Production Optimization of Maximum Reservoir Contact Well by Utilizing Acid Stimulation with Limited Entry Technique

Abstract

In recent years, a major Abu Dhabi offshore operating company has shifted towards utilizing Maximum Reservoir Contact (MRC) wells to improve oil production and long-term oil recovery. The initial MRC pilots demonstrated the importance of designing the well and completion to facilitate intervention and stimulation. Coiled tubing stimulation methods applied in these first wells were able to meet the objective by significantly improving overall oil production and water injection. However, as we move into tighter formations and longer wells the efficacy of coiled tubing is significantly reduced by limited accessibility and restrictions on the rate. The MRC strategy is being implemented in Reservoir II which is the largest reservoir in terms of Oil in-place. Reservoir II is a thick multilayered limestone reservoir characterized by its low permeability. This low permeability becomes more pronounced as one moves from the crest of the field to the periphery of the field. In such tight reservoirs (Reservoir II), conventional techniques may yield lower than expected production results. In an effort to improve production and ultimate recovery, a new stimulation and completion strategy is required that improves contact with the reservoir beyond the wellbore. In this paper we will discuss the design and implementation of a new technique intended to improve the production and recovery from tight reservoirs. This technique combines a fit-for-purpose limited entry type completion with high rate acid stimulation. Pre- and post-production comparisons demonstrate a substantial production increase and uniform contribution along the extended horizontal interval. We will review the design approach, job execution and evaluation of pre- and post-production performance. We highlight key technical challenges and risks encountered during the preparation, design, execution and evaluation stages of this operation and discuss how these were overcome and mitigated for the improvement and optimization of future MRC wells.