Completion design is a key factor in maximizing well inflow performance and deliverability throughout the life of a well. During the early stages of development of a green oil field located offshore Abu Dhabi, improved subsurface understanding from data gathering led to the modification of the initial completion design. This paper presents a systematic approach utilizing an integrated workflow to successfully optimize multi-zone horizontal well completions to lower development costs, reduce risks and increased field recovery. The final well architecture was implemented in the Early Production Scheme (EPS) and Full Field Development (FFD) phases of the development. The main achievements of the integrated completions design are: ○Increased well productivity and deliverability.○Optimized completion strategy for low efficient gas lift wells.○Reduced risks in well construction and completion phases.○Improved completion flexibility for life-of-well intervention operations.○Optimized slot allocation to increase recovery with more wells.○Utilized full benefits of conductor sharing technology.○Added flexibility to successfully appraise an undeveloped carbonate reservoir and to incorporate it into the development plan.○Adopted new methodology for lower completion design in multilayer reservoirs.○Considered simultaneous dual system injection and production (SIP) wells. The comprehensive approach presented is valuable in establishing a total life-cycle workflow during the early stage of field development, which can be embedded in any completion design strategy. The completion solutions highlight significant benefits from overcoming well-known challenges in offshore environment such as space limitations, slot availability, and cost optimization. The end product is a life-cycle design identified for each specific reservoir with reduced operational constraints and well intervention complexity.

The challenges of high heterogeneous multi-layer reservoirs were a driver for ADNOC to establish new well completion requirements. Based on this, the well completion strategy was revised in order to improve the completion design for a Dual Oil Producer (DOP) initially well planned without accessibility into the upper drain. The solution was successfully implemented by drilling the well having a Multilateral Dual String Level 5 Completion System to have full reservoir isolation and mechanical accessibility to TD in both drains. A major approach was implemented giving the utmost importance to all operational risks concerning drilling and completion. The design relies on the Latch Coupling (LC) pre-installed with the production casing as the foundation for the successful drilling and cementing the upper drain liner and for different completion runs. Thus, a level 5 multi-lateral completion coupled with Inflow Control Devices and Pre-perforated Liner in the upper and lower lateral respectively was successfully deployed. The main advantages of this technology compared to the initial proposal are: Brings effectively two single wells from one slot of the wellhead tower as it provides independent access & control for enhanced reservoir management (well stimulation, production logging and water shut-off). Substantial cost savings due to the utilization of one slot only. Conventional single designs need two slots to deliver equivalent completion requirements. The completion technology meets the Well Integrity Policy & Completion Guidelines stated by ADNOC to have full accessibility to all drains. This is the first Level 5 configuration installed in UAE integrated with a lower completion. The design enhances the benefits of the multilateral construction by providing full mechanical & pressure isolation at the junction throughout the life of the well. Furthermore, accessibility to both laterals from surface without the use of a re-entry deflector or any constraints was deemed to be paramount for a successful well construction.