Method for sinking a borehole with the use of a drilling mud and method for the production of the drilling mud

摘要

A well drilling method employing a well drilling mud formed of a compound comprising sodium montmorillonite and a finely divided mineral or mixture of minerals. A particular preferred compound comprises 77% by weight of sodium montmorillonite and 23% by weight of kaolinitic clay. A well drilling mud formed with the compound of the invention maintains substantially constant rheological characteristics over all operating temperatures encountered in the well drilling operation.