Success in Arresting Overall Field Decline and Increasing Oil Production in a Mature Field through Effective Production Enhancement Initiatives

Abstract

Abstract In a mature oil field that has been producing for over 30 years, declining reservoir pressure and increasing water-cut are the two major factors that are affecting oil production rates. It is a common understanding that without any effort, this decline in oil production will remain until the end of the field's economic life. One of the approach to address this issue is through production enhancement work which has been proven successful in an oilfield offshore of Sarawak not only at arresting the overall field decline, but also increasing the overall oil production. The practice for Production Enhancement (PE) work in this field mainly involves (i) shutting off the existing watered-out intervals, (ii) adding perforations to the existing sand and/or a different reservoir, (iii) zone change and gas lift valve change activities, (iv) re-activation of idle wells, (v) gas lift optimisation and well bean-up, (vi) reservoir management planning and (vii) restoring well integrity. Due to the limited deck space on the platform and the unavailability of living quarters, the application of a work barge was essential for this type of PE work to house the necessary equipment and chemical for the enhancement job as well as acting as an accommodation vessel for the personnel. Concurrent well intervention operations on two different platforms was the selected option for time and cost optimisation and quicker first oil. For the same reasons, 24 hours operation was implemented whenever circumstances permitted. Further cost optimisation was implemented in subsequent campaign by utilizing slickline only as means of well intervention as well as withdrawing the option to have a dedicated work barge on site to support the campaign. After the successful PE Campaign in four (4) consecutive years, this initiative has resulted in over 3500 bopd of incremental oil. The overall technical potential (TP) of the field also increased by more than 100 percent. This has effectively arrested the previously estimated 25 percent field decline before the campaigns and increased in the overall field production. This paper seeks to present the challenges, the plans and operational execution of the well intervention activities. The results of the successful PE campaign, implementation of best practices, lessons learnt and improvement plan will also be shared.