Abstract
An offshore Abu Dhabi carbonate oil field was discovered in 1969 and put on production in 1985. The field has two separate culminations producing from a reefal limestone formation deposited in the middle cretaceous. The northern culmination is characterized by good reservoir properties and supported with an active bottom water drive while the southern culmination is characterized by low reservoir properties and hence less support from the aquifer.
Initially the reservoir was developed by vertical and/or deviated oil producers and peripheral water injectors. Soon after production starts, wells water cut gradually increased to reach 50% within 4-5 years with drastic decline in oil production.
Horizontal drilling was implemented with an objective of increasing well exposure to reservoir, reducing drawdown and as such combating water coning/channeling phenomena. Although oil production from horizontal wells was substantially improved, water production trend and production decline, however, did not change in most of the cases.
Application of ESP in southern and northern culminations was initiated to overcome high water cut problem and hence elongates and improves wells production lifting capacity. ESP wells performance shows encouraging results, particularly in the southern culmination.
Managing this offshore reservoir at such high water production is one of the major challenges facing field development engineers. Reservoir heterogeneities, such as fractures and facies distribution, are believed to be main contributors to a water coning/channeling phenomena and to the escalation of water production trends. Therefore, understanding of geological, petrophysical, properties of the formation is the corner stone for , controlling water production problems and hence improving reservoir performance.
This paper provides an overview of the factors that are contributing to the rapid increase in water production and the associated decline in oil production, the vertical wells, horizontal & ESP performance. The paper also assesses new potential ideas for future development aiming towards increasing the sustainable production and recovery.
