Publications

Reservoir complexity and depleted reservoir pressure are the most challenges issues to applied waterflood project in Widuri field, Asri Basin, Southeast Sumatra. The water flooding project has been established in Widuri Field, Asri Basin since year 2000 and focused on the Miocene Gita member Talang Akar Formation, where 33-6 sand reservoir was deposited. The reservoir distribution trend is simply identified by acoustic impedance. The combination of log and detailed core analysis thorough Widuri B-10 well, which has 100% recovery of 56 ft core length, have contributed to the comprehensive analysis of depositional setting of the reservoir. 33-6 sand interpreted as a product of tidal channel sand in lower part and coarsening up tidal bar in upper portion, characterized by coupled sand coarsening - fining feature in Gamma Ray log. The heterogeneity resulted different flow behavior, either in oil production performance and water flooding application. It is perform the unique reservoir behavior, reservoir compartmentalization and heterogenic reservoir connectivity. Depleted pressure regime in 33-6 sand could be identified using advance seismic methods. In this case, seismic 4-D is used to monitor waterflooding and pressure depletion effect. There are three data set of seismic 4D (1991, 2000, 2004) for waterflood monitoring, the difference of the amplitude could be used to justify the trend of waterflooding. Quantitatively 33-6 sand categorized as AVO class IV, indicated by positive gradient value, due to the calcareous shale overlain at the top sand as mentioned in the core data. In geomodeling aspect, integrated seismic attribute combined with thrived facies analysis used to comprehend the detail reservoir and porosity-permeability relationship. Integrated subsurface work involving all aspects of Geology - Geophysical and Reservoir Engineering were established to understand the reservoir complexity and behavior. This work implemented to enhance the production performance and future reservoir management in 33-6 sand reservoir, Widuri Field.