A tubing conveyed perforating string depth calibration fluid level indicator

Abstract

The utility model belongs to the oil and gas exploitation field discloses a kind of oil pipe transmission perforating string depth correction liquid level indicator, including tubular indicator body, one end is equipped with connecting thread for receiving into well instrument, the other end is connected with chamfer tail plug, the movable shearing sleeve is arranged on the step surface of internal cavity, shearing sleeve abuts step surface and is sleeved with sliding sleeve, sliding sleeve one end extends into tail plug cavity, both are connected by shearing pin, while tail plug circumferential liquid inlet hole and sliding sleeve end face and tail plug cavity wall jointly form hydraulic chamber. The indicator adopts pure mechanical structure, without electronic components or battery, simplifies device and greatly improves reliability and adaptability under harsh working conditions such as deep well high temperature, can accurately correct liquid level depth, effectively prevent perforating gun misfire event, eliminate safety hazard and reduce rework, thereby improve oil exploration operation efficiency and production safety.

Description

Technical Field

[0001] This utility model belongs to the field of oil and gas extraction technology, specifically relating to a depth liquid level indicator for a perforation string in an oil tubing transmission system. Background Technology

[0002] In the field of oil exploration and development, perforation completion is currently the most widely used completion method both domestically and internationally. Approximately 80% of perforation completion operations utilize tubing-transfer perforation technology, and within this technology, 80% involve detonating the perforation gun using a rod-throwing method. The specific operation involves connecting the perforation gun to tubing and lowering it to a predetermined position within the well. A rod-throwing device is then used to detonate the perforation gun. To prevent explosions at the wellhead, the detonation device is equipped with a safety mechanism. Its operation requires a hydraulic column pressure of at least 300 meters within the well; otherwise, the detonation device cannot be activated properly.

[0003] However, in actual operations, due to factors such as well leakage and negative pressure, situations often arise where there is no liquid level or the liquid level depth is unknown in the well. This directly leads to the perforation gun failing to detonate properly (i.e., mis-detonation), thus constituting a quality incident. Undetonated perforation guns also pose significant safety risks during wellbore retrieval and subsequent dismantling, and require rework due to mis-detonation issues, significantly reducing operational efficiency and hindering efficient production in oil exploration and development. Patent publication number CN201934096U discloses a differential pressure liquid level gauge technology. This liquid level gauge acquires the wellbore liquid pressure through a data acquisition device inside the tube, then converts the measurement data into an audio signal through a data conversion device, and transmits the sound wave to the wellhead through an oil pipe connected to the upper connector. However, this technology requires the installation of electronic circuitry and a power battery, resulting in a complex structure and poor stability under harsh conditions such as deep well temperatures, making it difficult to meet the reliable liquid level detection requirements of actual operations.

[0004] It is evident that existing technologies suffer from several problems, including the inability to accurately determine the liquid level depth during perforation operations, leading to misfires of the perforation gun, and the complex structure and poor adaptability of existing liquid level detection devices to harsh working conditions. Utility Model Content

[0005] This invention provides a tubing-transfer perforation string depth liquid level indicator. Using this indicator can solve the problems of complex structure and poor adaptability to harsh working conditions of existing liquid level detection devices, and can meet the reliable liquid level detection requirements of actual operations.

[0006] To achieve the above objectives, the present invention adopts the following technical content: A tubing-transfer perforation string depth level indicator includes an indicator body with a tubular structure. One end of the indicator body is provided with a connecting thread for connecting to the well tool, and the other end is connected to a chamfered end cap. The indicator body has an internal cavity; A movable shearing sleeve is provided on the stepped surface of the inner cavity, and the shearing sleeve abuts against the stepped surface of the inner cavity; A sliding sleeve is inserted into the shear sleeve along the axial direction of the indicator body; one end of the sliding sleeve is inserted into the shear sleeve, and the other end is inserted into the cavity of the chamfered end cap. The sliding sleeve has multiple sliding sleeve pin holes on its circumference, and shear pins are inserted into the sliding sleeve pin holes; the sliding sleeve and the shear sleeve are connected by the shear pins. The chamfered tail plug has a liquid inlet hole on its circumference; The inlet hole, the end face of the sliding sleeve near the inlet hole, and the inner wall of the chamfered end cap cavity together form a hydraulic cavity.

[0007] Furthermore, the chamfered end cap is connected to the other end of the indicator body via a threaded connection.

[0008] Furthermore, a sealing element is provided between the outer wall of the sliding sleeve and the inner wall of the chamfered end cap.

[0009] Furthermore, a first sealing groove is provided circumferentially at the other end of the sliding sleeve; a sealing ring is installed in the first sealing groove.

[0010] Furthermore, a plurality of first sealing grooves are formed along the axial direction at the other end of the sliding sleeve, and a sealing ring is installed in each first sealing groove.

[0011] Furthermore, at the connection between the chamfered end cap and the indicator body, a second sealing groove is provided along the circumference of the chamfered end cap; a sealing ring is installed in the second sealing groove.

[0012] Furthermore, at the connection between the chamfered end cap and the indicator body, a plurality of second sealing grooves are provided along the axial direction of the chamfered end cap, and a sealing ring is installed in each second sealing groove.

[0013] Furthermore, the chamfered tail plug has multiple liquid inlet holes evenly distributed circumferentially.

[0014] Furthermore, the plurality of the sliding sleeve pin holes are evenly distributed along one end of the sliding sleeve.

[0015] Furthermore, a gap is reserved between the inner cavity and the sliding sleeve. When the shear pin is cut, the sliding sleeve can slide into the gap under the pressure of the hydrostatic column.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a tubular perforation string depth and fluid level indicator, comprising a tubular indicator body with a threaded connection at one end for receiving the well tool and a chamfered end cap at the other end. A movable shear sleeve is mounted on the stepped surface of the internal cavity. The shear sleeve abuts against the stepped surface and is fitted with a sliding sleeve, one end of which extends into the end cap cavity. The two are connected by a shear pin. Simultaneously, the circumferential inlet hole of the end cap, the end face of the sliding sleeve, and the end cap cavity wall together form a hydraulic chamber. During downhole operations, fluid flows into the hydraulic chamber through the inlet hole, establishing static pressure. When the pressure increases to a preset shear force threshold, the shear pin breaks, driving the sliding sleeve to slide axially, generating a mechanical displacement signal that directly indicates whether the fluid level meets operational requirements. This indicator adopts a purely mechanical structure, requiring no electronic components or batteries, simplifying the device and significantly improving reliability and adaptability under harsh conditions such as deep well temperatures. It can accurately correct fluid level depth, effectively prevent perforation gun misfires, eliminate safety hazards, and reduce rework, thereby improving the efficiency and safety of oil exploration operations.

[0017] Preferably, in this invention, the chamfered end cap is connected to the indicator body by a thread, which enhances the connection strength and sealing performance, and facilitates assembly and disassembly.

[0018] Preferably, in this invention, a sealing element is provided on the outer wall of the sliding sleeve and the inner wall of the tail plug to ensure the hydraulic cavity is sealed, prevent leakage, and improve calibration accuracy.

[0019] Preferably, in this invention, a sealing groove is provided at the other end of the sliding sleeve and a sealing ring is installed to enhance local sealing and ensure stable pressure transmission.

[0020] Preferably, in this invention, multiple sealing grooves are provided and sealing rings are installed to achieve multiple redundant seals and adapt to high-pressure working conditions.

[0021] Preferably, in this invention, a sealing groove is provided at the connection between the chamfered tail plug and the main body, and a sealing ring is installed to prevent well fluid from seeping in and to protect the internal structure.

[0022] Preferably, in this invention, the chamfered tail plug has circumferentially distributed liquid inlet holes to promote uniform and rapid fluid inflow and improve response sensitivity.

[0023] Preferably, in this invention, the pin holes of the sliding sleeve are evenly distributed to ensure a balanced distribution of shearing force and reliably shear the pins.

[0024] Preferably, in this invention, a gap is reserved between the inner cavity and the sliding sleeve to provide smooth space for the sliding sleeve to slide and ensure that the mechanical displacement signal is clearly generated. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of a tubing-transfer perforation string depth level indicator provided in an embodiment of the present invention.

[0026] Figure label: 1. Connecting thread; 2. Liquid level indicator body; 3. Inner cavity; 4. Shear sleeve; 5. Shear pin; 6. Pin hole; 7. Sliding sleeve; 8. First sealing groove; 9. Second sealing groove; 10. Liquid inlet hole; 11. Chamfered end plug. Detailed Implementation

[0027] To make the technical problem solved by this utility model, the technical solution, and the beneficial effects clearer, the following specific embodiments provide a further detailed description of this utility model. It should be understood that the specific embodiments described herein are merely illustrative of this utility model and are not intended to limit it.

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] In the description of the embodiments of this utility model, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the utility model product is usually placed during use, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0032] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0033] In the description of the embodiments of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0034] As mentioned in the background section, currently, during perforation operations in oil and gas wells via tubing, it is necessary to correct the depth of the perforating gun within the wellbore. This requires running logging instruments into the tubing to measure the formation natural gamma (GR) curve and tubing coupling (CCL) curve. Conventional instruments used for depth correction do not have the capability to measure the fluid level depth within the well. The fluid level depth in the well must be at least 300m above the target perforation layer to unlock the detonation system and safely detonate the perforating gun. However, in some wellbores, the fluid level depth does not meet the requirement of being 300m above the target perforation layer, or even falls below it. This will cause the perforating gun to mis-detonate, thus easily leading to quality and safety issues.

[0035] To address the aforementioned issues, this embodiment provides a tubing-transfer perforation string depth calibration fluid level indicator. This indicator converts fluid level height into fluid pressure to achieve precise indication of fluid level depth, aiming to improve the accuracy of fluid level height measurement in wells and the reliability of perforation gun detonation during tubing-transfer perforation depth calibration operations, reduce operating costs, and increase the perforation success rate of tubing-transfer perforation.

[0036] like Figure 1 As shown, this embodiment provides a tubing-transfer perforation string depth level indicator, including a tubular indicator body 2. The indicator body 2 is designed with two outer diameters: 35mm and 41mm, corresponding to models YM-35 and YM-41 respectively, to adapt to the usage requirements of different well conditions. One end of the indicator body 2 is machined with a connecting thread 1, which is used to securely connect the entire level indicator to the wellbore tool. The other end is connected to a chamfered end cap 11 by a thread. At the connection between the chamfered end cap 11 and the indicator body 2, multiple second sealing grooves 9 are formed along the circumference of the chamfered end cap 11. In this embodiment, two second sealing grooves are used. Each second sealing groove 9 is equipped with an O-ring seal, which can effectively prevent well fluid from leaking from the connection gap between the two.

[0037] In this embodiment, an inner cavity 3 is provided inside the indicator body 2. A stepped surface is provided on the inner wall of the inner cavity 3. The shear sleeve 4 is movably disposed on this stepped surface, and one end of the shear sleeve 4 can abut against the stepped surface. The stepped surface can provide initial axial limiting for the shear sleeve 4, and further limit the axial movement of the sliding sleeve 7 located in the shear sleeve 4. The shear sleeve 4 is an annular structure with a small hole. The sliding sleeve 7 is inserted into the inner hole of the shear sleeve 4 along the axial direction of the indicator body 2. One end of the sliding sleeve 7 extends completely into the interior of the shear sleeve 4, and the other end extends into the cavity of the chamfered end plug 11. To prevent liquid from flowing between the sliding sleeve 7 and the inner wall of the chamfered end plug 11, multiple first sealing grooves 8 are provided circumferentially along the axial direction at the end of the sliding sleeve 7 that extends into the cavity of the chamfered end plug 11. Each first sealing groove 8 is fitted with a rubber O-ring. These sealing rings can fit tightly against the inner wall of the chamfered end plug 11 to form a reliable sealing effect.

[0038] For example, to fix the sliding sleeve 7 and the shear sleeve 4, multiple sliding sleeve pin holes 6 are evenly distributed around the circumference of the end of the sliding sleeve 7 near the shear sleeve 4. During installation, one end of the shear pin 5 is passed through the pre-drilled hole on the shear sleeve 4, and the other end is inserted into the sliding sleeve pin hole 6, which firmly connects the sliding sleeve 7 and the shear sleeve 4 together, ensuring that the two will not move relative to each other when no force is applied. At the same time, four fluid inlet holes 10 are evenly opened around the circumference of the chamfered end plug 11. These fluid inlet holes 10, the end face of the sliding sleeve 7 near the fluid inlet holes 10, and the interior of the chamfered end plug 11 together form a closed hydraulic chamber. Subsequent well fluid can enter this hydraulic chamber through the fluid inlet holes 10, exerting pressure on the sliding sleeve 7. In addition, a certain gap is reserved between the inner cavity 3 and the sliding sleeve 7, providing space for the sliding sleeve 7 to move after the shear pin 5 cuts.

[0039] For example, the assembly process of the tubing transfer perforation string depth level indicator provided in this embodiment is as follows: First, slowly insert the sliding sleeve 7 into the inner hole of the shear sleeve 4. After adjusting it to a suitable position, align the sliding sleeve pin hole 6 with the small hole on the shear sleeve 4, and gently tap the shear pin 5 in to fix the sliding sleeve 7 and the shear sleeve 4 into a whole. Next, place the shear sleeve 4 with the sliding sleeve 7 fixed on it into the indicator body 2, ensuring that its end face abuts against the step surface. Before the sliding sleeve 7 is placed into the inner cavity 3, install rubber O-rings one by one into each of the first sealing grooves 8 of the sliding sleeve 7, and then install the sealing rings one by one into the second sealing grooves 9 of the chamfered end cap 11, ensuring that the sealing rings in each sealing groove are installed in place and without damage. Finally, hold the chamfered end cap 11 and align it with the thread on the other end of the indicator body 2, and slowly screw it in and tighten it. At this point, the assembly of the entire level indicator is complete.

[0040] When using this fluid level indicator for depth calibration of the perforation string in the field, the number of shear pins 5 to be installed must first be determined based on the actual conditions of the well, such as well fluid density and the target minimum fluid level height. This is done using the formula "H=P / ρg", where H represents the fluid level height, P represents the total pressure resistance of the installed shear pins 5, ρ represents the well fluid density, and g represents gravitational acceleration. The number of pins calculated using this formula ensures the accuracy of subsequent measurements. After calculation, the fluid level indicator is securely connected to the tail of the wellhead tool via the connecting thread 1 at one end of the indicator body 2. Then, the wellhead tool, equipped with the fluid level indicator, is slowly lowered into the oil and gas well using a cable.

[0041] When the fluid level indicator drops below the fluid level in the well, the fluid in the well will flow into the hydraulic chamber through the inlet hole 10 on the chamfered tail plug 11. As the fluid continuously fills the hydraulic chamber, the hydrostatic pressure gradually acts on the end face of the sliding sleeve 7 near the inlet hole 10. As the wellhead tool continues to be lowered, the fluid level depth increases, and the hydrostatic pressure also increases. When this pressure reaches the shear resistance value of the shear pin 5, the shear pin 5 will be sheared. At this time, the sliding sleeve 7, which is no longer fixed, will slide away from the chamfered tail plug 11 along the gap reserved between the inner cavity 3 and the sliding sleeve 7 under the continuous hydrostatic pressure, and eventually disengage from the mating position with the shear sleeve 4.

[0042] After the above process is completed, the fluid level indicator is lifted from the well to the surface via cable. Then, the chamfered end cap 11 at the other end of the indicator body 2 is unscrewed, and the sliding sleeve 7 and the shear sleeve 4 fitted on its outer wall are poured out from the inner cavity 3. Based on the number of shear pins 5 remaining on the poured-out parts (i.e. the number previously installed), and combined with the formula "H=P / ρg", the minimum fluid level in the well can be accurately corrected, thereby completing the depth correction operation of the tubing transmission perforation string.

[0043] In summary, this utility model provides a depth level indicator for tubing transfer perforation string, which has the following advantages compared to existing solutions: The tubing-transfer perforation string depth calibration fluid level indicator provided in this embodiment has a pre-set number of internal shear pins to fix the height of the hydrostatic column that the internal sliding sleeve of the fluid level indicator can withstand. The assembled fluid level indicator is connected to the tail of the logging instrument and lowered into the tubing along with the logging instrument. After the logging instrument enters the fluid level in the wellbore, the hydrostatic pressure begins to act on the end face of the internal sliding sleeve of the fluid level indicator. As the logging instrument descends deeper into the well below the fluid level, the hydrostatic pressure acting on the end face of the sliding sleeve increases. When the logging instrument reaches a certain fluid level depth, the hydrostatic pressure shears the shear pins, pushing the sliding sleeve to move. At this point, the hydrostatic pressure can be converted into fluid level height, thereby determining the fluid level depth in the wellbore. This allows for an assessment of whether the perforation technical requirements are met, preventing the perforation gun from failing to explode due to insufficient fluid level depth and low fluid pressure.

[0044] This invention employs an internal sliding sleeve structure design, which boasts advantages such as simple structure, low cost, and reliable performance. The shear pressure is determined by adjusting the number of pins, thereby enabling gradient judgment of the fluid level depth, ensuring reliable operation. This indicator has no internal wiring, eliminates the need for complex encoding and decoding of transmission signals, and is unaffected by factors such as high downhole temperatures. It achieves wellbore fluid level indication using the simplest means, possessing high practical value and broad application prospects.

[0045] The above embodiments are merely one of the implementation methods to achieve the technical solution of this utility model. The scope of protection claimed by this utility model is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this utility model.

Claims

1. A depth level indicator for a tubing-transfer perforation string, characterized in that, Including the indicator body (2) which has a tubular structure; One end of the indicator body (2) is provided with a connecting thread (1), which is used to connect to the well tool, and the other end is connected with a chamfered tail plug (11). The indicator body (2) has an inner cavity (3) inside; A movable shear sleeve (4) is provided on the stepped surface of the inner cavity (3), and the shear sleeve (4) abuts against the stepped surface of the inner cavity (3). A sliding sleeve (7) is inserted inside the shear sleeve (4) along the axial direction of the indicator body (2); one end of the sliding sleeve (7) is inserted inside the shear sleeve (4), and the other end is inserted into the cavity of the chamfered end cap (11); The sliding sleeve (7) has multiple sliding sleeve pin holes (6) in the circumferential direction, and shear pins (5) are inserted into the sliding sleeve pin holes (6); the sliding sleeve (7) and the shear sleeve (4) are connected by the shear pins (5); The chamfered tail plug (11) has a liquid inlet hole (10) in the circumferential direction; The inlet hole (10), the end face of the sliding sleeve (7) near the inlet hole (10), and the inner wall of the chamfered end cap (11) together form a hydraulic cavity.

2. The tubing perforation string depth level indicator according to claim 1, characterized in that, The chamfered end cap (11) is connected to the other end of the indicator body (2) by means of a threaded connection.

3. The tubing perforation string depth level indicator according to claim 1, characterized in that, A sealing element is provided between the outer wall of the sliding sleeve (7) and the inner wall of the chamfered end cap (11).

4. The tubing perforation string depth level indicator according to claim 3, characterized in that, The other end of the sliding sleeve (7) is provided with a first sealing groove (8) in the circumferential direction; a sealing ring is installed in the first sealing groove (8).

5. A tubing-transfer perforation string depth level indicator according to claim 4, characterized in that, The other end of the sliding sleeve (7) has a plurality of first sealing grooves (8) along the axial direction, and a sealing ring is installed in each first sealing groove (8).

6. The tubing perforation string depth level indicator according to claim 1, characterized in that, At the connection between the chamfered end cap (11) and the indicator body (2), a second sealing groove (9) is provided along the circumference of the chamfered end cap (11); a sealing ring is installed in the second sealing groove (9).

7. A tubing-transfer perforation string depth level indicator according to claim 6, characterized in that, At the connection between the chamfered end cap (11) and the indicator body (2), a plurality of second sealing grooves (9) are provided along the axial direction of the chamfered end cap (11), and a sealing ring is installed in each second sealing groove (9).

8. The tubing perforation string depth level indicator according to claim 1, characterized in that, The chamfered end cap (11) has multiple liquid inlet holes (10) evenly distributed in the circumferential direction.

9. A tubing-transfer perforation string depth level indicator according to claim 1, characterized in that, Multiple sliding sleeve pin holes (6) are evenly distributed along one end of the sliding sleeve (7).

10. A tubing-transfer perforation string depth level indicator according to claim 1, characterized in that, A gap is reserved between the inner cavity (3) and the sliding sleeve (7). When the shear pin (5) is cut, the sliding sleeve (7) can slide into the gap under the action of the hydrostatic column pressure.

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