Unstable formation treatment technique for rock salt well construction

Abstract

The invention discloses an unstable formation treatment technique for rock salt well construction, which fulfills unstable rock salt formation drilling and well completion operation by carrying out unstable formation isolation and two times of well cementation on an unstable formation in order to achieve the goal of successfully mining the lower rock salt mineral resource covered by the unstable formation. The unstable formation treatment technique includes the following steps: (1) drilling operation; (2) isolation technique; (3) two times of well cementation operations; (4) acceptance and well completion. The unstable formation treatment technique can systematically and reasonably mine the rock salt resource to increase the resource utilization rate; the unstable formation treatment technique can effectively protect the underground water resource of a rock salt mining area and the environment; and the unstable formation treatment technique lays a foundation for the mining of the deep rock salt in the lower part of a cavity via a completed well running through the cavity, shows a broaden prospect in exploiting the potentials of old mining areas, is highly worth popularizing for application, is significant for the progress of the solution mining technology in China, and can bring remarkable economic and social benefits.

Description

technical field [0001] The invention relates to the technical field of rock-salt well construction, in particular to a technology for treating unstable formations in rock-salt well construction. Background technique [0002] Rock salt is usually exploited by two water-soluble methods of "hydraulic fracturing" and "directional communication". "Hydraulic fracturing" is to use the incompressibility and pressure transmission of water, as well as the solubility of water to salt deposits, to form cracks in the ore layer between the two wells under high pressure, and quickly dissolve, wash and expand the cracks into compressed rocks. Then, inject fresh water from one of the wells to dissolve the ore layer and generate brine, and use the residual pressure of water injection to make the brine return to the ground from the other paired well. "Directional connection method" takes two wells as a production unit, one of which has a medium and small radius horizontal well for directional...

AI Technical Summary

Problems solved by technology

When mining the lower rock salt mine and forming a well, since the dissolution cavity is connected with the wellbore, leakage or loss of the wellbore will inevitably occur, causing the cementing cement slurry to enter the solution cavity of the upper mining layer along the channel of the leakage part, and cannot return to the surface; Or cause the cement slurry to be completely pushed out of the surface, so that the drilling and cementing operations cannot be carried out, resulting in the failure of the normal construction of the salt well, and ultimately resulting in the failure of the lower rock salt deposits to be mined