| The drilling fluid used in petroleum and geology exploration was monopolized by anion-type mud system. In this paper, a new kind of mud system, the cation-type mud system developed in 1980's is introduced, which is more effective in solving problems caused by hydration, swelling and dispersion of stratum clay. Sesbania gum is used in this mud system as viscosity enhancer and carrying agent to achieve the goal of making a general mud for both drilling and well completion. |