Management of Downhole Organic and Inorganic Scale Agglomeration for the Survival of a Marginally Economic Field

Abstract

Abstract This paper presents the organic and inorganic scale depositional issues in Field P, a marginal oilfield located offshore Peninsular Malaysia. Routine well interventions such as running pressure surveys, performing zone-switches and gaslift valve change-outs is not a straight-forward affair in Field P. The field not only experiences severe wax-buildups downhole - as field water production continues to increase, calcium carbonate scale has in recent years been precipitating along the tubing wall of most wells, forming an organic plus inorganic agglomeration which is a rare occurrence and not as easily removed as with a conventional solvent or acid soaking job; thus preventing wireline entry for production surveillance and enhancement activities. Several mechanical, chemical and even combination techniques have been deployed with varied levels of success at Field P, which produces waxy crude from a small and unmanned platform. Facilities constraints (i.e. small deckspace and limited crane lifting capacity), a low oil price environment and high cost for effective wax and scale removal all contribute to the list of challenges in arresting production decline and maintaining a healthy cashflow for an asset which is nearing the end of its economic life. This paper describes the different wax and scale removal and inhibition methods tested in Field P, challenges in implementation, treatment effectiveness, and lessons learnt which can be used as reference for asset teams facing similar issues. The study and recommendation to implement an optimal scale management plan is shared.