The Effectiveness of Salt Based Drilling Fluid System to Minimize Wellbore Instability Effect Through Shale Formation

Abstract

Over the years, a considerable number of drilling fluid systems have been developed to suit various and unpredictable sub-surface wellbore conditions on the operations. This kind of problem can lead to non-productive time (NPT), increases the drilling cost, stuck pipe, and others. Several problems of well bore instability caused by the interactions between the shale formations and the drilling fluid itself. The most common clay minerals in the sedimentary rocks are illites followed by montmorillonites, chlorite, and kaolinite. High Performance Water-based Mud (HPWBM) is a new and an advanced system of water-based mud that contains advanced combinations of technologies that are designed to drill through different layers of rock formations. In order to test the effectiveness of the drilling fluid system, high-performance water-based mud with different concentrations of KCl, NaCl, and advanced polymer mixtures were chosen as the most suitable drilling fluid system to encounter the wellbore instability problem due to its ability to encounter some potential problems such as shale swelling, solids packed off, and in order to maintain the water activity by increasing the chloride content within the drilling fluid system. The test will be conducted by Capillary Suction Time (CST), Shale Erosion Test, and Linear Swell Meter (LSM) in laboratory scale. The analysis results will show the appropriate use of drilling mud to deal with wellbore instability problems caused by shale formations.