Acid Stimulation in Agbami Deepwater- The Innovative Success Story

Abstract

Agbami Wells; Agbami A, Agbami B and Agbami C experienced significant production decline. A multi-disciplinary team from the Agbami Asset initiated a study to identify the cause of damage to the wells and the best mitigation strategy. The study confirmed fines migration as the primary cause of sandface impairment and recommended an acid formulation to cure the damage. Risk analysis was undertaken to ascertain the problems associated with flowing the acid back to the production facilities. An innovative deployment method involving a marine support vessel with dynamic positioning and Remote Operating Vehicle (ROV) was adopted. Utilizing the marine support vessel, a customized dual conduit of coil tubing was employed to bullhead acid into the formation. The acid was allowed to soak in the formation for a few hours and well opened to flow back naturally to surface. Other critical aspects of the job planning and implementation included ensuring pump rates were achieved, designing appropriate acid volumes and soak duration, proper planning of Site Integration Test (SIT) and coil tubing deployment strategy. Stimulating Agbami A, Agbami B and Agbami C led to a total incremental gain of 17,500 BOPD with a reduction in skin of over 70%. Productivity Index (PI) increased by over 50% on all the wells. Lessons Learned include: Dual coil string provides redundancy in the event of failure of one of the strings Identifying the cause of damage is critical in recommending acid stimulation for remedial work Adequate front end loading and proper stakeholder engagement was critical to ensure success This technical paper describes the steps involved in implementing a successful rigless acid stimulation operation on deep water wells offshore Nigeria and will be a key resource document for future acid stimulation wellwork.

Development of Acid Nanocapsules with Tailored Breaking Reservoir Temperature for the Removal of Formation Damage by Fines Migration

“…Nowadays, the academy and industry have focused on developing new technologies to improve acid stimulation in sandstone formations to mitigate the critical issues associated with the high reactivity of the acid solutions. − Most studies are focused on acid reformulation with chelating agents, solvents, and dispersants to increase the performance for fines removal . However, these new molecules increase costs, could lead to corrosion issues in the production system, and cause the formation of emulsions. − One innovative alternative is the encapsulation of acid solutions, which shows a huge potential due to the increase in the acid penetration, the control over undesirable reactions, and the reduction of the corrosion issues without lowering the acid efficiency. − …”