Salt mining method using horizontal branch hole butted well group

Abstract

The invention discloses a salt mining method using a horizontal branch hole butted well group. The method comprises the following steps: 1) drilling a first vertical well section to a lower salt bed of a salt mine, drilling a first lower horizontal well section to a preset horizontal branch hole target along the lower salt bed after deviation, and forming a first brine well by the first vertical well section and the first lower horizontal well section; 2) putting a casing into the first brine well for well cementation; 3) drilling a second vertical well section to the lower salt layer a set distance from the wellhead of the first brine well, drilling a second horizontal well section along the lower salt layer to the starting point of a preset horizontal branch hole after deviation, and forming a second brine well by the second vertical well section and the second lower horizontal well section; and other steps. By adopting the horizontal branch hole butted well group, the mining effectof multiple pairs of butted wells is achieved by drilling a pair of drilling holes, thereby lowering the drilling development cost to the greatest extent, and improving the mining efficiency effectively at the same time.

Description

technical field [0001] The invention belongs to the technical field of mining, and in particular relates to a salt mine mining method using horizontal branch holes to connect well groups. Background technique [0002] Drilling and water solution mining is a common method for salt deposit mining. There are two types of single well circulation and well group circulation water solution mining technology. Its common feature is to inject solvent—fresh water from the drilling well, and the fresh water dissolves the salt mine layer to form a salt solution (called brine in the salt mine mining industry). It is called mining brine. Single-well circular brine mining is generally densely arranged due to the limited dissolution range of salt mines. As the depth of salt mining increases, the cost of drilling is getting higher and higher. Moreover, the efficiency of circulating brine extraction in a single well is low, and there are many brine extraction accidents in the well. Therefo...

AI Technical Summary

Problems solved by technology

During the practice of salt mining in horizontal butt joint well groups, some deficiencies were found: 1. If the well spacing is too large, such as over 300 meters, the theoretically controlled ore block is relatively large, but in fact the dissolved cavity produced is only near the water injection well , the amount of ore in the middle of the controlled ore block cannot be effectively extracted, and the solution cavity near the water injection well spans too wide and collapses and the wellbore is damaged.

2. When the ultra-deep salt mine is mined, if the well spacing of the butt joint well group is too large, the horizontal open hole section in the salt layer will be easily closed and blocked due to the increase in ground temperature and the creep characteristics of rock salt.

If the well spacing is shortened, the total salt production of the well group is not high, and the corresponding drilling cost is high

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