Abstract As a mature field, Block 5 in the North of Sultanate Oman experience significant challenges in maintaining economical oil production rates. Horizontal well utilized in the full field development to enhance reservoir contact and increase well productivity. Despite of successful well drilling, many wells remain under economic performance due to the tightness of the reservoir rocks, and damage from completion and workover operations. Effective stimulation treatments are necessary to boost production rates. However, the treatments in long open-hole horizontal wells are complex and typically required significant capex. This paper aims to evaluate the effectiveness of large volume acidizing treatments and its strategy as a cost-efficient solution to improve production rates in tight reservoir formations. Large volume acidizing (LVA) treatments with foamed diversion adopted by Daleel Petroleum as a strategic approach to stimulate the tight formations with limited well productivity. This method is operationally simpler, requiring neither coiled tubing intervention nor complicated multi-stage completions. Unlike the multistage stimulation treatment with special completion system or coil tubing placement, the LVA able to reduce the cost up to 85% due to its simplicity. The cost different can be utilized to optimize the acid placement across the lateral with different material and technique. The project has evolved significantly since its inception in 2017. With the help of advanced simulation software, the project able to optimize the treatment volume, type of acid and diversion methodology. In the latest advancement, single-phase retarded acid system (SPRA) and multi modal degradable solid material diverter utilized to enhance stimulation efficiency in lateral coverage and penetration. The results have been promising, with most wells showing a significant and long-lasting increase in oil production rates—up to three times the previous levels. Total liquid gross rates have substantially increased, and artificial lifting systems have become more stable. On water injection wells, sustainable injection rates have been observed, surpassing those achieved with conventional acid stimulation treatments in the tight reservoirs of Block 5. The implementation of SPRA in the 2024 Campaign has extended reservoir contact and improved wormholing and acid penetration. Overall, post-stimulation well performance has demonstrated clear economic benefits, with an average 2.5-fold increase in production. This project aimed to develop a cost-efficient stimulation technique for horizontal wells with long tight formation lateral sections, achieved without upgrading wellhead pressure limitations or requiring Coiled Tubing intervention. Advanced treatment simulations using updated carbonate wormholing models have optimized acid dosage for treatments. Continuous evaluation and optimization have improved treatment designs, and lessons learned have been applied to enhance performance. The candidate screening criteria have evolved, with over 20 parameters reviewed through an integrated multi-disciplinary team effort. The experience and knowledge gained can be directly applied by other operators in Oman, offering best practices and serving as case studies for optimizing carbonate stimulation in similar reservoirs.
Mufargi et al. (Mon,) studied this question.