Fifteen Years of Successful Coiled Tubing Re-entry Drilling Projects in the Middle East: Driving Efficiency and Economics in Maturing Gas Fields

Abstract

During the last 15 years, coiled tubing drilling (CTD) projects in the Middle East (ME) have proven an efficient and economic means of increasing and sustaining production for the oil and gas industry. CTD was implemented in 1998 and since then established as a standard, viable solution for the existing re-entry challenges in various maturing fields and applications. During this time frame corresponding technologies and procedures have been developed and continuously improved to address existing and new challenges in this growing market segment. This paper describes the use of CTD from the first activity in Oman through operations in the Kingdom of Saudi Arabia, utilizing project data collected during 15 years of operational experience. The paper includes the technology and procedural changes that addressed new and special challenges observed within the aforementioned projects and drove production from these maturing fields such as: The coverage of low- and high-pressure reservoirs in various fields with high temperature and high H2S challenges.The movement from single re-entry wells to multilateral wellbore designs, alongside the envelope extension from pure directional wellbore placement according to plan, to real-time reservoir navigation by geo- and bio-steering processes.The introduction of special applications such as ERD and precise kick off from vertical wells with coiled tubing (CT) technology.The extension of drilling operations from overbalanced to fully underbalanced (UB) operation, with maximum N2 injection through the CT string and the requirement to deal with production while drilling.Development of other equipment to enable the pressure deployment of the BHA, allowing a move away from conventional tower set-ups to a dedicated highly mobile coil tubing rig. The projects resulted in constant technology improvement and implementation of new developments in all aspects of CTD technology. To achieve the necessary efficiency and economic goals for the re-entry projects, new technology must include downhole bottom hole assembly (BHA) technology, casing exit equipment, surface equipment of the overall rig and other associated equipment such as the underbalanced drilling (UBD) package. Similar to the utilized technology, the corresponding procedures were also optimized and new ones introduced to adapt to changing environments and challenges. Based on the previous and current achievements of CTD in the Middle East, this trend of adjusted developments and continuous improvements will continue to further drive project efficiencies and economics.