Publications

In a petrophysical sense, thin beds can be defined as beds that are thinner than the resolution of the regular logging tools used to characterize them (Tyagi, et.al., 2008). The effect of anisotropy on electrical log measurements has been known and understood for many years, but the thin bed analysis seems to have been rarely performed in the deep water of the Kutei Basin area. Reservoirs of the Jangkrik fields (Kutei Basin) are characterized by thin bed layers, made up of clastic rock sequences with dominant lithology sandstone inter-bedded with shale, siltstone and organic material as confirmed by drilling cuttings, logs response and 3 conventional cores in different wells. The presence of shale in thin beds reservoirs is affecting formation evaluation where the standard conventional log analyses are not designed to properly correct this effect. This implies that the measured log values do not represent the true bed properties and commonly over-estimate the water saturation. Therefore, it is important to use (at least) a combination of high resolution image log for sand count and 3-axial resistivity for volumetric model through Laminated Sand Shale Analysis (LSA or LSSA) approach for representative water saturation estimate. The wireline logging job can be easily performed in low deviated wells, however it becomes more challenging in slanted wells with 40 – 70 degree of inclination. In such conditions, the use of LWD resistivity inversion and LWD density image can provide the reliable results comparable with wireline. Both conventional and LSA/LSSA interpretation are analyzed and compared with the core data for further interpretation. Overall, the sand counts represent well the lithology’s fractions and variation. The LSA/LSSA water saturation is usually lower than conventional one and the results of the analysis confirm an additional net pay and hydrocarbon pore volume in thin bedded reservoirs over the results of conventional analysis.