| 摘要 |
Disclosed is a composition comprising a water swellable clay, and particularly a sodium montmorillonite clay such as bentonite, sodium carbonate, and a water-soluble biopolymer, and particularly a xanthan biopolymer. The composition when mixed with fresh water forms an aqueous drilling mud having the desirable fluid properties including a high gel strength profile of 10-second/10-minute/30-minute gel and a low API fluid loss for use in trenchless directional drilling including mini-horizontal directional drilling, guided boring, auger boring, pipe jacking, microtunneling, and river crossing. The composition mixed with an aqueous medium provides a water-based drilling mud applicable to trenchless directional drilling in an unconsolidated formation and particularly in an environment contaminated with salty water such as sea water. The composition contains a mixture of about 91 to 98% by weight of Wyoming bentonite, about 1 to 8% by weight of carbonate salt of alkali metal, and about 0.5 to 4% by weight of a selective xanthan biopolymer. |
