Publications

The Greater Bangkanai area, which consists of the West Bangkanai and Bangkanai PSCs, contains exploration potential and the Kerendan Field, the first gas producer in the Upper Kutai Basin from the Oligocene carbonates of the Upper Berai Formation. The main exploration focus for the area is to understand the full extent of the Kerendan Field and to search for further prospects in this and other plays. However, this work is limited by the poor quality and sparse coverage of existing seismic data. Ophir conducted a total of 8330 line kilometers of airborne Full Tensor Gravity (FTG) and aeromagnetic (MAG) surveys to complement the limited sparse 2D seismic and well data using a relatively low-cost and time-efficient operation in the Bangkanai and surrounding area. This potential-field method offers a unique picture of the subsurface, in which gravity anomalies are related to the rock density property and also rock composition. Spectral analysis of the FTG and MAG data resulted in a Radially Averaged Power Spectrum (RAPS) curve, that allows identification of key wavelength intervals and isolates the signature patterns from the dominant geology of the areaContact Lineament Processing (CLP) compliments documented regional geology and is particularly responsive to lateral variations of rock properties and is reliable to detect steep discontinuities such as fault planes and large structural block boundaries. The main NE-SW structural features bound prominent gravity anomalies. The integration of the Depth Slice and CLP analysis of FTG and MAG survey, leads to a particular finding in which Kerendan Structure sits above a large high-density, non-magnetized body that forms a continuous horst-like amplitude anomaly across the center of Lahei sub-basin gravity low. This level is equivalent with Eocene syn-rift strata and Oligocene carbonates and describes how the development of high-density carbonate lithology is influenced by structural control of the basement high structural grain in a NE-SW trend and bounded by major faults in similar trend.