GEOCHEMICAL AND PETROPHYSICAL ASSESSMENT OF TELISA SHALE GAS RESERVOIR: A CASE STUDY FROM SOUTH SUMATRA BASIN, INDONESIA

Abstract

The geochemical and petrophysical assessment of a shale gas reservoir in Telisa Formation in
South Sumatra Basin was carried out to identify the gas potential distribution. The assessment was performed
based on geochemical and petrophysical data, which were integrated with and seismic attributes to spatially
distribute the organic richness of the shale gas reservoir. The objectives of this paper are to characterize core
samples in terms of the total organic carbon (TOC), kerogen type and thermal maturity of shale gas layers that
were derived from the well log data. In addition, seismic attribute analysis such as acoustic impedance, which is
associated with TOC, was explored to spatially distribute the shale gas potential. The assessment results showed
that the organic richness of the Telisa shale gas reservoir is classified into fair quality with TOC in the range of
0.75-1 weight (wt) %. The kerogen type of the Telisa shale gas reservoir is considered as a mixture of type II/III
(oil/gas prone) to type III (gas prone). In terms of vitrinite reflectance, the Telisa shale reservoir is categorized as
in a mature stage, representing an oil window up to a wet gas window. The prospective reservoir distribution is
indicated by a shale lithology characterized by a high acoustic impedance range of 20000-24000 ((m/s). (g/cc)).