling the lower end of the double-wall drilling rod to be connected with a gas-water mixer, enabling the lower end of the gas-water mixer to be connected with the single-wall drilling rod, enabling the upper end of the double-wall drilling rod to be connected with a gas supply mechanism, enabling the single-wall drilling rod to be connected with a remote control blowout preventer, and enabling the remote control blowout preventer to be used for setting a wellhead;
s4: and closing the well sealing flashboard group of the remote control well plugging device, injecting compressed gas into the double-wall drill rod by using the gas supply mechanism, enabling the compressed gas to enter the gas-water mixer through the annular gap of the double-wall drill rod, enabling the compressed gas to flow into the inner barrel of the double-wall drill rod at the gas-water mixer, and enabling high-pressure fluid at the bottom of a well to flow into the inner barrel of the single-wall drill rod so as to decompose hydrates.
Compared with the prior art, the invention has the following technical effects:
the device and the method for rapidly exploiting the natural gas hydrate by gas drive provided by the invention are convenient to monitor and manage, reduce the underground risk, the lower end of the gas supply mechanism is connected with the upper end of the double-wall drill rod, the lower end of the double-wall drill rod is connected with one end of the gas-water mixer, the other end of the gas-water mixer is connected with the upper end of the single-wall drill rod, the lower end of the single-wall drill rod stretches into the conduit assembly and stretches into the hydrate layer together with the lower end of the conduit assembly, the single-wall drill rod and the conduit assembly can be communicated with the hydrate layer, the upper end of the conduit assembly is connected with the remote control blowout preventer, the remote control blowout preventer is used for replacing the conventional blowout preventer, the device is more suitable for exploiting the hydrate, no working condition of abnormal high pressure in the well is caused, the remote control blowout preventer does not need to be connected with the drilling vessel by wired water, gas, electricity and other pipelines, the invention simplifies the working flow, the gas supply mechanism is used for introducing high-pressure gas into the gas-water mixer through the annular gap of the double-wall drill rod, the gas-water mixer is used for introducing the high-pressure gas into the inner barrel of the double-wall drill rod, the inner barrel of the single-wall drill rod is negative in pressure relative to the hydrate layer, fluid in the hydrate layer flows into the inner barrel of the single-wall drill rod, the surrounding pressure of the hydrate is reduced at the moment and starts to decompose, the decomposed hydrate enters the inner barrel of the single-wall drill rod together with formation water and moves upwards continuously, finally reaches the gas-water mixer to be mixed with compressed gas, and rises to the drilling vessel together for subsequent separation operation.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an apparatus for gas-driven rapid gas hydrate recovery in accordance with the first embodiment;
FIG. 2 is an enlarged schematic view at A in FIG. 1;
FIG. 3 is a schematic diagram of one of the steps in the second embodiment;
FIG. 4 is a schematic diagram of the second embodiment in the second step;
FIG. 5 is a schematic diagram of the second embodiment at the third step;
FIG. 6 is a schematic diagram of the second embodiment at the time of step four;
in the figure: 100-gas drive rapid natural gas hydrate exploitation device, 1-drilling vessel, 2-nitrogen making machine, 3-air compressor, 4-injection pipe, 5-gas box, 6-slurry outlet pipe, 7-three-phase separator, 8-gas collecting pipe, 9-storage tank, 10-double-wall drill pipe, 11-single-wall drill pipe, 12-remote control blowout preventer, 13-bearing base plate, 14-surface casing, 15-production casing, 16-through hole, 17-well closing flashboard group, 18-acoustic controller, 19-valve island, 20-energy accumulator and 21-gas-water mixer.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a device and a method for rapidly mining natural gas hydrate by gas flooding, which are used for solving the technical problems of high difficulty and complex working flow of the existing natural gas hydrate mining.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Example 1
As shown in fig. 1-2, the present embodiment provides an apparatus 100 for gas-driven rapid-mining of natural gas hydrate, which comprises a gas supply mechanism, a double-wall drill pipe 10, a gas-water mixer 21, a single-wall drill pipe 11, a remote control blowout preventer 12 and a conduit assembly, wherein the gas supply mechanism is installed on a drilling vessel 1, is convenient for monitoring and management, reduces the risk of underground, the lower end of the gas supply mechanism is connected with the upper end of the double-wall drill pipe 10, the lower end of the double-wall drill pipe 10 is connected with one end of the gas-water mixer 21, the other end of the gas-water mixer 21 is connected with the upper end of the single-wall drill pipe 11, the lower end of the single-wall drill pipe 11 extends into the conduit assembly and extends into the hydrate layer together with the lower end of the conduit assembly, and the single-wall drill pipe 11 and the conduit assembly can be communicated with the hydrate layer, the upper end of the conduit assembly is connected with the remote control blowout preventer 12, the conventional blowout preventer is replaced by the remote control blowout preventer 12, the device is more suitable for hydrate exploitation, has no working condition of abnormal high pressure in a well, the remote control blowout preventer 12 is not required to be connected with a drilling ship 1 by using wired water, gas, electricity and other pipelines, the working flow is simplified, a gas supply mechanism is used for introducing high-pressure gas into a gas-water mixer 21 through an annular gap of a double-wall drill rod 10, the gas-water mixer 21 is used for introducing the high-pressure gas into an inner cylinder of the double-wall drill rod 10, the inner cylinder of the single-wall drill rod 11 is internally provided with a negative pressure relative to a hydrate layer, fluid in the hydrate layer flows into the inner cylinder of the single-wall drill rod 11, the surrounding pressure of the hydrate is reduced at the moment, the decomposed hydrate and stratum water enter the inner cylinder of the single-wall drill rod 11 together and are continuously moved upwards, finally reach the position of the gas-water mixer 21 to be mixed with the compressed gas together to be lifted onto the drilling ship 1 for subsequent separation operation, meanwhile, the double-wall drill rod 10 and the single-wall drill rod 11 are used as main exploitation pipelines to replace marine drilling risers, so that the working difficulty is reduced, and the working flow is simplified.
Specifically, the air feed mechanism includes nitrogen making machine 2, air compressor machine 3, injection pipe 4 and gas box 5, nitrogen making machine 2 links to each other with air compressor machine 3, and air compressor machine 3 links to each other with gas box 5 through injection pipe 4, gas box 5 is connected with the upper end of double-walled drilling rod 10, air compressor machine 3 is used for letting in gas box 5 through injection pipe 4 after compressing the nitrogen gas that nitrogen making machine 2 produced, gas box 5 is used for letting in annular gap with high-pressure nitrogen gas, annular gap is the clearance that forms between the inner tube outer wall and the urceolus inner wall of double-walled drilling rod 10, and then be convenient for let in gas-water mixer 21 with high-pressure nitrogen gas through annular gap.
The device 100 for rapidly producing natural gas hydrate by gas drive provided in this embodiment further comprises a slurry outlet pipe 6, a three-phase separator 7, a gas collecting pipe 8 and a storage tank 9 which are arranged on the drilling vessel 1, wherein one end of the slurry outlet pipe 6 is connected and communicated with the inner cylinder of the double-wall drill pipe 10, the other end of the slurry outlet pipe 6 is connected and communicated with the three-phase separator 7, the slurry outlet pipe 6 is used for guiding the mixture in the inner cylinder of the double-wall drill pipe 10 into the three-phase separator 7, the three-phase separator 7 is used for separating gas, liquid and solid, and further separating the mixture led out by the slurry outlet pipe 6, and the separated natural gas is led into the storage tank 9 through the gas collecting pipe 8 for collection.
The specific structure and principle of the air-water mixer 21 are consistent with the prior art, when the air compressor 3 injects compressed nitrogen with the volume of V1 and the pressure of P1 into the double-wall drill rod 10, the volume of the air becomes V2 and the pressure becomes P2 when the compressed nitrogen reaches the installation position H1 of the air-water mixer 21. According to the ideal gas state formula pv=nrt, assuming a constant gas temperature, the gas volume v2=v1×p1/P2, where p2=p1—Δp is an equation proportional to the installation position H1 of the gas-water mixer 21. Then the air compressor 3 can be considered to lift the V2 volume of water in the inner cylinder of the single-wall drill pipe 11 to the ship, so that the pressure in the single-wall drill pipe 11 is negative compared with the pressure in the hydrate layer, the fluid in the hydrate layer flows into the single-wall drill pipe 11, the surrounding pressure of the hydrate is reduced at the moment, the decomposed hydrate enters the single-wall drill pipe 11 together with formation water and moves upwards continuously, finally reaches the gas-water mixer 21 to be mixed with nitrogen, and rises to the deck of the drilling ship 1 together for subsequent separation operation.
The remote control blowout preventer 12 comprises a hydraulic connector, a blowout preventer stack 17, a high-pressure accumulator 20, a valve island 19 and an acoustic controller 18, wherein the hydraulic connector is positioned at a low-pressure wellhead at the upper end of the conduit assembly, the hydraulic connector can seal the low-pressure wellhead at the upper end of the conduit assembly, namely, the hydraulic connector (H4 type) is arranged at the lower part of the remote control blowout preventer 12, the hydraulic connector can realize the sealing of the remote control blowout preventer 12 and the low-pressure wellhead by the hydraulic connector through the ROV under water supply hydraulic pressure, the blowout preventer stack 17 is positioned below the double-wall drill rod 10 and above the conduit assembly and positioned at the periphery of the single-wall drill rod 11, the high-pressure accumulator 20, the valve island 19 and the acoustic controller 18 are all arranged at the upper end of the conduit assembly, and the acoustic controller 18 is used for receiving acoustic information sent out on the drilling vessel 1 and controlling the valve island 19 to open and close, and the underwater flashboard switch action can be realized only by providing corresponding acoustic signals on the water surface. When each element is installed and the single-wall drill rod 11 passes through the well sealing flashboard group 17, flashboard of the well sealing flashboard group 17 is controlled to be in a separated open state, namely, the flashboard is not contacted with the outer wall of the single-wall drill rod 11, before the single-wall drill rod 11 is lowered in place to open the gas drive, an acoustic control signal for closing the well sealing flashboard group 17 is sent to the remote control blowout preventer 12 on the drillship 1, the acoustic controller 18 after receiving the signal converts the acoustic signal into an electric signal and drives an electromagnetic hydraulic valve related to the valve island 19 to a corresponding working position, and at the moment, high-pressure liquid stored in the high-pressure energy accumulator 20 connected with the valve island 19 flows through the valve island 19 and finally flows to a driving cavity of the well sealing flashboard group 17, so that the closing action of the well sealing flashboard group 17 is realized. After the well closing flashboard group 17 is closed, flashboard of the well closing flashboard group 17 is tightly attached to the outer wall of the single-wall drill rod 11, the sea water above the well closing flashboard group 17 is sealed, and the hydraulic connector is sealed at the low-pressure wellhead before the well closing flashboard group 17 is closed, so that a pressure system formed in an annulus formed by the conduit assembly, the remote control well closing device 12 and the single-wall drill rod 11 is sealed from the sea water, and the influence of the sea water on depressurization is prevented.
The pipe assembly comprises a surface casing 14, a production casing 15 and a connecting element, wherein the upper end of the production casing 15 stretches into the lower end of the surface casing 14 and is limited in the surface casing 14 through the connecting element, the connecting element is a casing suspension, the upper end of the surface casing 14 is connected with the remote control blowout preventer 12, the lower end of the production casing 15 stretches into a hydrate layer, the lower end of a single-wall drill rod 11 can penetrate through the surface casing 14 and stretches into the production casing 15, a plurality of through holes 16 are formed in the lower end (corresponding to the position of the hydrate layer) of the outer wall of the production casing 15, so that a screen pipe is formed, and hydrates can conveniently enter the production casing 15 through the through holes 16 and then enter the inner barrel of the single-wall drill rod 11 again. The structure and connection relationship of the catheter assembly are consistent with the prior art, and are not described in detail herein.
The outer periphery of the surface casing 14 is also provided with a bearing base plate 13, the bearing base plate 13 is used for being supported on a seabed mud line and used for bearing the weight of the conduit assembly, and the specific connection mode and the bearing principle of the bearing base plate 13 and the surface casing 14 are consistent with the prior art.
Example two
As shown in fig. 3-6, the present embodiment discloses a method for gas-driven rapid gas hydrate exploitation, and the apparatus 100 for gas-driven rapid gas hydrate exploitation in the first embodiment is used, and includes the following steps:
s1: as shown in fig. 3, according to the earlier geological data, calculating the pressure of the hydrate layer in the drilled area, converting the force applied to the remote control blowout preventer 12 according to the hydrate layer pressure into the required surface casing 14 weight+the wall friction force suitable for the depth of the hole+the weight of the remote control blowout preventer 12, wherein the depth of the surface casing 14 is a variable, and the surface casing is dynamically adjustable, and a pipe assembly is arranged in a jet drilling mode, and the pipe assembly is left for 5 hours after the completion of the jet process (the specific standing time can be adjusted according to actual needs by a person skilled in the art), so that the stratum is recovered to absorb the production casing 15, and vacuum is formed to serve the subsequent well sealing;
s2: as shown in fig. 4, on the basis of the completion of the surface casing 14, a second drilling is started to drill the hydrate layer and form a dust and sand pocket downwards 20 meters beyond the lower ground of the hydrate layer, wherein the dust and sand pocket is used for precipitating drill cuttings and producing dust and sand, so that well burial is avoided;
s3: as shown in fig. 5, the well drilling tool in S1 and S2 is put into the production casing 15, the single-wall drill rod 11 and the double-wall drill rod 10, the lower end of the double-wall drill rod 10 is connected with the gas-water mixer 21, the lower end of the gas-water mixer 21 is connected with the single-wall drill rod 11, the upper end of the double-wall drill rod 10 is connected with the gas box 5, the gas box 5 is also connected with the top drive output shaft, the single-wall drill rod 11 is connected with the remote control blowout preventer 12, and the wellhead is sealed by the remote control blowout preventer 12;
s4: as shown in fig. 6, the well closing shutter group 17 of the remote control blowout preventer 12 is closed to avoid the communication of the hydrate layer with the sea floor, so that the closed pressure system is destroyed, the combination of the nitrogen making machine 2 and the air compressor 3 is used to inject compressed gas into the double-wall drill pipe 10, the compressed gas enters the gas-water mixer 21 through the annular gap of the double-wall drill pipe 10, and flows into the inner cylinder of the double-wall drill pipe 10 at the gas-water mixer 21, and as the high pressure nitrogen is mixed with the liquid, the density of the liquid is reduced, so that the high pressure fluid at the bottom of the well flows to the inner cylinder of the single-wall drill pipe 11, thereby reducing the pressure of the hydrate layer and decomposing the hydrate.
The composite structure of the double-wall drill pipe 10, the gas-water mixer 21 and the single-wall drill pipe 11 is used for forming a main exploitation pipeline, so that the structure and the configuration of a natural gas hydrate exploitation pipeline are simplified, the depressurization exploitation of the natural gas hydrate can be completed at the bottom of a well, and mineral particles do not need to be transported to a drilling ship 1 to be decomposed.
The principles and embodiments of the present invention have been described in this specification with reference to specific examples, the description of which is only for the purpose of aiding in understanding the method of the present invention and its core ideas; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In summary, the present description should not be construed as limiting the invention.
Claims (6)
1. A method for rapidly mining natural gas hydrate by gas flooding is characterized by comprising the following steps of: the device for rapidly opening the natural gas hydrate by using the gas drive comprises a gas supply mechanism, a double-wall drill rod, a gas-water mixer, a single-wall drill rod, a remote control blowout preventer and a conduit assembly, wherein the gas supply mechanism is arranged on a drilling ship, the lower end of the gas supply mechanism is connected with the upper end of the double-wall drill rod, the lower end of the double-wall drill rod is connected with one end of the gas-water mixer, the other end of the gas-water mixer is connected with the upper end of the single-wall drill rod, the lower end of the single-wall drill rod stretches into the conduit assembly and stretches into a hydrate layer together with the lower end of the conduit assembly, the single-wall drill rod and the conduit assembly can be communicated with the hydrate layer, the upper end of the conduit assembly is connected with the remote control blowout preventer, the gas supply mechanism is used for introducing high-pressure gas into the gas mixer through an annular gap of the double-wall drill rod, the gas-water mixer is used for introducing high-pressure gas into the inner cylinder into the double-wall drill rod, and decomposing fluid into a stratum gas-water mixture through the double-wall drill rod into the high-pressure gas-water mixer and the high-pressure gas-decomposed into the water mixture flowing into the stratum on the drilling ship; the device for rapidly exploiting natural gas hydrate by using the gas drive comprises the following steps:
s1: calculating the pressure of a hydrate layer in a drilled area according to the early geological data, selecting parameters of the conduit assembly according to the hydrate layer pressure, adopting the conduit assembly in a jet drilling mode, and standing for 5 hours after the jet process is finished;
s2: drilling, namely drilling a hydrate layer, and forming a dust and sand pocket downwards exceeding 20 meters below the hydrate layer, wherein the dust and sand pocket is used for precipitating drill cuttings and producing dust and sand;
s3: providing the drilling tools in the wells in S1 and S2, and lowering a production sleeve, the single-wall drilling rod and the double-wall drilling rod, enabling the lower end of the double-wall drilling rod to be connected with the gas-water mixer, enabling the lower end of the gas-water mixer to be connected with the single-wall drilling rod, enabling the upper end of the double-wall drilling rod to be connected with the gas supply mechanism, enabling the single-wall drilling rod to be connected with the remote control blowout preventer, and enabling the remote control blowout preventer to be used for setting a wellhead;
s4: and closing the well sealing flashboard group of the remote control well plugging device, injecting compressed gas into the double-wall drill rod by using the gas supply mechanism, enabling the compressed gas to enter the gas-water mixer through the annular gap of the double-wall drill rod, enabling the compressed gas to flow into the inner barrel of the double-wall drill rod at the gas-water mixer, and enabling high-pressure fluid at the bottom of a well to flow into the inner barrel of the single-wall drill rod so as to decompose hydrates.
2. The method for gas-driven rapid exploitation of natural gas hydrate according to claim 1, wherein the method comprises the following steps: the air supply mechanism comprises a nitrogen making machine, an air compressor, an injection pipe and an air box, wherein the nitrogen making machine is connected with the air compressor, the air compressor is connected with the air box through the injection pipe, the air box is connected with the upper end of the double-wall drill rod, the air compressor is used for compressing nitrogen produced by the nitrogen making machine and then introducing the nitrogen into the air box through the injection pipe, and the air box is used for introducing high-pressure nitrogen into the annular gap.
3. The method for gas-driven rapid exploitation of natural gas hydrate according to claim 1, wherein the method comprises the following steps: the device for rapidly exploiting natural gas hydrate by gas drive further comprises a slurry outlet pipe, a three-phase separator, a gas collecting pipe and a storage tank, wherein the slurry outlet pipe, the three-phase separator, the gas collecting pipe and the storage tank are arranged on a drilling ship, one end of the slurry outlet pipe is connected and communicated with the inner cylinder of the double-wall drill rod, the other end of the slurry outlet pipe is connected and communicated with the three-phase separator, the slurry outlet pipe is used for guiding out a mixture in the inner cylinder of the double-wall drill rod, the three-phase separator is used for separating the mixture guided out by the slurry outlet pipe, and the separated natural gas is led into the storage tank through the gas collecting pipe to be collected in the storage tank.
4. The method for gas-driven rapid exploitation of natural gas hydrate according to claim 1, wherein the method comprises the following steps: the remote control blowout preventer comprises a hydraulic connector, a well closing flashboard group, a high-pressure energy accumulator, a valve island and an acoustic controller, wherein the hydraulic connector is positioned at a low-pressure wellhead at the upper end of the conduit assembly, the hydraulic connector can seal the low-pressure wellhead at the upper end of the conduit assembly, the well closing flashboard group is positioned below the double-wall drill rod and above the conduit assembly and at the periphery of the single-wall drill rod, the high-pressure energy accumulator, the valve island and the acoustic controller are all arranged at the upper end of the conduit assembly, the acoustic controller is used for receiving acoustic information sent by a drilling ship and controlling the valve island to be opened and closed, and when the valve island is opened, high-pressure liquid in the high-pressure energy accumulator can enter a driving cavity of the well closing flashboard group and drive the well closing flashboard group to be attached to the periphery of the single-wall drill rod.
5. The method for gas-driven rapid exploitation of natural gas hydrate according to claim 1, wherein the method comprises the following steps: the pipe assembly comprises a surface casing, a production casing and a connecting element, wherein the upper end of the production casing extends into the lower end of the surface casing and is limited in the surface casing through the connecting element, the upper end of the surface casing is connected with the remote control blowout preventer, the lower end of the production casing extends into a hydrate layer, the lower end of the single-wall drill rod can penetrate through the surface casing and extend into the production casing, and a plurality of through holes are formed in the lower end of the outer wall of the production casing.
6. The method for gas-driven rapid exploitation of natural gas hydrate according to claim 5, wherein the method comprises the following steps: the periphery of the surface sleeve is also provided with a bearing base plate, and the bearing base plate is used for being supported on a seabed mud line.
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| CN111395962B (en) * | 2020-05-13 | 2024-04-26 | 吉林大学 | Sea area natural gas hydrate gas lift reverse circulation drilling system and exploitation method |
| CN112832706A (en) * | 2021-02-18 | 2021-05-25 | 中国地质科学院勘探技术研究所 | Multifunctional underwater wellhead device for ocean drilling |
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