Constant Bottomhole Pressure: Managed-Pressure Drilling Technique Applied in an Exploratory Well in Saudi Arabia

Abstract The proposed well is an exploratory well where the formation pressures were estimated based on the experience in drilling offset wells in the area. The 8 3/8" and 5 7/8" hole sections, have a wide range of predicted pore pressure, indicating a considerable span of uncertainty in addition to other related conventional drilling problems as tight hole and gas influx. In previous wells drilled in the area, many drilling problems and wellbore stability issues were experienced. One of the possible cuases of the mechanical instability could be attributed to the large fluctuations in the bottom hole pressure that is intrinsic to conventional drilling practices. These fluctuations are originated from the stopping and starting of drilling fluid circulation during jointed pipe connections, specifically, they result from the fluctuation in the equivalent circulating density (ECD), which occurs when the pumps are turned on and off. This fluctuation could triger a kick-Loss scenario that increases the Non Productive Time (NPT). drilling-related flat time further indicate a necessity for a technology that enables more precise wellbore pressure management. Constant Bottom Hole Pressure (CBHP) which is variation of MPD, is applicable to avoid changes in ECD by applying appropriate levels of surface backpressure, a technique that maintains constant bottom-hole pressure during the complete drilling operation. The primary objective of drilling this well using the Managed Pressured Drilling technology was to reach the target depth with minimum drilling complication, avoid uncontrolled event by maintaining a constant bottom hole pressure and properly managing the well in case an underbalanced condition occurs while drilling the 8 3/8" and 5 7/8" hole sections. As with any advanced drilling technique, successful application of MPD technology required a detailed understanding of the potential benefits as well as limitations. This paper summarizes the process that was used to identify, plan, and implement MPD as a technology to drill the well to the target depth and prevent conventional. Planning and operational results are presented in this paper.