Two-well horizontal connected well group retreating solution mining/cavity-building method

Abstract

The invention discloses a two-well horizontal connected well group retreating solution mining / cavity-building method. The method comprises the following steps of (1) drilling a straight well and an inclined well to a target stratum separately, and then drilling a horizontal wellbore to connect the straight well and the inclined well; lowering a first central pipe into the straight well, and lowering a second central pipe into the inclined well and the horizontal well; and (2) carrying out solution mining / cavity-building in a sectioned mode. During each mining / cavity-building process, fresh water flows out from the second central pipe, a salt coating layer in the affected area above the second central pipe is fully dissolved, and therefore a created cavity has a large volume, no insoluble area exists, the problem that "a middle part is insoluble" in two-well and the horizontal well solution mining / cavity-building is avoided, and the cavity is basically in the shape of a regular oblate spheroid after the completion of the entire mining / cavity-building process. The retreating cavity-building method utilizes the characteristic of the salt rock water solution that "where is injected, where is dissolved", completes the cavity-building horizontally and sectionally, effectively improves the mining rate of the salt rock, expands the volume of the dissolved cavity, specifies the shape ofthe dissolved cavity and increases the space for later use of the cavity and safety performance of the storage, and the cavity can store more various kinds of media (oil, gas, waste, etc.) safely.

Description

technical field [0001] The invention relates to the technical field of salt caverns, in particular to a water-soluble mining / cavity-making method for two-well horizontally connected well groups. Background technique [0002] In order to solve the increasingly serious energy crisis, it is imperative to establish an energy strategic reserve, and the construction of an underground salt cavern reserve is the most important part of the energy strategic reserve. The salt rock underground storage has a large storage capacity and a fast peak-shaving , security and economic advantages, it is now internationally recognized as the best underground storage place for strategic energy such as natural gas and oil, and has been widely developed. [0003] Among the existing cavity-making technologies, compared with single-well cavity-making, the water-soluble cavity-making of double-well horizontally connected well groups has many advantages such as short cavity-building period and large dis...

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Problems solved by technology

[0004] In view of this, the object of the present invention is to provide a double-well horizontally connected well group retreating water-soluble mining / cavity-making method to solve the problem of "intermediate insolubility" existing in the double-well horizontally connected well group water-soluble mining / cavity-making, At the same time solve the problem of low brine recovery rate in horizontal well group

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