CN215565813U - Sponge coring tool - Google Patents

Abstract

The utility model discloses a sponge coring tool, which is characterized in that a coring outer cylinder string assembly is formed by connecting an upper joint, a coring outer cylinder and a coring bit through threads, an inner cylinder string assembly consisting of a suspension assembly, a liquid injection and pressure release assembly, a liner pipe joint, a coring inner cylinder, a necking sleeve short section and a necking sleeve is placed in an inner cylinder string, and an oil absorption sponge liner is arranged in the inner cylinder string. The upper part and the lower part of the inner cylinder string are provided with floating pistons to seal the cavity of the inner cylinder, and sponge protective liquid is injected before drilling down. Through the sponge coring tool that uses this patent to provide, can utilize sponge material oil absorption characteristic to collect the crude oil that displaces in the core in the process of the brill-out in time and preserve for follow-up indoor oily saturation test. The oil saturation of the stratum core is obtained through a direct measurement mode, and the real reliability of the oil content evaluation of the stratum reservoir is improved.

Description

Sponge coring tool

Technical Field

The utility model belongs to the field of petroleum and natural gas drilling and coring, and particularly relates to a sponge coring tool.

Background

The data from the drill core is the only direct measurement of the reservoir rock properties, and any other informative data is an indirect assessment of these properties, the best way being to obtain a representative core. However, during conventional coring, reservoir fluids in the core may escape due to pressure decay and gas expansion during the coring process, so that the crude oil saturation of the core reaching the surface is no longer equal to the crude oil saturation of the underground state, and the crude oil saturation obtained in situ is inaccurate data.

CN201920630650.2 discloses a conventional hard formation coring tool, which utilizes a self-locking core claw to pull up and cut a core. CN201720425799.8 a horizontal well coring tool, discloses a hard formation coring tool that is suitable for horizontal well operation, has increased the bearing of rightting on traditional coring tool's basis, has improved the centre of inner tube, is fit for using in highly deviated well and horizontal well. CN201410505765.0 is a rotary insertion type coring tool for extremely loose strata, discloses a salvageable rope coring tool suitable for extremely loose strata, and has good application effect on extremely shallow extremely loose strata. CN201410427660.8 discloses a hydraulic pressurization type coring tool, which is suitable for coring in a soft stratum with a well deviation, wherein a core claw contracts to cut a core under hydraulic operation. CN201711116844.2 discloses a tool and a method for improving the saturation measurement of residual oil in a core by wrapping the core with a sealing liquid, but the content of the oil escaping during the tripping process cannot be judged. CN201420811866.6 a pressurize coring tool discloses a pressurize coring tool, and the core is sealed in the inner core barrel through the ball valve after the core advances the section of thick bamboo, and this kind of coring mode can make the core that obtains keep the normal position state, but has high operating risk, and the on-the-spot application is limited.

SUMMERY OF THE UTILITY MODEL

The utility model aims to overcome the defects of the prior art and provide a novel coring tool.A special oil-absorbing sponge is added in the coring tool, so that the formed core is wrapped in time in the coring process, and the sponge material can collect and store crude oil seeped in the core in time for subsequent indoor test and analysis. The sponge liner tube can tightly hold the rock core, so that fluid in the rock core is prevented from flowing away along a gap between the rock core and the sponge liner tube or mud enters the rock core along the gap between the rock core and the sponge liner tube to cause pollution, the phenomenon of core blockage or sponge liner tube damage caused by too small gap can be avoided, and the original oil saturation of the stratum can be accurately evaluated.

The technical scheme is as follows:

in order to achieve the purpose, the technical scheme provided by the utility model comprises the following steps:

a sponge coring tool comprises an outer barrel string assembly and an inner barrel string assembly, wherein the outer barrel string assembly mainly comprises an upper connector, a coring outer barrel and a coring bit which are sequentially connected in a threaded manner; the inner cylinder string assembly is mainly formed by sequentially connecting a suspension assembly, a liquid injection and pressure release assembly, a liner pipe joint, a coring inner cylinder, a necking sleeve short joint and a necking sleeve in a threaded manner; the inner cylinder string assembly is arranged inside the outer cylinder string assembly and is connected with the outer cylinder assembly through a suspension assembly thread; the sponge lining cylinder is placed in the inner core barrel, and the upper end and the lower end of the sponge lining cylinder are limited by the liner pipe joint and the end face of the short section of the necking sleeve; the lower floating piston is arranged in a cavity formed by the coring bit, the necking sleeve short section and the necking sleeve and is sealed with the coring inner cylinder through a second sealing element.

Further, still include floating piston, first sealing washer, gland spare cap, it is inside that floating piston arranges the suspension assembly in, through first sealing washer and suspension assembly sealed, it is spacing that the upper end passes through the gland spare cap, and the lower extreme is spacing through the suspension assembly step.

Furthermore, the liquid injection and pressure relief assembly mainly comprises a liquid injection joint, a pumping and injecting assembly and a pressure limiting assembly, wherein the pumping and injecting assembly and the pressure limiting assembly are connected with the liquid injection joint through threads; the pumping and injection assembly and the pressure limiting assembly are provided with a cross communication chamber and are communicated with an inner cavity of the liquid injection joint; the pumping and injecting assembly injects sponge protective liquid into the inner cylinder cavity through an external pipeline; and a proportional unloading valve is arranged in the pressure limiting assembly, and when the pressure of the inner cylinder cavity exceeds a set pressure, the pressure is released to the outer annular space.

Furthermore, the lower floating piston is mainly formed by sequentially connecting a piston mandrel, a limiting head, a spring box and a piston shell; the piston mandrel is connected with the piston shell through threads, the spring is arranged in a cavity formed by the piston mandrel and the spring box, two ends of the spring are limited by the limiting head and the end face of the spring box, and pretightening force is applied during assembly; the limiting head is arranged outside the spring box, the upper end of the limiting head is in contact with the step surface of the piston mandrel and is pressed by spring force, a first sealing element is arranged inside the limiting head to seal with the piston mandrel, a groove is arranged outside the limiting head, and the limiting head is sealed with the inner cylinder string by placing a sealing ring; piston drain holes are distributed on the spring box, and when the spring is compressed, fluid in the cavity can be discharged to the shaft annulus through the drain holes; the lower part of the piston shell is matched with the inner cavity of the coring bit and is provided with a righting strip and a diversion trench.

Furthermore, the lower floating piston, the inner cylinder string assembly, the suspension assembly and the upper floating piston form a closed chamber; before the core barrel is placed into the core barrel, high-pressure sponge protective liquid is injected in advance, when core taking operation is carried out, the core acts on the lower end face of the lower floating piston to drive the piston shell to compress the spring and move upwards, the first sealing element is made to be invalid, and the protective liquid in the core barrel is discharged through the piston discharge hole.

Further, the inner diameter of the sponge lining cylinder is smaller than the diameter of the core by 0 to 5-1mm, the outer diameter of the sponge lining cylinder is smaller than that of the coring inner cylinder, and after the core enters the sponge lining cylinder, the pre-injected protective liquid can be discharged through a drainage hole of the sponge lining cylinder; when measuring the oil saturation, the oil content of the sampling rock and the adsorbed oil content of the sponge material at the sampling position need to be measured simultaneously, and the stratum oil saturation is obtained through the weighted sum of the oil contents of the sampling rock and the sampling sponge.

Furthermore, a sponge coring tool adopts a three-layer tube single-action coring mode, wherein: the upper joint, the coring outer cylinder and the coring drill bit are connected in sequence through threads to form a coring outer cylinder string assembly. The suspension assembly, the liquid injection and pressure release assembly, the liner pipe joint, the coring inner cylinder, the necking sleeve short section and the necking sleeve are sequentially connected through threads to form an inner cylinder string assembly. The inner cylinder string assembly is arranged in the outer cylinder string assembly and is connected with an upper joint of the outer cylinder assembly through threads on the upper part of the suspension assembly. The sponge lining cylinder is inserted into the inner core barrel before the inner barrel string is assembled, and the upper end and the lower end of the sponge lining cylinder are limited through the liner pipe joint and the end face of the short section of the necking sleeve. The lower floating piston is arranged in a cavity formed by the coring bit, the necking sleeve short section and the necking sleeve and is sealed with the coring inner cylinder through a sealing element. The outer diameter of the upper part of the lower floating piston is slightly larger than the diameter of the coring bit opening and smaller than the rigid body inner diameter of the sponge lining cylinder.

The above scheme further comprises: the upper floating piston is arranged in a hole cavity in the suspension assembly and is sealed with the suspension assembly through a sealing element, the upper end of the upper floating piston is limited through a gland spare cap, and the lower end of the upper floating piston is limited through a step of the suspension assembly. After the upper floating piston is assembled, a certain up-and-down moving distance can be reserved in the hole cavity of the suspension assembly. According to the process requirement, protective liquid needs to be pre-filled in the inner cylinder in advance, and due to the change of the temperature and the pressure of the environment from a wellhead to a downhole, the liquid in the inner cylinder expands or contracts, and the upper floating piston can move up and down to offset the change of the pressure of the inner cylinder.

Furthermore, the upper part of the inner cylinder is provided with a liquid injection and pressure relief assembly, the assembly consists of a liquid injection joint, a pressure limiting assembly and a pumping and injecting assembly, and the pressure limiting assembly and the pumping and injecting assembly are connected with the liquid injection joint through threads. The pressure limiting assembly and the pumping and injecting assembly are provided with a cross communicating chamber and are communicated with an inner cavity of the liquid injection joint. The pumping and injecting assembly is provided with a quick connector, and can be connected with external equipment through a pipeline to realize the operations of pumping vacuum and injecting sponge protective liquid. The pressure limiting assembly is internally provided with a miniature proportional unloading valve, and the rated discharge pressure can be preset. When the pressure in the inner cavity of the inner cylinder exceeds the rated pressure, the pressure can be released to the inner cylinder and the outer cylinder annulus through the valve, so that the inner cylinder is kept in a safe working pressure range.

Furthermore, the lower floating piston is formed by sequentially connecting a piston mandrel, a limiting head, a spring box and a piston shell. The piston mandrel is connected with the piston shell through threads, the spring is placed in a cavity formed by the piston mandrel and the spring box, the two ends of the spring are limited by the limiting head and the end face of the spring box, and pretightening force is applied during assembly. The limiting head is arranged outside the spring box, the upper end of the limiting head is in contact with the step surface of the piston mandrel and is pressed by spring force, a sealing element is arranged inside the limiting head to be sealed with the piston mandrel, a groove is arranged outside the limiting head, and the limiting head is sealed with the inner cylinder in a string mode by placing a sealing ring. And when the spring is compressed, fluid in the cavity can be discharged to the annular space of the shaft through the drainage hole. The lower part of the piston shell is matched with the inner cavity of the coring bit and is provided with a righting strip and a diversion trench. Wherein the centering strip makes the inner tube cluster centered, and the guiding gutter improves the washing effect of drilling fluid to the piston among the circulation process, prevents that piston and drill bit card from dying.

Furthermore, the lower floating piston, the inner cylinder string assembly, the suspension assembly and the upper floating piston form a closed chamber. Before the core taking tool is put into the core taking device, the sponge protective liquid is injected in advance, and the sponge material is ensured to be kept in a clean state before the core enters the barrel. When the core is cored, the core acts on the lower end face of the lower floating piston after entering the barrel, the upper top piston shell compresses the spring and moves upwards, the inner seal of the piston is opened, and the protection liquid in the core barrel is discharged through the discharge hole.

Furthermore, the inner diameter of the sponge lining cylinder is smaller than the diameter of the core by 0.5-1mm, the core can be tightly wrapped by the sponge material after entering the sponge lining cylinder, and the crude oil displaced from the core in the process of tripping is adsorbed and stored by the sponge material. The protection liquid pre-injected in the upward process of the rock core can be released through the drain hole of the composite sponge lining cylinder and the channel in the lower floating piston. In the process of tripping, when measuring the oil saturation, the oil content of the sampling rock and the adsorbed oil content of the sponge material at the sampling position need to be measured simultaneously, and the total oil saturation of the stratum is obtained through the weighted sum of the oil contents of the sampling rock and the sampling sponge.

When the sponge coring tool is used, the specific construction process comprises the following steps:

(a) and hoisting the sponge coring tool into a wellhead by using a lifting short joint, and clamping the coring outer barrel by using a drill collar slip and a safety slip. The upper joint and the connecting thread of the coring outer cylinder are unscrewed by using hydraulic tongs, and the inner cylinder string is lifted by using a top drive or a traveling block to leak out the injection and pressure relief assembly;

(b) connecting a vacuum pump pipeline to a pumping and injecting assembly of a liquid injection and pressure relief assembly, pumping vacuum inside an inner cavity of the coring inner cylinder to enable the sponge to be in a compressed state, and then pulling out the vacuum pump pipeline;

(c) connecting the pipeline of the injection pump to the pumping and injection assembly of the injection and pressure release assembly, injecting sponge protective liquid or mixed salt water with similar salt saturation degree to the stratum into the inner cavity of the coring inner cylinder, setting the injection pressure to be 3-5MPa generally, enabling the upper floating piston and the lower floating piston of the inner cylinder to be in a compressed state, stopping the pump after the rated pressure is reached, and disassembling the pipeline joint.

(d) And (3) reconnecting the upper joint of the coring tool and the coring outer cylinder by using hydraulic pliers and fastening to the rated torque. Lifting the sponge coring tool by using a lifting short section, and detecting whether the sponge pre-protection liquid leaks;

(e) and connecting the sponge coring tool with a drilling tool and drilling down, starting a pump circulation drill when the drilling tool is more than 1m away from the well bottom, circulating the settled sand at the well bottom completely, pressing down the floating piston, slowly increasing the drilling pressure when the lower end surface of the piston shell contacts the well bottom, sealing and opening the lower floating piston, releasing the pressure of the inner cylinder, enabling the piston to enter the inner cylinder, and starting coring operation.

The utility model has the advantages that: through the sponge coring tool that uses this patent to provide, can utilize sponge material oil absorption characteristic in time to collect the crude oil that oozes in the core and preserve to subsequent indoor test analysis. The oil saturation of the stratum core is obtained through a direct measurement mode, and the real reliability of the oil content evaluation of the stratum reservoir is improved.

Drawings

Fig. 1 is a schematic structural view of a sponge coring tool according to the present invention.

Fig. 2 is a schematic structural view of the liquid injection and pressure release assembly of the present invention.

Fig. 3 is a schematic structural view of the lower floating piston of the present invention.

FIG. 4 is a schematic structural view of the coring inner cylinder and the sponge lining cylinder of the present invention.

In fig. 1: 1. the core-pulling device comprises an upper joint, 2 parts of a coring outer cylinder, 3 parts of a coring bit, 4 parts of a suspension assembly, 5 parts of a liquid injection and pressure release assembly, 6 parts of a liner pipe joint, 7 parts of a coring inner cylinder, 8 parts of a sponge liner, 9 parts of a necking sleeve short section, 10 parts of a necking sleeve, 11 parts of a core claw, 12 parts of a lower floating piston, 13 parts of a second sealing element, 14 parts of a gland spare cap, 15 parts of a first sealing ring, 16 parts of an upper floating piston, 17 parts of an inner cylinder cavity, 18 parts of a sponge liner discharge hole and 19 parts of a bit water hole.

In fig. 2: 5-1 of a liquid injection joint, 5-2 of a pumping and injecting assembly, 5-3 of a pressure limiting assembly, 5-4 of a junction communicating cavity, 5-5 of an inner cavity of the liquid injection joint, 5-6 of an outer annular space and 5-7 of an outer pipeline.

In fig. 3: 12-1 parts of a piston mandrel, 12-2 parts of a first sealing element, 12-3 parts of a limiting head, 12-4 parts of a spring, 12-5 parts of a spring box, 12-6 parts of a piston shell, 12-7 parts of a groove, 12-8 parts of a piston chamber, 12-9 parts of a piston discharge hole, 12-10 parts of a piston centering strip and 12-11 parts of a piston guide groove.

In fig. 4: 8-1 parts of sponge sampling blocks, 20 parts of cores and 20-1 parts of core sampling blocks.

Detailed Description

The technical solution of the present invention is further illustrated in detail by the following examples.

Referring to fig. 1, the utility model discloses a sponge coring tool with a schematic structure, and the embodiment of the sponge coring tool adopts a three-layer tube single-action coring mode, wherein: the upper joint 1, the coring outer cylinder 2 and the coring bit 3 are connected in sequence through threads to form a coring outer cylinder string assembly. The suspension assembly 4, the liquid injection and pressure release assembly 5, the liner pipe joint 6, the coring inner cylinder 7, the necking sleeve short section 9 and the necking sleeve 10 are sequentially connected through threads to form an inner cylinder string assembly. The inner cylinder string assembly is arranged in the outer cylinder string assembly and is a middle layer pipe, and is connected with the upper joint 1 of the outer cylinder assembly through threads on the upper part of the suspension assembly 4. The sponge lining cylinder 8 is inserted into the inner core barrel 2 before the inner barrel string is assembled, and serves as the innermost barrel which is in direct contact with the core, and the upper end and the lower end of the sponge lining cylinder are limited by the end faces of the liner pipe joint 6 and the short section 9 of the necking sleeve. The lower floating piston 12 is arranged in a cavity formed by the coring bit 3, the necking sleeve pup joint 9 and the necking sleeve 10 and is sealed with the coring inner cylinder 7 through a second sealing element 13. The outer diameter of the upper part of the lower floating piston 12 is slightly larger than the diameter of the core bit opening and is smaller than the rigid body inner diameter of the sponge lining cylinder 8. When core-taking operation is carried out, the core-taking outer cylinder 2 string rotates to rotate for core-taking, and the inner cylinder string and the lining cylinder string are in a non-rotating state relative to the core due to the effect of the suspension bearing.

The above embodiment further comprises: the upper floating piston 16 is arranged in a hole cavity in the suspension assembly 4 and is sealed with the suspension assembly 4 through a first sealing element, the upper end of the upper floating piston is limited through a gland spare cap 14, and the lower end of the upper floating piston is limited through a suspension assembly step. After the upper floating piston 16 is assembled, a certain distance of up-and-down movement can be arranged in the bore of the suspension assembly. Due to the process requirement, the inner cylinder needs to be pre-filled with protective liquid in advance, the liquid in the inner cylinder expands or contracts due to the change of the temperature and the pressure from the wellhead to the underground environment, and the upper floating piston 16 can move up and down in the hole cavity of the suspension assembly 4 to offset the change of the liquid pressure in the cavity of the inner cylinder.

Referring to fig. 2, the structure of the liquid injection and pressure release assembly is schematically illustrated. The liquid injection and pressure relief assembly 5 consists of a liquid injection joint 5-1, a pumping and injection assembly 5-2 and a pressure limiting assembly 5-3, wherein the pumping and injection assembly 5-2 and the pressure limiting assembly 5-3 are connected with the liquid injection joint 5-1 through threads. The pumping and injecting assembly 5-2 and the pressure limiting assembly 5-3 are provided with a cross communicating cavity 5-4 and communicated with an inner cavity 5-5 of the liquid injection joint. The pumping and injecting assembly 5-2 is provided with a quick connector and can be connected with external equipment through an external pipeline 5-7, so that the operations of pumping vacuum and injecting the sponge protective solution are realized. The pressure limiting assembly 5-3 is internally provided with a miniature proportional unloading valve, and the rated discharge pressure can be preset. When the pressure in the inner cavity of the inner cylinder exceeds the rated pressure, the pressure can be released to the inner cylinder and the outer cylinder annulus through the valve, so that the inner cylinder is kept in a safe working pressure range.

Referring to fig. 3, a schematic structural diagram of the lower floating piston is shown, and the specific embodiment is as follows: the lower floating piston 12 is formed by sequentially connecting a piston mandrel 12-1, a limiting head 12-3, a spring box 12-5 and a piston shell 12-6. The piston mandrel 12-1 is connected with the piston shell 12-6 through threads, the spring 12-4 is placed in a cavity formed by the piston mandrel 12-1 and the spring box 12-5, two ends of the spring are limited by the limiting head 12-3 and the end face of the spring box 12-5, and pretightening force is applied during assembly. The limiting head 12-3 is arranged outside the spring box 12-5, the upper end of the limiting head is in contact with the step surface of the piston mandrel 12-1 and is pressed by spring force, the limiting head 12-3 is internally provided with a first sealing element 12-2 which is sealed with the piston mandrel 12-1, the limiting head is externally provided with a groove 12-7 which is sealed by arranging a sealing ring and an inner cylinder string. Piston drain holes 12-9 are distributed on the spring box 12-5, and when the spring 12-4 is compressed, fluid in the piston chamber 12-8 can be discharged to the shaft annular space through the piston drain holes 12-9. The lower part of the piston shell 12-6 is provided with a centering strip 12-10 and a diversion trench 12-11 at the matching part with the inner cavity of the coring bit 3. The centralizing strips 12-10 enable the inner cylinder string to be centered, and the diversion trenches 12-11 improve the flushing effect of drilling fluid on the lower floating piston 12 in the circulation process and prevent the piston body and the coring bit 3 from being stuck.

The real-time scheme further comprises: the lower floating piston 12, the inner cylinder string assembly, the suspension assembly 4 and the upper floating piston 16 form a closed chamber. Before the core taking tool is put into the core taking device, the sponge protective liquid is injected in advance, and the sponge material is ensured to be kept in a clean state before the core enters the barrel. When the core is cored, the core 20 acts on the lower end face of the lower floating piston 12 after entering the barrel, the upper top piston shell 12-6 compresses the spring and moves upwards, so that the inner seal of the piston is opened, and the protection liquid in the core barrel is discharged through the piston discharge hole 12-9.

Referring to fig. 4, a schematic structural diagram of the lower floating piston is shown, and the specific embodiment is as follows: the inner diameter of the sponge lining cylinder 8 is smaller than the diameter of the core 20 by 0.5-1mm, the outer diameter of the sponge lining cylinder is smaller than the inner coring cylinder 7, the core 20 can be tightly wrapped by sponge materials after entering the sponge lining cylinder 8, and crude oil displaced from the core 20 in the process of tripping is absorbed by the sponge materials and stored. The protection liquid pre-injected in the upward process of the core 20 can be released through the sponge lining drainage hole 18 of the sponge lining 8 and the channel in the lower floating piston 12. In the process of tripping, when measuring the oil saturation, the oil content of the core sampling block 20-1 and the adsorbed oil content of the sponge sampling block 8-1 at the sampling position need to be measured simultaneously, and the total oil saturation of the stratum is obtained through the weighted sum of the oil contents of the core sampling block 20-1 and the sponge sampling block 8-1.

When the sponge coring tool is used, the specific construction process comprises the following steps:

(a) and hoisting the sponge coring tool into a wellhead by using a lifting short joint, and clamping the coring outer barrel 2 by using a drill collar slip and a safety slip. The upper joint 1 and the coring outer cylinder 2 are screwed off by hydraulic tongs, and the inner cylinder string is lifted by a top drive or a traveling block to leak a liquid injection and pressure relief assembly 5;

(b) connecting a vacuum pump pipeline to a pumping and injecting assembly 5-2 of a liquid injection and pressure relief assembly, pumping vacuum in the cavity 17 of the coring inner barrel to enable the sponge to be in a compressed state, and then pulling out the vacuum pump pipeline;

(c) connecting a pipeline for a liquid injection pump to a pumping and injection assembly 5-2 of the liquid injection and pressure relief assembly 5, injecting sponge protective liquid or mixed salt water with similar salt saturation of the stratum into a cavity 17 of the coring inner cylinder, generally setting the injection pressure to be 3-5MPa, enabling the upper floating piston 16 and the lower floating piston 12 of the inner cylinder to be in a compressed state, stopping the pump after the rated pressure is reached, and disassembling a pipeline joint.

(d) The upper joint 1 and the coring outer cylinder 2 of the coring tool are reconnected by hydraulic pliers and fastened to rated torque. Lifting the sponge coring tool by using a lifting short section, and detecting whether the sponge pre-protection liquid leaks;

(e) the sponge coring tool is connected with a drilling tool and is drilled downwards, when the drilling tool is more than 1m away from the well bottom, a pump circulation drill is started, after sediment at the well bottom is circulated completely, the floating piston 12 is pressed downwards, when the lower end face of the piston shell 12-6 contacts the well bottom, the drill pressure is slowly increased, the first sealing element 12-2 is opened, the pressure of the inner cylinder is released, the piston enters the inner part of the coring inner cylinder 7, and the coring operation is started.

While embodiments of the utility model have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the utility model, the scope of which is defined by the claims and their equivalents.

Claims (6)

1. A sponge coring tool comprises an outer barrel string assembly and an inner barrel string assembly, and is characterized in that the outer barrel string assembly is mainly formed by sequentially connecting an upper joint (1), a coring outer barrel (2) and a coring bit (3) in a threaded manner; the inner cylinder string assembly is mainly formed by sequentially connecting a suspension assembly (4), a liquid injection and pressure release assembly (5), a liner pipe joint (6), a coring inner cylinder (7), a necking sleeve short joint (9) and a necking sleeve (10) in a threaded manner; the inner cylinder string assembly is arranged inside the outer cylinder string assembly and is connected with the outer cylinder assembly through a suspension assembly (4) thread; the sponge lining cylinder (8) is placed inside the coring inner cylinder (7), and the upper end and the lower end of the sponge lining cylinder are limited by the end faces of the liner pipe joint (6) and the necking sleeve nipple (9); the lower floating piston (12) is arranged in a cavity formed by the coring bit (3), the necking sleeve short section (9) and the necking sleeve (10) and is sealed with the coring inner cylinder (7) through a second sealing element (13).

2. The sponge coring tool of claim 1, further comprising an upper floating piston (16), a first sealing ring (15), and a pressing cap (14), wherein the upper floating piston (16) is arranged inside the suspension assembly (4) and sealed with the suspension assembly (4) through the first sealing ring (15), the upper end of the upper floating piston is limited through the pressing cap (14), and the lower end of the upper floating piston is limited through a step of the suspension assembly (4).

3. The sponge coring tool according to claim 1, wherein the liquid injection and pressure relief assembly (5) mainly comprises a liquid injection joint (5-1), a pumping and injection assembly (5-2) and a pressure limiting assembly (5-3), and the pumping and injection assembly (5-2) and the pressure limiting assembly (5-3) are connected with the liquid injection joint (5-1) through threads; the pumping and injecting assembly (5-2) and the pressure limiting assembly (5-3) are provided with a cross communicating chamber (5-4) and are communicated with an inner cavity (5-5) of the liquid injection joint (5-1); the pumping and injecting assembly (5-2) injects sponge protective solution into the inner cylinder cavity (17) through the external pipeline (5-7); a proportional unloading valve is arranged in the pressure limiting assembly (5-3), and when the pressure of the inner cylinder cavity (17) exceeds a set pressure, the pressure is released to the outer annular space (5-6).

4. The sponge coring tool as set forth in claim 1, wherein the lower floating piston (12) is mainly composed of a piston mandrel (12-1), a stopper (12-3), a spring case (12-5), and a piston housing (12-6) connected in sequence; the piston mandrel (12-1) is connected with the piston shell (12-6) through threads, the spring (12-4) is arranged in a chamber (12-8) formed by the piston mandrel (12-1) and the spring box (12-5), the two ends of the spring are limited by the limiting head (12-3) and the end face of the spring box (12-5), and pretightening force is applied during assembly; the limiting head (12-3) is arranged outside the spring box (12-5), the upper end of the limiting head is in contact with the step surface of the piston mandrel (12-1) and is pressed by spring force, a first sealing element (12-2) and the piston mandrel (12-1) are arranged inside the limiting head (12-3) for sealing, a groove is arranged outside the limiting head, and the limiting head and the inner cylinder are sealed in series by arranging a sealing ring; piston drain holes (12-9) are distributed on the spring box (12-5), and when the spring (12-4) is compressed, fluid in the chamber (12-8) can be drained to the shaft annulus through the drain holes; the lower part of the piston shell (12-6) is provided with a centering strip (12-10) and a diversion trench (12-11) at the matching part with the inner cavity of the coring bit.

5. A sponge coring tool as claimed in claim 4 wherein the lower floating piston (12) forms a closed chamber with the inner barrel string assembly, the suspension assembly (4), the upper floating piston (16); before the core barrel is placed into the core barrel, high-pressure sponge protective liquid is injected in advance, when core taking operation is carried out, a core acts on the lower end face of a lower floating piston (12), a piston shell (12-6) is driven to compress a spring and move upwards, a first sealing element (12-2) is made to be invalid, and the protective liquid in the core barrel is discharged through a piston discharge hole (12-9).

6. A sponge coring tool as claimed in any one of claims 1 to 5 wherein the inner diameter of the sponge bushing (8) is less than the core diameter by 0 mm, 5 mm to 1mm, the outer diameter is less than the coring inner barrel (7), and the pre-injected protective fluid can be discharged through the sponge bushing drain hole (18) after the core (20) enters the sponge bushing (8); when the oil saturation is measured, the oil content of the sampling rock mass (20-1) and the adsorbed oil content of the sponge material (8-1) at the sampling position need to be measured simultaneously, and the formation oil saturation is obtained through the weighted sum of the oil contents of the sampling rock mass and the sampling sponge.

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