Water-based drilling fluid

The invention discloses a water-based drilling fluid, which comprises the following raw materials in parts by mass: 70-90 parts of seawater; 10-30 parts of a multifunctional base solution; and 0 to 100 parts of barite; wherein the sum of the mass parts of the seawater and the multifunctional base solution is 100 parts. The water-based drilling fluid has the functions of lubricating, plugging and inhibiting, and solves the problems of insufficient lubricity and poor borehole wall stabilizing effect of a conventional water-based drilling fluid system in the application process of a large-displacement well while meeting the environment-friendly requirements of the ocean on the drilling fluid. 本发明公开了一种水基钻井液，包括原料及其质量份数如下：海水70-90份；多功能基液10-30份；以及重晶石0-100份；其中，所述海水和多功能基液的质量份数之和为100份。本发明的水基钻井液，具有润滑、封堵、抑制功能，在满足海洋对于钻井液环保需求的同时，解决常规水基钻井液体系在大位移井应用过程中润滑性不足，井壁稳定效果差的问题。