A downhole pressure-resistant stabilizer and a lifting and unblocking method and a rotating and unblocking method thereof

Abstract

This invention discloses a downhole pressure stabilizer and its lifting and rotation unsealing methods, including a rubber sleeve sealing section, an internal and external pressure differential loading section, and a forced unlocking section. The rubber sleeve sealing section includes an outer central tube and a rubber sleeve, with the rubber sleeve fitted outside the outer central tube. The outer central tube and the rubber sleeve are connected to the internal and external pressure differential loading section. The forced unlocking section includes an inner central tube, a forced unlocking mechanism, and a connecting mechanism. The inner central tube is slidably disposed inside the outer central tube, the forced unlocking mechanism is connected to the inner central tube, and the connecting mechanism is disposed below the rubber sleeve. The forced unlocking mechanism drives the inner central tube to connect the inside and outside of the pressure stabilizer via the connecting mechanism. Using this invention, during pressure testing and layer replacement, without connecting the annulus, the pressure difference between the upper and lower parts of the packer is balanced, achieving long-term stability of the packer and extending its service life. In use, if lifting fails to unseal the packer, this invention can forcibly open the annulus to assist in unsealing.

Description

Technical Field

[0001] This invention relates to the field of downhole tool technology, specifically to a downhole pressure stabilizer and its lifting and unsealing methods and rotation unsealing methods. Background Technology

[0002] Multi-stage downhole packers are frequently used in stratified oil production technologies. However, due to the influence of tubing pressure testing and layer switching operations or changes in downhole reservoir pressure, packer instability and failure have gradually become significant factors affecting the success of the process. Packer failures in stratified oil production tubing lasting more than two years account for over 32.6% of all stratified oil production applications, with top packer failure accounting for approximately 68.9% of all failures. Currently, the main approaches to address packer failure include:

[0003] I. Compensation Method: A length compensator is added to the tubing string. When the tubing string experiences expansion and contraction stress, the compensator is released first to compensate for the length, reducing the stress on the packer slips due to pressure changes. However, this method only addresses the impact of tubing length expansion and contraction on the packer and does not specifically protect the packer's sealing stability. Especially when the pressure difference between the upper and lower parts of the packer is large, it is prone to failure due to damage to the rubber sleeve. Furthermore, when encountering a large well inclination or imperfect casing conditions at the setting position, the packer rubber sleeve itself is prone to incomplete setting, greatly limiting the compensation method. Examples include: "CN221442565U, A Steam Injection Thermal Insulation Compensator for Thermal Recovery Wells" and "CN117449830A, Test Tubing String for Double-Sealing Layered Modification and its Layered Testing Method".

[0004] II. Pressure Balancing Method: This method involves using pressure balancers or similar tools to balance the pressure in the tubing string under certain conditions, preventing packer sleeves from failing due to excessive pressure differentials. However, since pressure balancing cannot be performed arbitrarily during injection and production processes, as well as in other stratified tubing strings, this method has stringent application conditions and a narrow scope of application. Examples include invention patents such as "CN117211727B, a pressure balancing device for the annulus between double packers" and "CN117868734A, a pressure control tool for the closed annulus of high-pressure oil and gas wells."

[0005] III. Permanent Packer Method: To avoid packer failure, the permanent packer method is adopted. This significantly improves packer setting and sealing reliability when facing alternating downhole pressure changes, reducing the risk of leakage during operation. However, retrieving the tubing requires retrieval or drilling / milling, increasing construction procedures and application costs; examples include: "CN113669036A, A Hydraulic Controlled Layered Oil Production System" and "CN110905439B, An Integrated Downhole Tool Based on a Bidirectional Slip Hydraulic Permanent Packer," etc.

[0006] IV. Redundancy Method: To effectively seal locations with poor setting conditions within the casing, two or more packers with the same setting conditions are used simultaneously. When one packer fails, the other acts as a backup. Alternatively, a backup setting mechanism can be added. This backup setting structure can be used in conjunction with several other existing setting methods and can perform two independent setting operations under different working conditions, increasing the probability of successful setting and reducing losses for the operator. This method can reduce the packer failure rate to some extent, but in harsh downhole conditions such as alternating pressure, it often only extends the lifespan to a certain extent and is unlikely to fundamentally solve the problem. For example, "CN209799923U, a packer formation pressure setting structure," etc.

[0007] Publication No. CN118056981A discloses a downhole self-replacing sealing packer and its usage method, including a central tube, a rubber sleeve fitted outside the central tube, and a hydraulic transmission mechanism; the rubber sleeve includes an upper sealing rubber sleeve and a replacement sealing rubber sleeve, with an upper gap between the inner wall of the upper sealing rubber sleeve and the outer wall of the central tube, and a lower gap between the inner wall of the replacement sealing rubber sleeve and the outer wall of the central tube; the hydraulic transmission mechanism includes a cylinder liner, an isolation setting piston, and a replacement control piston; the cylinder liner is fitted outside the central tube, with its upper end connected to the lower end of the upper sealing rubber sleeve, and its lower end connected to the upper end of the replacement sealing rubber sleeve; a piston cavity is formed between the cylinder liner and the central tube, and both the isolation setting piston and the replacement control piston are placed inside the piston cavity; the lower end of the isolation setting piston is connected to the upper end of the replacement control piston.

[0008] The existing technology can isolate the packer from alternating pressure during layer replacement operations, but it cannot force unsealing when the formation pressure is low, the pressure difference between the inside and outside of the tubing is large, and the rubber sleeve is always tightly attached to the casing wall.

[0009] Publication No. CN113123753A discloses a soluble and easily drillable open-hole packer and its usage method, comprising: a mandrel, an upper connector, a lower connector, and an elastic rubber sleeve; the mandrel is a stepped cylindrical tube with a middle outer diameter larger than the outer diameters at both ends, and a channel connecting the inside and outside is opened in the middle part as a pressure transmission hole; the upper part of the mandrel is connected to the inner hole of the upper connector by a thread, the lower part of the mandrel is connected to the inner hole of the lower connector by a thread, and the elastic rubber sleeve is located outside the mandrel.

[0010] The existing technology can isolate the packer from alternating pressure during layer replacement operations, but it cannot force unsealing when the formation pressure is low, the pressure difference between the inside and outside of the tubing is large, and the rubber sleeve is always tightly attached to the casing wall.

[0011] Publication No.: CN111075387A discloses an expansion-type water-filled packer with a shoulder sleeve on the upper part of the rubber tube, including a central tube and a rubber tube assembly fitted on the outer wall of the central tube. The central tube has a radially penetrating pressure transmission hole. The rubber tube assembly includes an upper section, a middle section, and a lower section of the rubber tube, wherein the outer diameter of the middle section is larger than the outer diameter of the upper section and the lower section. An upper shoulder is formed at the connection between the middle section and the upper section, and a lower shoulder is formed at the connection between the middle section and the lower section. A shoulder sleeve is fitted on the outer wall of the upper section, and the lower end of the shoulder sleeve rests on the upper shoulder.

[0012] The existing technology can isolate the packer from alternating pressure during layer replacement operations, but it cannot force unsealing when the formation pressure is low, the pressure difference between the inside and outside of the tubing is large, and the rubber sleeve is always tightly attached to the casing wall.

[0013] In summary, the technical solutions, technical problems to be solved, and beneficial effects of the above-disclosed technologies are all different from those of the present invention. Regarding the more technical features, technical problems to be solved, and beneficial effects of the present invention, the above-disclosed technical documents do not provide any technical inspiration. Summary of the Invention

[0014] In view of the above-mentioned defects in the existing technology, the purpose of this invention is to provide a downhole pressure stabilizer and its lifting and unsealing method and rotation unsealing method.

[0015] To achieve the above objectives, the present invention adopts the following technical solution:

[0016] On one hand, the present invention provides a downhole pressure stabilizer, including a rubber sleeve sealing section, an internal and external pressure differential loading section, and a forced unlocking section; the rubber sleeve sealing section includes an outer central tube and a rubber sleeve, the rubber sleeve being sleeved outside the outer central tube, and the outer central tube and the rubber sleeve being connected to the internal and external pressure differential loading section; the forced unlocking section includes an inner central tube, a forced unlocking mechanism, and a connecting mechanism, the inner central tube being slidably disposed inside the outer central tube, the forced unlocking mechanism being connected to the inner central tube, and the connecting mechanism being disposed below the rubber sleeve; the forced unlocking mechanism drives the inner central tube to cause the connecting mechanism to connect the inside and outside of the pressure stabilizer.

[0017] In Embodiment 1 of the present invention, the forced unlocking mechanism includes a first connecting liquid cylinder liner, a first pressure balancing cylinder liner, a first pressure balancing piston, and a first upper connector;

[0018] Specifically, the lower inner wall of the first connecting liquid cylinder sleeve is connected to the rubber sleeve sealing section, and the upper outer wall of the first connecting liquid cylinder sleeve is connected to the lower inner wall of the first pressure balance cylinder sleeve.

[0019] Specifically, the inner central tube is inserted into the outer central tube, the inner central tube and the outer central tube are sealed together, and the upper end of the inner central tube is connected to the lower end of the first upper connector;

[0020] Specifically, the first upper connector is connected to the first pressure balance cylinder liner via a disconnectable component;

[0021] Specifically, the first pressure balancing piston is disposed in the annulus between the first pressure balancing cylinder sleeve and the inner central tube, the first pressure balancing piston is connected to the inner central tube, and a step is provided on the inner wall of the first pressure balancing cylinder sleeve above the first pressure balancing piston.

[0022] Specifically, the conducting mechanism is a first lower connector; the lower end of the outer central tube and the lower end of the rubber sleeve are connected to the inner and outer pressure difference loading section, the lower end of the inner and outer pressure difference loading section is provided with a first lower connector, the first lower connector is provided with a first inner and outer pressure balance hole, the lower end of the inner central tube extends to the first lower connector, the inner central tube seals the first inner and outer pressure balance hole, and after the inner central tube is unlocked and moved upward, the first inner and outer pressure balance hole is opened.

[0023] Furthermore, the first detachable component includes a first locking shear pin, the first upper connector is connected to the first key sleeve via the first locking shear pin, and the lower inner wall of the first key sleeve is connected to the upper outer wall of the first pressure balance cylinder sleeve.

[0024] Furthermore, the upper outer wall of the rubber tube is connected to a first upper baffle, and the lower outer wall of the rubber tube is connected to a first lower baffle.

[0025] Specifically, the outer wall of the upper end of the outer central tube is connected to the first connecting inner sleeve, the outer wall of the upper end of the first upper baffle is connected to the first sliding sleeve, the inner wall of the first sliding sleeve is slidably engaged with the outer wall of the first connecting inner sleeve, and the upper end of the first connecting inner sleeve is connected to the lower end of the first connecting hydraulic cylinder sleeve.

[0026] Furthermore, the internal and external pressure differential loading section includes a first hydraulic cylinder liner, a first lower connector, and a first pressure transmitting piston;

[0027] Specifically, the upper end of the first hydraulic cylinder sleeve is connected to the lower end of the first lower baffle, the outer wall of the upper end of the first lower connector is connected to the inner wall of the lower end of the first hydraulic cylinder sleeve, and the inner wall of the upper end of the first lower connector is connected to the outer wall of the lower end of the outer center tube.

[0028] Specifically, a first pressure-transmitting piston is provided in the annular space between the first hydraulic cylinder liner and the outer central tube, and the first pressure-transmitting piston is connected to the outer central tube through a first pressure-transmitting piston shear pin.

[0029] Specifically, the outer central tube is provided with a first external pressure transmission hole between the first pressure transmission piston and the first lower connector, and the inner central tube is provided with a first internal pressure transmission hole corresponding to the first external pressure transmission hole.

[0030] Furthermore, the inner central tube and the outer central tube are connected by a first locking block, which corresponds to the first pressure transmitting piston. The first locking block penetrates the wall of the outer central tube and is embedded in the outer wall of the inner central tube.

[0031] In Embodiment 3 of the present invention, the forced unlocking mechanism includes a second upper connector, a second spring, a second sealing inner cylinder, a second connecting sleeve, and a second lower connector;

[0032] Specifically, the inner central tube passes through the outer central tube, the outer wall of the inner central tube is sealed to the inner wall of the outer central tube, the upper outer wall of the inner central tube is connected to the second upper connector, and the lower end of the inner central tube is connected to the second sealing inner cylinder.

[0033] Specifically, the outer wall of the second sealing inner cylinder is provided with a large-diameter connecting section and a small-diameter sealing section. The small-diameter sealing section is connected to the second lower connector through a reverse thread and a second anti-rotation shear pin. The large-diameter connecting section is connected to the second connecting sleeve.

[0034] Specifically, the second connecting sleeve is fitted over the second lower connector, a load-bearing ring is provided on the inner wall of the lower end of the second connecting sleeve, and a load-bearing step is provided on the outer wall of the second lower connector, the load-bearing step being able to sit on the load-bearing ring;

[0035] Specifically, the conducting mechanism is a second internal and external pressure balance hole, the second lower connector is provided with the second internal and external pressure balance hole, the second sealing inner cylinder seals the second internal and external pressure balance hole, and the second connecting sleeve is provided with a sieve hole. When the second lower connector is seated in the second connecting sleeve, the second internal and external pressure balance hole is connected.

[0036] Furthermore, the upper outer wall of the rubber tube is connected to a second upper baffle, the lower outer wall of the rubber tube is connected to a second lower baffle, and the upper outer wall of the outer central tube is connected to a second positioning connector, the second upper connector being able to contact the second positioning connector;

[0037] Specifically, the upper outer wall of the second upper baffle is connected to the second sliding sleeve, and the inner wall of the second sliding sleeve is slidably engaged with the outer wall of the second positioning joint.

[0038] Furthermore, the internal and external pressure differential loading section includes a second hydraulic cylinder liner, a second pressure transmitting piston, and a second sealing joint;

[0039] Specifically, the upper end of the second hydraulic cylinder liner is connected to the lower end of the second lower baffle, the inner wall of the lower end of the second hydraulic cylinder liner is connected to the outer wall of the second sealing joint, and the inner wall of the second sealing joint is connected to the outer wall of the lower end of the outer center tube.

[0040] Specifically, the second pressure-transmitting piston is disposed in the annulus between the second hydraulic cylinder sleeve and the outer central tube, and the second hydraulic cylinder sleeve is connected to the second sealing joint through the second pressure-transmitting piston shear pin;

[0041] Specifically, the outer central tube is provided with a second external pressure transmission hole, which is located between the second pressure transmission piston shear pin and the second sealing joint, and the inner central tube is provided with a second internal pressure transmission hole corresponding to the second external pressure transmission hole.

[0042] Furthermore, a second spring is fitted between the second sealing joint and the second sealing inner cylinder of the inner central tube.

[0043] Furthermore, the inner central tube and the outer central tube are connected by a second locking block, the second locking block corresponds to the second pressure transmitting piston, the second locking block penetrates the wall of the outer central tube, and the second locking block is embedded in the outer wall of the inner central tube.

[0044] Secondly, the present invention provides a method for lifting and unsealing a downhole pressure-resistant stabilizer, using a downhole pressure-resistant stabilizer as described in Embodiment 1 of the present invention, comprising the following steps:

[0045] A pressure stabilizer is installed below the suspended packer or above the stratified packer, and connected to the stratified injection and production tubing string and lowered into the well.

[0046] Under the action of the internal and external pressure difference loading section, the rubber sleeve expands and tightly adheres to the inner wall of the casing when the pressure inside the tubing is greater than the external pressure, and retracts when the pressure inside the tubing is greater than the external pressure.

[0047] When the entire tubing string is unable to be pulled out due to formation pressure deficiency and large pressure difference between the inside and outside of the pressure stabilizer, the rubber sleeve remains tightly attached to the casing wall. In this case, the tubing string is lifted up, the first disconnectable part is cut off, the inner central tube moves up, and the first internal and external pressure balance hole on the first lower connector is exposed. After the first internal and external pressure balance hole connects the inner and outer tubing strings, the pressure gradually balances, and the tubing string can be pulled out smoothly.

[0048] In three aspects, the present invention provides a method for rotating and unsealing a downhole pressure-resistant stabilizer, using a downhole pressure-resistant stabilizer as described in Embodiment 3 of the present invention, comprising the following steps:

[0049] A pressure stabilizer is installed below the suspended packer or above the stratified packer, and connected to the stratified injection and production tubing string and lowered into the well.

[0050] Under the action of the internal and external pressure difference loading section, the rubber sleeve expands and tightly adheres to the inner wall of the casing when the pressure inside the tubing is greater than the external pressure, and retracts when the pressure inside the tubing is greater than the external pressure.

[0051] When the entire tubing string is unable to be pulled out due to formation pressure depletion and large pressure difference between the inside and outside of the pressure stabilizer, and the rubber sleeve remains tightly attached to the casing wall, rotate the tubing string forward until the second anti-rotation shear pin is cut off. Continue rotating the tubing string forward until the reverse thread of the second sealing inner cylinder disengages from the second lower connector. The second lower connector falls into the second connecting sleeve, and the second internal and external pressure balance hole of the second lower connector connects with the internal space and screen hole of the tubing string. The pressure of the internal and external tubing strings gradually balances, and the tubing string can be pulled out smoothly.

[0052] Compared with the prior art, the present invention has the following advantages:

[0053] 1. After using this invention, during pressure testing and layer replacement, without connecting the annulus, the pressure difference between the upper and lower parts of the packer is balanced, thus achieving long-term stability of the packer and extending its service life.

[0054] 2. When the seal cannot be broken by lifting, the present invention can be used to forcibly open the annulus of the oil sleeve to assist in breaking the seal.

[0055] 3. The rubber sleeve of the present invention has an independent pressure system and does not directly contact the fluid in the well. It has a two-level protection function, reduces the risk of failure, and reduces corrosion and scaling.

[0056] 4. After applying this invention, the packer failure rate decreased by more than 23% and the top seal failure rate decreased by more than 49% within two years. In particular, the success rate of layer replacement in stratified oil production increased by about 15%. In application, the unsealing rate of this invention is 100%. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the downhole pressure stabilizer in Example 1;

[0058] Figure 2 This is a schematic diagram of the downhole pressure stabilizer in Example 2;

[0059] Figure 3 This is a schematic diagram of the tubing structure for the application of downhole pressure stabilizers;

[0060] Figure 4 This is a schematic diagram of the structure after the application string of the downhole pressure stabilizer is lost.

[0061] In the diagram: 1. Depth adjustment sub, 2. Well washing valve, 3. Drop tool, 4. Packer, 5. Pressure stabilizer, 6. Resettable switch, 7. Sand filter, 8. Plug, 9. Fish top;

[0062] 101 First upper connector, 102 First key sleeve, 103 First pressure balance cylinder sleeve, 104 First pressure balance piston, 105 First connecting outer sleeve, 106 First inner central tube, 107 First connecting inner sleeve, 108 First sliding sleeve, 109 First upper baffle, 110 First outer central tube, 111 First rubber sleeve, 112 First hydraulic cylinder sleeve, 113 First pressure transmitting piston, 114 First locking block, 115 First lower connector, 116 First locking shear pin, 117 First fixing pin, 118 First pressure transmitting piston shear pin, 119 First outer pressure transmitting hole, 120 First inner pressure transmitting hole, 121 First inner and outer pressure balance hole;

[0063] 201 Second upper connector, 202 Second inner central tube, 203 Second positioning connector, 204 Second connecting sleeve, 205 Second outer central tube, 206 Second upper baffle, 207 Second rubber cylinder, 208 Second lower baffle, 209 Second hydraulic cylinder sleeve, 210 Second pressure transmitting piston, 211 Second locking block, 212 Second pressure transmitting piston shear pin, 213 Second sealing connector, 214 Second spring, 215 Second sealing inner cylinder, 216 Second connecting sleeve, 217 Second anti-rotation shear pin, 218 Second lower connector, 219 Second internal and external pressure balance hole, 220 Second external pressure transmitting hole, 221 Second internal pressure transmitting hole. Detailed Implementation

[0064] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0065] The present invention provides a downhole pressure stabilizer, comprising a rubber sleeve sealing section, an internal and external pressure differential loading section, and a forced unlocking section.

[0066] Example 1:

[0067] Please see Figure 1 In this embodiment, a downhole pressure-resistant stabilizer is provided:

[0068] The rubber sleeve sealing section includes a first outer central tube 110 and a first rubber sleeve 111. The first rubber sleeve 111 is sleeved outside the first outer central tube 110. The upper outer wall of the first rubber sleeve 111 is threaded to a first upper baffle 109, and the lower outer wall of the first rubber sleeve 111 is threaded to a first lower baffle. The upper outer wall of the first outer central tube 110 is threaded to a first connecting inner sleeve 107, and the upper outer wall of the first upper baffle 109 is threaded to a first sliding sleeve 108. The inner wall of the first sliding sleeve 108 is slidably engaged with the outer wall of the first connecting inner sleeve 107, so that the first rubber sleeve 111 can drive the first upper baffle 109 and the first sliding sleeve 108 to smoothly contract axially and expand radially. The upper end of the first connecting inner sleeve 107 is connected to a forced unlocking section, and the lower ends of the first lower baffle and the first outer central tube 110 are connected to an internal and external pressure differential loading section.

[0069] Specifically, the first rubber cylinder 111 is an integral part of a stainless steel cylinder and an outer rubber, and the middle part can expand and contract.

[0070] Specifically, the first rubber cylinder 111 is sealed with the first upper baffle 109, the first rubber cylinder 111 is sealed with the first lower baffle, the first upper baffle 109 is sealed with the first sliding sleeve 108, and the first sliding sleeve 108 is sealed with the first connecting inner sleeve 107 by O-rings.

[0071] The internal and external pressure differential loading section includes a first hydraulic cylinder sleeve 112, a first lower connector 115, and a first pressure transmitting piston 113. The upper end of the first hydraulic cylinder sleeve 112 is threadedly connected to the lower end of the first lower baffle. The upper outer wall of the first lower connector 115 is threadedly connected to the lower inner wall of the first hydraulic cylinder sleeve 112. The upper inner wall of the first lower connector 115 is threadedly connected to the lower outer wall of the first outer central tube 110. The first pressure transmitting piston 113 is provided in the annular space between the first hydraulic cylinder sleeve 112 and the first outer central tube 110. The first pressure transmitting piston 113 and the first outer central tube 110 are connected by a first pressure transmitting piston shear pin 118. The first outer central tube 110 is provided with a first external pressure transmitting hole 119 between the first pressure transmitting piston 113 and the first lower connector 115.

[0072] Specifically, the first hydraulic cylinder liner 112 and the first lower baffle, the first hydraulic cylinder liner 112 and the first pressure transmitting piston 113, the first hydraulic cylinder liner 112 and the first lower connector 115, and the first pressure transmitting piston 113 and the first outer central tube 110 are all sealed by O-rings.

[0073] The forced unlocking section includes a first inner central tube 106, a first connecting hydraulic cylinder sleeve 105, a first pressure balancing cylinder sleeve 103, a first pressure balancing piston 104, and a first upper connector 101. The lower inner wall of the first connecting hydraulic cylinder sleeve 105 is threadedly connected to the upper outer wall of the first connecting inner sleeve 107. The upper outer wall of the first connecting hydraulic cylinder sleeve 105 is threadedly connected to the lower inner wall of the first pressure balancing cylinder sleeve 103. The first inner central tube 106 is inserted into the first outer central tube 110. An O-ring seal is provided between the first inner central tube 106 and the first outer central tube 110. The upper outer wall of the first inner central tube 106 is threadedly connected to the lower inner wall of the first upper connector 101. The outer wall of the head 101 contacts the upper inner wall of the first pressure balancing cylinder sleeve 103 and is sealed by an O-ring. The outer wall of the first upper connector 101 is connected to the first key sleeve 102 by the first locking shear pin 116. The lower inner wall of the first key sleeve 102 is threadedly connected to the upper outer wall of the first pressure balancing cylinder sleeve 103 and locked by the first fixing pin 117. The first pressure balancing piston 104 is disposed in the annulus between the first pressure balancing cylinder sleeve 103 and the first inner central tube 106. The inner wall of the first pressure balancing piston 104 is threadedly connected to the outer wall of the first inner central tube 106. The inner wall of the first pressure balancing cylinder sleeve 103 is provided with a step to prevent the first pressure balancing piston 104 from coming out.

[0074] The first inner central tube 106 and the first outer central tube 110 are connected by a first locking block 114. The first locking block 114 corresponds to the first pressure transmitting piston 113. The first locking block 114 penetrates the wall of the first outer central tube 110 and is embedded in the outer wall of the first inner central tube 106. When the first pressure transmitting piston 113 moves to make room, the first locking block 114 can be squeezed out, thus releasing the connection between the first inner central tube 106 and the first outer central tube 110.

[0075] The lower end of the first inner central tube 106 extends to the first lower connector 115. The first lower connector 115 is provided with a first internal and external pressure balance hole 121. The first lower connector 115 is provided with O-rings above and below the first internal and external pressure balance hole 121. The first inner central tube 106 seals the first internal and external pressure balance hole 121. The first inner central tube 106 is provided with a first internal pressure transmission hole 120 corresponding to the first external pressure transmission hole 119. After the first inner central tube 106 is unlocked and moved upward, the first internal and external pressure balance hole 121 is opened, the space above the first pressure balance piston 104 is compressed, and the first pressure balance piston 104 bears the weight.

[0076] Specifically, the upper and lower edges of the mating surface between the first locking block 114 and the first inner central tube 106 are conical surfaces, which facilitates the first inner central tube 106 to squeeze out the first locking block 114.

[0077] Specifically, the first pressure balancing piston 104 and the first pressure balancing cylinder liner 103, and the first pressure balancing piston 104 and the first inner central tube 106 are sealed by O-rings.

[0078] The first upper connector 101, the first inner central tube 106, the first pressure balancing cylinder sleeve 103, and the first pressure balancing piston 104 constitute the pressure balancing chamber A. During setting or working pressure testing, under the action of pressure and various piston forces at the lower end, the first upper connector 101, the first inner central tube 106, the first key sleeve 102, and the first pressure balancing cylinder sleeve 103 may generate relative movement forces. These forces act on the unsealing pin 116 and may damage it. With the pressure balancing chamber A, the forces of setting or working pressure testing also act within the pressure balancing chamber A, which can counteract their relative movement forces and achieve a balancing effect. After the first inner central tube 106 is unlocked from the first outer central tube 110 and the first key sleeve 102, the pressure balancing chamber A transmits the supporting force.

[0079] Among them, the first outer central tube 110, the first connecting inner sleeve 107, the first upper baffle 109, the first rubber sleeve 111, the first lower baffle, the first hydraulic cylinder sleeve 112, and the upper end face of the first pressure transmitting piston 113 constitute the piston chamber B. The piston chamber B is filled with hydraulic transmission oil. When the first rubber sleeve 111 is damaged or damaged for other reasons, due to the sealing effect of the first pressure transmitting piston 113, the pressure inside and outside the tubing is still isolated, which does not affect the normal function of the oil production tubing. Moreover, the hydraulic transmission oil has the functions of protecting the pressure stabilizer and preventing corrosion.

[0080] The first hydraulic cylinder liner 112, the first outer central tube 110, the lower end face of the first pressure transmitting piston 113, and the first lower connector constitute a hydraulic chamber C, which transmits the layer-changing pressure to the first pressure transmitting piston 113 through the first inner pressure transmitting hole 120 and the first outer pressure transmitting hole 119.

[0081] The pressure stabilizer is connected to the bottom of the top packer via a thread. When released, it cuts off the first pressure transmission piston 113. Under pressure, the first rubber sleeve 111 adheres tightly to the casing well wall. When the internal and external pressure difference is balanced, the first rubber sleeve 111 automatically retracts and returns to its original position.

[0082] Its main features include:

[0083] First, it can basically eliminate the pressure difference acting on the top packer, isolate the influence of reservoir pressure on the packer, and ensure the stable sealing performance of the packer.

[0084] Second, the pressure stabilizer is filled with hydraulic transmission oil and sealed by the first pressure transmission piston 113 in the annulus between the first rubber cylinder 111 and the first outer central tube 110. Even if the first rubber cylinder 111 is damaged, the pressure in the first inner central tube 106 will remain stable and will not leak into the oil casing annulus, ensuring the normal operation of the oil production tubing.

[0085] III. The starting pressure of the pressure stabilizer can be adjusted, and the first pressure transmitting piston shear pin 118 and the first locking shear pin 116 can be set according to specific well depth or temperature and pressure parameters.

[0086] IV. It is equipped with a function to force the connection of the oil tubing and casing annulus. In cases where the pressure difference between the oil tubing and casing is too large and the tubing cannot be pulled out, the lifting tonnage can be increased to the set value, the first locking shear pin 116 can be cut, the first inner central tube 106 can be moved upward, the first inner and outer pressure balance hole 121 can be opened, the oil tubing and casing can be forcibly connected, and then the tubing can be pulled out.

[0087] Example 2:

[0088] Based on Example 1, the pressure stabilizer 5 can be applied to stratified injection and production tubing. Taking the wireless track-type stratified oil production tubing as an example, such as... Figure 3As shown, the completion string includes, from top to bottom, a deeper short section 1, a well-washing valve 2, a drop tool 3, at least two stratified injection-production units, and a plug. The stratified injection-production unit includes, in sequence, a packer 4, a resettable layer-changing switch 6, and a sand filter 7. The uppermost packer 4 is a suspended packer, and the other packers 4 are stratified packers.

[0089] A pressure stabilizer 5 is installed between the packer 4 and the resettable layer-changing switch 6 in the uppermost layer injection-production unit. The pressure stabilizer 5 is connected to the packer 4 and the resettable layer-changing switch 6 via a safety connector.

[0090] After the tubing is lowered to the predetermined position and the depth is confirmed to be correct, the tubing is pressurized and the packer 4 is set. The pressure stabilizer 5 is activated simultaneously, and the pressure is transmitted to the hydraulic chamber C of the pressure stabilizer 5, increasing the pressure until the first pressure transmission piston shear pin 118 cuts. The shearing force of the first pressure transmission piston shear pin 118 can be obtained by calculation or batch experiments of shear pins, and can be adjusted by the material and specifications of the shear pins.

[0091] After the first pressure-transmitting piston shear pin 118 cuts, the first pressure-transmitting piston 113 moves upward, compressing the hydraulic transmission oil inside the piston chamber B. Under the action of the hydraulic transmission oil, the middle part of the first rubber cylinder 111 expands and tightly adheres to the inner wall of the sleeve. As the first pressure-transmitting piston 113 moves upward, it releases the internal first locking block 114 and continues to pressurize until it is released.

[0092] Well string retention Figure 4 As shown, the tubing string is detached from the release tool 3, and the part above the fish top 9 is pulled out of the wellbore. The slips of the packer are stuck on the inner wall of the casing, suspending the lower tubing string.

[0093] During layer replacement, pressure is transmitted to the pressure stabilizer 5 through wellhead pressurization. The pressure in the piston chamber B inside the pressure stabilizer 5 increases, causing the first rubber sleeve 111 of the pressure stabilizer 5 to bulge and press against the well wall. Since the pressure stabilizer 5 is connected to the lower part of the suspended packer, the reservoir pressure acts on the lower end of the first rubber sleeve 111 of the pressure stabilizer 5. The first rubber sleeve 111 isolates the reservoir pressure, preventing it from directly contacting the lower end of the suspended packer rubber sleeve. Because the annular space formed by the upper part of the first rubber sleeve 111 and the lower part of the suspended packer rubber sleeve is filled with well fluid, when the well fluid replacement pressure acts on the upper end of the suspended packer, the lower end of the suspended packer rubber sleeve is a closed pressure chamber. The pressure difference between the upper and lower parts of the suspended packer rubber sleeve is basically in a balanced state, thereby isolating the pressure fluctuations between the upper and lower parts of the suspended packer rubber sleeve and protecting the stability of the suspended packer.

[0094] After the layer replacement is completed, when the pressure in the upper reservoir section is balanced with the pressure in the tubing, the pressure stabilizer 5 returns to its original position. If the pressure in the tubing is more than 1 MPa greater than the formation pressure, the pressure stabilizer 5 will continue to start.

[0095] The pressure stabilizer 5 can also protect the layered packer. In this case, the pressure stabilizer 5 needs to be connected to the upper end of the layered packer. When the layer replacement pressure is started, it can maintain the pressure difference balance between the upper and lower layers of the layered packer.

[0096] When the entire tubing string is unable to be pulled out due to a large pressure difference between the inside and outside of the pressure stabilizer 5 caused by a lack of formation pressure, and the string remains tightly attached to the casing wall, the tubing string can be lifted to the predetermined tonnage and the first locking shear pin 116 of the pressure stabilizer 5 can be cut. At this time, the first inner central tube 106 of the pressure stabilizer 5 moves upward, exposing the first internal and external pressure balance hole 121 on the first lower connector 115. After the first internal and external pressure balance hole 121 connects the inner and outer tubing strings, the pressure gradually balances, and the tubing string can be pulled out smoothly.

[0097] It should be noted that the aforementioned depth adjustment sub 1, well washing valve 2, hand release tool 3, packer 4, resettable switch 6, and sand setter 7 are all existing technologies, and their structures are clear to those skilled in the art.

[0098] Example 3:

[0099] Please see Figure 2 In this embodiment, a downhole pressure-resistant stabilizer is provided:

[0100] The rubber sleeve sealing section includes a second outer central tube 205 and a second rubber sleeve 207. The second rubber sleeve 207 is sleeved outside the second outer central tube 205. The upper outer wall of the second rubber sleeve 207 is threadedly connected to a second upper baffle 206, and the lower outer wall of the second rubber sleeve 207 is threadedly connected to a second lower baffle 208. The upper outer wall of the second outer central tube 205 is threadedly connected to a second positioning joint 203. The upper outer wall of the second upper baffle 209 is threadedly connected to a second sliding sleeve 204. The inner wall of the second sliding sleeve 204 is slidably engaged with the outer wall of the second positioning joint 203, so that the second rubber sleeve 207 can drive the second upper baffle 206 to smoothly contract axially and expand radially. The lower ends of the second lower baffle 208 and the second outer central tube 205 are connected to an internal and external pressure differential loading section.

[0101] Specifically, the second rubber cylinder 207 is an integral part of a stainless steel cylinder and an outer rubber, and the middle part can expand and contract.

[0102] Specifically, the second rubber cylinder 207 is sealed with the second upper baffle 206, the second rubber cylinder 207 is sealed with the second lower baffle 208, the second upper baffle 206 is sealed with the second sliding sleeve 204, and the second sliding sleeve 204 is sealed with the second positioning joint 203 by O-rings.

[0103] The internal and external pressure differential loading section includes a second hydraulic cylinder sleeve 209, a second pressure transmitting piston 210, and a second sealing joint 213. The upper inner wall of the second hydraulic cylinder sleeve 209 is threadedly connected to the lower outer wall of the second lower baffle 208. The lower inner wall of the second hydraulic cylinder sleeve 209 is threadedly connected to the outer wall of the second sealing joint 213. The inner wall of the second sealing joint 213 is threadedly connected to the lower outer wall of the second outer central tube 205. The second pressure transmitting piston 210 is disposed in the annular space between the second hydraulic cylinder sleeve 209 and the second outer central tube 205. The second hydraulic cylinder sleeve 209 is connected to the second sealing joint 213 through a second pressure transmitting piston shear pin 212. The second outer central tube 205 is provided with a second external pressure transmitting hole 220, which is located between the second pressure transmitting piston shear pin 212 and the second sealing joint 213.

[0104] Specifically, O-ring seals are provided between the second lower baffle 208 and the second hydraulic cylinder liner 209, between the second hydraulic cylinder liner 209 and the second pressure transmitting piston 210, between the second hydraulic cylinder liner 209 and the second sealing joint 213, and between the second pressure transmitting piston 210 and the second outer central tube 205.

[0105] The forced unlocking section includes a second upper connector 201, a second inner central tube 202, a second spring 214, a second sealing inner cylinder 215, a second connecting sleeve 216, and a second lower connector 218. The second inner central tube 202 passes through the second outer central tube 205. The outer wall of the second inner central tube 202 and the inner wall of the second outer central tube 205 are sealed by an O-ring. The second inner central tube 202 is provided with a second inner pressure transmission hole 221 corresponding to the second outer pressure transmission hole 220. The upper outer wall of the second inner central tube 202 is threadedly connected to the second upper connector 201. The second upper connector 201 can contact the second positioning connector 203 to prevent the second inner central tube 202 from detaching. The lower outer wall of the second inner central tube 202 is threadedly connected to the second sealing inner cylinder 215. The second spring 214 is sleeved between the second inner central tube 202 and the second sealing connector 213 and the second sealing inner cylinder 215.

[0106] The second inner central tube 202 and the second outer central tube 205 are connected by a second locking block 211. The second locking block 211 corresponds to the second pressure transmitting piston 113. The second locking block 211 penetrates the wall of the second outer central tube 205 and is embedded in the outer wall of the second inner central tube 202. When the second pressure transmitting piston 113 moves to make room, the second locking block 211 can be squeezed out, thus releasing the connection between the second inner central tube 202 and the second outer central tube 205.

[0107] The outer wall of the second sealing inner cylinder 215 is provided with a large-diameter connecting section and a small-diameter sealing section. The small-diameter sealing section is connected to the second lower connector 218 through a reverse thread and a second anti-rotation shear pin 217. The large-diameter connecting section is connected to the second connecting sleeve 216 through a thread. The second connecting sleeve 216 is fitted outside the second lower connector 218. A bearing ring is provided on the inner wall of the lower end of the second connecting sleeve 216. A bearing step is provided on the outer wall of the second lower connector 218. The bearing step can sit on the bearing ring. The second lower connector 218 is provided with a second internal and external pressure balance hole 219. An O-ring is provided between the second lower connector 218 and the second sealing inner cylinder 215 to seal the second internal and external pressure balance hole 219. The second connecting sleeve 216 is provided with a sieve hole. When the second lower connector 218 sits in the second connecting sleeve 216, the sieve hole and the second internal and external pressure balance hole 219 introduce the pressure inside the casing into the oil pipe to achieve oil-sleeve pressure balance.

[0108] Specifically, the second spring 214 is used to cause the second inner central tube 202 to squeeze out the second locking block 211 after the second pressure transmitting piston 210 moves upward, thereby releasing the rotation space in the tube column.

[0109] Specifically, the mating surface between the second locking block 211 and the second inner central tube is an arc surface, and the second locking block 211 is a ball pin, which facilitates the extrusion of the second locking block 211.

[0110] Specifically, O-ring seals are provided between the second upper connector 201 and the second inner central tube 202, the second sealing connector 213 and the second inner central tube 202, and the second inner central tube 202 and the second sealing inner cylinder.

[0111] Among them, the second outer center tube 205, the second positioning joint 203, the second upper baffle 206, the second rubber sleeve 207, the second lower baffle 208, the second hydraulic cylinder liner 209, and the upper end face of the second pressure transmitting piston 210 constitute the piston chamber D. The piston chamber D is filled with hydraulic transmission oil. When the second rubber sleeve 207 is damaged or damaged for other reasons, due to the sealing effect of the second pressure transmitting piston 210, the pressure inside and outside the tubing is still isolated, which does not affect the normal function of the oil production tubing. Moreover, the hydraulic transmission oil has the functions of protecting the pressure stabilizer and preventing corrosion.

[0112] The second outer central tube 205, the lower end face of the second pressure transmitting piston 210, the second hydraulic cylinder liner 209, and the second sealing joint 213 constitute the hydraulic chamber E, which transmits the layer-changing pressure to the lower end face of the second pressure transmitting piston 210 through the second outer pressure transmitting hole 220 and the second inner pressure transmitting hole 221.

[0113] The pressure stabilizer is connected to the bottom of the top packer via a thread. When released, it cuts the second pressure transmission piston shear pin 212. Under pressure, the second rubber sleeve 207 adheres tightly to the casing well wall. When the internal and external pressure difference is balanced, the second rubber sleeve 207 automatically retracts and returns to its original position.

[0114] Example 4:

[0115] Based on Example 2, the pressure stabilizer 5 can be applied to stratified injection and production tubing. Taking the wireless track-type stratified oil production tubing as an example, such as... Figure 3 As shown, the completion string includes, from top to bottom, a deeper short section 1, a well-washing valve 2, a drop tool 3, at least two stratified injection-production units, and a plug. The stratified injection-production unit includes, in sequence, a packer 4, a resettable layer-changing switch 6, and a sand filter 7. The uppermost packer 4 is a suspended packer, and the other packers 4 are stratified packers.

[0116] A pressure stabilizer 5 is installed between the packer 4 and the resettable layer-changing switch 6 in the uppermost layer injection-production unit. The pressure stabilizer 5 is connected to the packer 4 and the resettable layer-changing switch 6 via a safety connector.

[0117] After the tubing is lowered to the predetermined position and the depth is correct, the tubing is pressurized to set the packer 4, and the pressure stabilizer 5 is activated simultaneously. The pressure is transmitted through the second external pressure transmission hole 220 and the second internal pressure transmission hole 221 to the hydraulic chamber E of the pressure stabilizer 5, increasing the pressure until the second pressure transmission piston shear pin 212 cuts. The shearing force of the second pressure transmission piston shear pin 212 can be obtained by calculation or batch experiments of shear pins, and can be adjusted by the material and specifications of the shear pins.

[0118] After the second pressure transmitting piston shear pin 212 cuts, the second pressure transmitting piston 210 moves upward, compressing the hydraulic transmission oil inside the piston chamber D. Under the action of the hydraulic transmission oil, the middle part of the second rubber cylinder 207 expands and tightly adheres to the inner wall of the sleeve. As the second pressure transmitting piston 210 moves upward, it releases the internal second locking block 211 and continues to pressurize until it is released. The outer mechanism of the second outer central tube 205 is between the second upper connector 201 and the second sealed inner cylinder 215, and is limited by the second spring 215. The spring force supports its weight.

[0119] Well string retention Figure 4 As shown, the tubing string is detached from the release tool 3, and the part above the fish top 9 is pulled out of the wellbore. The slips of the packer are stuck on the inner wall of the casing, suspending the lower tubing string.

[0120] During layer replacement, pressure is transmitted through the wellhead to the pressure stabilizer 5, increasing the pressure in the piston chamber D inside the pressure stabilizer 5. This causes the second rubber sleeve 207 of the pressure stabilizer 5 to bulge and press against the well wall. Since the pressure stabilizer 5 is connected to the lower part of the suspended packer, the reservoir pressure acts on the lower end of the second rubber sleeve 207. The second rubber sleeve 207 isolates the reservoir pressure, preventing direct contact with the lower end of the suspended packer sleeve. Because the annular space formed by the upper part of the second rubber sleeve 207 and the lower part of the suspended packer sleeve is filled with well fluid, when the wellbore layer replacement pressure acts on the upper end of the suspended packer, the lower end of the suspended packer sleeve is a closed pressure chamber. The pressure difference between the upper and lower parts of the suspended packer sleeve is essentially balanced, thus isolating the pressure fluctuations above and below the suspended packer sleeve and protecting the stability of the suspended packer.

[0121] After the layer replacement is completed, when the pressure of the upper reservoir section and the pressure of the tubing are balanced, the pressure stabilizer 5 returns to its original position. If the pressure of the inner tubing is greater than the formation pressure by more than 1 MPa, the pressure stabilizer 5 will continue to start.

[0122] The pressure stabilizer 5 can also protect the layered packer. In this case, the pressure stabilizer 5 needs to be connected to the upper end of the layered packer. When the layer replacement pressure is started, it can maintain the pressure difference balance between the upper and lower layers of the layered packer.

[0123] When the entire tubing string is unable to be removed due to formation pressure depletion and a large pressure difference between the upper and lower parts of the pressure stabilizer 5, causing it to remain tightly pressed against the casing wall, the tubing string is rotated forward until the second anti-rotation shear pin 217 cuts it off. The tubing string is then rotated forward until the reverse thread of the second sealing inner cylinder 215 disengages from the second lower connector 218. The second lower connector 218 falls into the second connecting sleeve 216, and the second internal and external pressure balance hole 219 of the second lower connector 218 connects with the space inside the tubing string and the sieve hole of the second connecting sleeve 216. The pressure inside and outside the tubing string gradually balances, allowing the tubing string to be removed smoothly, achieving the function of forced connection of the annulus and forced unlocking. In addition, the pressure stabilizer 5 also has the functions of preventing corrosion and scaling, reducing casing damage, and lowering the risk of major overhauls.

[0124] It should be noted that the aforementioned depth adjustment sub 1, well washing valve 2, hand release tool 3, packer 4, resettable switch 6, and sand setter 7 are all existing technologies, and their structures are clear to those skilled in the art.

[0125] All components not discussed in detail in this application, as well as the connection methods of these components, are well-known technologies in this field. They can be directly applied and will not be elaborated further.

[0126] In this invention, the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0127] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0128] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0129] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A downhole pressure containment stabilizer comprising a rubber sleeve seal section, characterized by, It also includes an internal and external pressure differential loading section and a forced unlocking section; The rubber sleeve sealing section includes an outer central tube and a rubber sleeve, the rubber sleeve being sleeved outside the outer central tube, and the outer central tube and the rubber sleeve being connected to the inner and outer pressure difference loading section; The forced unlocking section includes an inner central tube, a forced unlocking mechanism, and a connecting mechanism. The inner central tube is slidably disposed inside the outer central tube. The forced unlocking mechanism is connected to the inner central tube. The connecting mechanism is disposed below the rubber cylinder. The forced unlocking mechanism drives the inner central tube to connect the inside and outside of the pressure-resistant stabilizer through the conduction mechanism.

2. A downhole pressure-resistant stabilizer according to claim 1, characterized in that The forced unlocking mechanism includes a first connecting hydraulic cylinder liner, a first pressure balancing cylinder liner, a first pressure balancing piston, and a first upper connector; The lower inner wall of the first connecting liquid cylinder sleeve is connected to the rubber sleeve sealing section, and the upper outer wall of the first connecting liquid cylinder sleeve is connected to the lower inner wall of the first pressure balance cylinder sleeve. The inner central tube is inserted into the outer central tube, and the inner central tube and the outer central tube are sealed together. The upper end of the inner central tube is connected to the lower end of the first upper connector. The first upper connector is connected to the first pressure-balanced cylinder liner via a disconnectable component; The first pressure balancing piston is disposed in the annulus between the first pressure balancing cylinder sleeve and the inner central tube. The first pressure balancing piston is connected to the inner central tube. A step is provided on the inner wall of the first pressure balancing cylinder sleeve above the first pressure balancing piston. The conducting mechanism is a first lower connector; the lower end of the outer central tube and the lower end of the rubber sleeve are connected to the inner and outer pressure difference loading section, the lower end of the inner and outer pressure difference loading section is provided with a first lower connector, the first lower connector is provided with a first inner and outer pressure balance hole, the lower end of the inner central tube extends to the first lower connector, the inner central tube seals the first inner and outer pressure balance hole, and after the inner central tube is unlocked and moved upward, the first inner and outer pressure balance hole is opened.

3. A downhole pressure-resistant stabilizer according to claim 2, characterized in that The first detachable component includes a first locking shear pin, the first upper connector is connected to the first key sleeve through the first locking shear pin, and the lower inner wall of the first key sleeve is connected to the upper outer wall of the first pressure balance cylinder sleeve.

4. A downhole pressure-resistant stabilizer according to claim 2, characterized in that The upper outer wall of the rubber tube is connected to the first upper baffle, and the lower outer wall of the rubber tube is connected to the first lower baffle. The outer wall of the upper end of the outer central tube is connected to the first connecting inner sleeve, the outer wall of the upper end of the first upper baffle is connected to the first sliding sleeve, the inner wall of the first sliding sleeve is slidably engaged with the outer wall of the first connecting inner sleeve, and the upper end of the first connecting inner sleeve is connected to the lower end of the first connecting hydraulic cylinder sleeve.

5. A downhole pressure-resistant stabilizer according to claim 4, characterized in that The internal and external pressure differential loading section includes a first hydraulic cylinder liner, a first lower connector, and a first pressure transmitting piston; The upper end of the first hydraulic cylinder sleeve is connected to the lower end of the first lower baffle, the outer wall of the upper end of the first lower connector is connected to the inner wall of the lower end of the first hydraulic cylinder sleeve, and the inner wall of the upper end of the first lower connector is connected to the outer wall of the lower end of the outer center tube. A first pressure-transmitting piston is provided in the annular space between the first hydraulic cylinder liner and the outer central tube. The first pressure-transmitting piston is connected to the outer central tube through a first pressure-transmitting piston shear pin. The outer central tube is provided with a first external pressure transmission hole between the first pressure transmission piston and the first lower connector, and the inner central tube is provided with a first internal pressure transmission hole corresponding to the first external pressure transmission hole.

6. A downhole pressure-resistant stabilizer according to claim 5, characterized in that The inner central tube and the outer central tube are connected by a first locking block, which corresponds to the first pressure transmitting piston. The first locking block penetrates the wall of the outer central tube and is embedded in the outer wall of the inner central tube.

7. A downhole pressure stabilizer according to claim 1, characterized in that, The forced unlocking mechanism includes a second upper connector, a second spring, a second sealing inner cylinder, a second connecting sleeve, and a second lower connector; The inner central tube passes through the outer central tube, the outer wall of the inner central tube is sealed to the inner wall of the outer central tube, the upper outer wall of the inner central tube is connected to the second upper connector, and the lower end of the inner central tube is connected to the second sealing inner cylinder. The outer wall of the second sealing inner cylinder is provided with a large-diameter connecting section and a small-diameter sealing section. The small-diameter sealing section is connected to the second lower connector through a reverse thread and a second anti-rotation shear pin. The large-diameter connecting section is connected to the second connecting sleeve. The second connecting sleeve is fitted outside the second lower connector. A load-bearing ring is provided on the inner wall of the lower end of the second connecting sleeve, and a load-bearing step is provided on the outer wall of the second lower connector. The load-bearing step can sit on the load-bearing ring. The conducting mechanism is a second internal and external pressure balance hole. The second lower connector is provided with the second internal and external pressure balance hole. The second sealing inner cylinder seals the second internal and external pressure balance hole. The second connecting sleeve is provided with a sieve hole. When the second lower connector is seated in the second connecting sleeve, the second internal and external pressure balance hole is connected.

8. A downhole pressure stabilizer according to claim 7, characterized in that, The upper outer wall of the rubber tube is connected to the second upper baffle, the lower outer wall of the rubber tube is connected to the second lower baffle, the upper outer wall of the outer center tube is connected to the second positioning connector, and the second upper connector can contact the second positioning connector. The upper outer wall of the second upper baffle is connected to the second sliding sleeve, and the inner wall of the second sliding sleeve is slidably engaged with the outer wall of the second positioning joint.

9. A downhole pressure stabilizer according to claim 8, characterized in that, The internal and external pressure differential loading section includes a second hydraulic cylinder liner, a second pressure transmitting piston, and a second sealing joint. The upper end of the second hydraulic cylinder sleeve is connected to the lower end of the second lower baffle, the inner wall of the lower end of the second hydraulic cylinder sleeve is connected to the outer wall of the second sealing joint, and the inner wall of the second sealing joint is connected to the outer wall of the lower end of the outer center tube. The second pressure-transmitting piston is disposed in the annulus between the second hydraulic cylinder sleeve and the outer central tube, and the second hydraulic cylinder sleeve is connected to the second sealing joint through the second pressure-transmitting piston shear pin; The outer central tube is provided with a second external pressure transmission hole, which is located between the second pressure transmission piston shear pin and the second sealing joint. The inner central tube is provided with a second internal pressure transmission hole corresponding to the second external pressure transmission hole.

10. A downhole pressure stabilizer according to claim 9, characterized in that, A second spring is fitted between the second sealing joint and the second sealing inner cylinder in the inner central tube.

11. A downhole pressure stabilizer according to claim 9, characterized in that, The inner central tube and the outer central tube are connected by a second locking block, which corresponds to the second pressure transmitting piston. The second locking block penetrates the wall of the outer central tube and is embedded in the outer wall of the inner central tube.

12. A method for lifting and unsealing a downhole pressure stabilizer, characterized in that, Using the downhole pressure stabilizer according to claim 2 includes the following steps: A pressure stabilizer is installed below the suspended packer or above the stratified packer, and connected to the stratified injection and production tubing string and lowered into the well. Under the action of the internal and external pressure difference loading section, the rubber sleeve expands and tightly adheres to the inner wall of the casing when the pressure inside the tubing is greater than the external pressure, and retracts when the pressure inside the tubing is greater than the external pressure. When the entire tubing string is unable to be pulled out due to formation pressure deficiency and large pressure difference between the inside and outside of the pressure stabilizer, the rubber sleeve remains tightly attached to the casing wall. In this case, the tubing string is lifted up, the first disconnectable part is cut off, the inner central tube moves up, and the first internal and external pressure balance hole on the first lower connector is exposed. After the first internal and external pressure balance hole connects the inner and outer tubing strings, the pressure gradually balances, and the tubing string can be pulled out smoothly.

13. A method for rotating and unsealing a downhole pressure stabilizer, characterized in that, Using the downhole pressure stabilizer according to claim 7 includes the following steps: A pressure stabilizer is installed below the suspended packer or above the stratified packer, and connected to the stratified injection and production tubing string and lowered into the well. Under the action of the internal and external pressure difference loading section, the rubber sleeve expands and tightly adheres to the inner wall of the casing when the pressure inside the tubing is greater than the external pressure, and retracts when the pressure inside the tubing is greater than the external pressure. When the entire tubing string is unable to be pulled out due to formation pressure deficiency and large pressure difference between the inside and outside of the pressure stabilizer, and the rubber sleeve remains tightly attached to the casing wall, rotate the tubing string forward until the second anti-rotation shear pin is cut off. Continue rotating the tubing string forward until the reverse thread of the second sealing inner cylinder and the second lower connector disengages, and the second lower connector falls into the second connecting sleeve. The second internal and external pressure balance hole of the second lower connector connects with the internal space and screen hole of the tubing string, and the pressure of the internal and external tubing strings gradually balances, allowing the tubing string to be pulled out smoothly.

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