Case Study: Step Change in Drilling Performance in Large Hole Section by Optimizing Bit, BHA, and Drilling Practices in Middle East

Abstract Drilling optimization in a 22″ section presents a complex challenge due to various influencing factors, including bit and BHA design, drilling parameters, hole cleaning, and formation characteristics. Optimizing these elements can significantly enhance drilling efficiency, lower well construction costs, and reduce environmental impacts. This study targets a vertical section through highly interbedded formations of loose sand, cherts, sticky shale, and hard anhydrite. The drilling process faced dysfunctions, causing multiple trips and a reduced rate of penetration. This paper explores strategies for optimizing each factor to achieve better performance outcomes. The operator and service company collaborated on an optimization study, beginning with a thorough review of well data from the past five years. Surface drilling parameters were plotted using a power curve with Mechanical Specific Energy (MSE) as a key indicator of drilling efficiency. The BHA design was adjusted to minimize twist-off risk, while stabilization points were refined to manage time inside the casing during shale drilling. Bit selection focused on a hybrid mechanism to enable both crushing and shearing. Additionally, hole cleaning and mud displacement practices were adapted to meet specific application challenges. The optimization yielded substantial improvements: the rate of penetration increased by 54%, and the number of trips was reduced from two or three to just one. This paper discusses lessons learned from this optimization process and provides recommendations for future projects, emphasizing the importance of continuous evaluation and adjustment in real-time to address dynamic formation conditions and drilling dysfunctions effectively. This study underscores the significance of iterative enhancements in bit and BHA design, drilling parameters, and field practices to drive step-change improvements in complex drilling applications. The paper details each phase, from planning through execution, and the outcomes associated with each decision point.