Underground supercharging device suitable for splitting grouting of marine hydrate reservoir

Abstract

The invention is applicable to the technical field of oil and gas resource development, and provides an underground pressurizing device applicable to marine hydrate reservoir splitting grouting, which comprises an upper short section connected with a lower short section and a pressurizing short section; the screw motor transmission shaft is connected with the reciprocating motion assembly; one end of the central flow channel is connected with the upper liquid inlet hole, the other end of the central flow channel is connected with the liquid discharge hole, and the liquid discharge hole is communicated with the cavity of the lower short section; the pressurizing cavity is located in the pressurizing short section and communicated with the high-pressure channel, the high-pressure channel is connected with the drain valve, and a lower liquid inlet hole is formed in the pressurizing cavity and communicated with the cavity of the lower short section; and the piston is arranged in the pressurizing cavity and is connected with the reciprocating motion assembly. Marine hydrate stratum grouting splitting can be achieved only through the circulating pump, reservoir transformation grout is injected into the well through the drilling rod by means of the circulating pump, and after the reservoir transformation grout passes through the pressurizing device, part of low-pressure grout is pressurized to be in a high-pressure state and then injected into a target stratum.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas resource development, and in particular relates to a downhole pressurizing device suitable for splitting and grouting of marine hydrate reservoirs. Background Art

[0002] Natural gas hydrates are cage-type compounds composed of water molecules and gas molecules, with the gas molecules mainly being methane. Marine natural gas hydrates are found in shallow seabed sediments at the edge of the continental shelf and are stable under high pressure and low temperature. my country has huge reserves of marine natural gas hydrates, which are considered a clean alternative to conventional energy. Natural gas hydrates are unconventional resources. Due to the low permeability of the formations where marine natural gas hydrates are found, the gas production rate during mining is low and cannot meet the needs of commercial development. The main mining methods include pressure reduction, heat injection, inhibitor injection, and CO2 replacement.

[0003] Fracturing grouting refers to injecting slurry into the formation, which "splits" the reservoir and forms slurry veins. After the slurry solidifies, it forms a porous, high-permeability reinforced skeleton, which improves the reservoir's conductivity while enhancing the overall strength of the reservoir, ensuring the safety and long-term development of hydrates. However, the conventional technology of injecting high-pressure slurry into the seabed formation requires expensive fracturing ships, and the long-distance grouting pressure is difficult to control, making it difficult to achieve precise fracturing of the hydrate reservoir. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a downhole pressure boosting device suitable for marine hydrate reservoir splitting grouting, aiming to solve the problems raised in the above-mentioned background technology.

[0005] The embodiment of the present invention is implemented as follows: a downhole pressurizing device suitable for splitting and grouting of marine hydrate reservoirs, comprising:

[0006] An upper short section, wherein the upper short section is connected with the lower short section and the booster short section in sequence, and a bottom end cover is provided at the tail of the booster short section;

[0007] The screw motor drive shaft is located at the front end and is connected to the reciprocating assembly to drive the reciprocating assembly to perform reciprocating motion;

[0008] A central flow channel is provided between the screw motor transmission shaft and the reciprocating moving component, one end of the central flow channel is connected to the upper liquid inlet hole provided on the screw motor transmission shaft, the other end of the central flow channel is connected to the liquid discharge hole provided on the reciprocating moving component, and the liquid discharge hole is connected to the cavity of the lower short section;

[0009] A boost chamber is located in the boost nipple and is connected to a high-pressure channel provided in the boost nipple. The high-pressure channel is connected to a drain valve. A lower liquid inlet hole is provided on the boost chamber and is connected to a cavity of the lower nipple.

[0010] The piston is installed in the pressurizing chamber and connected to the reciprocating assembly. The reciprocating assembly drives the piston to reciprocate to push the slurry into the pressurizing chamber and increase the pressure.

[0011] Preferably, the reciprocating assembly comprises:

[0012] A power conversion body connected to the screw motor transmission shaft, and the power conversion body is provided with a double helical groove;

[0013] The reciprocating power shaft is restrictedly installed in the lower short section. The reciprocating power shaft is provided with a pin shaft and a double helical groove for sliding connection. The reciprocating power shaft is connected to the piston. The screw motor transmission shaft drives the power conversion body to rotate. The pin shaft slides in the double helical groove to drive the reciprocating power shaft to perform reciprocating motion.

[0014] Preferably, the reciprocating power shaft is installed by limiting the internal spline of the lower short section, so that the reciprocating power shaft is driven to perform only linear reciprocating motion but not rotational motion.

[0015] Preferably, a low-pressure channel is provided on the lower short section, and the unpressurized slurry is discharged through the low-pressure channel.

[0016] Preferably, the device further comprises a dynamic sealing ring mounted on the power conversion body and located between the power conversion body and the reciprocating power shaft.

[0017] Preferably, the device further comprises a sealing ring, which is mounted on the piston and is located between the piston and the inner wall of the pressurizing chamber.

[0018] Preferably, the device further comprises a filter, and the filter is located outside the lower liquid inlet hole.

[0019] The embodiment of the present invention provides a downhole booster device suitable for marine hydrate reservoir splitting grouting. Under marine working conditions without special fracturing vessels and fracturing pumps, marine hydrate formation grouting splitting can be achieved by only using a circulating pump. The reservoir transformation slurry is injected into the downhole through a drill pipe by using a circulating pump. After passing through the booster device, part of the low-pressure slurry is pressurized to a high-pressure state and then injected into the target formation. After solidification, a consolidated body with good connectivity is formed, thereby improving the permeability and strength of the hydrate reservoir. Compared with conventional fracturing technology, the economic cost can be greatly reduced. The injection pressure can be accurately controlled at the target position of the reservoir to improve the reservoir transformation effect. Reservoir transformation is an effective means to improve the gas production efficiency of hydrates. The use of a downhole booster device can achieve cost reduction and efficiency improvement, providing a technical reserve for the commercial development of marine natural gas hydrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A schematic structural diagram of a downhole pressurizing device suitable for marine hydrate reservoir splitting grouting provided by an embodiment of the present invention;

[0021] Figure 2 for Figure 1 Middle AA section view;

[0022] Figure 3 A schematic diagram of the structure of a power conversion body in a downhole pressurization device suitable for marine hydrate reservoir splitting grouting provided by an embodiment of the present invention;

[0023] Figure 4 A plan view of a double spiral groove in a downhole pressurizing device suitable for marine hydrate reservoir splitting grouting provided in an embodiment of the present invention.

[0024] In the attached figure: 1-upper short section; 2-lower short section; 3-boosting short section; 4-bottom end cover; 5-screw motor drive shaft; 6-central flow channel; 7-upper liquid inlet hole; 8-power conversion body; 9-reciprocating power shaft; 10-pin shaft; 11-double spiral groove; 12-dynamic sealing ring; 13-drain hole; 14-piston; 15-sealing ring; 16-lower liquid inlet hole; 17-boosting chamber; 18-filter; 19-drain valve; 20-high pressure channel; 21-low pressure channel. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0026] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0027] like Figure 1 FIG. 1 is a structural diagram of a downhole pressurizing device suitable for marine hydrate reservoir splitting grouting provided by an embodiment of the present invention, comprising:

[0028] An upper short section 1, wherein the upper short section 1 is connected with a lower short section 2 and a booster short section 3 in sequence, and a bottom end cover 4 is provided at the tail of the booster short section 3;

[0029] The screw motor transmission shaft 5 is located at the front end and is connected to the reciprocating assembly to drive the reciprocating assembly to perform reciprocating motion;

[0030] A central flow channel 6 is provided between the screw motor transmission shaft 5 and the reciprocating assembly, one end of the central flow channel 6 is connected to the upper liquid inlet hole 7 provided on the screw motor transmission shaft 5, and the other end of the central flow channel 6 is connected to the liquid discharge hole 13 provided on the reciprocating assembly, and the liquid discharge hole 13 is connected to the cavity of the lower short section 2;

[0031] The boosting chamber 17 is located in the boosting nipple 3 and is connected to the high-pressure passage 20 provided in the boosting nipple 3. The high-pressure passage 20 is connected to the drain valve 19. The boosting chamber 17 is provided with a lower liquid inlet hole 16, which is connected to the cavity of the lower nipple 2.

[0032] The piston 14 is installed in the pressurizing chamber 17 and connected to the reciprocating assembly. The reciprocating assembly drives the piston 14 to reciprocate to push the slurry into the pressurizing chamber 17 and increase the pressure.

[0033] In one embodiment of the present invention, the downhole booster device suitable for splitting grouting of marine hydrate reservoirs is designed to solve the problems raised in the prior art. A reciprocating assembly is connected to a screw motor drive shaft 5, and a piston 14 and a booster chamber 17 and other structures are also provided. Specifically, when working, the front end of the downhole booster device is connected to a screw motor. After the reservoir transformation slurry used to split the formation drives the screw motor to rotate, it enters the central flow channel 6 through the upper liquid inlet hole 7 on the screw motor drive shaft 5. The reservoir transformation slurry in the central flow channel 6 enters the central cavity of the lower short section 2 through the discharge hole 13. The screw motor drive shaft 5 drives the reciprocating assembly to move back and forth when rotating. The reciprocating motion drives the piston 14 to reciprocate. When the reciprocating assembly moves to the upper limit, the piston 14 moves to the upper limit, the lower liquid inlet hole 16 is connected with the boosting chamber 17, and the reservoir transformation slurry in the central cavity of the lower short section 2 enters the boosting chamber 17 through the lower liquid inlet hole 16. When the reciprocating assembly and the piston 14 move downward, the pressure of the reservoir transformation slurry in the boosting chamber 17 increases, and the pressurized reservoir transformation slurry is transported to the drain valve 19 along the high-pressure channel 20. When the pressure of the reservoir transformation slurry is greater than the opening pressure of the drain valve 19, the drain valve 19 opens, and the reservoir transformation slurry in a high-pressure state is discharged to the outside of the downhole boosting device through the drain valve 19;

[0034] After completing a boosting cycle, the reciprocating assembly moves upward, the boosting chamber 17 is in a negative pressure state, and after the lower liquid inlet hole 16 is connected to the boosting chamber 17, the reservoir transformation slurry enters the boosting chamber 17 again, starting the next liquid inlet-boosting cycle.

[0035] like Figures 2 to 4 As shown, as a preferred embodiment of the present invention, the reciprocating assembly includes:

[0036] A power conversion body 8 is connected to the screw motor transmission shaft 5, and a double helical groove 11 is formed on the power conversion body 8;

[0037] The reciprocating power shaft 9 is installed in the lower short section 2. The reciprocating power shaft 9 is provided with a pin 10 which is slidably connected with the double helical groove 11. The reciprocating power shaft 9 is connected with the piston 14. The screw motor transmission shaft 5 drives the power conversion body 8 to rotate. The pin 10 slides in the double helical groove 11 to drive the reciprocating power shaft 9 to reciprocate.

[0038] Specifically, the reciprocating power shaft 9 is installed by limiting the internal spline of the lower short section 2, so that the reciprocating power shaft 9 is driven to perform only linear reciprocating motion but not rotary motion.

[0039] The power conversion body 8 has a double helical groove 11, and the reciprocating power shaft 9 is fixed with a pin 10. When the power conversion body 8 rotates, the pin 10 slides in the double helical groove 11 of the power conversion body 8, driving the reciprocating power shaft 9 to reciprocate. The reciprocating power shaft 9 is fixed by the internal spline of the lower short section 2 and does not rotate. The power conversion body 8 converts the rotary motion of the screw motor drive shaft 5 into axial reciprocating motion, pushing the piston 14 to reciprocate. The pin 10 is at the downward angle of the double helical groove 11. When sliding in the middle, the reciprocating power shaft 9 pushes the piston 14 to move downward, and when the pin shaft 10 slides in the upward angle of the double spiral groove 11, the reciprocating power shaft 9 drives the piston to move upward; when the reciprocating power shaft 9 runs to the upper limit position, the piston 14 runs to the upper limit position, the lower liquid inlet hole 16 is connected with the boosting chamber 17, and the reservoir transformation slurry in the central cavity of the lower short section 2 enters the boosting chamber 17 through the lower liquid inlet hole 16. When the reciprocating power shaft 9 and the piston 14 run downward, the pressure of the reservoir transformation slurry in the boosting chamber 17 increases.

[0040] like Figure 1 As shown, as a preferred embodiment of the present invention, a low-pressure channel 21 is opened on the lower short section 2, and the unpressurized slurry is discharged through the low-pressure channel 21.

[0041] The reservoir transformation slurry in the central flow channel 6 enters the central cavity of the lower short section 2 through the drainage hole 13. A part of the reservoir transformation slurry is discharged to the outside of the downhole booster through the low-pressure channel 21 and discharged to the orifice along the drill pipe annulus. After the low-pressure slurry passes through the solid control device on the deck, it is injected into the downhole through the drill pipe to form a circulation.

[0042] like Figure 1 As shown, as a preferred embodiment of the present invention, the device further comprises a dynamic seal ring 12, which is installed on the power conversion body 8 and is located between the power conversion body 8 and the reciprocating power shaft 9;

[0043] The device further comprises a sealing ring 15 which is mounted on the piston 14 and is located between the piston 14 and the inner wall of the pressurizing chamber 17 .

[0044] The sealing effect is improved by the dynamic sealing ring 12 and the sealing ring 15 .

[0045] like Figure 1 As shown, as a preferred embodiment of the present invention, the device further includes a filter 18 , and the filter 18 is located outside the lower liquid inlet hole 16 .

[0046] Before the reservoir reforming slurry enters the boosting chamber 17 through the lower liquid inlet hole 16 , it first passes through the filter 18 to remove larger solid particles and prevent the solid particles from affecting the service life of the piston 14 , the boosting chamber 17 and the drain valve 19 .

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A downhole pressurizing device suitable for splitting and grouting of marine hydrate reservoirs, characterized in that: include: An upper short section (1), wherein the upper short section (1) is connected to a lower short section (2) and a booster short section (3) in sequence, and a bottom end cover (4) is provided at the tail of the booster short section (3); A screw motor drive shaft (5), located at the front end and connected to the reciprocating assembly, is used to drive the reciprocating assembly to perform reciprocating motion; A central flow channel (6) is provided between the screw motor transmission shaft (5) and the reciprocating moving component, one end of the central flow channel (6) is connected to an upper liquid inlet hole (7) provided on the screw motor transmission shaft (5), and the other end of the central flow channel (6) is connected to a liquid discharge hole (13) provided on the reciprocating moving component, and the liquid discharge hole (13) is connected to the cavity of the lower short section (2); A boost chamber (17) is located in the boost nipple (3) and is connected to a high-pressure passage (20) provided in the boost nipple (3). The high-pressure passage (20) is connected to a drain valve (19). A lower liquid inlet hole (16) is provided on the boost chamber (17). The lower liquid inlet hole (16) is connected to the cavity of the lower nipple (2). The piston (14) is installed in the pressurizing chamber (17) and is connected to the reciprocating assembly. The reciprocating assembly drives the piston (14) to reciprocate, so as to push the slurry into the pressurizing chamber (17) and increase the pressure.

2. The downhole booster device suitable for marine hydrate reservoir splitting grouting according to claim 1 is characterized in that: The reciprocating assembly comprises: A power conversion body (8) is connected to the screw motor transmission shaft (5), and a double helical groove (11) is provided on the power conversion body (8); A reciprocating power shaft (9) is installed in a restricted manner in the lower short section (2). A pin shaft (10) is provided on the reciprocating power shaft (9) and is slidably connected to a double helical groove (11). The reciprocating power shaft (9) is connected to a piston (14). The screw motor transmission shaft (5) drives the power conversion body (8) to rotate, and the pin shaft (10) slides in the double helical groove (11), driving the reciprocating power shaft (9) to perform reciprocating motion.

3. The downhole booster device suitable for marine hydrate reservoir splitting grouting according to claim 2 is characterized in that: The reciprocating power shaft (9) is installed by limiting the internal spline of the lower short section (2), driving the reciprocating power shaft (9) to perform only linear reciprocating motion but not rotary motion.

4. The downhole pressurizing device suitable for marine hydrate reservoir splitting grouting according to claim 1, characterized in that: The lower short section (2) is provided with a low-pressure channel (21), and the unpressurized slurry is discharged through the low-pressure channel (21).

5. The downhole booster device suitable for marine hydrate reservoir splitting grouting according to claim 2, characterized in that: The device also includes a dynamic sealing ring (12) which is installed on the power conversion body (8) and is located between the power conversion body (8) and the reciprocating power shaft (9).

6. The downhole booster device suitable for marine hydrate reservoir splitting grouting according to claim 1, characterized in that: The device also includes a sealing ring (15) which is mounted on the piston (14) and is located between the piston (14) and the inner wall of the pressure-increasing chamber (17).

7. The downhole pressure boosting device suitable for marine hydrate reservoir splitting grouting according to claim 1, characterized in that: The device further comprises a filter (18), wherein the filter (18) is located outside the lower liquid inlet hole (16).

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