Sand Distribution Modeling of Middle Miocene Reservoir of “East Tarakan a Field” in Eastern Part of Tarakan Island, East Kalimantan

Abstract

The discovery well with initial name “East Tarakan A-1” was drilled in February 2007 to a total vertical depth of 10,000 feet and encountered gas reservoir in Middle Miocene-age sands with deltaic sediment facies. The Field is structurally high, faulted to the Mengatal producing zones. This sandstone is hydrocarbon producer in most of onshore fields of Tarakan Island. “East Tarakan A” Field has been suppported with 19 (nineteen) 2D Seismic data. There are three wells i.e: East Tarakan A-1, A2b and A3 with several logs data, mud log and biostratigraphic data. The study aims are firstly to built 3D structural model from time and depth structural maps based on seismic interpretation and well log analysis, secondly to create 3D properties model especially volume shale (V-shale) to get sand distribution. The sand distribution model is supported by 3D structural model, petrophysical analysis and seismic attributes as well as geostatistic method. Based on petrophysical analysis and wells correlation, sand reservoir interval of Middle Miocene (Meliat Fm) can be devided into two zones respectively top to bottom; zone-1 dan zone-2. RMS Amplitude analysis has been used to help constrain the sand distribution. Sand distribution with two zones indicates that sand distribution of zone-1 and zone-2 are generally located in distributary channel delta. NTG Distribution model of zone-1 and zone-2 indicates that reservoir zone distributed in distributary sand with trend of west to east. NTG of zone-1 is relatively better reservoir than the zone-2.