硅酸盐钻井液防塌机理研究与应用

Anti-sloughing mechanism and application of silicate drilling fluid

利用Zetasizer3000电位-粒度仪、Turbiscan红外分散稳定仪、Novasina活度仪以及SHM泥页岩水化-力学耦合模拟实验装置等先进的实验仪器和研究手段,对硅酸盐钻井液防塌作用机理进行了深入研究,并开发了一套硅酸盐钻井液配方。研究结果表明,5%硅酸盐水溶液的粒度分布较窄,协同使用的无机盐最佳加量为3%,且受硅酸盐模数和pH值影响较大;硅酸盐胶体溶液zeta电位为-41.0～-31.0 mV时,对泥岩钻屑分散体系具有很强的稳定作用;硅酸盐与泥页岩作用可以形成致密的“隔膜”,具有较理想的阻缓滤液侵入和压力传递作用。现场试验表明,该配方流变性合理、抑制性强,达到了稳定井壁的预期目的。

The anti-sloughing mechanism of silicate drilling fluid was thoroughly explored by using the advanced experimental apparatus and research approach including Zetasizer3000 potential ＆ granularity meter, Turbisean 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 effeeted by the silicate module and pH value. The silicate colloidal solution has strong stability action on the dispersion system of elaystone 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.