Publications

Tunu is a giant field delivering 1100 MMSCFd gas and 23000 bpd of condensate with 80-100 drilled wells per year (already 800 wells drilled) and almost 20 years of production from the Main Zone (between 2500-4500mSS). Shallow Pliocene formations (above 2500 mTVDss) have always been the main gas operational risk during drilling. Many shallow gas reservoirs have been recently identified as a new production horizon. There was limited work dedicated to the understanding of the nature of Tunu Shallow Zone (TSZ) gas accumulations. The first step was construction of a stratigraphic framework dividing the section into six major Genetic units. Each unit show is constituted by deltaic parasequences vertically stacked according to a regressivetransgressive pattern. The lower part of a Genetic unit is dominated by delta front deposits (shale prone and isolated mouth bars). The sand quantity increases upwards in the section dominated by delta plain distributary channels. The most regressive part of the sequence often shows the presence of fluvial channels. The top of genetic unit shows rapid decrease of sand quantity to thick marine shale. Shallow gas trapping system is a combination of not only stratigraphic features but also of geological structures and hydrodynamics. In Tunu, shallow gas accumulations could be characterized by two domains: The western flank region dominated by stratigraphic trapping in local structures (small changes of slope) with vertically stacked reservoirs and sharp lateral boundaries and the eastern crest area which shows more extended reservoirs with higher net pay controlled by the structure. The sequence stratigraphic framework defined is consistent with shallow gas accumulations distribution. * TOTAL E&P INDONESIE Combining the stratigraphic units with the trapping system has helped significantly to ensure and visualize the future development of these accumulations not only in Tunu but also in the neighboring Peciko and Bekapai fields.