A thermal insulation and pressure maintaining coring system and a coring method

Abstract

The present application relates to the technical field of pressure-maintaining and heat-insulating coring, in particular to a heat-insulating and pressure-maintaining coring system and a coring method, which realizes segmented and rapid installation and disassembly of a pressure-maintaining coring device, a fishing bullet clamping and suspending mechanism, an inner tube bullet clamping and suspending mechanism, a core pressure-maintaining section of an inner tube assembly, a middle tube high-pressure sealing mechanism and a middle tube drill bit in a low-temperature mouse hole on a drilling platform surface, and meets the low-temperature preservation requirement of hydrate core. Through rapid segmented disassembly, one set of fishing bullet clamping and suspending mechanism, inner tube bullet clamping and suspending mechanism and multiple sets of core pressure-maintaining sections of inner tube assembly, middle tube high-pressure sealing mechanism and middle tube drill bit can be rapidly connected and replaced during the coring process, multiple-time pressure-maintaining coring batch operation can be realized, and work efficiency is improved. The segmented and rapid installation and disassembly can also solve the problem that the pressure-maintaining coring device is too long to be connected.

Description

Technical Field

[0001] This invention relates to the field of pressure-holding and heat-insulating coring technology, and specifically to a pressure-holding and heat-insulating coring system and coring method. Background Technology

[0002] Natural gas hydrate pressure-maintaining coring addresses the issue of hydrate decomposition caused by temperature and pressure changes during coring. In pressure-maintaining coring operations, after coring is completed inside the well, the core is retrieved via rope to the drilling platform for disassembly. If disassembly time is prolonged at the wellhead of the pressure-maintaining corer, high temperatures in the air can transfer heat to the hydrate inside the corer. If the temperature becomes too high, the hydrate inside the corer may decompose, causing a rapid increase in pressure and compromising operational safety. Summary of the Invention

[0003] The purpose of this invention is to provide a heat-insulating and pressure-insulating coring system and coring method to solve the problems existing in the prior art.

[0004] To address the problems existing in the prior art, the present invention adopts the following technical solution:

[0005] A thermal insulation and pressure-maintaining coring system includes a pressure-maintaining coring tool used in conjunction with a low-temperature rat hole on the drilling platform. The low-temperature rat hole is located on the drilling platform of a drilling vessel or drilling platform. The thermal insulation and pressure-maintaining coring system includes a differential control part, a core pressure-maintaining part, and a central drill bit. The differential control part and the core pressure-maintaining part are detachably connected.

[0006] The pressure-holding core extractor is equipped with two sets of retrieval devices: a pressure-holding core extractor feeding retrieval device and a pressure-holding core extractor differential control retrieval device.

[0007] The differential control section includes a pressure-holding core extractor middle tube retrieval spring clip suspension mechanism and a pressure-holding core extractor inner tube spring clip suspension mechanism. The pressure-holding core extractor inner tube spring clip suspension mechanism is fixedly installed in the pressure-holding core extractor middle tube retrieval spring clip suspension mechanism and can slide axially relative to the pressure-holding core extractor middle tube retrieval spring clip suspension mechanism. The pressure-holding core extractor middle tube retrieval spring clip suspension mechanism includes a spring clip and a suspension ring.

[0008] The core pressure-maintaining section includes an inner tube assembly core pressure-maintaining section and a middle tube high-pressure sealing mechanism. The inner tube assembly core pressure-maintaining section is sleeved and suspended within the middle tube high-pressure sealing mechanism. An inner tube sealing limit joint is provided at the lower end of the inner tube assembly core pressure-maintaining section. A middle tube sealing joint is provided at the upper end of the middle tube high-pressure sealing mechanism. A limit ring is also sleeved at the lower part of the middle tube sealing joint. The inner tube sealing limit joint is sleeved within the middle tube sealing joint and can slide relative to it. The upper limit of its sliding is when the inner tube limit joint contacts the limit ring and forms a seal.

[0009] Before coring, the pressure-holding coring device is fed into the retrieval device through the drill pipe channel to the outer tube assembly. The suspension ring contacts and limits the contact with the seat ring of the outer tube assembly, and is simultaneously fixed to the spring clip and spring clip chamber. After coring, the pressure-holding coring device differentially controls the retrieval device to retrieve the pressure-holding coring device through the drill pipe channel. The outer tube assembly is connected to the drill pipe channel and lowered to the seabed for coring.

[0010] As an improvement to the technical solution of the heat preservation and pressure retention coring system of the present invention, the lower end of the pressure retention coring device sent into the retrieval device and the lower end of the pressure retention coring device differential control retrieval device are respectively provided with a first elastic retrieval hook and a third elastic retrieval hook.

[0011] The upper end of the suspension mechanism for the retrieval spring clip in the middle tube of the pressure-holding core extractor is provided with a first retrieval spear, which can be connected to the first elastic retrieval hook or the third elastic retrieval hook respectively.

[0012] The first elastic retrieval hook or the third elastic retrieval hook is connected to the first retrieval spear respectively, and the pressure-holding core extractor is fed into the retrieval device or the pressure-holding core extractor differential control retrieval device is correspondingly connected to the differential control part of the pressure-holding core extractor middle tube retrieval spring clip suspension mechanism.

[0013] The lower end of the inner tube spring clip suspension mechanism of the pressure-holding coring device is provided with a third quick-connect female connector, and the upper end of the core pressure-holding section of the inner tube assembly is provided with a third quick-connect male connector. The third quick-connect female connector is inserted into the third quick-connect male connector, and the connection is quickly made by rotating it horizontally at a certain angle and locking it to form a fixed connection. The inner tube spring clip suspension mechanism of the pressure-holding coring device and the core pressure-holding section of the inner tube assembly are locked together.

[0014] The pressure-holding core extractor's middle tube retrieval spring clip suspension mechanism also includes a release slide tube, a first connecting tube, a spring clip, a second connecting tube, and a second quick-connecting female connector. The pressure-holding core extractor's inner tube spring clip suspension mechanism includes an inner spring clip. The inner tube assembly core pressure-holding section includes a PC core tube. The middle tube high-pressure sealing mechanism includes a ball valve and a third spring.

[0015] Before coring, the core pressure-maintaining section of the inner tube assembly is fitted inside the high-pressure sealing mechanism of the middle tube on the drill deck. It is then hoisted to the cryogenic rig on the drill platform. The pressure-maintaining core sampler is then inserted into the retrieval device and connected to the retrieval spring clip suspension mechanism of the pressure-maintaining core sampler via the first elastic retrieval hook and the first retrieval spear. The differential control section is hoisted above the core pressure-maintaining section. The third quick-connect female connector is inserted into the third quick-connect male connector and rotated horizontally at a certain angle relative to the third quick-connect male connector to fix the inner tube spring clip suspension mechanism to the inner tube assembly. The core pressure holding section is formed, and the inner tube assembly core pressure holding section is disconnected from the middle tube sealing mechanism and suspended. The inner tube assembly core pressure holding section is lowered until the second connecting pipe contacts the middle tube sealing joint. The second quick connecting female joint is locked to the middle tube sealing joint, completing the connection between the differential control part and the core pressure holding part. The differential control part and the core pressure holding part are then lowered from the deck wellhead into the outer tube assembly through the pressure holding core sampler. The outer tube assembly has been lowered into the borehole on the seabed through the drill pipe connection. The pressure holding core sampler is then retrieved and sent into the retrieval device.

[0016] After the core is extracted, the differential control retrieval device of the pressure-holding core extractor is connected to the first retrieval spear through the third elastic retrieval hook. The third elastic retrieval hook and the fitting joint are inserted into the upper part of the third elastic retrieval hook, so that the lower part of the third elastic retrieval hook is disengaged from the first retrieval spear, and the two can slide relative to each other differentially.

[0017] The differential control of the lifting pressure-holding core sampler drives the unjammed slide tube to move upward, and the linkage lift drives the inner tube unjammed tube to move upward. The retracted inner spring clip makes elastic contact with the first connecting tube to achieve unjamming. When the PC core tube moves upward to above the ball valve, the ball valve is overturned under the action of the third spring, forming the lower seal of the middle tube high-pressure sealing mechanism.

[0018] Continue to lift the slide tube upwards so that its lower end contacts the spring clip, and retract the spring clip to make contact with the elastic limit of the spring clip chamber, thereby achieving the separation of the pressure-holding core extractor from the outer tube assembly;

[0019] Continue to lift the inner tube sealing limit joint until it is fully inside the limit ring, forming an upward limit and seal.

[0020] As an improvement to the technical solution of the heat preservation and pressure-maintaining coring system of the present invention, both sets of the retrieval devices include a lifting device. The lifting device can be connected to the pressure-maintaining coring device feeding retrieval device and the pressure-maintaining coring device differential control retrieval device, respectively. The lifting device includes a first quick-connect female connector. The pressure-maintaining coring device feeding retrieval device and the pressure-maintaining coring device differential control retrieval device each include a first quick-connect male connector and a second quick-connect male connector. The first quick-connect female connector can be inserted into the first quick-connect male connector and the second quick-connect male connector, and rotated horizontally by a certain angle and locked to form a fixed connection. The lifting device is replaceable and detachable from the pressure-maintaining coring device feeding retrieval device and the differential control part.

[0021] As an improvement to the technical solution of the heat preservation and pressure-maintaining core sampling system of the present invention, the first quick-connect female connector and the third quick-connect female connector have the same functional structure, and the first quick-connect male connector, the second quick-connect male connector and the third quick-connect male connector have the same functional structure.

[0022] As an improvement to the technical solution of the heat preservation and pressure retention coring system of the present invention, the pressure retention coring device is fed into the retrieval device including a counterweight rod. The upper end of the counterweight rod is provided with the first quick-connect male connector, and the lower end of the counterweight rod is connected to a single-acting bearing, a perforated connecting pipe, a limit nut, a perforated pipe connecting connector, a sliding rod, a release sliding sleeve, a water inlet, and a first elastic retrieval hook.

[0023] The lower counterweight bar presses the release sleeve into the upper part of the first elastic retrieval hook, causing the lower part of the first elastic retrieval hook to open and release. The pressure-holding core extractor is then sent into the retrieval device and separated from the retrieval spring suspension mechanism of the pressure-holding core extractor's central tube.

[0024] As an improvement to the technical solution of the heat preservation and pressure retention coring system of the present invention, the tube retrieval spring clip suspension mechanism of the pressure retention coring device further includes a first retrieval spear, a second retrieval hook, a second retrieval spear, a connector, a release slide tube, a release slide tube long groove, a spring clip bracket, a spring clip, a release slide tube second elastic pin long groove, a first connecting pipe, a first connecting pipe second elastic pin long groove, a suspension ring, a second connecting pipe, a third connecting pipe, and a second quick connection female connector;

[0025] The first retrieval spear is disposed at the upper end of the retrieval cartridge suspension mechanism of the middle tube of the pressure-holding core extractor, and the lower end of the first retrieval spear is fixedly connected to the second retrieval hook, and the second retrieval spear and the second retrieval hook are adapted to be connected.

[0026] The lower part of the second retrieval spear is connected to the spring clip bracket, and the spring clip is installed in the slot of the spring clip bracket and can be opened and closed elastically;

[0027] The first connecting tube is disposed below the spring clip bracket. The first connecting tube includes a second elastic pin groove, which is a through-hole of the first connecting tube and is arranged along the length of the first connecting tube. The release slide tube is provided with a through-hole release slide tube groove and a second elastic pin groove, which are arranged along the length of the release slide tube. The second elastic pin groove of the first connecting tube and the second release slide tube groove overlap each other. The second elastic pin passes through the second elastic pin groove of the first connecting tube and the second release slide tube groove. The release slide tube groove and the second elastic pin groove of the release slide tube form a 90° angle in the radial plane. The spring clip is disposed in the release slide tube groove. A suspension ring is sleeved on the lower end of the first connecting tube. The second connecting tube is connected to the lower part of the first connecting tube and fixes the suspension ring. The lower part of the second connecting tube is fixedly connected to the third connecting tube, and the lower part of the third connecting tube is provided with a second quick-connect female connector.

[0028] As an improvement to the technical solution of the heat preservation and pressure retention core extraction system of the present invention, the inner tube spring clip suspension mechanism of the pressure retention core extractor includes a second elastic pin, an inner tube release tube, an inner spring clip, a third elastic pin, an inner tube spring clip bracket, a single-action mechanism, an adjustable length connection and a second spring, and the third quick connection female connector includes a fourth elastic pin and a second transmission paddle.

[0029] The second elastic pin is inserted in the inner tube release tube, and the second elastic pin is inserted in the first connecting tube second elastic pin long groove and the release slide tube second elastic pin long groove of the pressure-holding core extractor middle tube retrieval spring clip suspension mechanism. The second elastic pin can drive the pressure-holding core extractor inner tube spring clip suspension mechanism to move axially to release the clip within the pressure-holding core extractor middle tube retrieval spring clip suspension mechanism.

[0030] When the release slide tube moves upward, the bottom end of the long groove of the second elastic pin of the release slide tube contacts the second elastic pin, which can drive the inner tube release tube to move upward accordingly, thereby retrieving the inner spring clip, disengaging the inner tube spring clip suspension mechanism of the pressure-holding core extractor from the middle tube retrieval spring clip suspension mechanism of the pressure-holding core extractor, and generating relative axial movement.

[0031] The inner spring clip is mounted on the inner tube spring clip bracket, the inner tube spring clip bracket is fixedly connected to the single-action mechanism, the adjustable length connection is fixedly connected to the single-action mechanism, and the length of the connection can be finely adjusted relative to the single-action mechanism through threads and a locking nut;

[0032] The two ends of the second spring respectively abut against one end of the length-adjusting connector and the second transmission lever, and the second transmission lever is fixed by the fourth elastic pin. The fourth elastic pin is set in the through-hole of the third quick-connect female connector to bear the thrust of the second spring, and is inserted into the groove at the top of the first quick-connect male connector to bear the connection torque. The third transmission lever can compress the second spring and slide upward to disengage from the groove at the top of the third quick-connect male connector. The third quick-connect female connector can be disengaged by rotating horizontally at a certain angle relative to the third quick-connect male connector.

[0033] As an improvement to the technical solution of the heat preservation and pressure retention coring system of the present invention, the differential control retrieval device of the pressure retention coring device includes a connecting rod, the upper end of the connecting rod is provided with a single-action mechanism, and the upper end of the single-action mechanism is provided with a second quick-connect male connector for connecting with the first quick-connect female connector.

[0034] As an improvement to the technical solution of the heat preservation and pressure-maintaining core sampling system of the present invention, the high-pressure sealing mechanism of the middle tube includes a middle tube sealing joint, a limiting ring, a middle tube short section, a middle tube, a ball valve drive short section, a spring limiting ring, a third spring, a drive tube, an upper ball valve seat, a ball valve tube, a ball valve, a lower ball valve seat, a lower support spring, a lower ball valve seat support ring, and a short section.

[0035] The inner tube assembly core pressure holding section includes a PC core tube, which is sleeved in the middle tube short section and the middle tube. The inner tube assembly core pressure holding section can move axially relative to the middle tube high pressure sealing mechanism.

[0036] The high-pressure sealing mechanism of the central tube works in conjunction with the PC core tube to achieve the effect of the ball valve sliding downward and rotating by a certain 90°, thus sealing the lower part of the central tube.

[0037] As an improvement to the technical solution of the heat preservation and pressure retention coring system of the present invention, the certain angle is 90°.

[0038] A method for obtaining the heart includes the following steps:

[0039] S1. Wellhead preparation: Install the inner tube assembly core pressure-maintaining section into the high-pressure sealing mechanism of the middle tube, and hoist it into the low-temperature rat hole on the drilling platform.

[0040] S2. The pressure-holding core sampler is sent into the retrieval tool or hoisting tool and the differential control part, and is connected to the first elastic retrieval hook and the first retrieval spear, in preparation for segmented and rapid connection with the core pressure-holding section of the inner tube assembly and the high-pressure sealing mechanism of the middle tube.

[0041] S3. Insert the third quick-connect female connector into the third quick-connect male connector, rotate the quick-connect to a certain angle, lock the differential control part and the core pressure-holding part, continue to lower the core pressure-holding section of the inner tube assembly, connect the second quick-connect female connector and the middle tube sealing connector, and realize the segmented quick connection of the pressure-holding core sampler in the rat hole on the drilling platform.

[0042] S4. The pressure-holding coring device is vertically lifted out of the rat hole or the low-temperature rat hole on the drilling platform and inserted into the drill pipe at the wellhead on the drilling platform. The pressure-holding coring device is then sent into the outer pipe assembly on the seabed through the retrieval device. When the pressure-holding coring device is lowered into the outer pipe assembly and the suspension ring contacts the seat ring, and the spring clip and spring clip chamber are elastically limited, the counterweight rod is lowered to press the release sleeve into the upper part of the first elastic retrieval hook, so that the lower part of the first elastic retrieval hook opens and releases the hook. After the rope is retrieved and the pressure-holding coring device is sent into the wellhead of the retrieval device, the drilling rig connects the drill pipe and begins drilling and coring.

[0043] S5. After the core is retrieved, the differential control retrieval device of the pressure-holding core retrieval device is replaced by the first quick-connect female connector. The rope is lowered and the differential control retrieval device of the pressure-holding core retrieval device contacts the first retrieval spear. At this time, the third elastic retrieval hook and the connector are inserted into the upper part of the third elastic retrieval hook, so that the lower part of the third elastic retrieval hook is unhooked from the first retrieval spear, and the two can slide relative to each other differentially.

[0044] The differential control of the lifting pressure-holding core sampler drives the unjammed slide tube to move upward, and the linkage lift drives the inner tube unjammed tube to move upward. The retracted inner spring clip makes elastic contact with the second connecting tube to achieve unjamming. When the PC core tube moves upward to above the ball valve, the ball valve is overturned under the action of the third spring, forming the lower seal of the middle tube high-pressure sealing mechanism.

[0045] Continue to lift the first unblocking slide tube so that its lower end contacts the spring clip, and retract the spring clip to contact the elastic limit contact of the spring clip chamber, thereby realizing the unblocking of the pressure-holding core extractor from the outer tube assembly;

[0046] Continue to lift the inner tube sealing limit joint until it is fully inserted into the limit ring, forming an upward limit and seal;

[0047] S6. Retrieve the drill pipe of the pressure-holding coring device and hoist it directly into the low-temperature rat hole on the drilling platform; lower the pressure-holding coring device differential control retrieval device until the unjammed slide tube is reset, the third elastic retrieval hook is re-hooked and connected to the first retrieval spear, and the unjammed slide tube is reset to its original position before differential sliding.

[0048] S7. Disconnect the second quick-connect female connector from the middle tube sealing connector, thus breaking the connection between the middle tube retrieval spring suspension mechanism and the middle tube high-pressure sealing mechanism of the pressure-holding core extractor.

[0049] Raise the suspension mechanism of the retrieval spring clip of the pressure-holding coring device. The suspension mechanism of the retrieval spring clip of the pressure-holding coring device slides downward until the inner tube spring clip bracket sits on the upper shoulder of the third connecting pipe at the upper limit. The third quick-connect female connector and the third quick-connect male connector are exposed. Use a tool to lift the fourth elastic pin to disengage the second torque transmission plate from the top of the third quick-connect male connector. Rotate 90° to disengage the third quick-connect female connector from the third quick-connect male connector, and disconnect the quick connection between the inner tube spring clip suspension mechanism of the pressure-holding coring device and the core pressure-holding section of the inner tube assembly.

[0050] S8. Preparation of the circulation wellhead: Install the new inner tube assembly core pressure-maintaining section into the new middle tube high-pressure sealing mechanism, and hoist it into the drilling platform to install the rat hole.

[0051] The beneficial effects of this invention are:

[0052] This invention enables the rapid, segmented installation and disassembly of the pressure-holding coring tool's central tube retrieval spring-clamp suspension mechanism, the inner tube spring-clamp suspension mechanism and the core pressure-holding section of the inner tube assembly, the high-pressure sealing mechanism of the central tube, and the central tube drill bit within the low-temperature rat hole on the drilling platform, meeting the requirements for low-temperature preservation of hydrate cores. Through rapid segmented disassembly, one set of retrieval spring-clamp suspension mechanism, the inner tube spring-clamp suspension mechanism, and multiple sets of inner tube assembly core pressure-holding sections, the high-pressure sealing mechanism of the central tube, and the central tube drill bit can be quickly connected and replaced during coring, enabling multiple rounds of pressure-holding coring batch operations and improving work efficiency. The rapid segmented disassembly also solves the problem of the pressure-holding coring tool being too long to connect and install. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the thermal insulation and pressure-maintaining core sampling system of the present invention;

[0054] Figure 2 This is a schematic diagram of the lifting device in this invention;

[0055] Figure 3 This is a schematic diagram of the structure of the pressure-holding core extractor being fed into the retrieval device in this invention;

[0056] Figure 4 This is a schematic diagram of the differential control retrieval device for pressure-holding coring in this invention;

[0057] Figure 5 This is a schematic diagram of the suspension mechanism of the tube spring clip in the pressure-holding core extractor of the present invention;

[0058] Figure 6 This is a schematic diagram of the inner tube spring clip suspension mechanism of the pressure-holding core extractor in this invention;

[0059] Figure 7 This is a schematic diagram of the core pressure-maintaining section of the inner tube assembly in this invention;

[0060] Figure 8 This is a schematic diagram of the connection between the high-pressure sealing mechanism of the central tube and the drill bit in this invention.

[0061] Figure 9 for Figure 8 Enlarged view of point A;

[0062] Figure 10 This is a schematic diagram of the structure during core extraction in this invention;

[0063] Figure 11 This is a schematic diagram of the connection structure between the pressure-holding core extractor and the retrieval device of the present invention.

[0064] Figure 12 This is a schematic diagram of the differential control retrieval device and the pressure-holding core extractor of the present invention.

[0065] Explanation of reference numerals in the attached figures:

[0066] 10-Pressure-holding core extractor fed into the retrieval device; 101-Lifting connector; 102-First quick-connect female connector; 1021-First spring; 1022-First torque transmission plate; 1023-First elastic pin; 103-First quick-connect male connector; 111-Counterweight rod; 112-Single-acting bearing; 104-Drilled connecting pipe; 105-Limit nut; 106-Drilled pipe connecting connector; 107-Slide rod; 108-Unlocking slide sleeve; 1081-Sprue; 109-First elastic retrieval hook; 110-First elastic retrieval hook mating connector;

[0067] 20-Pressure-holding core extractor tube retrieval spring clip suspension mechanism; 201-First retrieval spear; 202-Second retrieval hook; 203-Second retrieval spear; 204-Connector; 205-Spring clip bracket; 206-Unlocking slide tube; 2061-Unlocking slide tube long groove; 2062-Unlocking slide tube second elastic pin long groove; 207-Spring clip; 208-First connecting pipe; 2081-First connecting pipe second elastic pin long groove; 209-Suspension ring; 210-Second connecting pipe; 211-Third connecting pipe; 212-Second quick-connect female connector;

[0068] 30-Pressure-holding core extractor inner tube spring clip suspension mechanism: 301-Second elastic pin; 302-Inner tube release tube; 303-Inner spring clip; 304-Third elastic pin; 305-Inner tube spring clip bracket; 306-Single-action mechanism; 307-Adjustable length connection; 308-Third quick-connect female connector; 3081-Second spring; 3082-Fourth elastic pin; 3083-Second torque transmission lever;

[0069] 40-Inner tube assembly core pressure holding section; 401-Third quick-connect male connector; 402-Pressure transmitter; 403-Pressure transmitter connecting connector; 404-Inner tube sealing limit connector; 405-Steel ball; 406-Ball seat; 407-PC core tube; 408-Retaining spring and cutter head;

[0070] 50-Middle tube high-pressure sealing mechanism: 501-Middle tube sealing joint; 502-Limiting ring; 503-Middle tube short section; 504-Middle tube; 505-Ball valve drive short section; 506-Spring limiting ring; 507-Third spring; 508-Drive tube; 509-Upper ball valve seat; 510-Ball valve tube; 511-Ball valve; 512-Lower ball valve seat; 513-Lower support spring; 514-Lower ball valve seat support ring; 515-Short section; 5101-Ball valve drive pin; 5102-Ball valve shaft flipping sliding long hole; 5111-Ball valve shaft; 5112-Ball valve slide groove;

[0071] 60-Side-tube drill bit; 601-Side-tube drill bit; 6011-Spline torque transmission;

[0072] 70-Pressure-holding core extractor differential control retrieval device: 701-Second quick-connect male connector; 702-Single-action mechanism; 703-Connecting rod; 704-Third elastic retrieval hook; 705-Third elastic retrieval hook mating connector;

[0073] 80-Outer tube assembly; 801-Spring holder; 802-Seated ring; 803-Drill bit;

[0074] 90-Low-temperature rat hole; 901-External circulating water chiller; 901-Drilling platform. Detailed Implementation

[0075] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments.

[0076] like Figures 1 to 12 As shown, a thermal insulation and pressure-maintaining coring system includes a pressure-maintaining coring tool used in conjunction with a low-temperature rat hole 90 on the drilling platform. The low-temperature rat hole 90 on the drilling platform is set on the drilling platform of a drilling ship or drilling platform. The thermal insulation and pressure-maintaining coring system includes a differential control part, a core pressure-maintaining part, and a central tube drill bit. The differential control part and the core pressure-maintaining part are detachably connected.

[0077] The pressure-holding coring machine is equipped with two sets of retrieval devices, namely the pressure-holding coring machine feeding retrieval device 10 and the pressure-holding coring machine differential control retrieval device 70.

[0078] The differential control section includes a pressure-holding core extractor middle tube retrieval spring clip suspension mechanism 20 and a pressure-holding core extractor inner tube spring clip suspension mechanism 30. The pressure-holding core extractor inner tube spring clip suspension mechanism 30 is fixedly installed in the pressure-holding core extractor middle tube retrieval spring clip suspension mechanism 20 and can slide axially relative to the pressure-holding core extractor middle tube retrieval spring clip suspension mechanism 20. The pressure-holding core extractor middle tube retrieval spring clip suspension mechanism 20 includes a spring clip 207.

[0079] The core pressure holding section includes an inner tube assembly core pressure holding section 40 and a middle tube high-pressure sealing mechanism 50. The inner tube assembly core pressure holding section 40 is sleeved and suspended inside the middle tube high-pressure sealing mechanism 50. The lower end of the inner tube assembly core pressure holding section 40 is provided with an inner tube sealing limit joint 404. The upper end of the middle tube high-pressure sealing mechanism 50 is provided with a middle tube sealing joint 501. The lower part of the middle tube sealing joint 501 is also sleeved with a limit ring 502. The inner tube sealing limit joint 404 is sleeved inside the middle tube sealing joint 501 and can slide relative to it. The upper limit of its sliding is when the inner tube limit joint 404 contacts the limit ring 502 and forms a seal.

[0080] Before coring, the pressure-holding coring device is sent into the retrieval device through the drill pipe channel to the outer tube assembly 80. The suspension ring 209 contacts and limits the contact with the seat ring 802 of the outer tube assembly 80, while the spring clip 207 is fixed to the spring clip chamber 801. After coring, the pressure-holding coring device differentially controls the retrieval device to retrieve the pressure-holding coring device through the drill pipe channel. The outer tube assembly 80 is connected to the drill pipe channel and lowered to the seabed for coring.

[0081] This invention enables the rapid, segmented installation and disassembly of the pressure-holding coring device's central tube retrieval spring-clamp suspension mechanism 20, the pressure-holding coring device's inner tube spring-clamp suspension mechanism 30, the inner tube assembly core pressure-holding section 40, the central tube high-pressure sealing mechanism 50, and the central tube drill bit 60 within the low-temperature rat hole 90 on the drilling platform, meeting the requirements for low-temperature preservation of hydrate cores. Through rapid segmented disassembly, one set of retrieval spring-clamp suspension mechanism and inner tube spring-clamp suspension mechanism can be quickly connected and replaced with multiple sets of inner tube assembly core pressure-holding sections 40, central tube high-pressure sealing mechanisms 50, and central tube drill bits 803 during coring, enabling multiple rounds of pressure-holding coring batch operations and improving work efficiency. The segmented rapid installation and disassembly also solves the problem of the pressure-holding coring device being too long and difficult to connect.

[0082] In detail, this invention firstly includes a pressure-maintaining coring device used in conjunction with a cryogenic rat hole 90 on the drilling platform. The cryogenic rat hole 90 ensures a low-temperature environment during coring, preventing hydrate decomposition due to high ambient temperature during the coring process. The cryogenic rat hole includes an external circulating water chiller 901 and a drilling platform 902.

[0083] Secondly, this invention is equipped with a pressure-holding coring device delivery and retrieval device 10 and a pressure-holding coring device differential control retrieval device 70, which can be used to deliver or retrieve the pressure-holding coring device into or from the cryogenic rat hole 90 before and after coring. Before coring, the pressure-holding coring device delivery and retrieval device delivers the pressure-holding coring device through the drill pipe channel to the outer tube assembly 80, where the suspension ring 209 contacts and limits contact with the seat ring 802, and the spring clip 207 is fixed to the spring clip chamber 801. After coring, the pressure-holding coring device differential control retrieval device retrieves the pressure-holding coring device through the drill pipe channel, and the outer tube assembly 80 is connected to the drill pipe channel and lowered to the seabed for coring.

[0084] Both sets of retrieval devices include lifting devices, which can be connected to the pressure-holding core feeder retrieval device 10 and the pressure-holding core feeder differential control retrieval device 70, respectively. The lifting device includes a first quick-connect female connector 102. The pressure-holding core feeder retrieval device 10 and the pressure-holding core feeder differential control retrieval device 70 each include a first quick-connect male connector 103 and a second quick-connect male connector 701. The first quick-connect female connector 102 can be inserted into the first quick-connect male connector 103 and the second quick-connect male connector 701, and rotated horizontally by a certain angle to form a fixed connection. The lifting device, the pressure-holding core feeder retrieval device 10, and the differential control part are replaceable and detachable.

[0085] Furthermore, the differential control retrieval device 70 for pressure holding coring includes a connecting rod 703, the upper end of the connecting rod 703 is provided with a single-action mechanism 702, and the upper end of the single-action mechanism 702 is provided with a second quick-connect male connector 701 for connecting with the first quick-connect female connector 102.

[0086] The lower end of the second quick-connect male connector 701 is connected to a single-action mechanism 702, the lower end of the single-action mechanism 702 is connected to a connecting rod 703, and the lower end of the connecting rod 703 is provided with a third elastic retrieval hook 704 and a third elastic retrieval hook mating connector 705 that are detachably connected to each other. The third elastic retrieval hook 704 is located at the lower end of the connecting rod 703.

[0087] Third, the lower end of the pressure-holding core extractor inserted into the retrieval device 10 and the lower end of the pressure-holding core extractor differential control retrieval device 70 are respectively provided with a first elastic retrieval hook 109 and a third elastic retrieval hook 704.

[0088] The upper end of the suspension mechanism 20 for the retrieval cartridge in the middle tube of the pressure-holding core extractor is provided with a first retrieval spear 201, which can be connected to a first elastic retrieval hook 109 or a third elastic retrieval hook 704 respectively.

[0089] The first elastic retrieval hook 109 or the third elastic retrieval hook 704 are respectively connected to the first retrieval spear 201. The pressure-holding core extractor is sent into the retrieval device 10 or the pressure-holding core extractor differential control retrieval device 70 is correspondingly connected to the differential control part of the pressure-holding core extractor middle tube retrieval cartridge suspension mechanism 20.

[0090] The lower end of the inner tube spring clip suspension mechanism 30 of the pressure-holding coring device is provided with a third quick-connect female connector 308, and the upper end of the core pressure-holding section 40 of the inner tube assembly is provided with a third quick-connect male connector 401. The third quick-connect female connector 308 is inserted into the third quick-connect male connector 401, and the connection is quickly connected by rotating horizontally at a certain angle and locked to form a fixed connection. The inner tube spring clip suspension mechanism 30 of the pressure-holding coring device and the core pressure-holding section 40 of the inner tube assembly are locked together.

[0091] The pressure-holding core extractor's middle tube retrieval spring clip suspension mechanism 20 also includes a release slide tube 206, a second connecting pipe 210, a spring clip 207, a third connecting pipe 211, a second quick-connecting female connector 212, and a first release slide tube long groove 2061. The pressure-holding core extractor's inner tube spring clip suspension mechanism 30 includes an inner spring clip 303. The inner tube assembly core pressure-holding section 40 includes a PC core tube 407. The middle tube high-pressure sealing mechanism 50 includes a ball valve 511 and a third spring 507.

[0092] Before core sampling, the inner tube assembly core pressure-holding section 40 is mounted and suspended within the high-pressure sealing mechanism 50 of the middle tube on the drilling deck. It is then hoisted to the cryogenic rig on the drilling platform. The pressure-holding core sampler is then inserted into the retrieval device 10 and connected to the middle tube retrieval spring clip suspension mechanism 20 via the first elastic retrieval hook 109 and the first retrieval spear 201. The differential control section is hoisted above the core pressure-holding section. The third quick-connect female connector 308 is inserted into the third quick-connect male connector 401 and rotated horizontally at a certain angle relative to the third quick-connect male connector 401, thus fixing the inner tube spring clip suspension mechanism 30 to the inner tube assembly core. The pressure-holding section 40 is disconnected from the inner tube assembly core pressure-holding section 40 and the middle tube sealing mechanism 50. The inner tube assembly core pressure-holding section 40 is lowered until the third connecting pipe 211 contacts the middle tube sealing joint 501. The second quick connecting female joint 212 is locked to the middle tube sealing joint 501, completing the connection between the differential control part and the core pressure-holding part. The differential control part and the core pressure-holding part are then lowered from the deck wellhead into the outer tube assembly 80 through the pressure-holding core sampler into the seabed borehole. The pressure-holding core sampler is then retrieved and sent into the retrieval device 10.

[0093] After the core is retrieved, the pressure-holding core retriever differentially controls the retrieval device 70 to connect and contact the first retrieval spear 201 through the third elastic retrieval hook 704. The third elastic retrieval hook mating joint 705 is inserted into the upper part of the third elastic retrieval hook 704, so that the lower part of the third elastic retrieval hook 704 is disengaged from the first retrieval spear 201, and the two can slide relative to each other differentially.

[0094] The differential control of the lifting pressure-holding core extractor 70 drives the unblocking slide tube 206 to move upward, and the linkage lift drives the inner tube unblocking tube 302 to move upward. The retracted inner spring clip 303 makes elastic contact with the second connecting tube 210 to achieve unblocking. When the PC core tube 407 moves upward to above the ball valve, the ball valve 511 is overturned under the action of the third spring 507, forming the lower seal of the middle tube high-pressure sealing mechanism 50.

[0095] Continue to lift so that the lower end of the first unblocking slide tube long groove 2061 contacts the spring clip 207, and retract the spring clip 207 to make elastic limiting contact with the spring clip chamber 801, thereby realizing the unblocking of the pressure-holding core extractor from the outer tube assembly 80.

[0096] Continue to lift the inner tube sealing limit joint 404 until it is fully inserted into the limit ring 502, forming an upward limit and seal.

[0097] In this invention, the detachable connection between the differential control section and the core pressure holding section enables rapid segmented installation and disassembly within the 90° low-temperature rat hole on the drilling platform, improving the ease of installation and effectively avoiding hydrate decomposition due to high temperature. At the same time, the core pressure holding section can directly enter the pressure holding transfer test stage in the later stage, improving work efficiency.

[0098] Preferably, the first quick-connect female connector 102 and the third quick-connect female connector 308 have the same functional structure, and the first quick-connect male connector 103, the second quick-connect male connector 701 and the third quick-connect male connector 401 have the same functional structure.

[0099] Taking the connection of the first quick-connect female connector 102 and the first quick-connect male connector 103 as an example, the upper end of the first quick-connect female connector 102 is shoulder-shaped, and the shape of the first quick-connect male connector 103 is adapted to the first quick-connect female connector 102. When the first quick-connect female connector 102 is axially inserted into the first quick-connect male connector 103, it is rotated horizontally at a certain angle, so that the first quick-connect female connector 102 and the first quick-connect male connector 103 achieve a snap-fit ​​effect. More preferably, the certain angle is 90 degrees.

[0100] As a first embodiment of the present invention, such as Figure 2As shown, the lifting device includes a lifting connector 101, a first spring 1021, a first transmission lever 1022, a first elastic pin 1023, and a first quick-connect female connector 102. In use, a lifting tool can be connected to the lifting connector 101 to achieve lifting or lowering. The first quick-connect female connector 102 can be connected to the first quick-connect male connector 103 and the second quick-connect male connector 701 respectively, enabling the lifting device to be respectively connected to the pressure-holding core extractor feeding retrieval device 10 and the pressure-holding core extractor differential control retrieval device 70. The two ends of the first spring 1021 respectively abut against one end of the lifting connector 101 and the first transmission lever 1023, and the first transmission lever 1023 is fixed by the first elastic pin 1023. The first elastic pin 1023 is set in the through elongated hole of the first quick-connect female connector 102 to bear the thrust of the second spring 3081, and is inserted into the groove at the top of the first quick-connect male connector 103 to bear the torque. The first transmission lever 1023 can slide upward relative to the groove at the top of the first quick-connect male connector 103. The first quick-connect female connector 102 can be disengaged by rotating horizontally at a certain angle relative to the first quick-connect male connector 103.

[0101] As a second embodiment of the present invention, such as Figure 3 As shown, the pressure-holding core extractor fed into the retrieval device 10 includes a counterweight rod 111. The upper end of the counterweight rod 111 is provided with a first quick-connect male connector 103, and the lower end of the counterweight rod 111 is connected to a single-acting bearing 112, a perforated connecting pipe 104, a limit nut 105, a perforated pipe connecting connector 106, a sliding rod 107, a release sleeve 108, a sprue 1081, and a first elastic retrieval hook 109.

[0102] The lower counterweight rod 111 presses the release sleeve 108 into the upper part of the first elastic retrieval hook 109, causing the lower part of the first elastic retrieval hook 109 to open and release, and the pressure-holding core extractor is sent into the retrieval device 10 and separated from the retrieval spring clip suspension mechanism 20 in the middle tube of the pressure-holding core extractor.

[0103] The first quick-connect male connector 103 is connected to the first quick-connect female connector 102 of the lifting device, realizing the effect of quick segmented connection between the lifting device and the pressure-holding core extractor into the retrieval device 10; the first elastic retrieval hook 109 is set at the lower end of the counterweight rod 111 so that the first elastic retrieval hook 109 can be connected to the first retrieval spear 201, realizing the detachable segmented connection between the pressure-holding core extractor into the retrieval device 10 and the pressure-holding core extractor middle tube retrieval spring clip suspension mechanism 20.

[0104] As a third embodiment of the present invention, such as Figure 4As shown, the differential control retrieval device 70 for pressure-holding core extractor includes a connecting rod, and a single-action mechanism 702 is provided at the upper end of the connecting rod. A second quick-connect male connector 701 is provided at the upper end of the single-action mechanism 702 for connecting with the first quick-connect female connector 102, thereby realizing the effect of quick segmented connection between the lifting device and the differential control retrieval device for pressure-holding core extractor.

[0105] As a fourth embodiment of the present invention, such as Figure 5 As shown, the pressure-holding coring device tube retrieval spring clip suspension mechanism 20 also includes a first retrieval spear 201, a second retrieval hook 202, a second retrieval spear 203, a connector 204, a release slide tube 206, a release slide tube long groove 2061, a spring clip bracket 205, a spring clip 207, a release slide tube second elastic pin long groove 2062, a first connecting pipe 208, a first connecting pipe second elastic pin long groove 2081, a suspension ring 209, a second connecting pipe 210, a third connecting pipe 211, and a second quick-connect female connector 212;

[0106] The first retrieval spear 201 is set at the upper end of the retrieval cartridge suspension mechanism 20 of the pressure-holding core extractor tube. The lower end of the first retrieval spear 201 is fixedly connected to the second retrieval hook 202, and the second retrieval spear 203 is adapted to be connected to the second retrieval hook 202.

[0107] The lower part of the second retrieval spear 203 is connected to a cartridge holder 205, and the cartridge 207 is installed in the slot of the cartridge holder 205 and can be opened and closed elastically.

[0108] The first connecting pipe 208 is disposed below the spring clip bracket 205. The first connecting pipe 208 includes a first connecting pipe second elastic pin elongated groove 2081, which is a through elongated hole of the first connecting pipe 208 and is arranged along the length direction of the first connecting pipe 208. The release slide tube 206 is provided with a through release slide tube elongated groove 2061 and a release slide tube second elastic pin elongated groove 2062, which are arranged along the length direction of the release slide tube 206. The first connecting pipe second elastic pin elongated groove 2081 and the release slide tube elongated groove 2061 overlap each other. The second elastic pin 301 The first connecting pipe 208 is inserted into the second elastic pin groove 2081 and the release slide tube groove 2061; the release slide tube groove 2061 and the release slide tube second elastic pin groove 2062 form a 90° angle in the radial plane, and the spring clip 207 is set in the release slide tube groove 2061; the lower end of the first connecting pipe 208 is fitted with a suspension ring 209, the second connecting pipe 210 is connected to the lower part of the first connecting pipe 208 and fixes the suspension ring 209; the lower part of the second connecting pipe 210 is fixedly connected to the third connecting pipe 211, and the lower part of the third connecting pipe 211 is provided with a second quick-connect female connector 212.

[0109] As a fifth embodiment of the present invention, such as Figure 6As shown, the inner tube spring clip suspension mechanism 30 of the pressure-holding core extractor includes a second elastic pin 301, an inner tube release tube 302, an inner spring clip 303, a third elastic pin 304, an inner tube spring clip bracket 305, a single-action mechanism 306, an adjustable length connection 307, and a second spring 3081. The third quick-connect female connector 308 includes a fourth elastic pin 3082 and a second transmission paddle 3083.

[0110] The second elastic pin 301 is inserted into the inner tube release tube 302. The second elastic pin 301 is inserted into the second elastic pin long groove 2081 of the first connecting tube and the second elastic pin long groove 2062 of the release slide tube of the pressure-holding core extractor. The second elastic pin 301 can drive the inner tube release tube suspension mechanism 30 of the pressure-holding core extractor to move axially within the pressure-holding core extractor retrieval release tube suspension mechanism 20.

[0111] When the release slide tube 206 moves upward, the bottom end of the second elastic pin groove 2062 of the release slide tube contacts the second elastic pin 301, which can correspondingly drive the inner tube release tube 302 to move upward, thereby causing the inner spring clip 303 to be retracted, so that the inner tube spring clip suspension mechanism 30 of the pressure-holding core extractor is disengaged from the middle tube retrieval spring clip suspension mechanism 20 of the pressure-holding core extractor, and relative axial movement is generated.

[0112] The inner spring clip 303 is set on the inner tube spring clip bracket 305. The inner tube spring clip bracket 305 is fixedly connected to the single-action mechanism 306. The length adjustment connection 307 is fixedly connected to the single-action mechanism 306, and the length of the connection can be finely adjusted relative to the single-action mechanism 306 through the thread and the locking nut.

[0113] The two ends of the second spring 3081 respectively abut against one end of the length adjustment connector 307 and the second transmission paddle 3083, and the second transmission paddle 3083 is fixed by the fourth elastic pin 3082. The fourth elastic pin 3082 is set in the through elongated hole of the third quick-connect female connector 308 to bear the thrust of the second spring 3081, and is inserted into the groove at the top of the first quick-connect male connector 701 to bear the torque. The second transmission paddle 3083 can compress the second spring 3081 and slide upward relative to the groove at the top of the third quick-connect male connector 401. The third quick-connect female connector 308 can be disengaged by rotating horizontally at a certain angle relative to the third quick-connect male connector 401.

[0114] As a sixth embodiment of the present invention, such as Figure 7As shown, the inner tube assembly core pressure holding section 40 includes a third quick-connect female connector 308, a pressure transmitter 402, a pressure transmitter connecting connector 403, an inner tube sealing and limiting connector 404, a steel ball 405, a ball seat 406, a PC core tube 407, a retaining spring, and a cutter head 408. The third quick-connect female connector 308 can be connected to the third quick-connect male connector 401 to achieve a detachable connection between the inner tube assembly core pressure holding section 40 and the pressure holding core extractor inner tube spring clip suspension mechanism 30. During connection, the third quick-connect male connector 401 is inserted into the third quick-connect female connector 308 and rotated horizontally by 90° relative to the third quick-connect female connector 308 to lock the inner tube assembly core pressure holding section 40 and the pressure holding core extractor inner tube spring clip suspension mechanism 30.

[0115] As a seventh embodiment of the present invention, such as Figure 8 As shown, the high-pressure sealing mechanism 50 of the middle tube includes a middle tube sealing joint 501, a limiting ring 502, a middle tube short section 503, a middle tube 504, a ball valve drive short section 505, a spring limiting ring 506, a third spring 507, a drive pipe 508, an upper ball valve seat 509, a ball valve pipe 510, a ball valve 511, a lower ball valve seat 512, a lower support spring 513, a lower ball valve seat support ring 514, and a short section 515;

[0116] The inner tube assembly core pressure holding section 40 includes a PC core tube 407, which is sleeved in the middle tube short section 503 and the middle tube 504. The inner tube assembly core pressure holding section 40 can move axially relative to the middle tube high pressure sealing mechanism 50.

[0117] The high-pressure sealing mechanism 50 of the middle tube works in conjunction with the PC core tube 407 to achieve the effect of the ball valve 511 sliding downward and rotating by a certain 90°, thus sealing the lower part of the middle tube 504.

[0118] As an eighth embodiment of the present invention, such as Figure 9 As shown, the outer tube assembly 80 includes a spring-loaded chamber 801, a seat ring 802, and a drill bit 803.

[0119] Preferably, in the above embodiments, the angle is 90°.

[0120] This invention also discloses a method for obtaining the core, comprising the following steps:

[0121] A method for obtaining the core, characterized by comprising the following steps:

[0122] S1. Wellhead preparation: Install the inner tube assembly core pressure-maintaining section 40 into the middle tube high-pressure sealing mechanism 50, and hoist it into the low-temperature rat hole 90 on the drilling platform.

[0123] S2. The pressure-holding core sampler is sent into the retrieval tool 10 or the hoisting tool and the differential control part are connected to the first retrieval spear 201 through the first elastic retrieval hook 109, in preparation for segmented and rapid connection with the core pressure-holding section 40 of the inner tube assembly and the high-pressure sealing mechanism 50 of the middle tube.

[0124] S3. Insert the third quick-connect female connector 308 into the third quick-connect male connector 401, rotate relative to each other to quickly connect at a certain angle, lock the differential control part and the core pressure holding part, continue to lower the inner tube assembly core pressure holding section 40, connect the second quick-connect female connector 212 and the middle tube sealing connector 501, and realize the segmented quick connection of the pressure holding core sampler in the rat hole on the drilling platform.

[0125] S4. The pressure-holding coring device is vertically lifted out of the rat hole or the low-temperature rat hole 90 on the drilling platform and inserted into the drill pipe 901 at the wellhead on the drilling platform. The pressure-holding coring device is then sent into the retrieval device 10 and into the outer pipe assembly 80 on the seabed. When the pressure-holding coring device is lowered into the outer pipe assembly 80, the suspension ring 209 contacts the seat ring 802, and the spring clip 207 is elastically limited by the spring clip chamber 801, the counterweight rod 111 is lowered to press the release sleeve 108 into the upper part of the first elastic retrieval hook 109, so that the lower part of the first elastic retrieval hook 109 opens and is released. After the rope is retrieved, the pressure-holding coring device is sent into the retrieval device 10 and exits the wellhead. The drilling rig connects the drill pipe and begins drilling and coring.

[0126] S5. After the core is retrieved, the differential control retrieval device 70 of the pressure-holding core retrieval device is replaced through the first quick-connect female connector 102. The rope is lowered and the differential control retrieval device 70 of the pressure-holding core retrieval device contacts the first retrieval spear 201. At this time, the third elastic retrieval hook and the connector 705 are inserted into the upper part of the third elastic retrieval hook 704, so that the lower part of the third elastic retrieval hook 704 is unhooked from the first retrieval spear 201, and the two can slide relative to each other differentially.

[0127] The differential control of the lifting pressure-holding core extractor 70 drives the unblocking slide tube 206 to move upward, and the linkage lift drives the inner tube unblocking tube 302 to move upward. The retracted inner spring clip 303 makes elastic contact with the second connecting tube 210 to achieve unblocking. When the PC core tube 407 moves upward to above the ball valve, the ball valve 511 is overturned under the action of the third spring 507, forming the lower seal of the middle tube high-pressure sealing mechanism 50.

[0128] Continue to lift so that the lower end of the first unblocking slide tube long groove 2061 contacts the spring clip 207, and retract the spring clip 207 to make elastic limiting contact with the spring clip chamber 801, thereby realizing the unblocking of the pressure-holding core extractor from the outer tube assembly 80.

[0129] Continue to lift the inner tube sealing limit joint 404 until it is fully inserted into the limit ring 502, forming an upward limit and seal;

[0130] S6. The drill rod 901 of the pressure-holding coring device is retrieved and directly hoisted into the low-temperature rat hole 90 on the drilling platform; the differential control retrieval device 70 of the pressure-holding coring device is lowered until the unjammed slide tube 206 is reset, the third elastic retrieval hook 704 is re-hooked and connected to the first retrieval spear 201, and the unjammed slide tube 206 is reset to its original position before differential sliding.

[0131] S7. Disconnect the second quick-connect female connector 212 from the middle tube sealing connector 501, thus disconnecting the connection between the middle tube retrieval clip suspension mechanism 20 and the middle tube high-pressure sealing mechanism 50 of the pressure-holding core extractor.

[0132] Raise the pressure-holding coring device's inner tube retrieval spring clip suspension mechanism 20. The pressure-holding coring device's inner tube retrieval spring clip suspension mechanism 20 slides downward relative to the inner tube spring clip bracket 305 until it sits on the upper shoulder limit of the third connecting pipe 211. The third quick-connect female connector 308 and the third quick-connect male connector 401 are exposed. Use a tool to lift the fourth elastic pin 3082 to disengage the second torque transmission paddle 3083 from engaging with the top of the third quick-connect male connector 401. Rotate 90° to disengage the third quick-connect female connector 308 from the third quick-connect male connector 401, and disconnect the quick connection between the pressure-holding coring device's inner tube spring clip suspension mechanism 30 and the inner tube assembly core pressure-holding section 40.

[0133] S8. Preparation of the circulation wellhead: Install the new inner tube assembly core pressure holding section 40 into the new middle tube high pressure sealing mechanism 50, and hoist it into the drilling platform installation rat hole.

[0134] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

Claims

1. A heat-insulating and pressure-maintaining coring system, characterized in that, The system includes a pressure-maintaining coring device that works in conjunction with a low-temperature rat hole (90) on the drilling platform. The low-temperature rat hole (90) is set on the drilling platform of a drilling vessel or drilling platform. The pressure-maintaining coring system includes a differential control part, a core pressure-maintaining part, and a central tube drill bit. The differential control part and the core pressure-maintaining part are detachably connected. The pressure-holding core extractor is equipped with two sets of retrieval devices, namely the pressure-holding core extractor feeding retrieval device (10) and the pressure-holding core extractor differential control retrieval device (70). The differential control section includes a pressure-holding core extractor tube retrieval spring clip suspension mechanism (20) and a pressure-holding core extractor inner tube spring clip suspension mechanism (30). The pressure-holding core extractor inner tube spring clip suspension mechanism (30) is fixedly installed in the pressure-holding core extractor tube retrieval spring clip suspension mechanism (20) and can slide axially relative to the pressure-holding core extractor tube retrieval spring clip suspension mechanism (20). The pressure-holding core extractor tube retrieval spring clip suspension mechanism (20) includes a spring clip (207) and a suspension ring (209). The core pressure-holding section includes an inner tube assembly core pressure-holding section (40) and a middle tube high-pressure sealing mechanism (50). The inner tube assembly core pressure-holding section (40) is sleeved and suspended inside the middle tube high-pressure sealing mechanism (50). The lower end of the inner tube assembly core pressure-holding section (40) is provided with an inner tube sealing limit joint (404). The upper end of the middle tube high-pressure sealing mechanism (50) is provided with a middle tube sealing joint (501). The lower part of the middle tube sealing joint (501) is also sleeved with a limit ring (502). The inner tube sealing limit joint (404) is sleeved inside the middle tube sealing joint (501) and can slide relative to it. The upper limit of its sliding is when the inner tube limit joint (404) contacts the limit ring (502) and forms a seal. Before coring, the pressure-holding coring device is sent into the retrieval device through the drill pipe channel to the outer tube assembly (80). The suspension ring (209) contacts and limits the seat ring (802) of the outer tube assembly (80), while the spring clip (207) is fixed to the spring clip chamber (801). After coring, the pressure-holding coring device differentially controls the retrieval device to retrieve the pressure-holding coring device through the drill pipe channel. The outer tube assembly (80) is connected to the drill pipe channel and lowered to the seabed for coring.

2. The heat-insulating and pressure-maintaining coring system according to claim 1, characterized in that, The lower end of the pressure-holding core extractor fed into the retrieval device (10) and the lower end of the pressure-holding core extractor differential control retrieval device (70) are respectively provided with a first elastic retrieval hook (109) and a third elastic retrieval hook (704). The upper end of the pressure-holding core extractor's tube retrieval spring suspension mechanism (20) is provided with a first retrieval spear (201), which can be connected to the first elastic retrieval hook (109) or the third elastic retrieval hook (704) respectively. The first elastic retrieval hook (109) or the third elastic retrieval hook (704) is connected to the first retrieval spear (201) respectively. The pressure-holding core extractor is fed into the retrieval device (10) or the pressure-holding core extractor differential control retrieval device (70) is correspondingly connected to the differential control part of the pressure-holding core extractor middle tube retrieval spring clip suspension mechanism (20). The lower end of the inner tube spring clip suspension mechanism (30) of the pressure-holding coring device is provided with a third quick-connect female connector (308), and the upper end of the core pressure-holding section (40) of the inner tube assembly is provided with a third quick-connect male connector (401). The third quick-connect female connector (308) is inserted into the third quick-connect male connector (401), and the connection is quickly connected by rotating relatively horizontally at a certain angle and locked to form a fixed connection. The inner tube spring clip suspension mechanism (30) of the pressure-holding coring device and the core pressure-holding section (40) of the inner tube assembly are locked together. The pressure-holding core extractor's inner tube retrieval spring clip suspension mechanism (20) also includes a release slide tube (206), a second connecting pipe (210), a spring clip (207), a third connecting pipe (211), a second quick-connect female connector (212), and a first release slide tube long groove (2061). The pressure-holding core extractor's inner tube spring clip suspension mechanism (30) includes an inner spring clip (303). The inner tube assembly core pressure-holding section (40) includes a PC core tube (407). The middle tube high-pressure sealing mechanism (50) includes a ball valve (511) and a third spring (507). Before core sampling, the inner tube assembly core pressure-holding section (40) is fitted inside the middle tube high-pressure sealing mechanism (50) on the drilling deck and hoisted to the low-temperature rig on the drilling platform. The pressure-holding core sampler is then sent into the retrieval tool (10) and connected to the middle tube retrieval spring clip suspension mechanism (20) of the pressure-holding core sampler through the first elastic retrieval hook (109) and the first retrieval spear (201). The differential control part is hoisted above the core pressure-holding part. The third quick-connect female connector (308) is inserted into the third quick-connect male connector (401) and rotated horizontally at a certain angle relative to the third quick-connect male connector (401) to fix the inner tube spring clip suspension mechanism (30) and the inner tube assembly core. The pressure-holding section (40) is disconnected from the inner tube assembly core pressure-holding section (40) and the middle tube sealing mechanism (50) and suspended. The inner tube assembly core pressure-holding section (40) is lowered until the third connecting pipe (211) contacts the middle tube sealing joint (501). The second quick connecting female joint (212) is locked to the middle tube sealing joint (501), completing the connection between the differential control part and the core pressure-holding part. The differential control part and the core pressure-holding part are lowered from the deck wellhead to the outer tube assembly (80) through the pressure-holding core sampler into the retrieval device (10). The outer tube assembly (80) has been lowered into the borehole on the seabed through the drill pipe connection. The pressure-holding core sampler is retrieved and sent into the retrieval device (10). After the core is extracted, the differential control retrieval device (70) of the pressure-holding core extractor is connected to the first retrieval spear (201) through the third elastic retrieval hook (704). The third elastic retrieval hook and the fitting joint (705) are inserted into the upper part of the third elastic retrieval hook (704), so that the lower part of the third elastic retrieval hook (704) is disengaged from the first retrieval spear (201), and the two can slide relative to each other differentially. The differential control retrieval device (70) of the pressure-holding core extractor moves the unblocking slide (206) upward, and the linkage lift moves the inner tube unblocking tube (302) upward. The retracted inner spring clip (303) makes elastic contact with the second connecting pipe (210) to achieve unblocking. When the PC core tube (407) moves upward to above the ball valve, the ball valve (511) is overturned under the action of the third spring (507) to form the lower seal of the middle tube high pressure sealing mechanism (50). Continue to lift the slide tube long groove (2061) so that its lower end contacts the spring clip (207), and retract the spring clip (207) to contact the spring clip chamber (801) elastically, so as to realize the release of the pressure-holding core extractor from the outer tube assembly (80); Continue to lift the inner tube sealing limit joint (404) until it is fully inside the limit ring (502), forming an upward limit and seal.

3. The heat-insulating and pressure-maintaining coring system according to claim 2, characterized in that, Both sets of the retrieval devices include a lifting device, which can be connected to the pressure-holding core feeder retrieval device (10) and the pressure-holding core feeder differential control retrieval device (70), respectively. The lifting device includes a first quick-connect female connector (102). The pressure-holding core feeder retrieval device (10) and the pressure-holding core feeder differential control retrieval device (70) respectively include a first quick-connect male connector (103) and a second quick-connect male connector (701). The first quick-connect female connector (102) can be inserted into the first quick-connect male connector (103) and the second quick-connect male connector (701), and rotated horizontally by a certain angle and locked to form a fixed connection. The lifting device is replaceable and detachable from the pressure-holding core feeder retrieval device (10) and the differential control part.

4. The heat-insulating and pressure-maintaining coring system according to claim 3, characterized in that, The first quick-connect female connector (102) and the third quick-connect female connector (308) have the same functional structure, and the first quick-connect male connector (103), the second quick-connect male connector (701) and the third quick-connect male connector (401) have the same functional structure.

5. The heat-insulating and pressure-maintaining coring system according to claim 4, characterized in that, The pressure-holding core extractor fed into the retrieval device (10) includes a counterweight rod (111), the upper end of which is provided with the first quick-connect male connector (103), and the lower end of which is connected to a single-acting bearing (112), a perforated connecting pipe (104), a limit nut (105), a perforated pipe connecting connector (106), a sliding rod (107), a release sleeve (108), a sprue (1081), and a first elastic retrieval hook (109). Lowering the counterweight rod (111) presses the release sleeve (108) into the upper part of the first elastic retrieval hook (109), causing the lower part of the first elastic retrieval hook (109) to open and release, and the pressure-holding core extractor is sent into the retrieval device (10) and separated from the retrieval spring clip suspension mechanism (20) of the pressure-holding core extractor.

6. The heat-insulating and pressure-maintaining coring system according to claim 5, characterized in that, The pressure-holding core extractor tube retrieval spring clip suspension mechanism (20) further includes the first retrieval spear (201), the second retrieval hook (202), the second retrieval spear (203), the connector (204), the release slide tube (206), the release slide tube long groove (2061), the spring clip bracket (205), the spring clip (207), the release slide tube second elastic pin long groove (2062), the first connecting pipe (208), the first connecting pipe second elastic pin long groove (2081), the suspension ring (209), the second connecting pipe (210), the third connecting pipe (211), and the second quick-connect female connector (212); The first retrieval spear (201) is located at the upper end of the retrieval cartridge suspension mechanism (20) of the pressure-holding core extractor. The lower end of the first retrieval spear (201) is fixedly connected to the second retrieval hook (202), and the second retrieval spear (203) is adapted to be connected to the second retrieval hook (202). The lower part of the second retrieval spear (203) is connected to the spring clip bracket (205), and the spring clip (207) is installed in the groove of the spring clip bracket (205) and can be opened and closed elastically; The first connecting pipe (208) is disposed below the spring clip bracket (205). The first connecting pipe (208) includes a first connecting pipe second elastic pin elongated groove (2081), which is a through elongated hole of the first connecting pipe (208) and is arranged along the length direction of the first connecting pipe (208). The release slide tube (206) is provided with a through release slide tube elongated groove (2061) and a release slide tube second elastic pin elongated groove (2062), which are arranged along the length direction of the release slide tube (206). The first connecting pipe second elastic pin elongated groove (2081) and the release slide tube elongated groove (2061) overlap each other, and the second elastic pin (301) passes through it. In the first connecting pipe second elastic pin long groove (2081) and the release slide tube long groove (2061); the release slide tube long groove (2061) and the release slide tube second elastic pin long groove (2062) form an angle of 90° on the radial plane, and the spring clip (207) is set in the release slide tube long groove (2061); the lower end of the first connecting pipe (208) is fitted with a suspension ring (209), the second connecting pipe (210) is connected to the lower part of the first connecting pipe (208) and fixes the suspension ring (209); the lower part of the second connecting pipe (210) is fixedly connected to the third connecting pipe (211), and the lower part of the third connecting pipe (211) is provided with the second quick connection female connector (212).

7. The heat-insulating and pressure-maintaining coring system according to claim 6, characterized in that, The inner tube spring clip suspension mechanism (30) of the pressure-holding core extractor includes a second elastic pin (301), an inner tube release tube (302), an inner spring clip (303), a third elastic pin (304), an inner tube spring clip bracket (305), a single-action mechanism (306), an adjustable length connection (307), and a second spring (3081). The third quick-connect female connector (308) includes a fourth elastic pin (3082) and a second transmission paddle (3083). The second elastic pin (301) is inserted in the inner tube release tube (302). The second elastic pin (301) is inserted in the first connecting tube second elastic pin long groove (2081) and the release slide tube second elastic pin long groove (2062) of the pressure-holding core extractor middle tube retrieval spring clip suspension mechanism (20). The second elastic pin (301) can drive the pressure-holding core extractor inner tube spring clip suspension mechanism (30) to move axially in the pressure-holding core extractor middle tube retrieval spring clip suspension mechanism (20). When the release slide tube (206) moves upward, the bottom end of the second elastic pin groove (2062) of the release slide tube contacts the second elastic pin (301), which can correspondingly drive the inner tube release tube (302) to move upward, thereby causing the inner spring clip (303) to be retracted, so that the inner tube spring clip suspension mechanism (30) of the pressure-holding core extractor is disengaged from the middle tube retrieval spring clip suspension mechanism (20) of the pressure-holding core extractor, and relative axial movement is generated; The inner spring clip (303) is set on the inner tube spring clip bracket (305), the inner tube spring clip bracket (305) is fixedly connected to the single-action mechanism (306), and the length adjustment connection (307) is fixedly connected to the single-action mechanism (306), and the length of the connection can be finely adjusted relative to the single-action mechanism (306) by means of threads and locking nuts; The two ends of the second spring (3081) respectively abut against one end of the length adjustment connector (307) and the second transmission paddle (3083), and the second transmission paddle (3083) is fixed by the fourth elastic pin (3082). The fourth elastic pin (3082) is set in the through elongated hole of the third quick-connect female connector (308) to bear the thrust of the second spring (3081) and is inserted into the groove at the top of the third quick-connect male connector (401) to bear the connection torque. The second transmission paddle (3083) can compress the second spring (3081) and slide upward relative to the groove at the top of the third quick-connect male connector (401). The third quick-connect female connector (308) can be disengaged by rotating horizontally at a certain angle relative to the third quick-connect male connector (401).

8. The heat-insulating and pressure-maintaining coring system according to claim 7, characterized in that, The differential control retrieval device (70) for maintaining pressure and core retrieval includes a connecting rod (703), the upper end of the connecting rod (703) is provided with a single-action mechanism (702), and the upper end of the single-action mechanism (702) is provided with a second quick-connect male connector (701) for connecting with the first quick-connect female connector (102).

9. The heat-insulating and pressure-maintaining coring system according to claim 8, characterized in that, The high-pressure sealing mechanism (50) of the middle tube includes a middle tube sealing joint (501), a limiting ring (502), a middle tube short section (503), a middle tube (504), a ball valve drive short section (505), a spring limiting ring (506), a third spring (507), a drive tube (508), an upper ball valve seat (509), a ball valve tube (510), a ball valve (511), a lower ball valve seat (512), a lower support spring (513), a lower ball valve seat support ring (514), and a short section (515). The inner tube assembly core pressure-maintaining section (40) includes a PC core tube (407), which is sleeved in the middle tube short section (503) and the middle tube (504). The inner tube assembly core pressure-maintaining section (40) can move axially relative to the middle tube high-pressure sealing mechanism (50). The high-pressure sealing mechanism (50) of the middle tube and the PC core tube (407) cooperate with each other to achieve the effect of the ball valve (511) sliding downward and rotating by a certain 90° to seal the lower part of the middle tube (504).

10. A method for obtaining the core, characterized in that, It includes the following steps: S1. Wellhead preparation: Install the core pressure-maintaining section (40) of the inner tube assembly into the high-pressure sealing mechanism (50) of the middle tube, and hoist it into the low-temperature rat hole (90) on the drilling platform. S2. The pressure-holding core sampler is sent into the retrieval tool (10) or the hoisting tool and the differential control part are connected to the first retrieval spear (201) through the first elastic retrieval hook (109) and in preparation for segmented and rapid connection with the core pressure-holding section (40) of the inner tube assembly and the high-pressure sealing mechanism (50) of the middle tube. S3. Insert the third quick-connect female connector (308) into the third quick-connect male connector (401), rotate relative to each other to quickly connect at a certain angle, lock the differential control part and the core pressure holding part, continue to lower the core pressure holding section (40) of the inner tube assembly, connect the second quick-connect female connector (212) and the middle tube sealing connector (501) to realize the segmented quick connection of the pressure holding core sampler in the rat hole on the drilling platform; S4. The pressure-holding coring device is vertically lifted out of the rat hole or the low-temperature rat hole (90) on the drilling platform and inserted into the drill pipe (901) at the wellhead on the drilling platform. The pressure-holding coring device is then sent into the retrieval device (10) and into the outer pipe assembly (80) on the seabed. When the pressure-holding coring device is lowered into the outer pipe assembly (80), the suspension ring (209) contacts the seat ring (802), and the spring clip (207) and the spring clip chamber (801) are elastically limited, the counterweight rod (111) is lowered to press the release sleeve (108) into the upper part of the first elastic retrieval hook (109), so that the lower part of the first elastic retrieval hook (109) opens and is released. After the rope is retrieved, the pressure-holding coring device is sent into the retrieval device (10) and the wellhead is exited, the drilling rig connects the drill pipe and begins drilling and coring. S5. After the core is retrieved, the differential control retrieval device (70) of the pressure-holding core retrieval device is replaced by the first quick-connect female connector (102). The rope is lowered and the differential control retrieval device (70) of the pressure-holding core retrieval device comes into contact with the first retrieval spear (201). At this time, the third elastic retrieval hook and the connector (705) are inserted into the upper part of the third elastic retrieval hook (704), so that the lower part of the third elastic retrieval hook (704) is unhooked from the first retrieval spear (201), and the two can slide relative to each other differentially. The differential control retrieval device (70) of the pressure-holding core extractor moves the unblocking slide (206) upward, and the linkage lift moves the inner tube unblocking tube (302) upward. The retracted inner spring clip (303) makes elastic contact with the second connecting pipe (210) to achieve unblocking. When the PC core tube (407) moves upward to above the ball valve, the ball valve (511) is overturned under the action of the third spring (507) to form the lower seal of the middle tube high pressure sealing mechanism (50). Continue to lift so that the first unblocking slide tube long groove (2061) makes its lower end contact with the spring clip (207), and retract the spring clip (207) to make elastic limiting contact with the spring clip chamber (801), thereby realizing the unblocking of the pressure-holding core extractor from the outer tube assembly (80); Continue to lift the inner tube sealing limit joint (404) until it is fully inserted into the limit ring (502), forming an upward limit and seal; S6. The drill rod (901) of the pressure-holding coring device is retrieved and directly hoisted into the low-temperature rat hole (90) on the drilling platform. The differential control retrieval device (70) of the pressure-holding coring device is lowered until the unjammed slide tube (206) is reset. The third elastic retrieval hook (704) is re-hooked and connected to the first retrieval spear (201). The unjammed slide tube (206) is reset to its original position before differential sliding. S7. Disconnect the second quick-connect female connector (212) from the middle tube sealing connector (501), and disconnect the connection between the middle tube retrieval spring suspension mechanism (20) and the middle tube high pressure sealing mechanism (50) of the pressure-holding core extractor. Lift up the pressure-holding coring device middle tube retrieval spring clip suspension mechanism (20), and slide the pressure-holding coring device middle tube retrieval spring clip suspension mechanism (20) downwards until the inner tube spring clip bracket (305) sits on the upper shoulder limit of the third connecting pipe (211), and the third quick connection female connector (308) and the third quick connection male connector (401) are exposed. Use a tool to lift the fourth elastic pin (3082) to disengage the second transmission paddle (3083) from the top of the third quick connection male connector (401), rotate 90° to disengage the third quick connection female connector (308) and the third quick connection male connector (401), and disconnect the quick connection between the pressure-holding coring device inner tube spring clip suspension mechanism (30) and the inner tube assembly core pressure-holding section (40); S8. Preparation of the circulation wellhead: Install the new inner tube assembly core pressure-maintaining section (40) into the new middle tube high-pressure sealing mechanism (50), and hoist it into the drilling platform installation rat hole.

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