Objectives/Scope Oil production optimization under economical and operational constraints is of paramount importance to most E&P companies. Enhancing production from mature oilfields is often achieved through artificial lift operations. Decline in well performance is observed in most aging giant waterflooded reservoirs in Abu Dhabi. The objective of this paper is to propose an efficient method to improve well performance while optimizing long-term field development plans both for minimum investment and maximum recovery. Methods, Procedures, Process This paper presents a dynamic field management strategy to optimize the gas lift allocation with groups of wells performing under different operational constraints. The gas lift allocation optimization is the cornerstone of the field development plan optimization to increase the recovery from existing wells by applying optimal gas lift injection, to optimize the infill drilling planning to achieve the mandated target, and to minimize the requirements for infill drilling. Despite the large number of gas-lift optimization procedures proposed in the literature, this paper describes a very efficient methodology that is suitable for long-term field developments. In addition to optimization of individual well performance, we propose a new logic for gas lift allocation based upon well potential, history, and performance and the long-term investment planned for the field. This required dynamically to change the logic of allocation mechanism in real-time management manner which proved its efficiency when applied to a giant waterflooded reservoir suffering from water override and high water cut. The method’s logics implemented in terms of fields entities within a simulator field management framework are independent of reservoir model and can be easily scaled and applied to any other reservoir. Results, Observations, Conclusions The implementation of the proposed gas-lift based optimization strategy allowed to achieve the mandated field production by increasing the lifetime of existing wells, while delaying and reducing the number of infill wells. This resulted in a much more economic strategy while minimizing cost and risks of drilling activities. Applying this unique workflow, allow to activate the gas lift optimization function while the field still on plateau, which was not possible before following the default logic in all the simulators. The result showed significant improvement on the field scale in terms of gas lift and facility requirements as well as field production performance. In addition to that, realistic gas lift requirements was observed compared with the conventional methods. Economic analysis is still ongoing, however, huge cost saving is expected and will be presented in the technical paper. Novel/Additive Information In current economic situation, making field development more profitable can be achieved by applying the proposed approach which will help establishing solid foundation to develop fields at scale. This is due to the flexibility and intelligence of the logics applied in the methodology which combine both constraints from operations and uncertainty in the long run. As described, the method is generic and can be applied to other fields following the same workflow steps.

Objectives/Scope One of the reservoir units producing from a carbonate reservoir in Abu Dhabi field since 1980 is characterized by having relatively good rock quality to the South with deterioration in rock quality towards North. Inverted nine spot gas injection pattern started for this unit since 1992. Despite all the efforts to improve the recovery from this reservoir unit, still the recovery factor after 40 years of production did not exceed 15 %. This is in addition to the inability of the unit to sustain its production target. Methods, Procedures, Process A novel mixed pattern gas and water injection scheme proposed to improve this reservoir unit recovery. First, replace the existing gas injectors by water and add new water injectors in good-quality area to ensure good water injectivity. Second, reduce gas injection or add new gas injectors if needed in the poor-quality area to keep a minimum VRR of one splitting equally between water and gas injection. We developed a novel line drive pattern approach for locating the new water and gas injectors which we call it "Produce Shallow and Inject Water Deep (PSIWD)" for water injectors and "Produce Deep and Inject Gas Shallow (PDIGS)" for gas injectors. All the injectors are horizontal to imitate bottom aquifer for PSIWD in the good-quality area and gas cap for PDIGS in the poor area. Similarly, all the producers are horizontal located at the top of the reservoir in the good-quality area and at the bottom in the poor-quality area to reduce the water and gas early breakthrough. Results, Observations, Conclusions This approach simulated on a full field scale and proved its efficiency in increasing the recovery factor to 40 % and maintaining longer plateau for 18 years. On top of this, it is economically promising by reducing the OPEX for gas injection to 1.2 Billion USD savings that can reach to 2.4 Billion USD savings in the next 30 years with the application of full water injection (PSIWD) in both good and poor-quality areas. Novel/Additive Information Unlike the conventional line drive pattern with injecting and producing within the oil column, our proposed mixed line drive pattern water and gas injection with the application of PSIWD in the good-quality area and PDIGS in the poor-quality area has tendency to reduce the gas and water breakthrough thus ensure better sweep efficiency and higher pressure support. On top of this, the proposed development approach shows 40 % reduction in the cost per barrel compared to the current development approach due mainly to the OPEX reduction for the gas injection and the incremental increase in recovery.