Further Insight into Flow Contribution of Commingled Turbidite Reservoirs – A Deepwater Case Study

Abstract

The Ajanla field is a deepwater turbidite field located offshore Nigeria. PLT data acquired across two turbidite "A" and "B" reservoirs in the Ajanla-P well before production commenced in the field demonstrated flow potential of the reservoirs at a proportion of 85% | 15% and 100% | 0% drainage contribution at flowrates of 12,000 bbls/day and 5,000 bbls/day respectively. New infill drilling results and 4D seismic data acquired several years after production commenced have provided significant insight in the sweep pattern in the reservoirs. The 4D seismic data has indicated strongly channelized sweep in reservoir "A" but negligible pressureand saturation changes in reservoir "B". This interpretation was further verified by the results of the in-fill wells which showed low remaining hydrocarbon saturations in "A" but near virgin saturations in "B" after five years of commingled production from both reservoirs through Ajanla-P. This paper investigates the interplay of several factors such as well completions integrity and water injection constraints critical to effective development of turbidite reservoirs and also discusses how the various data sources were integrated to improve understanding of the dynamics between reservoirs "A" and "B" and their possible impact on the future development of the reservoirs.