Creating value in well and reservoir management through proactive surveillance

Abstract

1-Abstract: The paper describes how proactive surveillance adds value in fields that follow a clear well and reservoir management (WRM) strategy. It also shows that WRM plays an important role at all stages of field's life, hence the importance of having sustainable WRM processes. The sustainability of these processes relays on having surveillance plans that are applicable for each scenario and stage of the field's life. This proactive approach to surveillance gives frequent insight to the reservoir condition and proves to be valuable in mitigating unpleasant surprises. The paper also shows that while the principles of WRM e.g. surveillance and reviews remain intact; its resulting activities evolve with time. The evolution of these activities depends on the available technology, outcome of the reviews, field maturity, drive mechanism and oil prices. 2-Introduction: PDO and WRM at a glance. Petroleum Development Oman (PDO) is the major exploration and production company in the Sultanate of Oman, see figure-1. It accounts for about 90% of the country's crude-oil production and nearly all of its natural gas supply. In the late 90's PDO was challenged by its mature fields with faster decline rates, and low production contribution from drilling new wells. The company reacted to this by identifying key business processes that will reverse the production decline trend and focused on them. One of these process was well and reservoir management. Since then well and reservoir management (WRM) became a key business process, that is deeply embedded in the organisation and is practiced on daily basis. This focus on WRM has reduced the overall PDO production decline rates significantly. The paper describes how WRM is practiced in one of PDO's clusters of fields and how it helped increasing production. The cluster is located in the south of Oman and it consists of about 23 small fields. Production comes from a sandstone reservoir, that is found at depths ranging from 900 to 2500m with oil properties varying between 20–50API. The cluster consists of fields that are undergoing waterflood development and fields that are on depletion mode i.e. aquifer support is sufficient to maintain reservoir pressure. Extensive surveillance activities take place to optimise the performance of the waterfloods, artificial lift, locate bypassed oil and swept reservoir units. The value of theses surveillance activities are realised by having routine well and pattern reviews, where integrated data analysis takes place. The petroleum engineering team meets on regular basis to review the performance of the wells and the waterflood patterns. The optimisation activities that result from these reviews are captured in a common database called the opportunity register. The production optimisation activities in the opportunity register are ranked and added to the well intervention sequence. This process of following surveillance activities with structured reviews and planned well intervention sequence was the key in unlocking the full potential of the wells and reservoirs and has add a significant oil volume.