Publications

Rocks cutting samples of the Barakuda well show that the developing reservoir around the area is sandstone. The Barakuda well is an exploration well located in the Tarakan basin. The low-resistivity phenomena that occur in the reservoir interval indicate that the sandstone reservoir on this location is a heterogeneous sandstone. This means all rocks in the interval, including dirty sands, can be constructed by mixing clean sand and shale. This kind of case has a significant effect in petrophysics parameters if evaluated without considering the heterogenity. For example, the porosity and hydrocarbon saturation values would be underestimated if we assume the reservoir rocks are homogenous. Thus, we need to determine the reservoir sand types to evaluate the petrophysics parameters in the most compatible way. In this research, the heterogenity of the sandstone was analyzed using a correlation between the Thomas–Stieber (TS) and Yin–Marion (YM) models as petrophysics and rock physics analysis. These analyses are used to determine sand types in the reservoir interval. The TS model predicts the porosity resulting from various modes of sand-shale mixing. The YM model predicts the associated P-wave velocities. Together, they offer a higher degree of constraint of formation properties. The results show that from eight zones reservoir rocks, the first five zones are laminar shale and the last three are dispersed shale. Both these models had the same conclusion in determining sandstone types. Keywords: Heterogeneous sandstone, Thomas–Stieber and Yin–Marion models, laminar shale, dispersed shale, Tarakan basin.