Retrofit Gas Lift Deployment for Oil Production Optimization in OnshoreNiger Delta: A Case Study of EROTON E P Oil Fields

摘要

OML 18, operated by Eroton Exploration and Production Company (EROTON E&P) and located withinthe Coastal Swamp of Eastern Niger Delta contains several producing fields. As a brown asset with over50 years historical production and ageing infrastructure, rapidly declining oil production caused by risingwater cut and depleting reservoir pressure has become a normal feature for most of the reservoirs in theblock. There arises therefore, urgent need to maximize the value of these mature fields by deploying fit forpurpose and cost-effective technologies and methods. Thus, we deployed artificial lift technique using the abundant associated gas resources within the assetas one method of managing the rapid decline in oil production. Gas lift is a robust and inexpensive artificiallift solution which can be deployed at any period in the life-cycle of a well. The natural reservoir energy tomove liquids to the surface through a well at expected rates declines with production time. Changing welland reservoir conditions, such as declining pressure, increasing gas liquid ratios and rising water cut canmake consistent and predictable oil production a challenge. A review of the entire wells portfolio within the asset enabled an identification of all potential candidateswith potential to benefit from gas lift installation. This was followed by feasibility studies to establish aconnection between the magnitude of expected oil resources to be added, the oil rate potential, the existingcompletion status and surface facility equipment availability such as compression, gas lines and scrubbersetc. Screening of identified opportunities, often conducted in multi-disciplinary review sessions, yieldedranked list of opportunities for further maturation through design, execution and operation. Three (3) fieldswith over 60 wells and 38 developed reservoirs were selected for the review. The screening criteria includedbut not limited to reserves to be added, ease of execution, economics and regulatory approval requirements.Since these wells were not originally equipped with gas lift mandrel, alternative means of deploying gaslift equipment downhole had to be designed and implemented. Considering the advanced age of most ofthe wells, due consideration was given to well integrity in the final execution decision. Despite inherentchallenges, EROTON was able to successfully deploy in-house technical knowledge and experience toembark on rigless well intervention campaign to restore production using retrofit gas lift equipment inexisting wells, which have ceased to flow due to vertical lift issues, thus extending the life of the wells. We have successfully performed a safe and commercially viable production restoration exercise, returninga total of twelve (12) wells back to full production potential and achieving the well intervention objectives.The operation has accelerated production adding over 5,000 bopd. This paper will discuss the conceptof brown field life extension through retrofit gas lift, the workflow utilized and results from select fieldexamples. Well BAKU-07 in RAMA field is further discussed as one of the candidates successfully restoredvia this method.