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.

Agbami Well-BB was completed as a dual zone frac pack intelligent completion. Barely a month after the well was put on production, while carrying out optimization on the well to increase production, flow from the upper zone decreased and further testing indicated that the zone’s production had dropped significantly. From the analysis of the well, it was observed that productivity decrease was as a result of plugging upstream of the interval control valve (ICV). Analysis further showed that the plugging in the well was speculated to be caused by lost circulation material (LCM) pumped during the completion of the well, when significant fluid losses were observed through the frac pack after a fishing operation unsettled the sand control packer. To clean out the well and free the completion of the restriction caused by the LCM, the multi-disciplinary team set up recommended the use of the established method used for acid stimulation in Agbami. This involves the use of a subsea support vessel equipped with dynamic positioning and remote operating vehicle (ROV). Utilizing the subsea support vessel, customized dual conduit system utilizing two coil tubing strings connecting to the gas lift valve on the subsea tree were used to bullhead acid into the well. The well clean out operation increased production from the zone by about 8000 bopd and restored the zone to its initial productivity. Lessons learned include:Understanding the cause of the plugging was important in determining the acid recipeAll initial produced fluid from the flowback was routed to a single tank for isolation to prevent entry of possible contaminated fluid into the FPSO process system. This technical paper describes the troubleshooting on the well, acid selection process, well clean out and acidization procedure/operation, the results, best practices and lessons learned.