Reviving Non Prospect Field: Insight from Modern Delta, Cores, Outcrops, and Statistic to Subsurface Interpretation

Abstract

Tarakan Basin now become one of the top hydrocarbon producer for Pertamina EP – the Indonesia government-owned oil and gas company. Series of prograding deltaic deposit were developed since Late Miocene in this basin. Previously Sembakung field that located on the onshore area of the basin know as no prospect field, and couldn't developed more - until Pertamina EP came and look an opportunity with different point of view. Present shallow marine and delta deposit in Tarakan Basin represent the key to the past of evolution in this basin with various control of sedimentary process. To make a thoroughgoing analogue between the modern delta and the reservoar, a series of field observation was conducted parallel to the outcrop observation. Data gathered by recent sediment cores and salinity reading and well-core, became independent object for facies validation throughout the datas. This data combined with the outcrop to become a comprehensive input for geological model. The subsurface data, including well logs, 3D seismic with great quality showing the field controlled by a simple fourway anticline trending NW-SE. However, based on the production data that statistically distributed on the field, it shows non-linier relation between production and structural configuration, which the good production well located on its flank and vice versa. A high-resolution sequence stratigraphic interpretation at the 5th order then conducted to studying this matter. Based on the this framework, series of HST Deposit showing consistent relationship in production history as the major perforated oil zone with various Qoi rate – which means it doesn't connected each other. Combination of those farthermost data revealing that stratigraphic traps are majoring the reservoir configuration in this field. The development strategies of this field now entered a rejuvenated phase. With the remaining OOIP and reservoir with this deltaic architectural complex, the development are now focusing the out-step early highstand and transgressive system tract (backstepping) facies that having a high promise of virgin geometrically restricted (lensed) reservoir in this marginal field rather than well-connected and sand-rich HST & LST reservoir facies. An unconventional grid-base method with regard to the modern delta and subsurface facies geometry analogue – is wisely chosen as the best method for developing this marginal field.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015