Publications

Fractured basement reservoirs play an important role in hydrocarbon production in Indonesia. Accurately predicting water movement in these reservoirs is difficult and can have a profound impact on production if not well understood. In a fractured basement reservoir where spatial heterogeneity of reservoir is significant, uniform rise of water movement is less likely to happen. In the Dayung field, water production from wells located on the crest of the structure produce water earlier than wells on the flank. Attempts have been made to use a full field model to answer this problem but unfortunately were unsuccessful since the fracture distribution, porosity, and permeability systems in this field are hard to predict and model with existing data. Therefore, further qualitative analysis of the water movement is required to design a fit for purpose modeling approach. In order to improve the predictability of water movement in the Dayung Field and water production from the wells, surveillance data such as daily gas production, testing by difference, and static gradient surveys have been acquired. This data helps to better understand the level of water in the near wellbore reservoir. Combining this surveillance data with the static data such as well logs, seismic, and the results of water shut off jobs has improved understanding of the water movement during production. To best describe water movement in a fractured reservoir, utilization of static and dynamic surveillance data is recommended. In the case of Dayung field, it suggests that water movement is a combination of water encroachment and water coning. Mapping and geomechanical analysis suggests that the water leg may have limited volumes, which would support the weak aquifer expansion analysis. It is recommended to make a mechanistic or sector model for more detail study of water coning and prepare production strategy to support reservoir management.