Anti-sloughing mechanism and application of silicate drilling fluid

The anti-sloughing mechanism of silicate drilling fluid was thoroughly explored by using the advanced experimental apparatus and research approach including Zetasizer3000 potential and granularity meter, Turbiscan infrared dispersion steady indicator, Novasina activity meter and the simulation equipment of hydra-mechanics coupling of shales (SHM). One silicate drilling fluid formula was developed. It is shown that the grain distribution of 5% of silicate in water is relatively narrow, the optimum amount of the cooperation inorganic salt is 3%, and the grain distribution is deeply effected by the silicate module and pH value. The silicate colloidal solution has strong stability action on the dispersion system of claystone bit cuttings when zeta portential ranges from -41.0 mV to -31.0 mV. A compact isolate membrane to block or postpone the invasion of drilling fluid filtration and pressure transmission can be formed by silicate action with shales. The field test demonstrates that the drilling fluid has fitness rheology and strong rejection capability.