Research progress on improving shale stability of water-based drilling fluid by nano-materials
Maintaining wellbore stability has always been a technical challenge in oil and gas well drilling,which is particu-larly prominent in shale formations due to their micro and nano pores and laminae and high-water sensitivity.Improving the performance of drilling fluids is an important way to reduce wellbore instability.Nano-materials can be used as additives in water-based drilling fluids to enhance the stability of shale due to their unique particle size and properties.In this paper,the technical development of using nano-materials to enhance wellbore stability was reviewed,including the evaluation methods for shale stabilization,the types of nano-materials that can be used and their action mechanisms.It is important to conduct basic and theoretical research for nano-materials to be used in heterogeneous shale formation,develop new type of nano-mate-rials that is stable and effective under high temperature,high pressure and high salt conditions,and establish microscopic methods for shale stabilization evaluation.