Case Study of Multilaterals Drilling in Under-Balanced Coiled Tubing Drilling (UBCTD) Implementation and Challenges for the First Time in Operator Group of Companies

Abstract

Abstract Under Balanced Coiled Tubing Drilling technologies is well proven technology that has been piloted for the first time in OPERATOR for Gas sour Reservoirs this being the first time in the OPERATOR Group of Companies, (UBCTD) technology has proven to be able to enhance the production rate greatly compare with conventional overbalanced technique. However, the UBCTD technology has a limit on the lateral length due to buckling and lock up of the coiled-tubing string. Multilateral drilling can overcome this limit and allow wells drilled by UBCTD technology have a comparable total lateral length with the conventional ERD wells. Detailed planning was carried out for the technology implementation there were many challenges in the operations, nevertheless, this is the first project of it is kind on the company, the lessons gained from daily challenging operation considered the stepping stone of the technology implementation in Abu Dhabi. This paper shall spotlight on the project challenges and learnings gained from well to another and how it helps to improve the well performance. The technique for multilateral drilling is characterized according to definitions established in 1997 during the Technology Advancement of Multilaterals (TAML) Forum held in Aberdeen. These standards classify junctions as TAML Level 1, 2, 3, 4, 5, or 6 based on mechanical complexity, connectivity, and hydraulic isolation. In UBCTD wells, the most common multilateral technology is with TAML level 1, which is done by open-hole sidetracks with barefoot completion. Plan set to perform the two open hole sidetracks from the main lateral hole to examine the UBCTD multilateral design philosophy for the first time using UBCTD technology and drill a multilateral well with 3 laterals, each of the lateral lengths around 4,000 ft. Comprehensive planning and simulations were done to overcome the challenge of different reservoir pressure, wellbore instability and open-hole sidetrack operations. The sidetrack and multilateral well were proved to be successful with flawless drilling without any NPT and greatly enhanced production of the well. No doubt that coiled tubing under the balanced technology pilot was extremely successful in all aspects, the paper shall describe all challenges and mitigations in addition spotlight on the best practice of planning and drilling a multilateral well in UBCTD during the execution phase and how it is impacted on project wells delivery. Body text 2 paragraphs.