CN102798507A - Testing device and testing method for tightness of underground salt cavern gas storage - Google Patents

Abstract

The invention belongs to the field of oil and gas resource development, and in particular relates to a sealing test device and a test method for an underground salt cavern gas storage. The test device includes: a container, a bracket, and a hose. The bottom of the container is provided with a convex interface, and a flow control valve is installed on the convex interface. The container is located on the support tray, and the protruding interface at the bottom of the container passes through the through hole on the tray; a flow control valve is installed on the protruding interface. There is a scale line on the container to measure the change of the liquid level; the protruding interface is connected to the first control valve of the underground salt cavern gas storage through a hose to detect the change of brine pressure in the injection-production string. The stand has three legs, evenly spaced, each with independent telescoping. The implementation method includes the steps of: injecting brine; installing a sealing cover, a control valve, and a pressure gauge; installing a bracket and a container; and performing sealing measurement. The test device of the present invention has simple structure, concise implementation steps and easy on-site operation.

Description

Underground salt cavern gas storage leak test device and test method

technical field

The invention belongs to the field of oil and gas resource development, and in particular relates to an underground salt cavern gas storage sealing test device and implementation steps thereof. the

Background technique

The tightness of salt cavern gas storage is one of the important indicators to measure the safety of salt cavern gas storage. At present, there are mainly API standard method, Geostock method and patent publication number CN100514018A for salt cavern gas storage leak detection methods, and the invention name is: the method in the salt cavern gas storage seal pressure test method, which is found through analysis and field use. The above methods mainly have the following disadvantages:

(1) Disadvantages of the API method: a large amount of gas injection, special interface measuring instruments are required, the evaluation results are inaccurate, and the reliability is poor. the

(2) Disadvantages of the Geostock method: long test time and high cost; high requirements for test instruments and poor field operability. the

(3), the method disclosed in the document with the patent publication number CN100514018A: the operation process is loaded down with trivial details, the cost is high, and the workers' technical level is required to be higher when used on the spot. the

To sum up, the above three methods can be improved and improved in the sealing test method of salt cavern gas storage, so as to better meet the actual production needs. the

Contents of the invention

In order to overcome the defects of the prior art, the purpose of the present invention is to provide a sealing test device and testing method for underground salt cavern gas storage, so as to solve the problems existing in the sealing test of salt cavern gas storage. the

Technical scheme of the present invention is as follows:

A sealing test device for an underground salt cavern gas storage, comprising: a container, a bracket, and a hose, and a protruding interface is provided at the bottom of the container; The first control valve of the cavern gas storage is connected to detect the tightness of the salt cavern and the injection-production string. the

Preferably, the container is located on the support tray, and the protruding interface at the bottom of the container passes through the through hole on the tray; a flow control valve is installed on the protruding interface. the

Preferably, the container is a cylinder made of transparent material, with a height of 2m, an outer diameter of 25cm, an inner diameter of 20cm, and a measurement accuracy of 1cm. the

Preferably, there is an openable top cover on the upper end of the container, and the top cover is provided with vent holes to keep the pressure inside the container the same as the atmospheric pressure. the

Preferably, there is a tray on the bracket, the tray is circular and made of metal, with a diameter of 30cm and a thickness of 1cm, and a through hole with a diameter of 5cm at the center of the tray; there are railings in the height direction of the tray, and the railings are connected to the edge of the tray , the railing height is 50cm. the

Preferably, the bracket has three legs, which are evenly distributed; each leg has independent flexibility, and the length of the leg can be adjusted through the bolts on the leg; the bottom of the bracket leg is tapered, and can be inserted into the ground at a maximum of 20cm. the

Preferably, the minimum height of the support is 0.8m, and the maximum retractable length of the legs of the support is 30cm. the

A method for testing the tightness of an underground salt cavern gas storage, characterized in that it comprises the following steps:

(1) After the cavity construction of the salt cavern gas storage is completed, inject brine into the salt cavern through the injection-production string to the wellhead position; inject brine into the annulus between the injection-production string and the completion string to the wellhead position; Stand for 24 hours;

(2), install the first control valve, the second control valve and the first pressure gauge at the wellhead of the injection-production string, and keep the control valve closed; the first control valve is used to control the connectivity between the container and the salt cavern, The second control valve and the first pressure gauge are used to monitor and control the brine pressure change in the injection-production string and the salt cavern; the third control valve and the second pressure gauge are installed at the annular wellhead of the injection-production string and the completion string Table, used to monitor and control the change of brine pressure in the annular space;

(3) Place the bracket on the ground at the wellhead, and adjust the length of the legs to make the tray level with the ground plane; place the container on the bracket tray so that the protruding interface at the bottom of the container passes through the through hole on the bracket tray, and the pipe fittings will The protruding interface at the bottom of the container is connected with the first control valve; inject brine into the container to the height of 4/5 of the container;

(4) Open the flow control valve and the first control valve to communicate with the container and the salt cavern; monitor the change of the liquid level and record the change data of the liquid level. the

Preferably, the test time is not less than 24 hours, and the liquid level is recorded every 0.5 hours. the

Preferably, the brine is saturated brine; when the pressure gauge shows a large value, the brine can be released through the control valve to ensure the safety of the test device; during the test, the bracket and the container are kept parallel to the ground plane. the

The invention is applicable to multi-interlayer salt cavern gas storage and salt dome type salt cavern gas storage; the test device has simple structure, low cost and high reliability; the specific implementation steps are simple, easy to operate on site, and have low requirements on the technical level of workers. Facilitate on-site promotion and use. the

Description of drawings

Figure 1 is a schematic diagram of an underground salt cavern gas storage leak test device;

Fig. 2 is a schematic diagram of container structure;

Fig. 3 is a schematic diagram of the support structure;

Figure 4 is a schematic diagram of the specific implementation of an underground salt cavern gas storage leak test device;

In the figure: 1. Surface, 2. Cement sheath, 3. Completion string, 4. Annulus, 5. Injection-production string, 6. Packer, 7. Slips, 8. Salt cavern, 90, Top cover, 91, brine, 92, container, 93, bracket, 94, railing, 95, tray, 96, bracket leg, 97, bolt, 98, vent hole, 99, protruding interface, 910, flow control valve, 911, Hose, 101, first control valve, 102, first sealing cap, 103, second pressure gauge, 104, third control valve, 105, first pressure gauge, 106, second control valve, 107, second sealing build. the

Detailed ways

As shown in Fig. 1 to Fig. 4, an underground salt cavern gas storage leak test device includes: a container 92, a bracket 93, a hose 911, and a protruding interface 99 is provided at the bottom of the container. The protruding interface is connected with the first control valve 101 of the salt cavern 8 through a hose, and detects the change of the brine pressure in the injection string 5 . The container is placed on the tray 95 above the support 93, and the protruding interface passes through the round hole in the middle of the tray. the

As shown in Figure 2, a flow control valve 910 is installed on the protruding interface at the bottom of the container to control the flow; a top cover 90 that can be opened and closed is arranged on the top of the container, and a vent 98 is arranged on the top cover to keep the pressure in the container. The atmospheric pressure is the same; the hose is connected to the protruding interface at the bottom of the container; the container is filled with brine 90; the container is a cylinder made of transparent material, the height of the container is 2m, the outer diameter is 25cm, the inner diameter is 20cm, and the measurement accuracy is 1cm . the

As shown in Figure 3, the support has three support legs 96, which are evenly distributed, and bolts 97 are installed on each support leg to independently adjust the length of each support leg; the bottom of the support legs is tapered, and the maximum can be inserted 20cm below the ground surface; The minimum height of the bracket is 0.8m, and the maximum length of the bracket legs that can be retracted is 30cm. A tray 95 is installed on the bracket, the tray is circular and made of metal, with a diameter of 30cm and a thickness of 1cm, and a through hole with a diameter of 5cm at the center of the tray; there is a railing 94 in the height direction of the tray, and the railing is connected to the edge of the tray , the railing height is 50cm. the

As shown in Figure 4, the first sealing cover 102 is installed at the wellhead of the injection-production string 5 to seal the entire injection-production string; the second sealing cover 107 is installed in the annulus between the injection-production string and the completion string 3 At the wellhead position, the entire annulus 4 is sealed. The first control valve 101 is installed on the first sealing cover for controlling the connectivity between the container and the salt cavern; the second control valve 106 and the first pressure gauge 105 are also installed on the first sealing cover for monitoring the injection-production pipe The brine pressure in the column changes; when the brine pressure is high, close the first control valve and open the second control valve to release the brine to ensure the safety of the device. The third control valve 104 and the second pressure gauge 103 are installed on the second sealing cover to monitor the change of the brine pressure in the annulus between the completion string and the injection-production string, and open the third control valve when the brine pressure is high , to release the brine and ensure the safety of the device. the

The completion pipe string goes deep into the salt cavern 8 from the surface 1 and connects with the top of the salt cavern. The completion pipe string has an outer diameter of 244.5mm, a wall thickness of 10.03mm, steel grade N80, and a threaded joint of partial trapezoidal buckle; the completion pipe string The cement slurry made of grade G oil well cement, quartz sand and external additives is cemented together with the formation. The average thickness of the cement sheath 2 is 3cm; the outer diameter of the injection-production string is 177.8mm, the wall thickness is 9.19mm, the steel grade is N80, and the thread The joint is a partial trapezoidal buckle, which is located in the completion string and coincides with the axis of the completion string. At the bottom of the completion string, special packers 6 and slips 7 for salt cavern gas storage are used to connect together. the

The implementation process of the leak test of the underground salt cavern gas storage shown in Fig. 1 to Fig. 4 is as follows:

(1) After the cavity construction of the salt cavern gas storage is completed, inject saturated brine into the salt cavern from the injection-production string until the wellhead position; during the brine injection process, inject in strict accordance with the injection rate designed during the cavity construction process Brine; at the same time, inject brine into the annulus of the completion string and the injection-production string until the position of the wellhead; stand still for 24 hours. the

(2), after the brine injection is completed, install the first sealing cover at the wellhead of the injection-production string to seal the entire injection-production string; the second control valve and the first pressure gauge are installed on the first sealing cover, It is used to monitor and control the brine pressure change in the injection-production string; at the same time, a first control valve is installed on the first sealing cover to control the annular space between the container and the salt cavern, and the first control valve remains closed; A third control valve and a second pressure gauge are installed at the wellhead of the annulus between the injection-production string and the completion string to monitor and control changes in brine pressure in the annulus. the

(3) Place the bracket on the ground at the wellhead, place the container on the tray of the bracket, and pass the protruding interface at the bottom of the container through the round hole in the center of the tray; use a hose made of polyvinyl chloride to connect the bottom of the container The protruding interface is connected to the first control valve, and the connection is firm and reliable, and the flow control valve is closed; the saturated brine is injected into the container to the position of 1.8m on the scale; the leg length of the bracket is adjusted by bolts to keep the tray and container level with ground level. the

(4), open the flow control valve, the first control valve, and communicate with the container and the salt cavern; record the liquid level change position every 30 minutes, and record continuously for 36 hours. the

During the whole test process, the brine pressure in the injection-production string and the annulus was always within the pressure range of the equipment, and the second and third control valves were not opened to release the brine. the

After 36 hours of testing, the height of the liquid level in the container dropped from 1.8m to 0.95m, and the drop height of the liquid level was 0.85m and less than 1m. Therefore, it is considered that the airtightness of the salt cavern gas storage meets the design requirements. the

Claims (10)

1. An underground salt cavern gas storage airtightness testing device, comprising: a container, a bracket, and a flexible pipe, and the bottom of the container is provided with a convex interface; it is characterized in that: the container is provided with a scale line, and the convex interface is connected to The first control valve of the underground salt cavern gas storage is connected to detect the tightness of the salt cavern and the injection-production string. 2. A sealing test device for underground salt cavern gas storage according to claim 1, characterized in that: the container is located on the support tray, the protruding interface at the bottom of the container passes through the through hole on the tray; the protruding interface is installed There is a flow control valve. 3. The leak test device for underground salt cavern gas storage according to claim 1-2, characterized in that: the container is a cylinder made of transparent material with a height of 2m, an outer diameter of 25cm, and an inner diameter of 20cm. The accuracy is 1cm. 4. The leak test device for underground salt cavern gas storage according to claim 1-3, characterized in that: there is an openable top cover on the upper end of the container, and the top cover is provided with vent holes to keep the pressure in the container and Atmospheric pressure is the same. 5. A sealing test device for underground salt cavern gas storage according to claims 1-4, characterized in that: there is a tray on the support, the tray is circular and made of metal, with a diameter of 30 cm and a thickness of 1 cm. There is a through hole with a diameter of 5cm at the center of the tray; there are railings in the height direction of the tray, which are connected to the edge of the tray, and the height of the railing is 50cm. 6. The leak test device for underground salt cavern gas storage according to claims 1-5, characterized in that: the bracket has three legs, which are evenly distributed; The length of the legs can be adjusted; the bottom of the legs of the stand is tapered and can be inserted up to 20cm below the ground. 7. The leak test device for underground salt cavern gas storage according to claims 1-6, characterized in that: the minimum height of the support is 0.8m, and the maximum shrinkable length of the legs of the support is 30cm. 8. A method for testing the tightness of an underground salt cavern gas storage, using the testing device of claims 1-7, characterized in that it comprises the following steps: (1) After the cavity construction of the salt cavern gas storage is completed, inject brine into the salt cavern through the injection-production string to the wellhead position; inject brine into the annulus between the injection-production string and the completion string to the wellhead position; Stand for 24 hours; (2), install the first control valve, the second control valve and the first pressure gauge at the wellhead of the injection-production string, and keep the control valve closed; the first control valve is used to control the connectivity between the container and the salt cavern, The second control valve and the first pressure gauge are used to monitor and control the brine pressure change in the injection-production string and the salt cavern; the third control valve and the second pressure gauge are installed at the annular wellhead of the injection-production string and the completion string gauge, used to monitor and control the change of brine pressure in the annular space; (3) Place the bracket on the ground at the wellhead, and adjust the length of the legs to make the tray level with the ground plane; place the container on the bracket tray so that the protruding interface at the bottom of the container passes through the through hole on the bracket tray, and the pipe fittings will The protruding interface at the bottom of the container is connected to the first control valve; inject brine into the container to the height of 4/5 of the container; (4) Open the flow control valve and the first control valve to communicate with the container and the salt cavern; monitor the change of the liquid level and record the change data of the liquid level. 9. The method for testing the tightness of underground salt cavern gas storage according to claim 8, characterized in that: the test time is not less than 24 hours, and the liquid level is recorded every 0.5 hours. 10. The method for testing the tightness of underground salt cavern gas storage according to claims 8-9, characterized in that: the brine is saturated brine; when the pressure gauge shows large data, the brine can be released through the control valve to ensure the test The safety of the device; during the test, the support and container are kept parallel to the ground plane.

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