Drilling and Evaluation Technologies Extend Operating Limits in Challenging High-Pressure Deepwater Environments

Abstract

With the world's dependence on hydrocarbon-based energy sources driving global demand, new drilling opportunities require technological innovation to increase efficiencies and optimize production. Some newer drilling operations, particularly in the deepwater arena, involve extreme environments such as ultra-high pressures and demand different approaches to ensure flawless execution. This paper presents the variety of challenges, critical success factors, and lessons learned when drilling these ultra-high pressure wells in the Gulf of Mexico's demanding waters. With downhole pressures approaching 30,000 psi and escalating rig costs, the need for dependable rotary steerable systems (RSS) along with advanced formation evaluation technology is needed now more than ever. With well depths surpassing 30,000 ft below the mudline and increasing water depths, ultra-high-pressure requirements present a new and challenging frontier for both operators and service companies. These new environments demand advances to existing technologies' operational limits to endure such pressure extremes, while also accurately positioning the wellbore in the reservoir and obtaining critical geological information as the well is drilled. A recent example in this pressure regime in the deepwater Gulf of Mexico will be reviewed. In cases, pressure limits of the currently available technology are extended while successfully meeting drilling and evaluation goals. Emphasis is placed on the need for operators and service companies alike to focus on thorough pre-job planning while paying close attention to complete system pressure ratings, high-pressure tool inventory management and detailed reviews. As always, communication is one of the critical success factors to ensure success. The drilling and evaluation technologies delivered real-time formation pressure and geological information, along with continuous directional control, allowing operators to make vital decisions while drilling. This real-time decision-making capability reduced the time required to execute casing point selection and subsequent sidetrack plans. Additionally, by following an application-based philosophy to technology selection, critical drilling and evaluation questions were answered in real time, reducing risks for nonproductive time (NPT) in these extreme environments. The case results showcased the ability to set a new performance standard, extend the conventional operating envelope, and deliver answers while drilling. Introduction The deepwater environment and the potential for large hydrocarbon discoveries have driven technology innovation for a substantial period of time. Advances in rig design, downhole tools, data communications and dozens of others have all rested on the challenges associated with pushing and extending limits. Considering only the drilling of a deepwater well, the associated problems are quite substantial. Throw in a variety of additional complications: a large volume of salt, geologic uncertainty, directional work in excess of 25,000 ft TVD, and a final TVD in the area of 33,000 ft, and one has an extensive set of obstacles to overcome (Fig. 1). It is critical to determine how to effectively surmount these problems rather than adopting an attitude of resignation and concluding that "it can't be done." How does one push the limits of technology while managing the known risks, extend the limits of technology and mitigate the "suspected" risks, and build a model for success?