CN-121993254-A - System and method for injecting gas and discharging brine in salt cavern gas storage

Abstract

The invention provides a gas injection and halogen removal system and method for a salt cavern gas storage. The gas injection and brine discharge system of the salt cavern gas storage comprises a gas injection and production string, a soluble brine discharge string and a switch valve used for injecting balls into the soluble brine discharge string and injecting a dissolving liquid to dissolve the soluble brine discharge string after the gas injection and brine discharge are completed, wherein the gas injection and production string is sleeved on the outer side of the soluble brine discharge string, a gap is reserved between the gas injection and production string and the soluble brine discharge string, and the switch valve is connected with the soluble brine discharge string.

Inventors

• FU PAN
• Guan Yueyang
• DAI KUN
• ZHANG HONG
• DIAO HAOYU
• CHANG ZHI
• XIA YAN
• YUAN GUANGJIE
• BAN FANSHENG
• LIU TIANEN
• WANG XIANGYANG
• ZHUANG XIAOQIAN
• Pang Yuhan
• SONG HENGYU

Assignees

• 中国石油天然气集团有限公司
• 中国石油集团工程技术研究院有限公司

Dates

Publication Date

20260508

Application Date

20241101

Claims (10)

1. 1. The gas injection and brine discharge system of the salt cavern gas storage is characterized by comprising a gas injection and production string, a soluble brine discharge string and a switch valve, wherein the switch valve is used for injecting balls into the soluble brine discharge string after the gas injection and brine discharge are completed and injecting a dissolving liquid to dissolve the soluble brine discharge string, the gas injection and production string is sleeved on the outer side of the soluble brine discharge string, a gap is reserved between the gas injection and production string and the soluble brine discharge string, and the switch valve is connected with the soluble brine discharge string.
2. 2. The salt cavern gas storage gas injection and brine discharge system of claim 1 wherein the dissolvable brine discharge pipe column is a brine discharge aluminum pipe and the dissolution solution is an acid solution.
3. 3. The salt cavern gas storage gas injection and brine discharge system of claim 1 wherein the bottom of the dissolvable brine discharge pipe column is provided with a ball seat for seating a steel ball.
4. 4. The gas injection and brine discharge system of the salt cavern gas storage is characterized in that after gas injection and brine discharge are completed, a steel ball is arranged at the bottom of the soluble brine discharge pipe column, and a dissolving liquid is arranged in the middle of the soluble brine discharge pipe column.
5. 5. The salt cavern gas storage gas injection and brine discharge system according to claim 1, wherein a well completion packer is installed on the outer side of the injection and production string, and the injection and production string is installed on the top of the salt cavity through the well completion packer.
6. 6. The gas injection and brine discharge system of the salt cavern gas storage is characterized in that after gas injection and brine discharge are completed, the interface of the natural gas and the brine is 1-2 meters away from sediment at the bottom of a salt cavity.
7. 7. A salt cavern gas storage gas injection and brine discharge system as in claim 1 wherein the injection and production string is coaxially disposed with the dissolvable brine discharge string.
8. 8. A method for gas injection and brine discharge of a salt cavern gas storage, characterized in that the method for gas injection and brine discharge of the salt cavern gas storage based on the gas injection and brine discharge system of the salt cavern gas storage of any one of the claims 1 to 7 comprises the following steps: S1, after gas injection and halogen discharge are completed, opening a switch valve; S2, throwing balls into a dissolvable halogen discharge pipe column through a switch valve and injecting dissolving liquid; S3, dissolving the soluble brine discharge pipe column through a dissolving liquid to complete the operation of salt cavity gas injection and production.
9. 9. A method for gas injection and halogen removal of a salt cavern gas storage according to claim 8, wherein prior to step S1, comprising: s11, before gas injection and halogen removal, setting a filling and production pipe and a well completion packer through an operation machine; S12, after completion of setting of the well completion packer, a dissolvable halogen discharge pipe column and a ball seat are put in, and a switching valve is installed; s13, injecting natural gas through an injection and production pipe column and an annular space of the dissolvable brine discharge pipe column when injecting gas and discharging brine, wherein the dissolvable brine discharge pipe column can discharge brine in a salt cavity; and S14, when the gas injection and brine discharge are completed, stopping the gas injection and brine discharge after the interface of the natural gas and the brine is 1-2 meters away from the sediment at the bottom of the salt cavity.
10. 10. The method for injecting gas and discharging brine in salt cavern gas storage according to claim 8, wherein in the step S2, steel balls are put into a soluble brine discharge pipe column through a switch valve, acid liquor is injected into the soluble brine discharge pipe column through the switch valve, and in the step S3, after the ball injection and the injection of the dissolution liquor are completed, the method is kept for a preset time until the soluble brine discharge pipe column is dissolved, and then the operation of injecting gas and producing brine in a salt cavity is completed.

Description

System and method for injecting gas and discharging brine in salt cavern gas storage Technical Field The invention relates to the technical field of salt cavern underground storage building, in particular to a salt cavern gas storage gas injection and halogen discharge system and method. Background The salt cavern underground storage is an underground cavern space which is created by utilizing a thicker salt layer or a salt dome in the underground and adopting a manual mode through a water dissolution method, can be used for storing natural gas or other storage media, and is one of main types of storage. The type of reservoir has the advantages of high safety, large capacity, high injection and production speed and low running cost, and has been widely used abroad. The construction of the salt cavern gas storage is divided into three processes of drilling, cavity building and gas injection and brine discharge, wherein gas injection and brine discharge are the first links of gas injection and production after the cavity building of the salt cavern gas storage is completed, natural gas is injected into the annular space of the injection production pipe column and the brine discharge pipe column, brine in the salt cavity is discharged by utilizing the brine discharge pipe, the brine discharge pipe column is lifted out by utilizing the snubbing serving device after the brine discharge is completed, and finally gas injection and production are carried out. The high-pressure natural gas exists in the salt cavern cavity in the whole process, so that a large operation risk exists in the process of lifting the brine discharge pipe column under pressure, and the operation investment is high (taking a certain gas storage as an example, the cost of lifting the pipe column by a single well is about 120-150 ten thousand yuan). Disclosure of Invention The invention aims to solve the technical problem of providing a gas injection and halogen removal system and method for a salt cavern gas storage. The technical scheme includes that the salt cavern gas storage gas injection and brine discharge system comprises a gas injection and production pipe column, a soluble brine discharge pipe column and a switch valve, wherein the switch valve is used for injecting balls into the soluble brine discharge pipe column and injecting dissolving liquid to dissolve the soluble brine discharge pipe column after gas injection and brine discharge are completed, the gas injection and production pipe column is sleeved on the outer side of the soluble brine discharge pipe column, a gap is reserved between the gas injection and production pipe column and the soluble brine discharge pipe column, and the switch valve is connected with the soluble brine discharge pipe column. The technical scheme has the beneficial effects that the existing brine discharge pipe column is replaced by the soluble brine discharge pipe column, the brine discharge pipe column does not need to be started after gas injection brine discharge is completed, the soluble brine discharge pipe column is injected with the dissolving liquid through the wellhead, the soluble brine discharge pipe column can be automatically dissolved, and the injection and production operation of the salt cavity is completed. The method replaces the existing working procedure of lifting the brine discharge pipe column under pressure, greatly reduces the safety risk and the operation cost of gas injection brine discharge, and has the advantages of simple operation, low construction risk and strong practicability. The switching valve connected with the soluble brine discharge pipe column is used for throwing balls and injecting a dissolving liquid. The dissolution liquid is used for reacting with the dissolvable brine discharge pipe column after brine discharge is completed, dissolving the dissolvable brine discharge pipe column, and finally completing the gas injection and production operation of the salt cavity. The gap is arranged, so that the injection of gas storage media such as natural gas or air is facilitated. Further, the dissolvable halogen discharge pipe column is a halogen discharge aluminum pipe, and the dissolution liquid is acid liquid. The technical scheme has the advantages that the existing brine discharge pipe column is replaced by the soluble aluminum pipe, the brine discharge pipe column does not need to be lifted after gas injection brine discharge is completed, acid liquid is injected into the brine discharge pipe column through a wellhead, and the brine discharge pipe column is automatically dissolved, so that the injection and production operation of a salt cavity is completed. The method replaces the existing working procedure of lifting the brine discharge pipe column under pressure, greatly reduces the safety risk and the operation cost of gas injection brine discharge, and has the advantages of simple operation, low construction risk and strong practicability. The brine di