oa New Idea in Original Oil Water Contact (OOWC) Reconstruction for Mature Oil Field - Example from Terbang Field

‘Terbang’ field is located in Central Sumatra Basin and discovered in 1971 with 49 wells in 14 oil reservoirs where 141,407 MMSTB oil has been booked for the OOIP (2007). The RF in still reach 34.36 % (Nov, 2013) & WC from all the wells is 97.6%: an indication of overestimated OOIP where Boi, porosity (Φ) and Sw are not seems to produce the overestimation. The overestimation comes from the net pay volume where the OOWC as the boundary is never addressed carefully. For that, this paper integrates a new methodology to produce a better OOWC assessment by consider the depletion history (1971-recent). A new idea that be purposed here is to utilize data that rarely be used in OOWC interpretation: rock sample oil stain from 2159 side well core samples that integrated with log & swab test and completion data. This integration produce reservoir depletion history that used to reconstruct the original condition and OOWC position before first well drilled. Result: almost all the reservoirs multiple and complex OOWC controlled by compartmentalization and spill point. These never been seen before due to limited of seismic resolution, means this methodology shows a better result than the previous study result.