CN115126433A - Plug-in pressure-maintaining corer suitable for soft formation and method of using the same - Google Patents

Abstract

The invention relates to a plug-in pressure-maintaining corer suitable for soft strata and a method for using the same, comprising an outer tube of the corer, a core tube, a penetration shoe, a flap valve, a pressure-maintaining inner tube and a pressure-measuring and pressure-releasing interface Piston: The piston and flap valve are installed in the outer tube of the corer, the piston is connected to the outer tube of the corer through a pin, the upper end of the core tube is connected to the piston, and the penetration shoe is connected to the lower end of the core tube; The lower end is against the valve seat, and the pressure-maintaining valve cover is limited in the annulus between the pressure-maintaining inner tube and the core-extractor outer tube. Under the action of external force, the inner tube can be moved to seal with the outer tube of the core extractor; when the pressure-maintaining inner tube moves to a certain height, the flap valve is closed. In this application, the hydraulic drive piston is used to drive the core pipe and the penetration shoe to penetrate into the soft formation, so as to obtain the pressure-holding core; the flow hole can effectively prevent the damage of the bottom hole tool; the pressure measurement and pressure relief interface is convenient for pressure measurement and safe pressure relief , which can improve safety performance.

Description

Plug-in pressure-maintaining corer suitable for soft formation and method of using the same

technical field

The invention relates to the technical field of pressure-maintaining coring, in particular to a plug-in pressure-maintaining coring device suitable for soft strata and a method for using the same.

Background technique

Core is an important physical geological data for studying and understanding underground geology and mineral conditions.

An appropriate amount of wells must be selected within the scope of the oil field, and a certain number of cores must be drilled for the relevant oil and gas layers. Through observation, analysis and research, we can understand: ① the age, lithology, and sedimentary characteristics of the stratum; ② reservoir characteristics Physical and chemical properties and oil, gas and water conditions; ③ oil-generating layer characteristics and oil-generating indicators; ④ subsurface structure (such as faults, joints, dips, etc.); ⑤ basic data for qualitative and quantitative interpretation of various logging methods; ⑥ The movement and distribution of oil, gas, and water, and the changes in stratigraphic structure during the production process; the core can also be used for water injection or laboratory experimental analysis of various enhanced oil recovery methods and production and stimulation measures. It is used to estimate oil reserves, prepare reasonable development It is an essential basic information for improving the development effect and recovery factor of reservoir water injection.

Core drilling refers to the drilling method in which the core is carved and taken out during drilling to study the underground geological conditions. Core drilling is usually rotary drilling. Drilling machinery is used to cut, grind and break the rock in various ways, so that the drill bit continues to drill deep into the rock layer and carve the core.

However, the hardness of the target formation can be soft or hard. For medium-hard or hard formations with uniform lithology and good columnarity, the commonly used hydraulic motor drives the drill bit to drill forward, and then pull out the core. For loose and soft strata, there are mainly mechanical pressure coring, hydraulic pressure coring and fully enclosed coring. The above coring methods for loose and soft strata mainly use ball valve pressure-retaining or no pressure-retaining extraction. Coring effect, ball valve pressure maintaining has the problem of small core diameter, and it is difficult to meet the current demand without pressure maintaining core.

SUMMARY OF THE INVENTION

In order to adapt to the acquisition of pressure-maintaining cores in soft formations, the present application provides a plug-in pressure-maintaining core remover, which uses hydraulically driven pistons to drive core pipes and penetration shoes to penetrate into soft formations, thereby obtaining pressure-maintaining cores.

This application is achieved through the following technical solutions:

Plug-in pressure-holding corer for soft formations, including corer outer tube, core tube, penetration shoe, flap valve, pressure-holding inner tube and piston:

The outer tube of the corer is provided with a lower limit structure for restricting the downward movement of the piston and a first upper limit structure for restricting the upward movement of the pressure-holding inner tube, and the first upper limit structure is located above the lower limit structure;

The piston is installed in the outer tube of the core extractor, the piston has a first sealing ring, the piston and the outer tube of the core extractor are connected together by pins, and the piston is provided with a connection structure for connecting the pulling device;

The upper end of the core tube is connected with the piston, and the penetration shoe is connected with the lower end of the core tube;

The flap valve includes a valve seat and a pressure-maintaining valve cover. The valve seat is connected to the outer pipe of the core taker. One side of the pressure-holding valve cover is movably connected to the top side of the valve seat. There is a valve on the top of the valve seat that is adapted to the pressure-holding valve cover. seat sealing surface;

The lower end of the pressure-maintaining inner tube is pressed against the valve seat, the pressure-maintaining valve cover is limited in the annular space between the outer wall of the pressure-maintaining inner tube and the inner wall of the outer tube of the corer, and the gap between the pressure-maintaining valve cover and the outer tube of the corer is limited. There is or no spring; the piston can pass through the valve seat and enter the pressure-holding inner pipe under the action of external force and seal with the pressure-holding inner pipe. The pressure-holding inner pipe is used to limit the second upper limit of the upward movement of the piston structure; the pressure-maintaining inner tube can be moved to abut against the first upper limit structure under the action of external force and seal with the outer tube of the core remover; when the pressure-maintaining inner tube moves to a certain height in the outer The pressure valve cover loses its restraint and falls back to the top of the valve seat and seals against the valve seat.

Optionally, the inner wall of the outer tube of the core remover is provided with a first shoulder to form the lower limit structure, the inner wall of the pressure maintaining inner tube is provided with a second shoulder to form the second upper limit structure, and the inner wall of the outer tube of the core remover is provided with a second upper limit structure. The third shoulder constitutes the first upper limit structure, the second shoulder is located above the first shoulder, and the third shoulder is located above the second shoulder.

Optionally, a second sealing ring is installed on the third shoulder, and when the upper end of the pressure-holding inner tube moves to abut against the third shoulder, the second sealing ring is used to achieve sealing between the two.

In particular, there is at least one flow-through hole on the tube wall of the outer tube of the core extractor, the flow-through hole is located above the lower limit structure, and the axial distance between the flow-through hole and the lower limit structure is greater than the axis of the piston to thickness.

Optionally, the outer tube of the core remover has an upper section of the outer tube and a lower section of the outer tube, the lower end of the upper section of the outer tube is threadedly connected with the upper end of the lower section of the outer tube; the inner diameter of the upper section of the outer tube is larger than the diameter of the lower section of the outer tube, and the lower section of the outer tube can be sealed with the piston. , the first shoulder, the flow hole and the pin hole are arranged on the lower section of the outer tube, the third shoulder is arranged on the upper section of the outer tube, and the pressure-holding inner tube is located in the upper section of the outer tube.

Optionally, the pressure-holding inner pipe has a first section, a second section and a third section that are manufactured in one piece, the first section, the second section and the third section are connected in sequence, and the first section, the second section and the third section are The diameters of the segments are successively reduced, a second upper limit structure is formed at the connection between the first segment and the second segment, and the second segment can be sealed with the piston.

Optionally, the piston is provided with a pressure measurement and pressure relief interface, the pressure measurement and pressure relief interface penetrates the upper and lower surfaces of the piston, and a one-way valve is installed at the pressure measurement and pressure relief interface. Check Valves Existing check valves are optional.

In particular, the pressure measurement and pressure relief interface includes a valve cavity, a first hole and a second hole. The lower end of the first hole penetrates the lower surface of the piston, the upper end of the first hole penetrates the valve cavity, and the upper end of the second hole penetrates the upper surface of the piston. The lower end of the orifice passes through the valve cavity;

The one-way valve includes a valve core and a second spring, the valve cavity is a stepped hole, the valve core is adapted to the small hole of the valve cavity, and the valve core is provided with a valve core sealing ring for sealing and matching with the hole wall, and the second spring is installed. The valve core is located above the second spring. Under the action of the second spring, the valve core is installed in the small hole of the valve cavity and abuts on the inner shoulder of the pressure measuring and pressure relief interface.

In particular, the piston has the following two types: the first type, the diameter of the second hole is smaller than the diameter of the valve cavity, the diameter of the first hole is greater than or equal to the diameter of the valve cavity, and the second hole is provided with an axial through hole. The threaded head is threadedly connected with the first hole, the lower end of the second spring abuts on the threaded head, and under the action of the second spring, the valve core abuts on the shoulder at the connection between the second hole and the valve cavity; The one-way valve includes or does not include a valve stem adapted to the second hole, the valve stem is installed in the second hole, and the lower end of the valve stem is connected with the valve core;

The second type, the diameter of the first hole is smaller than the diameter of the valve cavity, the diameter of the second hole is greater than or equal to the diameter of the valve cavity, the second hole is equipped with a threaded head with an axial through hole, and the screw head is threaded with the second hole. connection, the lower end of the second spring abuts on the inner shoulder at the connection between the first orifice and the valve cavity, under the action of the second spring, the valve core abuts on the threaded head; the one-way valve includes or does not include and The valve stem is fitted with two holes, the valve stem is installed in the axial through hole, and the lower end of the valve stem is connected with the valve core.

The method of using the plug-in pressure-holding corer suitable for soft formations includes the following steps:

After the corer is lowered to the target formation, the drilling fluid is introduced, and the drilling fluid has a tendency to drive the piston downward, and then the pin is cut. After the pin is cut, the piston moves downward under the action of the drilling fluid, driving the core. The tube and the penetration shoe carry out the downward coring movement, and the obtained core enters the inside of the core tube;

After the core completely enters the core tube, the lower end of the piston is also located on the lower limit structure of the outer tube of the corer. When the outer tube of the corer is provided with a flow hole, the drilling fluid flows out to the corer through the flow hole. outside the outer tube;

After the core enters the core tube completely, connect the piston through the pulling device at the wellhead;

The piston is pulled up by the pulling device to drive the piston, the core pipe, the penetration shoe and the core to move upward, so that the core enters the pressure-maintaining inner pipe, and the piston is sealed with the pressure-holding inner pipe;

Continue to pull up to drive the pressure-maintaining inner tube to move upward synchronously, the upper end of the pressure-maintaining inner tube is seated on the first upper limit structure of the outer tube of the core extractor, and the piston is seated on the second upper limit structure of the pressure-keeping inner tube to ensure The upper end of the pressure inner tube is sealed with the outer tube of the core taker by means of the second sealing ring; at the same time, the pressure keeping inner tube moves upward to pass over the flap valve, thereby providing space for the overturning of the pressure keeping valve cover, and the pressure keeping valve cover is turned over. The sealing of the lower end is completed until it is closed with the valve seat, thereby forming a pressure-holding space.

Compared with the prior art, the present application has the following beneficial effects:

1. In this application, the hydraulic drive piston is used to drive the core tube and the penetration shoe to penetrate into the soft formation, so as to obtain the pressure-holding rock core; the flap valve is used to realize the pressure-holding seal at the lower end, which can solve the problem of small core diameter caused by the ball valve. ;

2. After the core enters the core tube, the flow hole is automatically opened, which can effectively avoid the damage to the bottom hole tool caused by the bottom hole pressure;

3. The application is provided with a pressure measurement and pressure relief interface, which is convenient for pressure measurement and safe pressure relief, and can improve safety performance.

Description of drawings

The accompanying drawings described herein are used to provide a further understanding of the embodiments of the present application, and constitute a part of the present application, and do not constitute a limitation on the embodiments of the present invention.

Fig. 1 is the structural representation of the plug-in pressure-maintaining corer under the initial state in the embodiment;

Fig. 2 is the partial enlarged view of A place in Fig. 1;

3 is a schematic structural diagram when the flap valve and the pressure-holding inner pipe are installed in the outer pipe of the core extractor in the embodiment;

Fig. 4 is the structural representation of the pressure-holding inner pipe in the embodiment;

Fig. 5 is the structural representation of the one-way valve and the first kind of piston in the embodiment;

Fig. 6 is the structural representation of the first piston in the embodiment;

Fig. 7 is the structural representation of the one-way valve and the second kind of piston in the embodiment;

Fig. 8 is the structural representation of the second kind of piston in the embodiment;

Fig. 9 is the structural schematic diagram when the plug-in pressure-maintaining core extractor has just acquired the core in the embodiment;

10 is a schematic structural diagram when the lifting device is connected to the plug-in pressure-maintaining corer in the embodiment;

Figure 11 is a schematic structural diagram of the piston and the core pipe during the upward lifting process in the embodiment;

FIG. 12 is a schematic structural diagram when the pressure-maintaining inner tube is lifted to abut against the outer tube of the core extractor in the embodiment.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments. Obviously, the described embodiments are some, but not all, embodiments of the present invention. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict. It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. For the same and similar parts among the various embodiments, refer to each other Can.

In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the The orientation or positional relationship that is usually placed when the product of the invention is used, or the orientation or positional relationship that is commonly understood by those skilled in the art, is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must be It has a specific orientation, is constructed and operates in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms "first", "second", etc. are only used to differentiate the description and should not be construed to indicate or imply relative importance.

In the description of the present invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "arranged", "installed", "connected" and "connected" should be understood in a broad sense, for example, it may be a fixed connection, It can also be a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or the internal communication between the two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

As shown in FIG. 1 , the plug-in pressure-maintaining corer suitable for soft formation disclosed in this embodiment includes a corer outer tube 1 , a core tube 2 , a penetration shoe 3 , a flap valve 4 , and a pressure-maintaining inner tube 1 . Tube 5 and piston 6.

The core pipe 2, the pressure-holding inner pipe 5 and the piston 6 are all located in the outer pipe 1 of the core extractor, the flap valve 4 is mounted on the outer pipe 1 of the core extractor, the upper end of the core pipe 2 is fixedly connected with the piston 6, and the core The lower section of the tube 2 is connected to the penetration shoe 3 .

The outer tube 1 of the core extractor is provided with a lower limit structure for restricting the downward movement of the piston 6 and a first upper limit structure for restricting the upward movement of the pressure maintaining inner tube 5, and the first upper limit structure is located above the lower limit structure. The pressure-maintaining inner tube 5 can be moved to abut against the first upper limit structure under the action of an external force, and is in sealing fit with the core extractor outer tube 1 . The piston 6 enters into the pressure-maintaining inner tube 5 under the action of an external force, and is in sealing fit with the pressure-maintaining inner tube 5 .

As shown in FIG. 2 , the flap valve 4 includes a valve seat 41 and a pressure-maintaining valve cover 42, the valve seat 41 is connected to the outer pipe 1 of the core taker, and one side of the pressure-holding valve cover 42 is movably connected to the top side of the valve seat 41, The top of the valve seat 41 has a valve seat sealing surface adapted to the pressure-retaining valve cover 42 . The valve seat 41 can be turned and closed by its own weight, and a spring can also be added to provide a triggering elastic force.

In a possible design, the flap valve 4 further includes a first spring 43 , and the first spring 43 is installed on the inner wall of the core extractor outer tube 1 or installed in a groove on the outer surface of the pressure-maintaining valve cover 42 . In a possible design, one side of the pressure-maintaining valve cover 42 is hinged with the top of the valve seat 41, and there is a torsion spring at the hinge.

As shown in FIG. 1 , in the initial state, the lower end of the pressure-maintaining inner pipe 5 abuts on the valve seat 41 , and the pressure-maintaining inner pipe 5 restricts the pressure-maintaining valve cover 42 to the outer wall of the pressure-maintaining inner pipe 5 and the core extractor outer pipe 1 . In the annulus of the inner wall, the pressure maintaining valve cover 42 is opened; the first spring 43 is compressed between the pressure maintaining valve cover 42 and the outer tube 1 of the core extractor.

In the initial state, the piston 6 and the outer tube 1 of the core extractor are connected together by a pin 7; the piston 6 is located under the flap valve 4. The piston 6 and the outer tube 1 of the core extractor are provided with pin holes 15 which are adapted to the pins 7 , and the pins 7 are radially installed in the pin holes 15 .

It should be noted that the number of the pins 7 is reasonably set according to the needs, and it is usually advisable to set two pins 7 symmetrically.

A first shoulder 11 is arranged on the inner wall of the outer tube 1 of the core taker to form a lower limit structure, a second shoulder 51 is arranged on the inner wall of the pressure-holding inner tube 5 to constitute a second upper limit structure, and a third shoulder 13 is arranged on the inner wall of the outer tube 1 of the core taker The first upper limit structure is formed, the second shoulder 51 is located above the first shoulder 11 , and the third shoulder 13 is located above the second shoulder 51 .

In a possible design, a second sealing ring 14 is installed on the third shoulder 13 . When the upper end of the pressure-holding inner tube 5 moves to abut against the third shoulder 13 , the second sealing ring 14 is used to realize two seal between them.

In a possible design, the wall of the outer tube 1 of the core extractor has at least one flow hole 12 penetrating the inner and outer walls thereof, the flow hole 12 is located above the first shoulder 11, and the flow hole 12 is connected with the first The axial distance of the shoulder 11 is greater than the axial thickness of the piston 6 .

It is worth noting that the number of the flow-through holes 12 is reasonably set as required, and generally, at least two flow-through holes 12 are preferably arranged at equal intervals in the circumferential direction.

In a possible design, as shown in FIG. 3 , the outer tube 1 of the core extractor has an upper section 101 of the outer tube and a lower section 102 of the outer tube, and the lower end of the upper section 101 of the outer tube is threadedly connected to the upper end of the lower section 102 of the outer tube. The inner diameter of the upper section 101 of the outer tube is larger than the diameter of the lower section 102 of the outer tube, the lower section 102 of the outer tube can be sealed with the piston 6, the first shoulder 11, the flow hole 12 and the pin hole 15 are arranged on the lower section 102 of the outer tube, and the third The shoulder 13 is provided on the upper section 101 of the outer tube, and the pressure-holding inner tube 5 is located in the upper section 101 of the outer tube.

In a possible design, as shown in FIG. 4 , the pressure-holding inner tube 5 has a first section 501 , a second section 502 and a third section 503 which are integrally manufactured, and the first section 501 , the second section 502 and the third section The segments 503 are connected in sequence, the diameters of the first segment 501, the second segment 502 and the third segment 503 are sequentially reduced, and a second shoulder 51 is formed at the connection between the first segment 501 and the second segment 502, and the second segment 502 can be connected to the The piston 6 is sealed and matched to form the sealing section of the pressure-maintaining inner tube 5 .

In a possible design, as shown in FIGS. 5-8 , an annular groove is formed on the outer wall of the piston 6 , and a first sealing ring 61 is installed in the annular groove. The piston 6 is provided with a pressure measurement and pressure relief interface, the pressure measurement and pressure relief interface penetrates the upper and lower surfaces of the piston 6, and a one-way valve 8 is installed at the pressure measurement and pressure relief interface. In particular, the pressure measurement and pressure relief interface includes a valve cavity 62 , a first hole 63 and a second hole 64 , the lower end of the first hole 63 penetrates the lower surface of the piston 6 , the upper end of the first hole 63 penetrates the valve cavity 62 , and the upper end of the second hole 64 Passing through the upper surface of the piston 6 , the lower end of the second hole 64 passes through the valve cavity 62 . The one-way valve 8 includes a valve core 81 and a second spring 82. The valve cavity 62 is a stepped hole. The valve core 81 is installed in the small hole of the valve cavity 62 and is sealed with the hole wall through the valve core sealing ring. The valve core 81 is the second The spring 82 is installed in the large hole of the valve chamber 62 . The valve core 81 is located above the second spring 82. Under the action of the second spring 82, the valve core 81 is installed in the small hole of the valve cavity 62 and abuts on the inner shoulder of the pressure measuring and pressure relief interface.

In order to facilitate the installation of the one-way valve 8, the piston 6 of two structures is provided in this embodiment. The first type, as shown in FIG. 5 and FIG. 6 , the diameter of the second hole 64 is smaller than the diameter of the valve cavity 62 , the diameter of the first hole 63 is greater than or equal to the diameter of the valve cavity 62 , and the second hole 64 is equipped with a shaft To the thread head 63 of the through hole 66 , the thread head 63 is threadedly connected with the first hole 63 , the lower end of the second spring 82 abuts on the thread head 63 , under the action of the second spring 82 , the valve core 81 abuts against the second On the shoulder where the hole 64 connects with the valve cavity 62 . In particular, the one-way valve 8 further includes a valve stem 83 adapted to the second hole 64 , the valve stem 83 is installed in the second hole 64 , and the lower end of the valve stem 83 is connected with the valve core 81 . In particular, the valve stem 83 and the valve core 81 are integrally manufactured.

In the second type, as shown in FIGS. 7 and 8 , the diameter of the first hole 63 is smaller than the diameter of the valve cavity 62 , the diameter of the second hole 64 is greater than or equal to the diameter of the valve cavity 62 , and the second hole 64 is equipped with a shaft To the threaded head 63 of the through hole 66, the threaded head 63 is threadedly connected with the second hole 64, the lower end of the second spring 82 abuts on the inner shoulder at the connection between the first hole 63 and the valve cavity 62, and the second spring 82 Under the action of , the valve core 81 abuts on the threaded head 63 . In particular, the one-way valve 8 further includes a valve stem 83 adapted to the second hole 64 , the valve stem 83 is installed in the axial through hole 66 , and the lower end of the valve stem 83 is connected with the valve core 81 .

In a possible design, the penetration shoe 3 is a conical cylinder, the big end of which is fixedly connected with the lower end of the core pipe 2 .

The piston 6 is provided with a connecting structure for connecting the pulling device, so that the piston 6 and the core pipe 2 can be pulled upwards. In a possible design, the top of the piston 6 is provided with a spearhead 9, and the pulling device can choose a wire rope 91 and an overshot 92, which are conventional techniques in the art, and will not be repeated here.

How to use the plug-in pressure-holding corer:

Before coring, the pin 7 connects the piston 6 with the outer tube 1 of the coring device, as shown in Figure 1;

After the corer is lowered to the target formation, the drilling fluid is introduced, and the drilling fluid has a tendency to drive the piston 6 to move downward, and then the pin 7 is cut. After the pin 7 is cut, the piston 6 moves downward under the action of the drilling fluid. , drive the core tube 2 and the penetration shoe 3 to carry out the downward coring movement, and the obtained core enters the interior of the core tube 2;

After the core has completely entered the core tube 2, the lower end of the piston 6 is also seated on the first shoulder 11 of the outer tube 1 of the corer. At this time, the flow hole 12 is opened, and the drilling fluid flows out to the core through the flow hole 12. Outside the outer tube 1 of the device to prevent pressure and avoid damage to the core extractor, as shown in Figure 9;

After the core has completely entered the core tube 2, it is put into the overshot 92 through the wire rope 91 at the wellhead, and the overshot 92 is connected to the spearhead 9, as shown in Figure 10;

Pulling the wire rope 91 drives the piston 6, the rock core tube 2 and the rock core to move upward, so that the rock core enters the pressure maintaining inner tube 5, and the first sealing ring 41 of the piston 6 enters the sealing section of the pressure maintaining inner tube 5 for sealing. As shown in Figure 11;

Continue to pull the wire rope 91 to drive the pressure maintaining inner tube 5 to move upward synchronously, the upper end of the pressure maintaining inner tube 5 is seated on the third shoulder 13 of the core extractor outer tube 1, and the upper end of the pressure maintaining inner tube 5 relies on the second sealing ring 14 Sealed with the corer outer tube 1; at the same time, the pressure keeping inner tube 5 moves upward to cross the flap valve 4, and then provides space for the overturning of the pressure keeping valve cover 42. Under the action of the first spring 43, the pressure keeping The valve cover 42 is turned over to close with the valve seat 1 to complete the sealing of the lower end, thereby forming a pressure-holding space, as shown in FIG. 12 ;

After the corer is lifted from the bottom of the well to the ground, the pressure measurement and pressure relief interface and the one-way valve 8 provided on the piston 6 can be used to complete the measurement of the internal pressure of the core pipe 2, and the measurement can be passed before the core is taken out. The pressure relief interface is used for pressure relief to ensure safe operation. The specific operation is: connect the external pressure measuring element or pressure relief mechanism to the pressure measuring and pressure relief interface, push the valve core 81 downward to compress the second spring 82, and the valve core sealing ring on the valve core 81 loses the sealing effect, so that the core tube 2 The internal pressure can be measured or unloaded through this interface.

The application can maintain the pressure to obtain the core of the soft stratum. By opening the pressure measuring and pressure relief interface on the piston, the internal pressure of the core pipe can be measured through the channel, and the pressure can be unloaded through the channel to prevent the operation with pressure. Can effectively improve security.

The above specific embodiments further describe the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above are only specific embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Within the spirit and principle of the present invention, any modifications, equivalent replacements, improvements, etc. made should be included within the protection scope of the present invention.

Claims (10)

1. A plug-in pressure-maintaining coring device suitable for soft and soft formations, characterized in that: it includes: The outer tube (1) of the core extractor is provided with a lower limit structure for restricting the downward movement of the piston (6) and a first upper limit structure for restricting the upward movement of the pressure maintaining inner tube (5). The first upper limit structure is located at Above the lower limit structure; The piston (6) is installed in the outer tube (1) of the core extractor. The piston (6) has a first sealing ring (61), and a pin (7) is passed between the piston (6) and the outer tube (1) of the core extractor. connected together, the piston (6) is provided with a connecting structure for connecting the pulling device; the core pipe (2), the upper end of which is connected with the piston (6); The penetration shoe (3) is connected with the lower end of the core pipe (2); The flap valve (4) includes a valve seat (41) and a pressure-maintaining valve cover (42). The valve seat (41) is connected to the outer pipe (1) of the core extractor, and one side of the pressure-maintaining valve cover (42) is connected to the valve seat (41) One side of the top is flexibly connected, and the top of the valve seat (41) has a valve seat sealing surface adapted to the pressure maintaining valve cover (42); The pressure-maintaining inner pipe (5), the lower end of which is abutted on the valve seat (41), and the pressure-maintaining valve cover (42) is limited to the outer wall of the pressure-maintaining inner pipe (5) and the inner wall of the core extractor outer pipe (1) In the annular space between the pressure-retaining valve cover (42) and the core extractor outer tube (1), a spring is or is not provided; Under the action of external force, the piston (6) can pass through the valve seat (41) into the pressure-maintaining inner pipe (5) and seal with the pressure-maintaining inner pipe (5). A second upper limit structure that restricts the upward movement of the piston (6); the pressure-holding inner tube (5) can be moved to the first upper limit structure under the action of external force and sealed with the core extractor outer tube (1). Cooperate; When the pressure-maintaining inner tube (5) moves to a certain height in the core extractor outer tube (1), the pressure-maintaining valve cover (42) loses its restraint and falls back to the top of the valve seat (41) and seals with the valve seat (41). . 2. The plug-in pressure-maintaining core remover suitable for soft formations according to claim 1, characterized in that: the inner wall of the outer tube (1) of the core remover is provided with a first shoulder (11) to constitute the lower limit position Structure, the inner wall of the pressure-holding inner tube (5) is provided with a second shoulder (51) to form the second upper limit structure. Position structure, the second shoulder (51) is located above the first shoulder (11), and the third shoulder (13) is located above the second shoulder (51). 3. The plug-in pressure-maintaining core extractor suitable for soft strata according to claim 2, characterized in that: a second sealing ring (14) is installed on the third shoulder (13), and when the pressure-maintaining inner pipe ( 5) When the upper end moves to abut against the third shoulder (13), the second sealing ring (14) realizes the sealing between the two. 4. The plug-in pressure-maintaining corer suitable for soft formations according to any one of claims 1-3, characterized in that: there is at least one through-hole on the wall of the outer tube (1) of the corer The flow holes (12) on its inner and outer walls are located above the lower limit structure, and the axial distance between the flow holes (12) and the lower limit structure is greater than the axial thickness of the piston (6). 5. The plug-in pressure-maintaining core remover suitable for soft formations according to claim 1, characterized in that: the outer tube (1) of the core remover has an upper section (101) and a lower section (102) of the outer tube, and the outer The lower end of the upper pipe section (101) is threadedly connected with the upper end of the lower section (102) of the outer pipe; The inner diameter of the upper section (101) of the outer tube is larger than the diameter of the lower section (102) of the outer tube, and the lower section (102) of the outer tube can be sealed with the piston (6), the first shoulder (11), the flow hole (12) and the pin hole (15) is arranged on the lower section (102) of the outer tube, the third shoulder (13) is arranged on the upper section (101) of the outer tube, and the pressure-holding inner tube (5) is located in the upper section (101) of the outer tube. 6. The plug-in pressure-maintaining core remover suitable for soft strata according to claim 1 or 5, characterized in that: the pressure-maintaining inner pipe (5) has a first section (501), a second section (501) and a second Section (502) and third section (503), first section (501), second section (502) and third section (503) are connected in sequence, first section (501), second section (502) and third section The diameters of the three segments (503) decrease in turn, the connection between the first segment (501) and the second segment (502) forms a second upper limit structure, and the second segment (502) can be sealed with the piston (6). 7. The plug-in pressure-maintaining corer suitable for soft formations according to claim 1, characterized in that: the piston (6) is provided with a pressure-measuring and pressure-relief interface, and the pressure-measuring and pressure-relief interface penetrates the piston (6) A check valve (8) is installed on the upper and lower surfaces of the pressure measuring and pressure relief interface. 8. The plug-in pressure-holding corer suitable for soft formations according to claim 7, characterized in that: the pressure-measuring and pressure-relief interface comprises a valve cavity (62), a first hole (63) and a second hole (64), the lower end of the first hole (63) penetrates the lower surface of the piston (6), the upper end of the first hole (63) penetrates the valve cavity (62), and the upper end of the second hole (64) penetrates the upper surface of the piston (6), The lower end of the second hole (64) penetrates through the valve cavity (62); The one-way valve (8) includes a valve core (81) and a second spring (82), the valve cavity (62) is a stepped hole, and the valve core (81) is adapted to the small hole of the valve cavity (62). (81) is provided with a valve core sealing ring for sealing with the hole wall, and the second spring (82) is installed in the large hole of the valve cavity (62); The valve core (81) is located above the second spring (82), and under the action of the second spring (82), the valve core (81) is installed in the small hole of the valve cavity (62) and abuts against the pressure measurement and pressure relief interface on the inner shoulder. 9. The plug-in pressure-holding corer suitable for soft formations according to claim 8, characterized in that: the piston (6) has the following two types: First, the diameter of the second hole (64) is smaller than the diameter of the valve cavity (62), the diameter of the first hole (63) is greater than or equal to the diameter of the valve cavity (62), and the second hole (64) is equipped with a device The threaded head (63) of the axial through hole (66), the threaded head (63) is threadedly connected with the first hole (63), the lower end of the second spring (82) abuts on the threaded head (63), and the second spring Under the action of (82), the valve core (81) abuts on the shoulder at the connection between the second orifice (64) and the valve cavity (62); the one-way valve (8) includes or does not include the second orifice (64) ) adapted valve stem (83), the valve stem (83) is installed in the second hole (64), and the lower end of the valve stem (83) is connected to the valve core (81); In the second type, the diameter of the first orifice (63) is smaller than the diameter of the valve cavity (62), the diameter of the second orifice (64) is greater than or equal to the diameter of the valve cavity (62), and the second orifice (64) is equipped with a device. The threaded head (63) of the axial through hole (66) is threadedly connected with the second hole (64), and the lower end of the second spring (82) abuts against the first hole (63) and the valve cavity (62). ) on the inner shoulder of the connection, under the action of the second spring (82), the valve core (81) abuts on the threaded head (63); the one-way valve (8) includes or does not include and the second orifice (64) A matching valve rod (83), the valve rod (83) is installed in the axial through hole (66), and the lower end of the valve rod (83) is connected with the valve core (81). 10. The using method of the plug-in pressure-holding corer suitable for soft strata according to any one of claims 1-9, characterized in that: comprising the following steps: After the corer is lowered to the target formation, the drilling fluid is introduced, and the drilling fluid tends to drive the piston (6) to move downward, and then the pin (7) is cut off. After the pin (7) is cut, the piston (6) will The downward movement under the action of the drilling fluid drives the core tube (2) and the penetration shoe (3) to carry out the downward coring movement, and the obtained core enters the inside of the core tube (2); After the core has completely entered the core tube (2), the lower end of the piston (6) is also located on the lower limit structure of the corer outer tube (1). 12), the drilling fluid flows out to the outside of the corer outer tube (1) through the flow hole (12); After the core has completely entered the core tube (2), the piston (6) is connected at the wellhead through a pulling device; The piston (6) is pulled up by the pulling device to drive the piston (6), the core tube (2), the penetration shoe (3) and the core to move upward, so that the core enters the pressure-holding inner tube (5), the piston (6) Sealed with the pressure-holding inner pipe (5); Continue to pull up to drive the pressure-maintaining inner tube (5) to move upward synchronously, the upper end of the pressure-maintaining inner tube (5) is seated on the first upper limit structure of the On the second upper limit structure of the pressure inner pipe (5), the upper end of the pressure maintaining inner pipe (5) is sealed with the core extractor outer pipe (1) by means of the second sealing ring (14); at the same time, the pressure maintaining inner pipe (5) Move up to pass the flap valve (4), and then provide space for the overturning of the pressure maintaining valve cover (42), and the pressure maintaining valve cover (42) is overturned to close with the valve seat (1) to complete the sealing of the lower end, thereby Form a pressure-holding space.

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