阅读说明：本技术 井下安全阀的活塞进液口清洗方法及验证方法 (Cleaning method and verification method for liquid inlet of piston of underground safety valve ) 是由 罗运川 于 2018-05-17 设计创作，主要内容包括：本发明公开了一种井下安全阀的活塞进液口清洗方法及验证方法,其中验证方法采用井下安全阀的活塞进液口清洗系统,包括以下步骤：S1：验证井下安全阀的活塞进液口是否为杂质堵塞,采用液压泵通过液控管线对井下安全阀进行整体抽吸,以此给安全阀活塞进液口提供一个负压,促使复位弹簧和扭簧动作。同时,通过观察井口油压变化来判断井下安全阀是否有所动作,若反复抽吸仍无动作则可判断为其他外部原因,若反复抽吸有所动作则可以判断为杂质堵塞,若为杂质堵塞则进行以下步骤；S2：清洗,向活塞进液口处加注化学清洗液,化学清洗液流入至活塞进液口后,将溶解掉的杂质沿相反的方向流动排出液控管线。(The invention discloses a method for cleaning a liquid inlet of a piston of an underground safety valve and a verification method, wherein the verification method adopts a system for cleaning the liquid inlet of the piston of the underground safety valve, and comprises the following steps: s1: whether the liquid inlet of the piston of the underground safety valve is blocked by impurities is verified, the underground safety valve is integrally pumped by the hydraulic pump through the hydraulic control pipeline, so that a negative pressure is provided for the liquid inlet of the piston of the safety valve, and the action of the reset spring and the torsion spring is promoted. Meanwhile, whether the underground safety valve acts or not is judged by observing the change of the oil pressure of the wellhead, if the underground safety valve does not act after repeated pumping, other external reasons can be judged, if the underground safety valve acts after repeated pumping, impurity blockage can be judged, and if the underground safety valve blocks, the following steps are carried out; s2: and cleaning, namely filling chemical cleaning liquid to the liquid inlet of the piston, and discharging dissolved impurities out of the hydraulic control pipeline in a flowing manner along the opposite direction after the chemical cleaning liquid flows into the liquid inlet of the piston.)

1. A method for cleaning a piston liquid inlet of an underground safety valve adopts a piston liquid inlet cleaning system of the underground safety valve, and is characterized by comprising the following steps:

s1: verifying whether a liquid inlet (16) of a piston of the underground safety valve is blocked by impurities or not,

the underground safety valve is integrally pumped by a hydraulic pump through a hydraulic control pipeline (6), whether the underground safety valve can be normally closed or not is observed, if the underground safety valve cannot be normally closed, other external reasons can be judged, if the underground safety valve is normally closed, impurity blockage can be judged, and if the underground safety valve is impurity blockage, the following steps are carried out;

s2: the cleaning is carried out, and the cleaning is carried out,

and chemical cleaning liquid is filled into the liquid inlet (16) of the piston, and after the chemical cleaning liquid flows into the liquid inlet (16) of the piston, dissolved impurities flow in the opposite direction and are discharged out of the hydraulic control pipeline (6).

2. The method for cleaning the liquid inlet of the piston of the downhole safety valve as claimed in claim 1, wherein the method comprises the following steps: in the step S2, chemical cleaning liquid is added into the hydraulic control pipeline (6) through the hydraulic pump, and the chemical cleaning liquid flows to the piston liquid inlet (16) through the hydraulic control pipeline (6) and then is reversely discharged through the cleaning pipeline (7).

3. The method for cleaning the liquid inlet of the piston of the downhole safety valve as claimed in claim 1, wherein the method comprises the following steps: and in the step S2, chemical cleaning liquid is introduced into the cleaning pipeline (7) through the hydraulic pump, flows to the piston liquid inlet (16) through the cleaning pipeline (7) and is reversely discharged through the hydraulic control pipeline (6).

4. The method for cleaning the liquid inlet of the piston of the subsurface safety valve according to claim 1, wherein a step P is further included between the step S1 and the step S2: the mixture is dissolved and then is added with water,

chemical cleaning agent, descaling agent and dissolving agent are injected into the piston liquid inlet (16) through the cleaning pipeline (7) to dissolve impurities.

5. The method for cleaning the liquid inlet of the piston of the subsurface safety valve as claimed in claim 4, wherein a step Q is further included between the P and the S2: the washing is carried out, and the washing is carried out,

chemical cleaning liquid is added into the piston liquid inlet (16) through the cleaning pipeline (7) or the hydraulic control pipeline (6), and the chemical cleaning liquid is repeatedly pumped and pressed to wash impurities at the piston liquid inlet (16).

6. A method for cleaning a piston liquid inlet of a downhole safety valve according to any one of claims 2-5, characterized in that the outer diameter of the cleaning line (7) is smaller than 1/4 of the inner diameter of the pilot operated line (6).

7. A method for verifying abnormal closing of an underground safety valve adopts a piston liquid inlet cleaning system of the underground safety valve, and is characterized by comprising the following steps:

s1: verifying whether a liquid inlet (16) of a piston of the underground safety valve is blocked by impurities or not,

verifying whether a piston liquid inlet (16) of the underground safety valve is blocked by impurities or not, and integrally pumping the underground safety valve through a hydraulic control pipeline (6) by adopting a hydraulic pump so as to provide a negative pressure for the piston liquid inlet (16) of the safety valve and promote a reset spring (5) and a torsion spring (4) to act; meanwhile, whether the underground safety valve acts or not is judged by observing the change of the oil pressure of the wellhead, if the underground safety valve does not act after repeated pumping, other external reasons can be judged, if the underground safety valve acts after repeated pumping, impurity blockage can be judged, and if the underground safety valve blocks, the following steps are carried out;

s2: the cleaning is carried out, and the cleaning is carried out,

and chemical cleaning liquid is filled into the liquid inlet (16) of the piston, and after the chemical cleaning liquid flows into the liquid inlet (16) of the piston, dissolved impurities flow in the opposite direction and are discharged out of the hydraulic control pipeline (6).

Technical Field

The invention relates to the technical field of underground safety valves, in particular to a cleaning method and a verification method for a liquid inlet of a piston of an underground safety valve.

Background

The underground safety valve is an underground tool which is arranged in an oil gas well and can be closed emergently to prevent well blowout and ensure the safe production of the oil gas well when a production facility generates fire alarm, pipeline breakage and irresistible natural disasters (such as earthquake, ice condition, strong typhoon and the like) abnormal conditions. According to the fifteenth file of the large production safety accident potential judgment standard (trial) of chemical and hazardous chemical production and operation units (number three (2017) 121) of safety supervision custody steward: safety accessories such as safety valves, rupture discs and the like are not normally put into use, and are judged to be serious accident potential according to relevant laws and regulations, department regulations and national standards.

At present, most of underground safety valves used in various gas fields at home are Baker, Wilford, Haributton, BJ and other foreign pure imported underground safety valves, and some manufacturers at home also produce the underground safety valves, but due to the difference in manufacturing process, the performance of the underground safety valves is obviously not as reliable as that of the foreign imported underground safety valves. A downhole safety valve must be installed on a gas well, particularly a sulfur-containing gas well, according to the industry standard, and the downhole safety valve has the main functions; first, shutdown is performed under normal conditions (e.g., normal production shutdown, well site equipment overhaul, etc.). And secondly, emergency closing is realized under abnormal conditions such as sudden fire, pipeline breakage or irresistible natural disasters in the production process, so that the safe production of the oil-gas well is ensured. And thirdly, for a high-sulfur-content gas well, the high-sulfur-content gas well is an important component for preventing natural gas leakage and is an important protective barrier for ensuring construction safety and life and property safety.

The underground safety valve is generally installed within a range of 90-110 meters away from a well head, the opening and closing state of a valve clack of the underground safety valve is controlled through a hydraulic pipeline of a well head safety control system, and the control pressure of the hydraulic pipeline is generally 8000-10000 Psi (different manufacturers, the set value of hydraulic control pressure is changed approximately). Although the manufacturers of the underground safety valves are different, the structural principles of the underground safety valves are different. The downhole safety valve is mainly structurally divided into a piston moving part, a power spring part, a self-balancing part and a valve clack opening and closing part. The working principle of the hydraulic control valve is that the opening and closing of the safety valve are controlled by the pressurization and the pressure relief of hydraulic oil. Namely: when a wellhead hydraulic control pipeline is pressurized, hydraulic oil enters the piston cavity to push the piston to move downwards, the spring is compressed, and the valve clack of the underground safety valve is opened. And (3) the ground hydraulic control pressure is discharged, the spring recovers deformation to enable the piston to move upwards, and the valve clack of the underground safety valve resets under the action of the torsion spring to close the safety valve.

In the production field of oil and gas fields, hydraulic pipelines used by the underground safety valve are all 1/4' hydraulic pipelines, and the inner diameter of the hydraulic pipelines is about 2 mm. And only one hydraulic pipeline enters the oil sleeve annulus to control the safety valve switch, and no oil return pipeline is designed. During long-term use, the base oil and additive components in the hydraulic oil are consumed or deteriorated with time due to the influence of gravity, pressure and temperature, namely, the hydraulic oil is aged; in the process of using the hydraulic oil, insoluble substances generated by pipeline abrasion and other reasons can be accumulated, and the phenomenon is also equivalent to generalized aging. The generated aging substances are continuously accumulated to the oil inlet of the safety valve piston under the action of gravity, so that the viscosity of hydraulic oil is changed, and the friction resistance of the hydraulic oil is increased. Some 'ageing substances' can even directly block the oil inlet hole of the piston. Under the condition that other parameters are not changed, the viscosity of hydraulic oil is increased or the oil inlet hole of the piston is blocked, so that the resistance during the action of the piston is increased. When the resistance is larger than or equal to the elastic force of the spring for recovering deformation, even if the hydraulic control pressure is relieved by the wellhead safety control system, the pressure in the piston cannot be correspondingly released, and the spring cannot recover deformation, so that the underground safety valve cannot be normally closed. Therefore, the design of the underground safety valve without an oil return pipeline is a major defect, so that hydraulic oil in the pipeline cannot be cleaned and replaced regularly, the oil way is inevitably blocked for a long time, the piston of the underground safety valve is suppressed, and the spring fails, so that the safety valve is abnormally closed. Such design deficiencies greatly compromise the service life of the downhole safety valve. It can be said that the failure of the downhole safety valve hydraulic system is only a time problem, which depends mainly on the temperature and pressure of the production well, the length of the safety valve switching interval period and the quality of the oil added into the hydraulic control pipeline.

In conclusion, after the safety valve in the prior art is used for a long time, impurities can be retained and accumulated at the liquid inlet of the piston, so that the liquid inlet of the piston is blocked, the oil pressure at the liquid inlet is increased, the piston cannot normally reset under the elastic action of the spring, and the valve clack cannot normally close. The service life of the underground safety valve is greatly shortened.

Disclosure of Invention

The invention aims to provide a method for cleaning a liquid inlet of a piston of an underground safety valve and a verification method, and the method has the advantages that: when the liquid inlet of the piston is blocked, the suction operation can be carried out above the ground to reduce the friction resistance of the hydraulic oil at the liquid inlet of the piston and remove impurities at the oil inlet of the piston, so that the piston can automatically reset under the elastic action of the spring, the safety valve is normally closed, and the underground safety valve does not need to be taken out for replacement or maintenance. The safety valve is simple to operate, economical, practical, controllable in risk, safe and scientific, and can effectively prolong the service life of the safety valve.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a method for cleaning a piston liquid inlet of an underground safety valve adopts the piston liquid inlet cleaning system of the underground safety valve, and comprises the following steps:

s1: verifying whether the liquid inlet of the piston of the underground safety valve is blocked by impurities or not,

the method comprises the following steps of integrally pumping an underground safety valve through a hydraulic control pipeline by adopting a hydraulic pump, observing whether the underground safety valve can be normally closed, judging other external reasons if the underground safety valve cannot be normally closed, judging impurity blockage if the underground safety valve is normally closed, and performing the following steps if the underground safety valve is impurity blockage;

s2: the cleaning is carried out, and the cleaning is carried out,

and injecting chemical cleaning liquid to the liquid inlet of the piston, and discharging dissolved impurities out of the hydraulic control pipeline in the opposite direction after the chemical cleaning liquid flows into the liquid inlet of the piston.

The invention is further configured to: and in the step S2, adding chemical cleaning liquid into the hydraulic control pipeline through the hydraulic pump, wherein the chemical cleaning liquid flows to the liquid inlet of the piston through the hydraulic control pipeline and is reversely discharged through the cleaning pipeline.

The invention is further configured to: and in the step S2, chemical cleaning liquid is introduced into the cleaning pipeline through the hydraulic pump, flows to the liquid inlet of the piston through the cleaning pipeline and is reversely discharged through the hydraulic control pipeline.

The invention is further configured to: further comprising between the S1 and the S2 a step P: the mixture is dissolved and then is added with water,

chemical cleaning agent, descaling agent, dissolving agent and other chemical solvents are injected into the liquid inlet of the piston through the cleaning pipeline to dissolve impurities.

The invention is further configured to: the step Q is also included between the P and the S2: the washing is carried out, and the washing is carried out,

chemical cleaning liquid is added into the liquid inlet of the piston through a cleaning pipeline or a hydraulic control pipeline, and the chemical cleaning liquid is repeatedly pumped and pressed to wash impurities at the liquid inlet of the piston.

The invention is further configured to: the outer diameter of the purge line is less than 1/4 of the inner diameter of the pilot line.

A method for verifying abnormal closing of an underground safety valve adopts a piston liquid inlet cleaning system of the underground safety valve, and comprises the following steps:

s1: verifying whether the liquid inlet of the piston of the underground safety valve is blocked by impurities or not,

whether the liquid inlet of the piston of the underground safety valve is blocked by impurities is verified, the underground safety valve is integrally pumped by the hydraulic pump through the hydraulic control pipeline, so that a negative pressure is provided for the liquid inlet of the piston of the safety valve, and the action of the reset spring and the torsion spring is promoted. Meanwhile, whether the underground safety valve acts or not is judged by observing the change of the oil pressure of the wellhead, if the underground safety valve does not act after repeated pumping, other external reasons can be judged, if the underground safety valve acts after repeated pumping, impurity blockage can be judged, and if the underground safety valve blocks, the following steps are carried out;

s2: the cleaning is carried out, and the cleaning is carried out,

and injecting chemical cleaning liquid to the liquid inlet of the piston, and discharging dissolved impurities out of the hydraulic control pipeline in the opposite direction after the chemical cleaning liquid flows into the liquid inlet of the piston.

The invention has the following advantages:

1. the method for verifying the abnormal closing of the underground safety valve is simple to operate and has intuitive result. And the hydraulic pump is adopted to pump the whole safety valve through a hydraulic control pipeline, so that the underground safety valve is closed. The closing state of the safety valve can be confirmed by observing the oil pressure change of the production well;

2. chemical solvent can be filled above the ground through a cleaning pipeline, so that impurities accumulated at a liquid inlet of the piston are fully dissolved to form a substance with lower viscosity, the substance is convenient to discharge back to the well opening after the cleaning pipeline is washed, the pressure holding condition of the piston in a hydraulic cavity is relieved, and the spring can restore the piston by means of the elastic action of self-restoring deformation;

3. chemical cleaning liquid is filled into the liquid inlet of the piston through a cleaning pipeline or a liquid control pipeline, the chemical cleaning liquid is repeatedly pumped and pressed to wash impurities at the position of the liquid inlet of the piston, part of impurities are scattered, and then chemical solvent is injected into the liquid inlet of the piston, so that the cleaning efficiency and the cleaning quality can be improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.

The structures, ratios, sizes, and the like shown in the present specification are only used for matching with the contents disclosed in the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions that the present invention can be implemented, so that the present invention has no technical significance, and any structural modifications, changes in the ratio relationship, or adjustments of the sizes, without affecting the effects and the achievable by the present invention, should still fall within the range that the technical contents disclosed in the present invention can cover.

FIG. 1 is a schematic structural view showing a closed state of a downhole safety valve in embodiment 1;

FIG. 2 is a schematic structural view showing the open state of the subsurface safety valve in embodiment 1;

FIG. 3 is an enlarged view of a portion of FIG. 2 at A;

FIG. 4 is a schematic diagram showing the steps of a method for cleaning a liquid inlet of a piston in an embodiment 3, wherein the method is implemented as a downhole safety valve.

Wherein: 1. a safety valve body; 11. an upper joint; 12. a lower joint; 13. an upper limiting plate; 14. a lower limiting plate; 15. a hydraulic chamber; 16. a piston liquid inlet;

2. a piston; 21. a baffle ring; 22. a thrust ramp;

3. a valve flap;

4. a torsion spring;

5. a return spring;

6. a hydraulic control line;

7. and cleaning the pipeline.

Detailed Description

The present invention is described in terms of particular embodiments, other advantages and features of the invention will become apparent to those skilled in the art from the following disclosure, and it is to be understood that the described embodiments are merely exemplary of the invention and that it is not intended to limit the invention to the particular embodiments disclosed. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The utility model provides a piston inlet cleaning system of subsurface safety valve, as shown in figure 1, the subsurface safety valve includes safety valve body 1 and piston 2, and 1 both ends of safety valve body are top connection 11 and lower clutch 12 respectively, and top connection 11 is used for being connected with last takeover (not drawn in the figure), and lower clutch 12 is used for being connected with lower takeover (not drawn in the figure), and safety valve body 1 is used for controlling the intercommunication between takeover and the lower takeover and closes.

The piston 2 is in a hollow tubular shape, the inner wall of the safety valve body 1 is rotatably connected with a valve clack 3, the valve clack 3 is fixedly connected with a rotating shaft (not marked in the figure) at a rotating center, a torsion spring 4 is arranged on the rotating shaft, one end of the torsion spring 4 is fixedly connected with the rotating shaft of the valve clack 3, the other end of the torsion spring is fixedly connected with the inner wall of the safety valve, the lower end surface of the piston 2 is positioned above the valve clack 3, and the valve clack 3 is in sealing butt joint with the lower end; the piston 2 slides downwards along the inner wall of the safety valve body 1 and then pushes the valve clack 3 to rotate around the rotating shaft of the valve clack 3, and the lower port of the piston 2 is gradually opened. The outer wall of the piston 2 is fixedly connected with a baffle ring 21, the inner wall of the safety valve body 1 is fixedly connected with an upper limiting plate 13 and a lower limiting plate 14, the baffle ring 21 is located between the upper limiting plate 13 and the lower limiting plate 14, and after the piston 2 slides upwards along the safety valve body 1, the baffle ring 21 can be abutted to the upper limiting plate 13 to limit the piston 2 to continuously slide upwards. A return spring 5 is arranged between the baffle ring 21 and the lower limiting plate 14, two ends of the return spring 5 are respectively abutted against the baffle ring 21 and the lower limiting plate 14, the extension direction of the return spring 5 is the same as the sliding direction of the piston 2, and the return spring 5 is always kept in a compressed state.

A sealed hydraulic cavity 15 formed between the piston 2 and the upper limiting plate 13 is drilled on the wall of the safety valve body 1, a thrust inclined plane 22 is arranged on the outer wall of the piston 2, and the thrust inclined plane 22 is positioned in the hydraulic cavity 15; a piston liquid inlet 16 is formed in the inner wall of the hydraulic cavity 15, a hydraulic control pipeline 6 is fixedly connected to the outer wall of the safety valve body 1, one end of the hydraulic control pipeline 6 is communicated with the hydraulic cavity 15 through the piston liquid inlet 16, and the other end of the hydraulic control pipeline is communicated with the ground and connected with a hydraulic pump (not shown in the figure); the thrust inclined plane 22 inclines towards the square part close to the central axis of the safety valve body 1 along the direction close to the liquid inlet 16 of the piston, and the hydraulic pump charges liquid or pumps liquid into the hydraulic cavity 15 through the hydraulic control pipeline 6 to change the hydraulic pressure in the hydraulic cavity 15; combine fig. 2, promote piston 2 lapse and compression reset spring 5 through thrust inclined plane 22 after the hydraulic pressure increase of hydraulic pressure chamber 15 inside to drive valve clack 3 and open, valve clack 3 opens the in-process and promotes torsional spring 4 gradually and takes place elastic deformation, and hydraulic pressure in the hydraulic pressure chamber 15 reduces the back, and piston 2 slides upwards under reset spring 5's thrust effect and resets, and torsional spring 4 resumes elastic deformation gradually and promotes valve clack 3 rotation and resets and close piston 2 lower port.

As shown in fig. 3, the piston inlet cleaning system comprises a cleaning line 7, the cleaning line 7 is inserted inside the hydraulic control line 6, one end of the cleaning line 7 extends to the piston inlet 16, and the other end of the cleaning line is connected to the ground and connected with a separate hydraulic pump. When more impurities are accumulated in the piston liquid inlet 16 to cause the piston liquid inlet 16 to be blocked or the hydraulic pressure at the piston liquid inlet 16 is increased, liquid can be pumped to the piston liquid inlet 16 through the cleaning pipeline 7, and by combining the figure 2, the hydraulic pressure at the piston liquid inlet 16 can be reduced, so that the hydraulic pressure in the hydraulic cavity 15 is reduced, the piston 2 is convenient to reset, the valve clack 3 is normally closed, chemical cleaning liquid can be filled through the cleaning pipeline 7, and the chemical cleaning liquid flows to the piston liquid inlet 16 along the cleaning pipeline 7 and reversely discharges the impurities from the hydraulic control pipeline 6; chemical cleaning liquid can be introduced into the piston liquid inlet 16 through the hydraulic control pipeline 6, and impurities are reversely discharged from the cleaning pipeline 7 by the chemical cleaning liquid. Subsequent normal use of being convenient for, and need not take out change or maintenance with subsurface safety valve from the underground, convenient operation, and greatly prolonged subsurface safety valve's life.

Example 2

The verification method for judging whether the liquid inlet 16 of the piston of the underground safety valve is blocked by impurities comprises the steps of adopting a hydraulic pump to integrally suck the underground safety valve through a hydraulic control pipeline, observing whether the underground safety valve can be normally closed or not, and judging that the liquid inlet of the piston is blocked by the impurities if the underground safety valve is normally closed; if the power-off is still impossible, the external reason can be judged.

Example 3

A method for cleaning a liquid inlet of a piston of an underground safety valve comprises the following steps:

s1: verifying whether the liquid inlet 16 of the piston of the downhole safety valve is blocked by impurities,

the method comprises the following steps of integrally pumping the underground safety valve through a hydraulic control pipeline 6 by adopting a hydraulic pump, observing whether the underground safety valve can be normally closed, judging other external reasons if the underground safety valve cannot be normally closed, judging impurity blockage if the underground safety valve is normally closed, and performing the following steps if the underground safety valve is impurity blockage;

p: the mixture is dissolved and then is added with water,

chemical cleaning agents, descaling agents, dissolving agents and other chemical solvents are injected into the piston liquid inlet 16 through the cleaning pipeline 7 to dissolve impurities;

q: the washing is carried out, and the washing is carried out,

chemical cleaning liquid is added into the piston liquid inlet 16 through the cleaning pipeline 7 or the hydraulic control pipeline 6, and the chemical cleaning liquid is repeatedly pumped and pressed to wash impurities at the piston liquid inlet 16;

s2: the cleaning is carried out, and the cleaning is carried out,

and (3) filling chemical cleaning liquid into the liquid inlet 16 of the piston, and discharging dissolved impurities out of the hydraulic control pipeline 6 in an opposite direction after the chemical cleaning liquid flows into the liquid inlet 16 of the piston.

At S2, chemical cleaning fluid is introduced into the hydraulic control line 6 through the hydraulic pump, and the chemical cleaning fluid flows to the piston inlet 16 through the hydraulic control line 6 and is then discharged reversely through the cleaning line 7.

In S2, a chemical cleaning solution may be introduced into the cleaning chamber through the hydraulic pump, and the chemical cleaning solution may be discharged through the cleaning line 7 to the piston inlet 16 and then through the hydraulic control line 6.

Example 4

The utility model provides a piston inlet cleaning system of downhole safety valve, the difference with embodiment 1 lies in, downhole safety valve still includes the liquid pipeline that returns, and liquid pipeline one end that returns stretches to piston inlet 16 department, and the other end stretches to above-ground, is connected with the hydraulic pump with the one end that the liquid pipeline that returns is located above-ground, can carry out suction cleaning operation to piston inlet 16 department.

The liquid return pipeline can be integrated inside the hydraulic control pipeline 6, and the channel of the hydraulic control pipeline 6 and the channel of the liquid return pipeline are arranged side by side. The liquid return pipeline can also be independently arranged outside the hydraulic control pipeline 6 and fixedly connected with the outer wall of the underground safety valve.

Example 5

In embodiment 3, the washing is also called flushing, the cleaning pipeline 7 is made of special material, the length of the cleaning pipeline is 120 meters, the outer diameter of the cleaning pipeline is 1/4 smaller than the inner diameter of the hydraulic control pipeline 6, and the cleaning pipeline has the characteristics of soft texture, flexibility, strong tensile resistance, certain pressure bearing capacity, traction capacity of a tip chamfer belt and the like, for example, the cleaning pipeline 7 can also be slowly inserted into the hydraulic control pipeline 6, one end of the cleaning pipeline gradually extends to a piston liquid inlet, and the other end of the cleaning pipeline is connected with a ground adaptive hydraulic pump, so that the cleaning pipeline and the inner diameter of the hydraulic control pipeline 6 form a U-shaped pipe channel for filling and displacement operation.

The chemical cleaning liquid reacts with aged hydraulic oil to reduce the kinematic viscosity of oil dirt and impurities, so that the chemical cleaning liquid can be smoothly returned to the ground.

The hydraulic oil in the hydraulic control pipeline 6 is gradually pumped out through the cleaning pipeline 7 until the aged hydraulic oil is exhausted, and new hydraulic oil is added to displace the inner space of the hydraulic control pipeline 6, so that the underground safety valve is recovered to be normal, and the service life of the underground safety valve is effectively prolonged.

Example 6

A piston liquid inlet verification method or a cleaning method of an underground safety valve comprises the following steps:

s1: verifying whether the liquid inlet 16 of the piston of the downhole safety valve is blocked by impurities,

whether a piston liquid inlet (16) of the underground safety valve is blocked by impurities is verified, the underground safety valve is integrally sucked by a hydraulic pump through a hydraulic control pipeline (6), so that a negative pressure is provided for the safety valve piston liquid inlet (16) to promote the action of a reset spring (5) and a torsion spring (4). Meanwhile, whether the underground safety valve acts or not is judged by observing the change of the oil pressure of the wellhead, if the underground safety valve does not act after repeated pumping, other external reasons can be judged, if the underground safety valve acts after repeated pumping, impurity blockage can be judged, and if the underground safety valve blocks, the following steps are carried out;

p: the mixture is dissolved and then is added with water,

chemical cleaning agents, descaling agents, dissolving agents and other chemical solvents are injected into the piston liquid inlet 16 through the cleaning pipeline 7 to dissolve impurities;

q: the washing is carried out, and the washing is carried out,

chemical cleaning liquid is added into the piston liquid inlet 16 through the cleaning pipeline 7 or the hydraulic control pipeline 6, and the chemical cleaning liquid is repeatedly pumped and pressed to wash impurities at the piston liquid inlet 16;

s2: the cleaning is carried out, and the cleaning is carried out,

and (3) filling chemical cleaning liquid into the liquid inlet 16 of the piston, and discharging dissolved impurities out of the hydraulic control pipeline 6 in an opposite direction after the chemical cleaning liquid flows into the liquid inlet 16 of the piston.

At S2, chemical cleaning fluid is introduced into the hydraulic control line 6 through the hydraulic pump, and the chemical cleaning fluid flows to the piston inlet 16 through the hydraulic control line 6 and is then discharged reversely through the cleaning line 7.

In S2, a chemical cleaning solution may be introduced into the cleaning chamber through the hydraulic pump, and the chemical cleaning solution may be discharged through the cleaning line 7 to the piston inlet 16 and then through the hydraulic control line 6.

Although the invention has been described in detail above with reference to a general description and specific examples, it will be apparent to one skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.