A method and system for displacing downhole annulus protective fluid in an oil-water environment within a wellbore.

Abstract

This invention belongs to the field of advanced downhole manufacturing technology, specifically relating to a method and system for displacing protective fluid in the annulus of the wellbore. It addresses the challenges of creating a locally dry environment for metal welding and repair in complex downhole media environments, specifically for in-situ repair and structural reinforcement of oil and gas wellbores. The system consists of an upper packer, a middle chamber section, a lower packer, and an electric dehydrator. The upper and lower packers employ a multi-sleeve, spacer ring combination structure, reliably sealing both ends of the target well section to form an isolated working chamber. The electric dehydrator integrates mechanical transmission and electrical control modules, using a motor-driven screw-piston mechanism to actively discharge fluid and replace media within the chamber. Based on the principle of electric liquid phase displacement, this invention can construct and maintain a stable local environment suitable for in-situ metal welding and repair in downhole, overcoming the limitations of traditional working environments and achieving precise media control in the downhole local space. This provides advanced in-situ repair assurance for the long-term safe operation of wellbore structures.

Description

Technical Field

[0001] This invention relates to the field of downhole operations technology for oil and gas wells, and particularly to a system and method for creating a liquid-free, stable environment at a specific location within the wellbore, which is especially suitable for high-requirement operations such as downhole welding, downhole photography, precision inspection, and safety perforation. Background Technology

[0002] During well workover and production operations in oil and gas fields, high-precision operations such as welding, photography, inspection, or equipment replacement are often required at specific locations downhole. These operations typically require a closed environment with no free liquids and a controlled atmosphere around the work site to prevent explosion risks, ensure work quality, and protect precision instruments and equipment.

[0003] Currently, conventional techniques mainly rely on the continuous injection of high-pressure protective fluid from the wellhead into the annulus, using its hydrostatic pressure to displace the existing fluid in the annulus to a certain depth downhole, thereby forming a section in the upper part of the wellbore occupied by the protective fluid. However, this method has the following significant drawbacks:

[0004] a) Low displacement efficiency and high media consumption: A large amount of high-pressure protective fluid needs to be continuously injected to maintain the pressure balance of the liquid column, resulting in high operating costs and poor economic efficiency.

[0005] b) Environmental cleanliness is difficult to guarantee: It can only achieve the displacement of the main liquid, but cannot effectively remove residual liquid and volatile components in the dead corners of the annulus, making it difficult to meet the environmental requirements of demanding operations such as high-quality welding;

[0006] c) Stability is limited by pressure control accuracy: the liquid level position depends entirely on the injection pressure control, while the downhole working conditions are complex and changeable, and pressure fluctuations can easily cause the liquid level to fluctuate, resulting in poor working environment stability.

[0007] d) Insufficient precise control capability in local sections: For operation scenarios where a waterless environment needs to be constructed only in a local area of ​​the middle section of the wellbore, the existing methods have a wide range of applications and cannot achieve precise slug control, which can easily affect non-target well sections.

[0008] In summary, existing annular liquid displacement technology is no longer adequate to meet the increasingly demanding requirements of downhole operating environments. There is an urgent need to develop a new displacement method and system that can efficiently, accurately, and reliably create a stable and dry media environment in a designated section of the wellbore. Summary of the Invention

[0009] This invention aims to address the problems existing in the prior art and fill a gap in current research, providing an annular displacement system for downhole oil, water, and gas environments. This system can be applied to deep water and other high-pressure environments, providing equipment support for in-situ welding and repair of metal components in extreme deep well environments. It also provides a reference for application scenarios of imaging, inspection, and equipment replacement in deep well environments.

[0010] The technical solution adopted by this invention to solve its technical problem is:

[0011] An annular protective fluid displacement system for an oil-water environment in a wellbore includes an upper packer, a downhole tool guard, a lower packer, and an electric dehydrator connected sequentially from top to bottom. The upper packer is used to seal the upper end of the annular working section and integrates a one-way injection protective fluid channel inside. The displacement medium pipeline leads to the annular working section below the upper packer. The downhole tool guard is used to install and protect the tools required for downhole operations. The lower packer cooperates with the upper packer to form a sealed annular working section. The electric dehydrator is used to extract the remaining oil, water, and gas in the annular working section and, in conjunction with the displacement medium pipeline, drains the fluid in the annular working section.

[0012] The upper packer includes an upper packer connector a, an upper packer sleeve a, an upper spacer ring a, an upper packer sleeve b, an upper spacer ring b, an upper packer sleeve c, an upper packer connector b, an upper packer center tube, and a displacement medium pipeline. The upper packer connector a is threadedly connected to the upper packer center tube, and its end face is provided with a through hole for the displacement medium pipeline and cable to pass through. The upper packer sleeve a, upper spacer ring a, upper packer sleeve b, upper spacer ring b, and upper packer sleeve c are sequentially sleeved on the outside of the upper packer center tube from top to bottom, and their two ends are clamped by the upper packer connector a and the upper packer connector b, respectively. The upper packer connector b is threadedly connected to the upper packer center tube and has a through hole for the displacement medium pipeline to pass through. The displacement medium pipeline is connected between the through holes of the upper packer connector a and the upper packer connector b and is used to introduce protective fluid medium into the annular working section.

[0013] The lower packer includes a lower packer connector a, a lower packer sleeve a, a lower spacer ring a, a lower packer sleeve b, a lower spacer ring b, a lower packer sleeve c, a lower packer connector b, and a lower packer center tube. The lower packer connector a is threadedly connected to the lower packer center tube. The lower packer sleeve a, lower spacer ring a, lower packer sleeve b, lower spacer ring b, and lower packer sleeve c are sequentially fitted onto the outside of the lower packer center tube from top to bottom, and both ends are clamped by the lower packer connector a and the lower packer connector b, respectively. The lower packer connector b is threadedly connected to the lower packer center tube and is used to connect to an electric water separator. Each sleeve is used to pack the well casing, and each spacer ring is used to isolate adjacent sleeves.

[0014] The electric dewatering device includes a dewatering short circuit and an electrical control short circuit connected from top to bottom; the upper dewatering connector of the dewatering short circuit is threadedly connected to the lower packer and is used to pump fluid in the annular working section; the electrical control short circuit is threadedly connected to the dewatering short circuit, providing power to the dewatering short circuit and realizing electrical control, and the cable supplies power to the entire electric dewatering device and transmits control signals.

[0015] The dewatering short connector also includes a hydraulic body, a dewatering outer cylinder, a hydraulic cylinder, a lead screw protective cover, a piston, a lead screw, a lead screw nut connector, a lead screw sealing short connector, a bearing short connector, a sealing ring back cap, a sealing ring, bearing a, bearing b, and a bearing back cap. The hydraulic body is sequentially threaded to the dewatering upper connector and the dewatering outer cylinder, and has a through hole at the top that communicates with the annular working section. The hydraulic cylinder is connected to the hydraulic body, and the piston is located inside the hydraulic cylinder and threadedly connected to the lead screw nut connector. The lead screw is threaded to the lead screw nut connector, and bearing a, bearing b, and a sealing ring are installed on its surface. The bearing short connector supports the lead screw, and the sealing ring achieves dynamic sealing of the lead screw. The rotation of the lead screw drives the piston to move linearly within the hydraulic cylinder to draw fluid.

[0016] The electrical control short circuit includes a coupling, a straightening cable guide, an electrical control module adapter, a motor protective cover, a motor, a circuit board protective cover a, a circuit board, a circuit board bracket, a circuit board protective cover b, an electrical control outer cylinder, a circuit board output connector, and a water separator lower connector. The coupling connects the motor's output shaft to the lead screw for power transmission. The motor is housed inside the motor protective cover and electrically connected to the circuit board. The circuit board is mounted on the circuit board bracket, protected by circuit board protective covers a and b, electrically connected to the cable, and used to control the motor. The straightening cable guide is used to straighten and protect the cable, and the water separator lower connector is used to connect other downhole tools.

[0017] The lead screw protective cover is connected between the hydraulic cylinder and the lead screw sealing short circuit to protect the lead screw and lead screw nut joint; the sealing ring back cap is threadedly connected to the lead screw sealing short circuit to prevent the sealing ring from falling off; the bearing back cap is threadedly connected to the lead screw to axially limit bearings a and b to prevent them from loosening.

[0018] The electrical control module is connected between the water removal outer cylinder and the electrical control outer cylinder, and is internally connected to the straightening cable guide; the motor protective cover is threadedly connected to the straightening cable guide, and its bottom is engaged with the groove of the circuit board bracket; the electrical control outer cylinder is connected between the electrical control module adapter and the lower connector of the water remover, and is used to protect the internal components of the electrical control from short circuits; the circuit board cable outlet connector is threadedly connected to the circuit board protective cover b, and is used to thread and fix the cable.

[0019] The upper and lower ends of the downhole tool protective cover are threadedly connected to the upper packer connector b and the lower packer connector a, respectively, forming a closed accommodating cavity inside, which is used to adapt to the installation of different types of downhole operating tools and to protect them.

[0020] A method for displacing annular protective fluid in an oil-water environment within a wellbore, comprising the following steps:

[0021] S1. On the ground, complete the assembly and sealing performance test of the displacement system, connect the displacement medium pipeline to the protective fluid medium source, connect the cable to the ground power supply and control equipment, so that the piston is at the top of the hydraulic cylinder, and lower the assembled tool string into the target working section of the wellbore through the coiled tubing.

[0022] S2. Send control commands to the tool string to cause the rubber sleeves of the upper and lower packers to expand and set, forming a closed annular working section in conjunction with the well casing;

[0023] S3. The protective fluid medium is continuously injected into the annular working section through the displacement medium pipeline via the ground pumping equipment. At the same time, the electric water separator is started. The motor drives the screw to rotate and drives the piston to move downward, drawing the well fluid and oil and gas in the annular working section into the hydraulic cylinder. The protective fluid injection rate and the fluid suction rate are matched synchronously to maintain the pressure stability in the annular working section until the original fluid in the annular working section is completely replaced by the protective fluid medium.

[0024] S4. After the displacement is completed, start the downhole tools in the downhole tool protection cover and carry out downhole welding, inspection and perforation operations in the annulus working section.

[0025] The beneficial effects of the downhole annulus protection fluid displacement method and system for oil-water environments in wellbores according to the present invention are as follows:

[0026] This invention employs a synergistic mechanism of "upper protective fluid filling and lower active drainage," which almost completely removes all free and residual fluids from the isolation section through a hydraulic piston. This overcomes the inherent defects of traditional technologies that rely solely on air pressure to remove residual oil, water, and gas, creating a truly dry and high-purity media environment downhole. This lays a solid foundation for high-quality and challenging welding operations downhole.

[0027] The operating location is precise and controllable. Through the physical isolation of the double packers, the medium environment can be precisely controlled within the target operating section, such as one meter to several meters, achieving precise control from "section" to "point". This avoids the problem of traditional methods affecting excessively long well sections, making the operation highly targeted and causing no interference to the producing layer or other well sections.

[0028] This invention offers high operational efficiency and cost-effectiveness. It only requires replacing a small section of the liquid within the isolation chamber, significantly reducing liquid consumption compared to traditional technologies and resulting in a substantial decrease in overall operating costs. Its economic advantages are evident, making it particularly suitable for high-cost scenarios such as deep wells and offshore platforms.

[0029] This invention opens up new application areas. Its successful implementation makes high-end operations that were previously impossible due to environmental constraints, such as downhole live welding, ultra-high precision optical inspection, and the installation and commissioning of precision downhole instruments, possible. This expands the technological boundaries of downhole operations and has significant industry implications. Attached Figure Description

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and specific implementation methods.

[0031] Figure 1 A schematic diagram of the overall structure of the annular protective fluid displacement system for oil-water environments within a wellbore;

[0032] Figure 2 This is a sectional view of the upper packer;

[0033] Figure 3 This is a sectional view of the lower packer;

[0034] Figure 4 This is a cross-sectional view of an electric water separator.

[0035] Figure 5 This is a cross-sectional view of the water removal section of an electric water separator.

[0036] Figure 6 This is a cross-sectional view of the electrical control short circuit of an electric water separator.

[0037] In the diagram: Upper packer 1; Downhole tool protective cover 2; Lower packer 3; Electric water separator 4;

[0038] Upper packer connector a1.1; Upper packer sleeve a1.2; Upper diaphragm ring a1.3; Upper packer sleeve b1.4; Upper diaphragm ring b1.5; Upper packer sleeve c1.6; Upper packer connector b1.7; Upper packer center tube 1.8; Displacement medium pipeline 1.9;

[0039] Lower packer connector a3.1; Lower packer sleeve a3.2; Lower spacer ring a3.3; Lower packer sleeve b3.4; Lower spacer ring b3.5; Lower packer sleeve c3.6; Lower packer connector b3.7; Lower packer center tube 3.8;

[0040] Water removal short-circuit 4.1; Electrical control short-circuit 4.2;

[0041] 4.1.1 Water-removing connector; 4.1.2 Hydraulic body; 4.1.3 Water-removing outer cylinder; 4.1.4 Hydraulic cylinder; 4.1.5 Lead screw protective cover; 4.1.6 Piston; 4.1.7 Lead screw; 4.1.8 Lead screw sealing short circuit; 4.1.9 Bearing short circuit; 4.1.10 Sealing ring back cap; 4.1.11 Sealing ring; 4.1.12 Bearing a; 4.1.13 Bearing b; 4.1.14 Bearing back cap; 4.1.15

[0042] 4.2.1 Coupling; 4.2.2 Cable guide; 4.2.3 Electrical control module adapter; 4.2.4 Motor protective cover; 4.2.5 Motor; 4.2.6 Circuit board protective cover a; 4.2.7 Circuit board; 4.2.8 Circuit board bracket; 4.2.9 Circuit board protective cover b; 4.2.10 Electrical control outer cylinder; 4.2.11 Circuit board cable outlet connector; 4.2.12 Water separator lower connector; 4.2.13 Cable. Detailed Implementation

[0043] The technical solution of the present invention will be described in detail below with reference to the figures, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer definition of the scope of protection of the present invention.

[0044] This invention relates to an annular protective fluid displacement system for oil-water environments within wellbores. (See also...) Figure 1 The system is mainly composed of an upper packer 1, a downhole tool protective cover 2, a lower packer 3, and an electric water separator 4 connected from top to bottom. The components work together to achieve media displacement in a designated annular section of the wellbore, creating a stable, fluid-free working environment for high-precision downhole operations.

[0045] 1. Upper packer

[0046] See Figure 2 The upper packer 1 includes an upper packer connector a1.1, an upper packer rubber sleeve a1.2, an upper diaphragm ring a1.3, an upper packer rubber sleeve b1.4, an upper diaphragm ring b1.5, an upper packer rubber sleeve c1.6, an upper packer connector b1.7, an upper packer central tube 1.8, and a displacement medium pipeline 1.9. Its core function is to seal the upper end of the working section of the packer ring and to introduce protective fluid medium into the working section.

[0047] The upper packer connector a1.1 is connected to the upper packer center tube 1.8 by threads. The end face is opened with a through hole for connecting the displacement medium pipe 1.9 and the cable 4.2.13. Its side is connected to the upper packer rubber tube a1.2 to achieve clamping and fixing of the rubber tube.

[0048] The upper and lower ends of the upper packer sleeve a1.2 are connected to the upper packer connector a1.1 and the upper packer ring a1.3 respectively, and the inner ring is sleeved with the upper packer center tube 1.8 for packing the well casing.

[0049] The inner ring of the upper spacer a1.3 is sleeved with the center tube 1.8 of the upper packer and is located between the upper packer rubber tube a1.2 and the upper packer rubber tube b1.4 to achieve isolation between the two rubber tubes;

[0050] The upper and lower ends of the upper packer sleeve b1.4 are connected to the upper diaphragm ring a1.3 and the upper diaphragm ring b1.5 respectively, and the inner ring is sleeved with the center tube 1.8 of the upper packer, which works with the upper packer sleeve a1.2 to achieve the sealing of the well casing;

[0051] The inner ring of the upper spacer b1.5 is sleeved with the center tube 1.8 of the upper packer and is located between the upper packer rubber tube b1.4 and the upper packer rubber tube c1.6 to achieve isolation between the two rubber tubes;

[0052] The upper packer sleeve c1.6 is connected to the upper packer ring b1.5 and the upper packer connector b1.7 on both sides respectively, and the inner ring is sleeved with the upper packer center tube 1.8 to further enhance the sealing effect of the well casing;

[0053] The upper packer connector b1.7 is connected to the upper packer center tube 1.8 by threads. The upper end abuts against the upper packer rubber sleeve c1.6 and has a through hole for the displacement medium pipeline 1.9 to pass through. The lower end is used to connect to the downhole tool protective cover 2, and at the same time realizes the support and clamping of the rubber sleeve.

[0054] The upper packer center tube 1.8 is the core support component of the upper packer 1. Its upper and lower end faces are threaded to the upper packer connector a1.1 and the upper packer connector b1.7 respectively. The upper packer rubber sleeve a1.2, the upper spacer ring a1.3, the upper packer rubber sleeve b1.4, the upper spacer ring b1.5, and the upper packer rubber sleeve c1.6 are sequentially sleeved on the outside to provide installation support for each sealing component.

[0055] The two ends of the displacement medium pipeline 1.9 are connected to the through holes of the upper packer connector a1.1 and the upper packer connector b1.7, respectively, and are used to introduce protective fluid medium into the annular working section between the upper and lower packers to displace the original well fluid in the annular section.

[0056] II. Downhole Tool Protective Cover 2

[0057] The downhole tool protective cover 2 has a cylindrical structure. Its upper end face is connected to the upper packer connector b1.7 of the upper packer 1 by a thread, and its lower end face is connected to the lower packer connector a3.1 of the lower packer 3 by a thread. The interior forms a closed accommodating space for installing and protecting various tools required for downhole welding, inspection, and perforation operations, and preventing the tools from being corroded and damaged by the oil and water environment inside the wellbore.

[0058] III. Lower Packer 3

[0059] See Figure 3 The lower packer 3 includes a lower packer connector a3.1, a lower packer rubber sleeve a3.2, a lower diaphragm ring a3.3, a lower packer rubber sleeve b3.4, a lower diaphragm ring b3.5, a lower packer rubber sleeve c3.6, a lower packer connector b3.7, and a lower packer center tube 3.8. Its core function is to seal the lower end of the annular working section and cooperate with the upper packer 1 to form a closed annular working section.

[0060] The lower packer connector a3.1 is connected to the downhole tool protective cover 2 by a thread, and is also connected to the lower packer center tube 3.8 by a thread. Its lower end is connected to the lower packer rubber sleeve a3.2 to achieve clamping and fixing of the rubber sleeve.

[0061] The lower packer sleeve a3.2 is connected to the lower packer connector a3.1 and the lower packer ring a3.3 on both sides respectively, and the inner ring is sleeved with the lower packer center tube 3.8 for sealing the well casing;

[0062] The inner ring of the lower septum a3.3 is sleeved with the central tube 3.8 of the lower packer and is located between the lower packer rubber cylinder a3.2 and the lower packer rubber cylinder b3.4 to achieve isolation between the two rubber cylinders;

[0063] The lower septum sleeve b3.4 is connected to the lower septum ring a3.3 and the lower septum ring b3.5 on both sides respectively, and the inner ring is sleeved with the lower packer center tube 3.8, which works with the lower septum sleeve a3.2 to achieve the sealing of the well casing;

[0064] The inner ring of the lower septum b3.5 is sleeved with the central tube 3.8 of the lower packer and is located between the lower packer rubber tube b3.4 and the lower packer rubber tube c3.6 to achieve isolation between the two rubber tubes;

[0065] The lower packer sleeve c3.6 is connected to the lower diaphragm ring b3.5 and the lower packer connector b3.7 on both sides, and the inner ring is sleeved with the lower packer center tube 3.8 to further enhance the sealing effect of the well casing;

[0066] The lower packer connector b3.7 is connected to the electric dewatering device 4 via a thread, and is also connected to the lower packer center tube 3.8 via a thread. Its side is connected to the lower packer rubber cylinder c3.6 to achieve clamping and fixing of the rubber cylinder.

[0067] The lower packer center tube 3.8 is the core support component of the lower packer 3. Its upper and lower end faces are threaded to the lower packer connector a3.1 and lower packer connector b3.7 respectively. The lower packer rubber sleeve a3.2, lower spacer ring a3.3, lower packer rubber sleeve b3.4, lower spacer ring b3.5 and lower packer rubber sleeve c3.6 are sequentially sleeved on the outside, providing installation support for each sealing component.

[0068] IV. Electric water separator 4

[0069] See Figures 4 to 6 The electric water separator 4 is connected to the lower end of the lower packer 3 and includes two parts: water removal short circuit 4.1 and electric control short circuit 4.2. Its core function is to remove oil, water and gas fluids from the annular working section between the upper and lower packers, and to completely drain the original fluids in the working section in conjunction with the displacement medium pipeline 1.9.

[0070] (a) Water removal short circuit 4.1

[0071] The water removal short-connector 4.1 includes the water removal upper connector 4.1.1, hydraulic body 4.1.2, water removal outer cylinder 4.1.3, hydraulic cylinder 4.1.4, lead screw protective cover 4.1.5, piston 4.1.6, lead screw 4.1.7, lead screw nut connector 4.1.8, lead screw sealing short-connector 4.1.9, bearing short-connector 4.1.10, sealing ring back cap 4.1.11, sealing ring 4.1.12, bearing a 4.1.13, bearing b 4.1.14, and bearing back cap 4.1.15, which are the fluid suction actuators of the electric water separator 4.

[0072] The water removal connector 4.1.1 is connected to the lower packer connector b3.7 of the lower packer 3 via a thread, and is also connected to the hydraulic body 4.1.2 via a thread, thereby achieving a fixed connection between the water removal connector 4.1 and the lower packer 3.

[0073] The hydraulic body 4.1.2 is connected to the upper water removal connector 4.1.1 and the outer water removal cylinder 4.1.3 in sequence by threads, and is internally connected to the hydraulic cylinder 4.1.4. Ten equidistant through holes are opened on its upper part to allow the fluid in the annular working section to enter the hydraulic cylinder 4.1.4.

[0074] The outer cylinder 4.1.3 is connected to the hydraulic body 4.1.2 and the electrical control short circuit 4.2 in sequence by threads, providing protection for the internal components of the water removal short circuit 4.1;

[0075] Hydraulic cylinder 4.1.4 is connected to hydraulic body 4.1.2, and its lower end is connected to lead screw guard 4.1.5 by thread. It is used to store the pumped fluid and provide stroke for the reciprocating motion of piston 4.1.6.

[0076] The lead screw protective cover 4.1.5 is connected in sequence to the hydraulic cylinder 4.1.4 and the lead screw sealing short circuit 4.1.9 via threads, and is used to protect the internal lead screw 4.1.7 and lead screw nut joint 4.1.8;

[0077] The piston 4.1.6 is connected to the threaded nut 4.1.8 by a thread, and its side is sealed to the inner wall of the hydraulic cylinder 4.1.4 by a sealing groove. It achieves the suction of fluid in the annular working section through linear reciprocating motion.

[0078] The lead screw 4.1.7 is connected to the coupling 4.2.1 via a mating mechanism, and is threaded into the lead screw nut 4.1.8. Its surface is equipped with bearing a 4.1.13, bearing b 4.1.14, sealing ring back cap 4.1.11, and sealing ring 4.1.12. Its lower end is threaded into the bearing back cap 4.1.15, and is used to transmit the power and torque output from the electronic control short circuit 4.2.

[0079] The threaded connector 4.1.8 engages with the lead screw 4.1.7 via threads, converting the rotational motion of the lead screw 4.1.7 into the linear reciprocating motion of the piston 4.1.6;

[0080] The lead screw sealing short circuit 4.1.9 is connected to the lead screw protective cover 4.1.5 and the bearing short circuit 4.1.10 in sequence via threads, providing a transition for the sealing and support of the lead screw 4.1.7;

[0081] The bearing short circuit 4.1.10 is connected to the screw sealing short circuit 4.1.9 via a thread. Bearings a4.1.13 and b4.1.14 are installed inside. The lower end is connected to the boss on the motor protective cover 4.2.4. It is used to fix and support the transmission components and ensure that they move smoothly and centeredly along the design axis.

[0082] The sealing ring back cap 4.1.11 is connected to the lead screw sealing short circuit 4.1.9 by a thread, and the inner ring is sleeved with the lead screw 4.1.7 to prevent the sealing ring 4.1.12 from falling off;

[0083] The sealing ring 4.1.12 is connected to the screw sealing short circuit 4.1.9 and the sealing ring back cap 4.1.11. The inner ring is sleeved with the screw 4.1.7. After the sealing ring is installed in the inner and outer diameter sealing ring grooves, the dynamic sealing of the screw 4.1.7 is achieved.

[0084] Bearings a4.1.13 and b4.1.14 are both connected to bearing short circuit 4.1.10, and their inner rings are sleeved with lead screw 4.1.7, together ensuring that lead screw 4.1.7 rotates smoothly along the central axis;

[0085] The bearing cap 4.1.15 is connected to the lead screw 4.1.7 by a thread, and its two end faces abut against bearing a4.1.13 and bearing b4.1.14 respectively, to prevent bearing a4.1.13 and bearing b4.1.14 from loosening.

[0086] (ii) Electrical control short circuit 4.2

[0087] The electrical control short circuit 4.2 includes the coupling 4.2.1, the straightening cable guide 4.2.2, the electrical control module adapter 4.2.3, the motor protective cover 4.2.4, the motor 4.2.5, the circuit board protective cover a 4.2.6, the circuit board 4.2.7, the circuit board bracket 4.2.8, the circuit board protective cover b 4.2.9, the electrical control outer cylinder 4.2.10, the circuit board outlet connector 4.2.11, the water separator lower connector 4.2.12, and the cable 4.2.13, which are the power output and control components of the electric water separator 4.

[0088] Coupling 4.2.1 is used to transmit the power and torque of the output shaft of motor 4.2.5 to lead screw 4.1.7, so as to achieve seamless power connection;

[0089] The cable straightener 4.2.2 is connected to the circuit board protective cover a4.2.6 and the motor protective cover 4.2.4 by threads, and is connected to the electrical control module adapter 4.2.3 on the outside. It is used to straighten and protect the cable 4.2.13 to prevent the cable from being worn or tangled.

[0090] The electrical control module adapter 4.2.3 is connected to the water removal outer cylinder 4.1.3 and the electrical control outer cylinder 4.2.10 via threads, and is internally connected to the straightening wire guide 4.2.2 to realize the transition connection between the water removal short circuit 4.1 and the electrical control short circuit 4.2;

[0091] The motor protective cover 4.2.4 is connected to the straightener wire guide 4.2.2 by threads, the bottom is connected to the groove of the circuit board bracket 4.2.8, and the inside is connected to the bearing short circuit 4.1.10 to protect the internal motor 4.2.5;

[0092] The motor 4.2.5 is located inside the motor protective cover 4.2.4. Its lower end is electrically connected to the circuit board 4.2.7, and its upper end is connected to the coupling 4.2.1 through a groove, providing power for the rotation of the lead screw 4.1.7.

[0093] The circuit board protective cover a4.2.6 is connected to the circuit board protective cover b4.2.9 and the straightener 4.2.2 by threads, and cooperates with the circuit board protective cover b4.2.9 to form a closed space to protect the internal circuit board 4.2.7;

[0094] Circuit board 4.2.7 is mounted on circuit board bracket 4.2.8 and is electrically connected to cable 4.2.13 and motor 4.2.5 respectively. It is used to receive ground control signals and realize the control of parameters such as start-stop and speed of motor 4.2.5.

[0095] The circuit board bracket 4.2.8 is connected to the motor protective cover 4.2.4 through a groove, providing fixation and support for the circuit board 4.2.7 and ensuring the installation stability of the circuit board;

[0096] The circuit board protective cover b4.2.9 is connected to the circuit board cable outlet connector 4.2.11 and the circuit board protective cover a4.2.6 via threads, further enhancing the protection effect on the circuit board 4.2.7;

[0097] The outer cylinder of the electrical control unit 4.2.10 is connected to the electrical control module adapter 4.2.3 and the lower connector of the water separator 4.2.12 via threads, providing overall protection for all internal components of the electrical control short circuit 4.2;

[0098] The circuit board cable outlet connector 4.2.11 is connected to the circuit board protective cover b4.2.9 via threads, and is used to thread and fix the cable 4.2.13 to ensure the sealing and stability of the cable connection;

[0099] The lower connector 4.2.12 of the water separator is connected to the outer cylinder of the electrical control unit 4.2.10 via threads, and is used to connect other downhole tools to enable the system to be used in conjunction with other downhole equipment.

[0100] Cable 4.2.13 runs through the entire system, with one end connected to the ground power supply and control equipment, and the other end connected to the circuit board 4.2.7, providing power for the entire displacement system and enabling the transmission of control signals between the ground and the well.

[0101] V. Method of using the present invention

[0102] Based on the annular protective fluid displacement system in the above-mentioned oil-water environment within the wellbore, the annular protective fluid displacement method of the present invention adopts a top-charge and bottom-pump displacement mechanism, specifically including the following steps:

[0103] Step 1: Ground commissioning and packer setting:

[0104] The upper packer 1, downhole tool protective cover 2, lower packer 3 and electric water separator 4 are assembled in sequence to form a tool string. The sealing performance of the tool string is tested on the ground to ensure that there is no leakage at each connection and sealing component.

[0105] Connect the displacement medium pipeline 1.9 to the ground protective fluid medium source, connect the cable 4.2.13 to the ground power supply equipment and control equipment, debug the electrical control system, and ensure that the motor 4.2.5, circuit board 4.2.7 and other components are working properly. At this time, make the piston 4.1.6 of the electric water separator 4 at the top of the hydraulic cylinder 4.1.4.

[0106] The assembled and debugged tool string is lowered into the wellbore through coiled tubing. After the tool string is transported to the target working section of the wellbore, a control command is sent to the downhole tool string to cause the upper packer sleeves a1.2, b1.4, and c1.6 of the upper packer 1 and the lower packer sleeves a3.2, b3.4, and c3.6 of the lower packer 3 to gradually expand and fit tightly against the wellbore casing, thereby achieving the sealing of the upper and lower ends of the annular working section. A closed annular working section is formed between the upper packer 1 and the lower packer 3.

[0107] Step 2: Annular medium displacement

[0108] The media displacement in the annular operation section adopts the method of filling the upper part with protective fluid and actively pumping out the original fluid at the lower part. The specific operation is as follows:

[0109] The protective fluid medium is continuously injected into the annular working section through the displacement medium pipeline 1.9 via the surface pumping equipment. Under the action of gravity, the less dense protective fluid medium accumulates above the annular working section, while the denser original well fluid in the wellbore accumulates below the annular working section. As the protective fluid medium is continuously injected, the pressure in the annular working section gradually increases.

[0110] When the electric dewatering device 4 is started, the ground control equipment sends a control signal to the circuit board 4.2.7 via cable 4.2.13. The circuit board 4.2.7 controls the motor 4.2.5 to rotate at the specified speed according to the signal. The motor 4.2.5 drives the lead screw 4.1.7 to rotate via the coupling 4.2.1. The lead screw nut 4.1.8 converts the rotational motion of the lead screw 4.1.7 into the linear downward motion of the piston 4.1.6.

[0111] When piston 4.1.6 moves downward, a negative pressure is formed in hydraulic cylinder 4.1.4. The original well fluid, oil, and gas in the annular working section will be continuously drawn into hydraulic cylinder 4.1.4 through the through hole on hydraulic body 4.1.4 under the action of pressure difference.

[0112] During the fluid pumping process, the surface pumping equipment continuously delivers protective fluid medium into the annular working section to replenish the pressure and ensure that the pressure in the annular working section is stable until the original well fluid, oil and gas inside the annular working section are completely pumped into the hydraulic cylinder 4.1.4 and completely replaced by the protective fluid medium in the annular working section, forming a stable protective fluid medium environment.

[0113] Step 3: Conduct downhole operations.

[0114] Once the original fluid in the annular working section has been completely drained and the protective fluid environment has stabilized, the downhole tools inside the downhole tool protective cover 2 are activated to carry out high-precision downhole operations such as downhole welding, precision testing, and safe perforation in the closed, fluid-free annular working section. After the operation is completed, the packer sleeve is retracted by the ground control command to remove the tool string from the wellbore, thus completing the entire operation process.

Claims

1. An annular protective fluid displacement system for oil-water environments within a wellbore, characterized in that, The system includes an upper packer (1), a downhole tool protection cover (2), a lower packer (3), and an electric water separator (4) connected sequentially from top to bottom. The upper packer (1) is used to seal the upper end of the annular working section and integrates a one-way injection protective fluid channel inside. The displacement medium pipeline (1.9) leads to the annular working section below the upper packer (1). The downhole tool protection cover (2) is used to install and protect the tools required for downhole operations. The lower packer (3) cooperates with the upper packer (1) to form a closed annular working section. The electric water separator (4) is used to extract the remaining oil, water, and gas in the annular working section and cooperates with the displacement medium pipeline (1.9) to drain the fluid in the annular working section.

2. The annular protective fluid displacement system for oil-water environment in wellbore according to claim 1, characterized in that, The upper packer (1) includes an upper packer connector a (1.1), an upper packer sleeve a (1.2), an upper spacer ring a (1.3), an upper packer sleeve b (1.4), an upper spacer ring b (1.5), an upper packer sleeve c (1.6), an upper packer connector b (1.7), an upper packer center tube (1.8), and a displacement medium pipeline (1.9); the upper packer connector a (1.1) is threadedly connected to the upper packer center tube (1.8), and its end face is provided with a through hole for the displacement medium pipeline (1.9) and cable (4.2.13) to pass through; the upper packer sleeve a (1.2), the upper spacer ring a (1.3), and the upper packer sleeve b (1.4), the upper spacer ring b (1.5), the upper packer sleeve c (1.6), the upper packer connector b (1.7), the upper packer center tube (1.8), and the upper packer center tube (1.8) are all connected to the upper packer center tube (1.8). The upper packer sleeve b (1.4), upper diaphragm ring b (1.5), and upper packer sleeve c (1.6) are sequentially fitted onto the outside of the upper packer center tube (1.8) from top to bottom, and are clamped at both ends by upper packer connector a (1.1) and upper packer connector b (1.7) respectively. Upper packer connector b (1.7) is threaded to the upper packer center tube (1.8) and has a through hole for the displacement medium pipe (1.9) to pass through. The displacement medium pipe (1.9) is connected between the through hole of upper packer connector a (1.1) and upper packer connector b (1.7) and is used to introduce protective fluid medium into the annular working section.

3. The annular protective fluid displacement system for oil-water environment in wellbore according to claim 1, characterized in that, The lower packer (3) includes a lower packer connector a (3.1), a lower packer sleeve a (3.2), a lower spacer ring a (3.3), a lower packer sleeve b (3.4), a lower spacer ring b (3.5), a lower packer sleeve c (3.6), a lower packer connector b (3.7), and a lower packer center tube (3.8); the lower packer connector a (3.1) is threadedly connected to the lower packer center tube (3.8), and the lower packer sleeve a (3.2) and lower spacer ring a (3.3) are connected to the lower packer center tube (3.8). The lower packer rubber sleeve b (3.4), lower diaphragm ring b (3.5), and lower packer rubber sleeve c (3.6) are sequentially fitted onto the outside of the lower packer center tube (3.8) from top to bottom, and their two ends are clamped by the lower packer connector a (3.1) and the lower packer connector b (3.7) respectively. The lower packer connector b (3.7) is threadedly connected to the lower packer center tube (3.8) and is used to connect the electric water separator (4). Each rubber sleeve is used to seal the well casing, and each diaphragm ring is used to isolate adjacent rubber sleeves.

4. The annular protective fluid displacement system for oil-water environment in wellbore according to claim 1, characterized in that, The electric dewatering device (4) includes a dewatering short circuit (4.1) and an electrical control short circuit (4.2) connected from top to bottom; the upper dewatering connector (4.1.1) of the dewatering short circuit (4.1) is threadedly connected to the lower packer (3) for pumping fluid in the annular working section; the electrical control short circuit (4.2) is threadedly connected to the dewatering short circuit (4.1) to provide power to the dewatering short circuit (4.1) and realize electrical control; the cable (4.2.13) supplies power to the entire electric dewatering device (4) and transmits control signals.

5. The annular protective fluid displacement system for oil-water environment in wellbore according to claim 4, characterized in that, The dewatering short connector (4.1) further includes a hydraulic body (4.1.2), a dewatering outer cylinder (4.1.3), a hydraulic cylinder (4.1.4), a lead screw protective cover (4.1.5), a piston (4.1.6), a lead screw (4.1.7), a lead screw nut connector (4.1.8), a lead screw sealing short connector (4.1.9), a bearing short connector (4.1.10), a sealing ring back cap (4.1.11), a sealing ring (4.1.12), bearing a (4.1.13), bearing b (4.1.14), and a bearing back cap (4.1.15); the hydraulic body (4.1.2) is sequentially threadedly connected to the dewatering upper connector (4.1.1) and the dewatering outer cylinder (4.1.3), and has an opening at the top for communication with the annular working section. The hydraulic cylinder (4.1.4) is connected to the hydraulic body (4.1.2), and the piston (4.1.6) is located inside the hydraulic cylinder (4.1.4) and threadedly connected to the nut connector (4.1.8). The lead screw (4.1.7) is threadedly engaged with the nut connector (4.1.8), and its surface is equipped with bearing a (4.1.13), bearing b (4.1.14), and sealing ring (4.1.12). The bearing short circuit (4.1.10) supports the lead screw (4.1.7), and the sealing ring (4.1.12) achieves dynamic sealing of the lead screw (4.1.7). The rotation of the lead screw (4.1.7) drives the piston (4.1.6) to make linear motion inside the hydraulic cylinder (4.1.4) to draw fluid.

6. The annular protective fluid displacement system for oil-water environment in wellbore according to claim 4, characterized in that, The electrical control short circuit (4.2) includes a coupling (4.2.1), a straightener (4.2.2), an electrical control module adapter (4.2.3), a motor protective cover (4.2.4), a motor (4.2.5), a circuit board protective cover a (4.2.6), a circuit board (4.2.7), a circuit board bracket (4.2.8), a circuit board protective cover b (4.2.9), an electrical control outer cylinder (4.2.10), a circuit board cable outlet connector (4.2.11), and a water separator lower connector (4.2.12); the coupling (4.2.1) connects the output shaft of the motor (4.2.5) to the lead screw (4.2.5). 1.7), used to transmit power; the motor (4.2.5) is set inside the motor protective cover (4.2.4) and electrically connected to the circuit board (4.2.7); the circuit board (4.2.7) is mounted on the circuit board bracket (4.2.8), protected by the circuit board protective cover a (4.2.6) and the circuit board protective cover b (4.2.9), electrically connected to the cable (4.2.13) and used to control the motor (4.2.5); the straightener (4.2.2) is used to straighten and protect the cable (4.2.13), and the water separator lower connector (4.2.12) is used to connect the other downhole tools.

7. The annular protective fluid displacement system for oil-water environment in wellbore according to claim 5, characterized in that, The lead screw protective cover (4.1.5) is connected between the hydraulic cylinder (4.1.4) and the lead screw sealing short circuit (4.1.9) to protect the lead screw (4.1.7) and the lead screw nut joint (4.1.8); the sealing ring back cap (4.1.11) is threadedly connected to the lead screw sealing short circuit (4.1.9) to prevent the sealing ring (4.1.12) from falling off; the bearing back cap (4.1.15) is threadedly connected to the lead screw (4.1.7) to axially limit bearing a (4.1.13) and bearing b (4.1.14) to prevent them from loosening.

8. The annular protective fluid displacement system for oil-water environment in wellbore according to claim 6, characterized in that, The electrical control module adapter (4.2.3) is connected between the water removal outer cylinder (4.1.3) and the electrical control outer cylinder (4.2.10), and is internally connected to the straightening cable guide (4.2.2); the motor protective cover (4.2.4) is threadedly connected to the straightening cable guide (4.2.2), and its bottom is engaged with the groove of the circuit board bracket (4.2.8); the electrical control outer cylinder (4.2.10) is connected between the electrical control module adapter (4.2.3) and the water separator lower connector (4.2.12), and is used to protect the internal components of the electrical control short circuit (4.2); the circuit board cable outlet connector (4.2.11) is threadedly connected to the circuit board protective cover b (4.2.9), and is used to thread and fix the cable (4.2.13).

9. The annular protective fluid displacement system for oil-water environment in wellbore according to any one of claims 1 to 8, characterized in that, The upper and lower ends of the downhole tool protective cover (2) are threadedly connected to the upper packer connector b (1.7) and the lower packer connector a (3.1) respectively, forming a closed accommodating cavity inside, which is used to adapt to the installation of different types of downhole operation tools and to protect them.

10. A method for displacing annular protective fluid in an oil-water environment within a wellbore, characterized in that, The annular protective fluid displacement system based on the oil-water environment in the wellbore according to any one of claims 1 to 9 is implemented by including the following steps: S1. Complete the assembly and sealing performance test of the displacement system on the ground, connect the displacement medium pipeline (1.9) to the protective fluid medium source, connect the cable (4.2.13) to the ground power supply and control equipment, so that the piston (4.1.6) is at the top of the hydraulic cylinder (4.1.4), and lower the assembled tool string into the target working section of the wellbore through the coiled tubing. S2. Send control commands to the tool string to cause the rubber sleeves of the upper packer (1) and lower packer (3) to expand and set, forming a closed annular working section in conjunction with the well casing. S3. The protective fluid medium is continuously injected into the annular working section through the displacement medium pipeline (1.9) via the ground pumping equipment. At the same time, the electric water separator (4) is started. The motor (4.2.5) drives the lead screw (4.1.7) to rotate and drive the piston (4.1.6) to move downward, so as to draw the well fluid and oil and gas in the annular working section into the hydraulic cylinder (4.1.4). The protective fluid injection rate and the fluid suction rate are matched synchronously to maintain the pressure stability in the annular working section until the original fluid in the annular working section is completely replaced by the protective fluid medium. S4. After the displacement is completed, start the downhole operation tools in the downhole tool protection cover (2) and carry out downhole welding, inspection and perforation operations in the annular operation section.

Images