A liquid flow collection sampling control method and device

Abstract

The application discloses a kind of liquid flow collection sampling control method and device, based on a kind of liquid flow collection locking control device is realized, the liquid flow collection locking control device includes multiple and surrounds integrated on the center pipe of pipe column, the device includes upper joint, elastic claw valve core, outer sleeve, center rod, floating piston, lower piston, C type limit ring, liquid inlet passage, liquid outlet passage and air cavity;The method comprises: by opening balance valve, air cavity is communicated with floating piston, floating piston is driven to move using wellbore pressure, well fluid is pressed into sample chamber, sample is collected;Sampling is about to end, floating piston drives the secondary movement of center rod and lower piston connected with it, when lower piston moves to the preset sampling stroke end point, triggers a limit mechanism, makes the C type limit ring pop out and is clamped into the limit groove of lower joint, complete sealing, complete disposable sampling and sealing.

Description

Technical Field

[0001] This invention belongs to the technical field of downhole sampling tools for oil and gas wells, specifically relating to a liquid flow collection and locking control method and device for downhole fluid sampling. Background Technology

[0002] In oil and gas field exploration and development, obtaining authentic, uncontaminated formation fluid samples is crucial for reservoir evaluation. Traditional downhole sampling techniques, such as electric submersible pumps and mechanical piston samplers, suffer from problems such as complex mechanical structures and high failure rates. Furthermore, spring-driven samplers experience force attenuation due to material creep under prolonged high-temperature environments, resulting in uncontrollable sampling volume.

[0003] In recent years, techniques have emerged that utilize the natural pressure difference between the wellbore and the formation for sampling, attempting to simplify the process. However, these passive pressure difference sampling methods suffer from problems such as unstable pressure difference, uncontrollable sampling process, susceptibility to wellbore fluid contamination, and insufficient post-sampling sealing reliability, performing particularly poorly under complex well conditions.

[0004] Therefore, there is an urgent need in this field for a high-temperature and high-pressure downhole sampling solution that is simple in structure, requires no external power, has a stable and reliable sampling process, and can ensure sample fidelity. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a purely mechanical liquid flow collection and locking control method and device that utilizes wellbore pressure to drive sampling and automatically locks the seal in one go. This method aims to solve technical problems such as failure of existing sampling instruments at high temperatures, inaccurate sampling due to spring creep, instability of passive differential pressure sampling, and poor reliability of high-pressure seals.

[0006] The technical solution adopted in the first aspect of this application is as follows: a liquid flow collection and sampling control method, the method being implemented based on a liquid flow collection locking control device, which comprises multiple devices integrated around the central tube of a tubing column, the liquid flow collection locking control device comprising an upper connector, a spring-claw valve core, an outer sleeve, a central rod, a floating piston, a lower piston, a C-type limiting ring, a liquid inlet channel, a liquid outlet channel, and an air cavity; the method includes the following steps:

[0007] In the initial state, the space between the floating piston and the air chamber is filled with high-temperature grease to form a grease chamber, while the air chamber is empty. One end of the lower piston is threaded to the central rod, and the liquid inlet channel is connected to the right side of the floating piston. The lower end of the lower piston is connected to the liquid path of the central tube of the tubing column through the central tube perforation. The upper spring claw valve core completes the initial locking and limiting of the lower piston. At the same time, the central tube perforation and the sampling short section conversion head control the generation of overall fluid interception pressure to avoid the lower piston being subjected to large impacts. By opening the balance valve, the air chamber is connected to the wellbore, and the wellbore pressure drives the floating piston to move once, and the well fluid is injected into the sample chamber, and the sample is collected.

[0008] As sampling nears completion, the floating piston drives the connected central rod and lower piston to move a second time. When the lower piston reaches the preset sampling stroke endpoint, a limiting mechanism is triggered, causing the C-shaped limiting ring to pop out and engage in the limiting groove of the lower connector, thus sealing the connection. Simultaneously, the upper spring claw valve core is pushed upward, cutting off the tiny hydraulic perforated flow channel between the grease chamber and the air chamber, completing a single sampling and sealing operation. By employing the above technical solution: a pressure sensor is installed at the perforation of the central tube. When the pressure sensor receives a pressure signal and the signal reaches a threshold, the circuit board activates the motor to start driving, opening the balance valve and performing a series of actions. At this time, the wellbore pressure acting on the other end of the lower piston becomes the net thrust driving the lower piston, achieving purely mechanical active sampling and completing the suction in one go. After the lower piston reaches its position, the C-shaped elastic limiting ring pops out instantly, locking the lower piston and blocking the sample from the wellbore channel, achieving zero backflow and zero contamination, ensuring high reliability of sampling in harsh downhole environments.

[0009] Preferably, after the lower piston is about to move into position, the floating piston drives the central rod to pull the lower piston relative to the outer sleeve, causing a slight displacement. This displacement releases the radial constraint on the C-shaped limiting ring, allowing it to pop out radially under elastic force and lock into the limiting groove of the lower connector. An inlet channel and an outlet channel are provided between the lower piston and the sample chamber. Two sealing assemblies are provided between the inlet channel and the outer sleeve. When the floating piston pulls the lower piston into position via the central rod, the two sealing assemblies are compressed to form a seal. By adopting the above technical solution, utilizing a clever and reliable mechanical linkage locking mechanism, and using the slight relative displacement at the end of the lower piston's stroke as a trigger signal, the constraint on the C-shaped limiting ring is automatically released, ensuring the continuity and necessity of the locking action and the sampling action. Once sampling is completed, it automatically locks, effectively preventing sample backflow or contamination due to incomplete locking. This structure is simple, sensitive, and requires no additional control, further improving the automation and reliability of the entire sampling process. Simultaneously, the two sealing assemblies further enhance the sealing effect.

[0010] Preferably, after the C-type limiting ring is locked, the wellbore pressure acting on both ends of the lower piston generates a continuous axial sealing force due to the area difference. This sealing force increases with the increase of wellbore pressure, forming a pressure self-tightening seal. By adopting the above technical solution, the pressure self-tightening effect is introduced, greatly improving the reliability and adaptability of the seal. By designing an effective pressure-bearing area difference at both ends of the lower piston, the wellbore pressure generates a continuous net sealing force on this area difference after locking, which automatically and linearly increases with the increase of wellbore pressure, thereby achieving dynamic adaptability. In the high-pressure environment of deep and ultra-deep wells, this design can provide a sealing effect far exceeding that of conventional constant preload seals, fundamentally solving the industry problem of easy seal failure under high-pressure conditions.

[0011] Preferably, while the floating piston completes the driving sampling, it simultaneously drives the sealing head at the end of the central rod to squeeze the spring claw valve core, thereby automatically sealing the micro-hydraulic perforated flow channel between the sample chamber and the air chamber, achieving a seal. By adopting the above technical solution, the potential risk of back pressure chamber after sampling is solved. The principle is that at the end of the sampling action, the spring claw valve core and other mechanisms are triggered by mechanical linkage to permanently seal the air chamber, forming a sealed air cushion. This can eliminate the negative pressure that may be generated in the air chamber due to temperature and pressure fluctuations during subsequent drilling or changes in working conditions. This negative pressure will form a reverse force, weakening or even destroying the formed seal, ensuring the long-term static stability of the locked state, and providing additional protection for the integrity of the sample during the process of lifting it to the ground.

[0012] A second aspect of this application provides a liquid flow collection locking control device for implementing the above method, comprising:

[0013] The upper connector constitutes the upper connection structure of the device;

[0014] The adapter is used to connect the upper connector and the outer sleeve, and is equipped with micro-hydraulic perforated flow channels;

[0015] The spring claw valve core is located inside the adapter and is used to seal the tiny hydraulic perforated flow channel between the sample chamber and the air chamber;

[0016] The outer sleeve is connected to the upper connector via an adapter to form the main outer shell of the device;

[0017] The center rod is located inside the outer sleeve and can move relative to the outer sleeve. A push block is provided at the end near the spring claw valve core.

[0018] A floating piston is fitted onto the central rod and positioned between the push block and the lower piston;

[0019] The lower piston, connected to the lower part of the central rod, moves under the pressure of the wellbore to sample the well fluid;

[0020] A C-type limiting ring is disposed between the lower piston and the lower connector. In the unlocked state, it is radially constrained, and in the locked state, it pops out and gets stuck in the limiting groove of the lower connector.

[0021] The lower connector constitutes the lower connection structure of the device, and is equipped with an inlet pipe for liquid inlet and the limiting groove, which is connected to the central tube perforation of the sampling short section conversion head intercepting flow channel.

[0022] By adopting the above technical solution: this device is the functional entity of the above method. Its components work together to form a complete mechanical hydraulic logic system. The upper connector and outer sleeve provide overall structural support and pressure boundary. The central rod, as the transmission core, transmits the driving force of the floating piston to the lower piston. The floating piston is the key component for realizing wellbore pressure capture and conversion. The lower piston directly performs sampling and sealing functions. The C-type limit ring and the limit groove of the lower connector constitute the final locking actuator. It has a compact structure and excellent high temperature and high pressure resistance.

[0023] Preferably, the device further includes a balancing valve, which controls the opening and closing of the air passage connecting the air chamber and the wellbore.

[0024] Preferably, a limiting block and / or limiting ring are also included to precisely limit the travel of the floating piston and / or the center rod.

[0025] By adopting the above technical solution, the limiting block and limiting ring act as stroke controllers. Through their mechanical hard limiting, the final stroke of the lower piston can be precisely controlled, thereby directly determining the volume of the sample chamber. The sampling volume becomes a fixed and accurately predictable value, ensuring the consistency and comparability of data between different samplings and overcoming the defect of uncontrollable differential pressure sampling volume in traditional methods.

[0026] Preferably, the end of the lower piston that contacts the sample chamber is provided with a double sealing assembly, which includes a sealing ring and a retaining ring combination.

[0027] By adopting the above technical solutions: sealing rings, such as O-rings, are key to achieving static sealing and directly prevent sample leakage. The addition of retaining rings, such as PTFE retaining rings, prevents the sealing rings from being squeezed into the gaps between parts and damaged under high pressure. The combined design of sealing rings and retaining rings significantly improves the durability and reliability of the sealing assembly under ultra-high pressure conditions.

[0028] Preferably, the floating piston is configured to convert the ambient pressure of the wellbore into mechanical power to drive the central rod and the lower piston. By adopting the above technical solution, this preferred solution positively defines the core role of the floating piston in terms of function, emphasizes the essential nature of the power source of this device, whose input is the ambient pressure of the wellbore and whose output is the mechanical power to drive the sampling action, highlighting the fundamental difference between this application and traditional technologies that rely on external power sources or internal energy storage elements.

[0029] Preferably, the upper connector is connected to the outer sleeve via an adapter.

[0030] By adopting the above technical solution, the adapter is not just a structural component. It has a precisely machined cavity and flow channel inside to accommodate and control the movement of the spring claw valve core. It is the control center for the key process switching from initial pressure balance to establishing driving pressure difference. Integrating this function into the adapter avoids directly machining complex valve cavities on the outer sleeve or upper connector, which greatly reduces the machining difficulty and risk of the core pressure-bearing component.

[0031] The adapter can be tested on the surface as an independent functional unit (such as testing the valve core's opening and closing function), ensuring the reliability of the entire system before downhole operations. During maintenance, specific functional modules can be replaced, making the operation convenient and cost-effective.

[0032] Preferably, the liquid inlet channel includes a liquid injection pipe disposed inside the lower piston and a gap between the lower piston and the outer sleeve that communicates with the liquid injection pipe;

[0033] The liquid outlet channel includes a liquid outlet pipe located inside the lower piston. One end of the liquid outlet pipe is connected to the sample chamber, and the other end is connected to the liquid inlet pipe through a ring plug and a threaded plug.

[0034] Compared with the prior art, the present invention has the following outstanding substantive features and significant progress:

[0035] 1. Achieves ultra-high environmental adaptability and reliability: High temperature and pressure resistance limits significantly improve the success rate of operations and tool life under extreme and complex well conditions such as deep wells, ultra-deep wells, and high temperature and high pressure.

[0036] 2. Ensures high fidelity of sampled data: By actively establishing differential pressure, performing a single-stage suction, and mechanically locking off the sampling process in a continuous sequence, this invention achieves proactive and precise control over the sampling process. This method effectively avoids the random sampling volume caused by unstable differential pressure in traditional passive differential pressure sampling, as well as the problems of light hydrocarbon escape and fluid contamination caused by the preferential entry of wellbore fluid into the sample chamber, thereby greatly improving the representativeness and authenticity of the collected formation fluids.

[0037] 3. Provides dynamically adaptive ultra-high pressure sealing capability: This invention utilizes the effective area difference between the two ends of the piston after locking to convert the wellbore environmental pressure into a continuous axial sealing force, forming a unique pressure self-tightening effect. This sealing force automatically and linearly increases with the increase of well depth (i.e., the increase of wellbore pressure), dynamically adapting to the downhole pressure environment. It fundamentally solves the industry problem that conventional static seals are easily broken down, squeezed out, or leaked under ultra-high pressure conditions, achieving zero leakage after sampling and long-term sealing stability.

[0038] 4. Achieved precision and automation in the sampling process: By precisely controlling the piston stroke through limit blocks / rings, the single sampling volume becomes a fixed and precisely preset value, ensuring the consistency and comparability of sampling data from different wells and different stratigraphic layers. Simultaneously, the entire process, from startup, sampling, locking to back pressure chamber closure, is completed by a mechanical linkage, a one-time action requiring no intermediate intervention, exhibiting a high degree of automation and effectively avoiding sample contamination caused by human error or repeated aspiration. Attached Figure Description

[0039] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0040] Figure 1 This is a schematic diagram of the appearance of the sampling device according to an embodiment of this application;

[0041] Figure 2 This is a schematic diagram of the initial sampling state according to an embodiment of this application;

[0042] Figure 3 This is a schematic diagram of the sampling process state in an embodiment of this application;

[0043] Figure 4 This is a schematic diagram of the locked state according to an embodiment of this application;

[0044] Figure 5 This is another cross-sectional structural schematic diagram of an embodiment of this application (showing the liquid channel);

[0045] Figure 6 This is an embodiment of the present application. Figure 3 Enlarged structural diagram at point A in the middle;

[0046] Figure 7 This is a schematic diagram of a portion of the structure integrated into the central tube of the tubular column according to an embodiment of this application;

[0047] Figure 8 This is an embodiment of the present application. Figure 4 Enlarged structural diagram at point B;

[0048] Figure 9 This is an embodiment of the present application. Figure 2Enlarged structural diagram of the right side of the middle section (dashed lines indicate the liquid inlet path);

[0049] Figure 10 This is an embodiment of the present application. Figure 9 Enlarged structural diagram at point C;

[0050] Figure 11 Examples of embodiments in this application Figure 5 Enlarged structural diagram on the right (dashed lines indicate the liquid outlet path).

[0051] The technical features in the attached figures are labeled as follows:

[0052] 101. Central tube of the tubing; 102. Perforated central tube; 103. Sampling short section conversion head flow channel; 104. Micro hydraulic perforated flow channel; 105. Air cavity; 1. Upper connector; 2. Adapter; 3. Spring claw valve core; 4. Outer sleeve; 5. Limiting block; 6. Limiting ring; 7. Central rod; 8. Floating piston; 9. Lower piston; 10. C-type limiting ring; 11. Lower connector; 12. Plug with ring; 13. Threaded plug; 14. Sample cavity; 15. Limiting groove; 16. Liquid inlet pipe; 17. Secondary sealing assembly; 18. Injection pipe; 19. Gap; 20. Liquid outlet pipe; 21. Push block. Detailed Implementation

[0053] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0054] To achieve the above-mentioned inventive concept and objectives, the technical solution adopted in this application is as follows:

[0055] Reference Figures 1-11 The technical solution adopted in the first aspect of this application is as follows: A fluid flow collection and sampling control method, the method being implemented based on a fluid flow collection and locking control device, which comprises multiple devices integrated around the central tube 101 of the tubing string to increase the sampling capacity of a single well run or to achieve stratified sampling. Each independent fluid flow collection and locking control device includes an upper connector 1, a spring-claw valve core 3, an outer sleeve 4, a central rod 7, a floating piston 8, a lower piston 9, a C-type limiting ring 10, a fluid inlet channel, a fluid outlet channel, and an air cavity; the method includes the following steps:

[0056] In the initial state, the space between the floating piston 8 and the air cavity 105 is filled with high-temperature grease to form a grease cavity, and the air cavity 105 is in an empty state. One end of the lower piston 9 is threadedly connected to the central rod 7, and the liquid inlet channel is connected to the right side of the floating piston 8 and other core components. The method includes the following steps:

[0057] In the initial state, the space between the floating piston 8 and the air cavity 105 is filled with high-temperature grease to form a grease cavity, and the air cavity 105 is in an empty state. One end of the lower piston 9 is threadedly connected to the central rod 7, and the liquid inlet channel is connected to the right side of the floating piston 8. The lower end of the lower piston 9 is connected to the liquid path of the central tube 101 of the tubing column through the central tube perforation 102. The upper spring claw valve core 3 completes the initial locking and limiting of the lower piston 9. At the same time, the central tube perforation 102 and the sampling short section conversion head interception flow channel 103 control the generation of the overall fluid interception pressure to avoid the lower piston 9 being subjected to large impacts. By opening the balance valve, the air cavity is connected to the wellbore, and the wellbore pressure drives the floating piston 8 to move once, and the well fluid is injected into the sample chamber 14, and the sample is collected.

[0058] As sampling is about to end, the floating piston 8 drives the connected central rod 7 and lower piston 9 to move a second time. When the lower piston 9 moves to the preset sampling stroke end point, a limiting mechanism is triggered, causing the C-shaped limiting ring 10 to pop out and lock into the limiting groove 15 of the lower connector 11, limiting it with the lower connector 11 and completing the seal. Simultaneously, the upper spring claw valve core 3 is pushed up to the contracted state, cutting off the tiny hydraulic perforated flow channel 104 between the grease chamber and the air chamber 105, completing the one-time sampling and sealing.

[0059] The basic principle of this embodiment is as follows: A pressure sensor is installed at the perforation of the central tube. When the pressure sensor receives a pressure signal, and the pressure signal reaches a threshold, the circuit board activates the motor to start driving and open the balance valve. By opening the balance valve, the air chamber pressure and the wellbore pressure are instantly balanced. At this time, the wellbore pressure acting on the other end of the lower piston 9 becomes the net thrust driving the lower piston 9, realizing purely mechanical active sampling and completing the suction in one go. After the lower piston 9 is in place, the C-type limit ring 10 pops out instantly, locking the lower piston 9 and blocking the sample from the wellbore channel, realizing zero backflow and zero contamination. This fundamentally eliminates the risk of electronic components failing at high temperatures and the problem of driving force attenuation caused by spring creep at high temperatures, ensuring high reliability of sampling in harsh downhole environments.

[0060] Reference Figures 2-4In this embodiment, the specific steps of triggering a limiting mechanism are as follows: after the lower piston 9 is about to move into place, the floating piston 8 drives the central rod 7 to pull the lower piston 9 relative to the outer sleeve 4 to produce a small displacement. This displacement releases the radial constraint on the C-shaped limiting ring 10, so that it is radially ejected under the action of elastic force and stuck into the limiting groove 15 of the lower connector 11. There is a liquid inlet channel and a liquid outlet channel between the lower piston 9 and the sample chamber 14. There are two sealing components 17 between the liquid inlet channel between the lower piston 9 and the outer sleeve 4. When the floating piston 8 pulls the lower piston 9 into place through the central rod 7, it squeezes the two sealing components 17 to form a seal.

[0061] By utilizing a clever and reliable mechanical linkage locking mechanism, the small relative displacement at the end of the stroke of the lower piston 9 is used as a trigger signal to automatically release the constraint on the C-type limit ring 10, ensuring the continuity and necessity of the locking action and the sampling action. Once sampling is completed, it automatically locks, effectively preventing sample backflow or contamination caused by incomplete locking. This structure is simple, sensitive, and requires no additional control, further improving the automation and reliability of the entire sampling process. At the same time, the double sealing assembly 17 can further achieve sealing.

[0062] In this embodiment, after the C-type limiting ring 10 is locked, the wellbore pressure acting on both ends of the lower piston 9 generates a continuous axial sealing force due to the area difference. This sealing force increases with the increase of the wellbore pressure, forming a pressure self-tightening seal. The introduction of the pressure self-tightening effect greatly improves the reliability and adaptability of the seal. By designing an effective pressure-bearing area difference between the two ends of the lower piston 9, the wellbore pressure generates a continuous net sealing force on this area difference after locking, which automatically and linearly increases with the increase of the wellbore pressure, thus achieving dynamic adaptability. In the high-pressure environment of deep and ultra-deep wells, this design can provide a sealing effect far exceeding that of conventional constant preload seals, fundamentally solving the industry problem of easy seal failure under high-pressure conditions.

[0063] In this embodiment, while the floating piston 8 completes the driving sampling, the sealing head at the end of the central rod 7 is driven to squeeze the spring claw valve core 3 to automatically close the communication channel between the sample chamber 14 and the air chamber. This solves the potential risk of back pressure chamber after sampling. The principle is that at the end of the sampling action, the spring claw valve core 3 and other mechanisms are triggered by mechanical linkage to permanently seal the air chamber, forming a sealed air cushion. This can eliminate the negative pressure that may be generated in the air chamber due to temperature and pressure fluctuations during subsequent drilling or changes in working conditions. This negative pressure will form a reverse force, weakening or even destroying the formed seal, ensuring the long-term static stability of the locked state, and providing additional protection for the integrity of the sample during the process of lifting it to the ground.

[0064] The more specific sampling execution process is as follows:

[0065] 1. Initial state (e.g.) Figure 2 (as shown)

[0066] The device is lowered to the target formation in the well. At this time, the balancing valve is in the closed state, isolating the air chamber (or back pressure chamber) inside the device from the external wellbore pressure environment;

[0067] At this moment, the upper cavity of the floating piston 8 is filled with high-temperature grease, and the upper balance valve is not activated. At this time, the air cavity 105 and the floating piston 8 cannot be connected. Since the cavity is filled with grease, the floating piston will not move under hydrostatic pressure.

[0068] The upper end of the lower piston 9 is connected to the center rod 7. Initially, the upper end of the lower piston 9 is in contact with the lower end of the floating piston 8, while the lower end of the lower piston 9 is always exposed to the wellbore pressure inside the tubing through the center tube perforation 102 on the tubing center tube 101.

[0069] The spring claw valve core 3 is in the extended state under the action of spring or preload, and its claws lock the central rod 7 or related structure, forming a preliminary axial limit on the lower piston 9 to prevent the tool from malfunctioning during transportation or going downhole.

[0070] The pressure build-up rate can be controlled by the central tube perforation 102 and the sampling short section conversion head interception channel 103 connected to it, so as to avoid the wellbore pressure suddenly acting entirely on the lower piston 9 and generating hydraulic shock.

[0071] 2. Startup and sampling phase (e.g.) Figure 3 and Figure 6 (as shown)

[0072] When a sample needs to be collected, the balance valve is opened by ground control or a preset condition in the well (a pressure sensor is installed at the perforation of the central tube of the assembly product. When the pressure sensor receives a pressure signal and the pressure signal reaches a threshold, the circuit board activates the motor to start driving and realize the opening of the balance valve). After the balance valve is opened, the well pressure (large area) acting on the lower end face of the floating piston 8 and the air cavity pressure acting on its upper end face (the pressure is basically 0 after the balance valve is released) generate a net upward thrust (pointing towards the sample chamber 14). This net thrust overcomes the initial limiting force and drives the floating piston 8 to move upward (i.e. towards the sample chamber 14). When it starts, the lower piston will be subjected to a certain impact force, which may be accompanied by a small displacement. However, the amount of movement is small and will be limited by the spring claw valve core 3 on the upper part of the central rod 7.

[0073] During this movement, the formation fluid in the wellbore enters through the inlet pipe 16 of the lower connector 11, flows through the inlet channel inside or around the lower piston 9 (for example, first enters the injection pipe 18 inside the lower piston, and then passes through the gap 19 between the lower piston 9 and the outer sleeve 4), and is finally injected and stored in the sample chamber 14 surrounded by the lower piston 9, the outer sleeve 4, etc.

[0074] 3. Secondary movement, locking, and final sealing stage (e.g.) Figure 4 , Figure 8 , Figure 9 and Figure 10 (as shown) Figure 9 The dashed line indicates the direction of liquid flow.

[0075] Under continuous pressure, the floating piston 8 moves upward until it reaches the limit of the center rod 7. Driven by the pressure difference, it will drive the center rod 7 and the lower piston 9 to continue moving upward, generating a secondary relative displacement. At this time, the C-type limit ring 10 enters the sealing surface and seals the sampling liquid. The upper claw valve core 3 of the center rod 7 also contracts under the drive of a large force, sealing the micro hydraulic perforated flow channel 104. After the sealing is completed, it moves upward to the structural limit, and the locking is completed.

[0076] The key function of this displacement is that it releases the radial constraint originally applied to the C-type retaining ring 10 (for example, a cone or step on the lower piston 9 or outer sleeve 4 leaves the retaining ring). The C-type retaining ring 10 is made of an elastic material (such as spring steel), and once the radial constraint is released, it quickly pops out radially under the action of its own elastic restoring force.

[0077] The popped-out C-shaped limiting ring 10 fits precisely into the pre-machined annular limiting groove 15 on the stationary lower connector 11, such as... Figure 4 and Figure 6 As shown. This action achieves a mechanical hard lock between the lower piston 9 and the lower connector 11, fundamentally blocking the path of the sample chamber 14 to the wellbore through the liquid inlet channel.

[0078] Simultaneously, during the final stage of the upward movement of the central rod 7, the push block 21 (or can be directly regarded as a sealing head) at its top contacts and pushes the spring claw valve core 3 upward. After the spring claw valve core 3 is pushed upward, its claws retract or the valve core displaces, completely closing the only channel connecting the sample chamber 14 and the air chamber—that is, the tiny hydraulic perforated flow channel 104 machined on the adapter 2. Thus, the sample chamber 14 is completely sealed into an independent pressure vessel isolated from the outside world.

[0079] At the mating surface between the lower piston 9 and the sample chamber 14, a double sealing assembly 17 (such as a combination of an O-ring and a retaining ring) is provided. When the lower piston 9 is pulled to the final locked position, the double sealing assembly 17 is fully compressed to form a reliable static seal.

[0080] 4. Formation of pressure self-tightening seal:

[0081] After locking, the upper and lower end faces of the lower piston 9 continue to be exposed to the wellbore environment pressure. Due to the effective pressure bearing area difference between the two ends of the piston (usually the pressure bearing area of ​​the lower end face is larger than that of the upper end face), even if the pressure values ​​at both ends are equal (both are wellbore pressure), a continuous net sealing force will be generated in the piston axial direction. This force points in the direction that makes the seal tighter (i.e., the direction that presses down on the second sealing assembly 17).

[0082] The magnitude of this sealing force is directly proportional to the wellbore pressure. This means that the higher the wellbore pressure (such as in deeper well sections), the greater the additional sealing force generated, the stronger the sealing effect, achieving a unique pressure self-tightening effect, perfectly adapting to the high-pressure environment downhole.

[0083] The entire sampling process, from initiation to sealing, is completed automatically in one go through precise mechanical linkage, ensuring extremely high reliability under harsh environments of high temperature and high pressure.

[0084] Reference Figures 1-6 A second aspect of this application provides a liquid flow collection locking control device for implementing the above method, comprising:

[0085] Upper connector 1 constitutes the upper connection structure of the device;

[0086] Adapter 2, used to connect upper connector 1 and outer sleeve 4, is provided with micro hydraulic perforated flow channel 104;

[0087] The spring claw valve core 3 is placed inside the adapter 2 and is used to seal the tiny hydraulic perforated flow channel 104 between the sample chamber 14 and the air chamber;

[0088] The outer sleeve 4 is connected to the upper connector 1 via the adapter 2 to form the main outer shell of the device;

[0089] The center rod 7 is located inside the outer sleeve 4 and can move relative to the outer sleeve 4. A push block 21 is provided at one end near the spring claw valve core 3.

[0090] The floating piston 8 is sleeved on the central rod 7 and is located between the push block 21 and the lower piston 9;

[0091] The lower piston 9 is connected to the lower part of the central rod 7 and moves under the action of wellbore pressure to sample the well fluid;

[0092] The C-type limiting ring 10 is disposed between the lower piston 9 and the lower connector 11. In the unlocked state, it is radially constrained, and in the locked state, it pops out and gets stuck in the limiting groove 15 of the lower connector 11.

[0093] The lower connector 11 forms the lower connection structure of the device, and is provided with a liquid inlet pipe 16 for liquid inlet and the limiting groove 15.

[0094] This device is the functional entity of the aforementioned method. Its components work together to form a complete pure mechanical-hydraulic logic system. The upper connector 1 and the outer sleeve 4 provide overall structural support and pressure boundaries. The central rod 7 serves as the transmission core, transmitting the driving force of the floating piston 8 to the lower piston 9. The floating piston 8 is a key component for realizing wellbore pressure capture and conversion. The lower piston 9 directly performs sampling and sealing functions. The C-type limiting ring 10 and the limiting groove 15 of the lower connector 11 constitute the final locking actuator. The entire device eliminates complex electrical control and easily damaged elastic energy storage elements, has a compact structure, excellent high temperature and high pressure resistance, and realizes all the functions required by the design method.

[0095] In this embodiment, a balancing valve is also included, which controls the opening and closing of the air passage connecting the air chamber and the wellbore.

[0096] In this embodiment, a limiting block 5 and / or a limiting ring 6 are also included to precisely limit the movement stroke of the floating piston 8 and / or the central rod 7. The limiting block 5 and the limiting ring 6 act as stroke controllers. Through their mechanical hard limiting, the final stroke of the lower piston 9 can be precisely controlled, thereby directly determining the volume of the sample chamber 14. The sampling volume becomes a fixed and accurately predictable value, ensuring the consistency and comparability of data between different samplings, and overcoming the defect of uncontrollable differential pressure sampling volume in traditional methods.

[0097] In this embodiment, a dual-seal assembly 17 is provided at the end of the lower piston 9 that contacts the sample chamber 14. The dual-seal assembly 17 includes a combination of a sealing ring and a retaining ring. The sealing ring, such as an O-ring, is key to achieving static sealing and directly prevents sample leakage. The addition of the retaining ring, such as a polytetrafluoroethylene (PTFE) retaining ring, prevents the sealing ring from being squeezed into the gap between parts and damaged under high pressure. The combined design of the sealing ring and the retaining ring significantly improves the durability and reliability of the sealing assembly under ultra-high pressure conditions.

[0098] In this embodiment, the floating piston 8 is configured to convert the ambient pressure of the wellbore into mechanical power to drive the central rod 7 and the lower piston 9 to move. Its input is the ambient pressure of the wellbore, and its output is the mechanical power to drive the sampling action. This highlights the fundamental difference between this application and traditional technologies that rely on external power sources or internal energy storage elements.

[0099] In this embodiment, the upper connector 1 is connected to the outer sleeve 4 via the adapter 2. The adapter 2 is not only a structural component, but also has a precisely machined cavity and flow channel inside, which is used to accommodate and control the movement of the spring claw valve core 3. It is the control center for the key process switching from initial pressure balance to establishing driving pressure difference. Integrating this function into the adapter 2 avoids directly machining complex valve cavities on the outer sleeve 4 or the upper connector 1, which greatly reduces the machining difficulty and risk of the core pressure-bearing component.

[0100] Adapter 2 can be tested on the surface as an independent functional unit (such as testing the valve core's opening and closing function), ensuring the reliability of the entire system before downhole operations. During maintenance, functional modules can be replaced selectively, making operation convenient and cost-effective.

[0101] In this embodiment, the liquid inlet channel includes a liquid injection pipe 18 disposed inside the lower piston 9 and a gap 19 between the lower piston 9 and the outer sleeve 4 that communicates with the liquid injection pipe 18.

[0102] The liquid outlet channel includes a liquid outlet pipe 20 disposed inside the lower piston 9. One end of the liquid outlet pipe 20 is connected to the sample chamber 14, and the other end is connected to the liquid inlet pipe 16 through a ring plug 12 and a threaded plug 13.

[0103] Reference Figure 5 and Figure 11 When the device is pulled back to the ground, loosen the ring plug 12 and the threaded plug 13 to open the liquid outlet channel. By applying pressure at the upper connector 1, the floating piston 8 pushes the sample out of the device.

[0104] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for controlling liquid flow collection and sampling, characterized in that, The method is based on a liquid flow collection and locking control device, which includes multiple devices integrated around the central tube (101) of the tubing column. The liquid flow collection and locking control device includes an upper connector (1), a spring claw valve core (3), an outer sleeve (4), a central rod (7), a floating piston (8), a lower piston (9), a C-type limiting ring (10), an inlet channel, an outlet channel, and an air chamber (105). The method includes the following steps: In the initial state, the space between the floating piston (8) and the air cavity (105) is filled with high-temperature grease to form a grease cavity, and the air cavity (105) is in an empty state. One end of the lower piston (9) is threadedly connected to the central rod (7), and the liquid inlet channel is connected to the right side of the floating piston (8). The lower end of the lower piston (9) is connected to the liquid path of the central tube (101) of the tubing column through the central tube perforation (102). The spring claw valve core (3) is in the extended state under the action of the spring, and its spring claws hold the central rod (7). The upper spring claw valve core (3) completes the process. The pair of lower pistons (9) are initially locked and limited, and the overall fluid interception pressure is controlled by the central tube perforation (102) and the sampling short section conversion head interception channel (103) to avoid the lower pistons (9) being subjected to large impacts; by opening the balance valve, the air chamber is connected to the well barrel, and the floating piston (8) is driven to move once by the well barrel pressure. The well fluid enters through the inlet pipe (16) of the lower connector (11), flows through the inlet channel inside or around the lower piston (9), and is pressed into the sample chamber (14), and the sample is collected; As the sampling is about to end, the floating piston (8) drives the connected center rod (7) and the lower piston (9) to move a second time. When the lower piston (9) moves to the preset sampling stroke end point, a limiting mechanism is triggered, causing the C-shaped limiting ring (10) to pop out and be inserted into the limiting groove (15) of the lower connector (11), limiting the lower connector (11) and completing the seal. Simultaneously, the upper spring claw valve core (3) is pushed up, the spring claw retracts, and the spring claw valve core (3) is displaced to cut off the tiny hydraulic perforated flow channel (104) between the grease chamber and the air chamber, completing the one-time sampling and sealing.

2. The liquid flow collection and sampling control method according to claim 1, characterized in that, After the lower piston (9) is about to move into place, the floating piston (8) drives the central rod (7) to pull the lower piston (9) relative to the outer sleeve (4) to produce a small displacement. This displacement releases the radial constraint on the C-type limiting ring (10), so that it pops out radially under the action of elastic force and is stuck in the limiting groove (15) of the lower connector (11). There is an inlet channel and an outlet channel between the lower piston (9) and the sample chamber (14). There are two sealing assemblies (17) between the inlet channel of the lower piston (9) and the outer sleeve (4). When the floating piston (8) pulls the lower piston (9) into place through the central rod (7), it squeezes the two sealing assemblies (17) to form a seal.

3. The liquid flow collection and sampling control method according to claim 2, characterized in that, While the floating piston (8) completes the driving sampling, the sealing head at the end of the driving center rod (7) squeezes the claw valve core (3) to automatically close the tiny hydraulic perforated flow channel (104) between the sample chamber (14) and the air chamber, thus achieving a seal.

4. The liquid flow collection and sampling control method according to claim 3, characterized in that, After the C-type limiting ring (10) is locked, the wellbore pressure acting on both ends of the lower piston (9) generates a continuous axial sealing force due to the area difference. This sealing force increases with the increase of the wellbore pressure, forming a pressure self-tightening seal.

5. A liquid flow collection and locking control device for implementing the method of claim 4, characterized in that, include: The upper connector (1) constitutes the upper connection structure of the device; The adapter (2) is used to connect the upper connector (1) and the outer sleeve (4), and is provided with a micro hydraulic perforated flow channel (104). The spring claw valve core (3) is placed inside the adapter (2) to seal the tiny hydraulic perforated flow channel (104) between the sample chamber (14) and the air chamber (105). The outer sleeve (4) is connected to the upper connector (1) via the adapter (2) to form the main outer shell of the device; The center rod (7) is located inside the outer sleeve (4) and can move relative to the outer sleeve (4). A push block (21) is provided at one end near the spring claw valve core (3). A floating piston (8) is fitted onto the central rod (7) and positioned between the push block (21) and the lower piston (9); The lower piston (9) is connected to the lower part of the central rod (7) and moves under the action of wellbore pressure to sample the well fluid; A C-type limiting ring (10) is disposed between the lower piston (9) and the lower connector (11). In the unlocked state, it is radially constrained, and in the locked state, it pops out and gets stuck in the limiting groove (15) of the lower connector (11). The lower connector (11) forms the lower connection structure of the device. It is provided with an inlet pipe (16) for liquid inlet and the limiting groove (15) is connected to the central tube perforation (102) of the sampling short section conversion head intercepting flow channel (103).

6. The apparatus according to claim 5, characterized in that, It also includes a balancing valve, which controls the opening and closing of the air passage connecting the air chamber and the wellbore.

7. The apparatus according to claim 5, characterized in that, It also includes a limiting block (5) and / or a limiting ring (6) for precisely limiting the travel of the floating piston (8) and / or the center rod (7).

8. The apparatus according to claim 5, characterized in that, The lower piston (9) is provided with a double sealing assembly (17) at the end that contacts the sample chamber (14). The double sealing assembly (17) includes a combination of a sealing ring and a retaining ring.

9. The apparatus according to claim 5, characterized in that, The floating piston (8) is configured to convert the ambient pressure of the wellbore into mechanical power to drive the central rod (7) and the lower piston (9) to move.

10. The apparatus according to claim 5, characterized in that, The liquid inlet channel includes a liquid injection pipe (18) disposed inside the lower piston (9) and a gap (19) between the lower piston (9) and the outer sleeve (4) that communicates with the liquid injection pipe (18). The liquid outlet channel includes a liquid outlet pipe (20) disposed inside the lower piston (9). One end of the liquid outlet pipe (20) is connected to the sample chamber (14), and the other end is connected to the liquid inlet pipe (16) through a ring plug (12) and a thread plug (13).

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