| The chemical industry uses salt or "sodium chloride" as a basic raw material in many of their manufacturing processes. Salt saturated brine is sometimes produced by solution mining the rock salt from inside these underground salt domes. A large diameter borehole is drilled to about 4000 - 5000' deep using standard oil industry drilling methods. A series of pipes or "casings" are cemented into the borehole to provide environmental protection to the surrounding sediments. Next an injection pipe and a production pipe are lowered to the bottom of the borehole. Fresh water is pumped through the injection pipe, the salt is dissolved, and the resulting salt saturated brine is pumped to the surface through the production pipe. A pad oil material, typically " diesel" is pumped into the roof of the salt cavern that is formed in the mining process. This pad oil floats on top of the fresh water and brine and acts to control the mining and protect the cavern roof from mining upwards instead of outwards. Significant geomechanical design work is engineered into these caverns to ensure long term safety and stability. Once the caverns are mined out to their desired size and shape, they can be converted to underground storage wells. |
