A Sustainable Approach to Drilling in Shale Formations with Fresh Water-Based Mud System

Abstract

Abstract Drilling through shale formations poses significant challenges due to clay reactivity. The issues can lead to several problems, including water influx, well control issues, abnormal pressures, differential sticking, and significant formation losses. This paper presents the development of a new water-based mud that addresses these challenges. Customized water-based muds (WBMs) can inhibit shale hydration and minimize these risks. This study evaluates a novel polymeric additive for improved WBM shale inhibition. The objective is to characterize the novel WBM and demonstrate its ability to reduce shale swelling and deliver stable drilling compared to traditional WBMs. Novel water-based muds (NWBMs) have been developed to address the limitations of conventional water-based drilling fluids in reactive shale formations. This study systematically evaluated the performance of the NWBM system using freshwater through laboratory experiments and field trials. Rheological characterization showed that the NWBM exhibited enhanced viscosity and gel strength compared to traditional systems. The NWBM increased rheological properties and lowered shale swelling by 50% versus reference WBMs. X-ray diffraction (XRD) and cationic exchange capacity (CEC) tests were conducted to characterize the shale mineralogy. Scanning electron microscopy (SEM) provided visual evidence of the dense, low-porosity filter cakes achieved with the NWBM. Successful offshore examples validated the NWBM's ability to maintain wellbore stability and avoid stuck pipe events in problematic formations. Offshore field trials exhibited 50% fewer sticking events, 30-40% faster ROP, and no wellbore instability issues through problematic shales with the use of NWBM. The integrated results highlight the NWBM's technical advantages for improved drilling performance in complex reactive shales.