Use of Managed Pressure Drilling Paved the Way to a Massive Gas Field Discovery in Egypt Western Desert: Case History

Abstract

The BTE – 2 was planned as a land based deep vertical exploration well in Egypt (the deepest ever drilled by Bapetco), designed to evaluate the Abu Roash, Bahariya and Kharita formations, testing the Kharita gas reservoirs and leading into the development of the entire BTE prospect. The complexities included HT classification, formation pressures uncertainties, deep total depth, and introducing a new technology, Managed Pressure Drilling (MPD), to the rig. MPD played a pivotal role in the major discovery of the exploratory "BTE – 2" well, which led to initial estimated in place volumes of 0.8 TCF for the BTE prospect. MPD allowed the operator to reach the reservoir section by successfully navigating the 0.45 ppg operating window in the upper section. MPD also created a wide range of benefits throughout drilling the 1080 meters section, including managing the BHP through the narrow drilling window, real time prognosis of the pore pressure and fracture gradients incorporating the use of Pressure While Drilling technology, efficiently managing drilling through severe conditions, optimizing logging operations and MPD running and cementing of the 7 inches liner. A high Intensity kick was detected by the MPD system in Abu Roash "G" formation. Implementing the MPD assisted shut in method helped minimizing influx size. The kick was initially circulated conventionally and the MPD system was engaged during the second circulation while slightly increasing the Mud Weight. Using the MPD system helped to control the annular pressure profile during multiple rig pump problems and motor stalling events. Due to the small operating window, running the 7 inches liner was a major challenge, even while using the MPD system. Non homogeneous drilling fluid, high loss rates and high PP added complexity to the process. Establishing a closed loop system created a safer and better monitoring and controlling system for the 7 inches liner running operations. Managed Pressure Cementing was the only valid and reliable method to cement the 7 inches liner in place. The MPD system was used to manage the slim drilling window, and the Coriolis flow meter helped to identify the required pressure values to minimize associated losses. Employing the MPD Constant Bottom Hole Pressure (CBHP) technique resulted in numerous learnings, especially when the MPD technique is a first use for the drilling rig crews. This paper highlights and emphasizes the distinguished learnings (not specific to a particular project) that could help in planning and implementation of future MPD wells.