Publications

This study focuses on identifying and quantifying behind pipe potentials of overlooked hydrocarbon zones that have not been perforated. This study will open up opportunities to recover the production of untapped resources in Sanga sanga area. This paper discusses three work flow that have been conducted, which prove to be effective in identifying any overlooked opportunities: 1) Overlaying of acoustic and neutron logs; 2) Petrophysical re-evaluation; 3) Artificial Neural Network (ANN) based on selected logs. Every work flow has different method. The first technique is overlying acoustic and neutron logs. It is possible to substitute a normal overlaying method of density and neutron logs; this technique shows a good discrepancy between hydrocarbon and non-hydrocarbon. In several cases, this technique resolves a hydrocarbon zone that cannot be captured based on normal density - neutron logs, and also the high gamma of hydrocarbon reservoir zone. The second work flow is re-evaluation of petrophysical parameters. This is done by adding depositional facies as filtering parameters. This study propose new cut off for low to very low quality reservoirs that never been proposed before. In addition, this technique shows a great significant increase of potential resources in Sanga sanga area especially for unlocking the low to very low quality hydrocarbon reservoirs. The third work flow is using ANN method. ANN is used for predicting hydrocarbon or non-hydrocarbon reservoirs by using mathematical algorithm. Selected wireline logs combine with proven flow of hydrocarbon as input parameters and processed with ANN method resulting a great promising of hidden hydrocarbon reservoirs with a high statistic number. All of the three work flow are applicable to open hidden hydrocarbon reservoirs with similar conditions, those are 1) borehole condition should be good; 2) vertically should be divided into several sequences or zones; and 3) clearly flown or not flown hydrocarbon zone as validation. To sum up, all of those method are increasing the net pay potential of hydrocarbon zones, the results of potential net pay is increasing, varies from 10% - 25% compare to the existing net pay petrophysical known hydrocarbon zone. This study illustrates how to determine overlooked hydrocarbon reservoirs in highly mature fields by using a common wireline logs with very low cost, reliable, and effective approach. Also, this study is expected to open other untapped hydrocarbon reservoirs especially in other mature fields and for other mature basins.