Efficient and Flexible Reservoir Field Management Gas-Lift Optimization Approach to Unlock the Production Potential & Economic Investment of Giant Carbonate Reservoir
Authors: Ismail Ahmed Mohamed , Alnaqbi Jawaher Mohamed , Mustafa Hussein , Su Shi , Alfonzo Adelis 
Published: November 2020

Abstract

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.