Construction method of double-shaft horizontal docking salt cavern storage

Abstract

The invention discloses a double-vertical shaft horizontal butt joint salt cavern deposit construction method. The method comprises the following steps of: (1) respectively constructing two vertical shafts on a salt rock ore layer; (2) constructing a horizontal well between the two vertical shafts; (3) respectively arranging a technical sleeve and an inner pipe in each vertical shaft; and (4) injecting clear water into one vertical shaft, discharging brine water from the other vertical shaft, exchanging the positions for water inflow and brine discharge after a period of time, and circulating in such a way till the shape of a cavity is similar to a horizontal calabash, thereby completing cavity construction. By utilizing the method, the construction speed of the salt rock cavern can be increased, a single-well casing arrangement process can be simplified, and the cavity construction cost can be reduced; and the concentration of the extracted brine water can be ensured on the premise of meeting the shape control of the cavity construction, and the brine water can be directly conveyed to a brine water treatment enterprise.

Description

technical field [0001] The invention relates to a cavity-building method for a salt rock underground storage, in particular to a method for constructing a double-shaft horizontally connected salt cavern storage. Background technique [0002] Salt rock is a kind of soft rock with good physical and mechanical properties. Its low permeability and good self-recovery ability make salt rock an ideal underground energy storage place recognized at home and abroad. Salt rock has soluble chemical properties, so water-soluble cavity-making technology is generally used to build rock salt underground storage instead of traditional mining methods. At present, the salt rock water-solution cavity-making technology adopted at home and abroad is mainly single-well water-solution cavity-building technology. The main feature of this cavity-building method is that the shape of the cavity is controlled by timely adjusting the space position of the casing (technical casing, outer casing, inner ca...

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Problems solved by technology

However, this method also has its own limitations: 1. The single-well water-soluble cavity-making technology uses three-layer casing, which makes the cavity-building process complicated; 2. The single-well cavity-making process is slow due to the slow rate of ore dissolution, and it takes a long time to build salt caverns. Long; 3. When encountering multi-interlayer salt rock formations, the single well cavity construction technology has poor control over the shape and cannot control the interlayer collapse well. The salt rocks that can be built in underground storage in my country are all layered salt rocks. It has the characteristics of thin thickness, many interlayers, low grade, and large burial depth (the burial depth of Yunying rock in Hubei is 1000m). Due to the existence of interlayers, it is difficult to control the shape of the dissolved cavity. In addition, the grade of domestic salt rock is low, and impurities Uneven distribution makes the shape of the cavity expand unevenly during water-soluble cavity formation, and the expected stable cavity shape cannot be achieved

However, the fracturing method to connect two wells requires that the roof and floor of the rock salt mining layer must be strong, and the success rate of its pressure flow is less than 50%, which wastes a lot of resources, and the direction and layer of pressure flow cannot be controlled, which seriously pollutes the formation

[0004] The natural solution method is often used to connect two or more wells through solution mining in the late stage of use. The mining of the ore layer has reached the late stage, and the connection effect of the wells is poor, resulting in a large waste of resources, high cost of well construction, and poor usable value, etc.

[0005] Based on the above analysis, the existing surface water-solution cavity-making methods have the following deficiencies: 1. It is difficult to effectively control the shape of the cavity in a timely manner; 2. In the case of multiple interlayers, the utilization rate of single-well cavity-making space is low; 3. The concentration of brine is low , long cavity time

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