First Multilateral Well in the Most Congested Field in Abu Dhabi, Case of Study

Abstract

This paper will highlight the first level 2 Multi-lateral well in BAB Field with permanent limited entry liner completion in the lower borehole to enhance accessibility and production. The well presents a technical milestone to the company in the development of multiple reservoir by combining two (2) wells from different reservoir and produce from both by using same surface well construction. At initial stage, the economics related to the implementation of the multilateral approach were analysed. Calculation was done by comparing the cost related to the technology application against the cost to prepare one (1) location plus completing a well up to the 7″ liner and mobilizing the rig twice. Then, it was necessary to select the candidate wells to be drilled from the same slot where synergy between Study team and drilling team was in place in order to ensure proper target alignment to make feasible the drilling and completion operations at the same time that the production targets were fulfilled. This project confirmed the feasibility of multilateral well application in a very congested field in terms of wells construction and surface facilities. In order to achieve such goal full synergy must be in place to select proper wells candidates and align targets. Cost reduction is massive considering the elimination of three (3) well phases plus avoidance of one (1) location construction and also the elimination of 1 rig move represents a big impact in terms of economics. Furthermore, the impact in terms of the risk reduction must be considered By combining two (2) wells in one (1) and eliminating three (3) phases in the standard well construction the harmful impact of location preparation, drilling fluids and cuttings on the environment is reduced by 45%, especially with oil base mud system. Geological problems can be observed during drilling each phase of a new well. However, drilling multilateral wells will reduce this occurrence. Well was completed with 7″× 4-1/2″ top packer, 4-1/2″ Slotted tubing and seven (7) swellable packers in lower borehole as well as Dual upper completion with 7″ single retrievable and 9-5/8″ dual retrievable packer and 2-7/8″ and 3-1/2″ tubing combination in both short and long string. This paper presents ADNOC Onshore first and successful experience in the deployment of new acquired technology for the Drilling multi-lateral / dual completion systems in BAB Field. The screening criteria for selecting the system as well as the benefits realized and lessons learned from this experience are also discussed together with the design simulations required to ensure the success of the well construction.