Reversing the Production Decline and Maximizing Late-life Value of a Mature Oilfield in Offshore South China – A Brownfield Re-Development Project Success Story

Abstract

A brownfield new horizontal wells re-development project was initiated in mid-2012 to arrest the production decline rate of Panyu oilfield with average field water cut of 91% and to further increase its reserve recovery.The new horizontal wells campaign were targeting at the remaining less than 5m thin oil column with strong bottom water drive and the previously unexploited 2m thin layers reserves. However, the re-development and exploiting these targets present operational challenges with increasing complexity. Not only the horizontal well needs to be optimally placed within complex target zone, the lateral also needs to be placed as close as possible to the reservoir top to keep it away from the unknown current fluid contact.This paper features the best practices implemented to optimize the standoff between horizontal section and oil water contact that is very sensitive to well performance and reserve recovery. This includes precise landing with low incident angle and lateral placement within less than 0.5m window below the reservoir top utilizing the directional electromagnetic and wellbore imaging applications for detail reservoir profiles description and current OWC level identification while drilling.Multiple wells' field cases will be discussed in the paper based on 25 horizontal wells completed during the course of the project. Several key outcomes that have been observed during the execution and upon the completion of the well will be highlighted, including:-Clear identification of the reservoir geo-bodies and their interfaces including the current fluid contact level -Optimum lateral placement in the best position to drain the remaining hydrocarbon -Reversing the production decline trend and exceeding the cumulative incremental oil by 45% over the forecast.Finally, the authors conclude that significant oil reserve can remain in mature fields and be recovered through re-entry horizontal wells drilling program. The implementation of the best practices in operation is the key enabler to effectively place the trajectory in the best place to drain the remaining hydrocarbon that lead to maximizing the late-life value of a mature oilfield.