2D source rock maturity model with integrated geology, geophysics and geochemistry data in HL field Jambi Sub Basin, South Sumatra Basin

Abstract

South Sumatra basin is one of the back arc tertiary basin in western part of Indonesia. It consists of 31 grabens and 2 grabens complexes which are divided into three general basin systems. Modeling of maturity generation has been performed in Jambi sub basin with Talang Akar formation as source rock target from 5 well along in HL field. This study aims to examine their hydrocarbon generation and expulsion history. Geochemical evaluation showed that Talang Akar formation is very potential as a source rock, with an average TOC value of around 1–8 wt %. The reconstruction of 2D modeling and thermal show that HL field evolved initially as a rift basin in Miocene with uplift in the Oligocene. The present-day calculation of heat flow in HL Field shows 7.27 HFU. The differences in the present-day heat flow with paleo heat flow have been corrected using vitrinite reflectance to know validate the paleo heat flow. In Paleo heat flow increased since the main rifting form late Oligocene until early Miocene. rifting finished, paleo heat flow will indirectly reduce the heat. During Middle Miocene there was a post rift phase which considered as influence on source rock maturation and hydrocarbon generation as quite Talang Akar formation is currently passing oil generation window. Thermal maturation model indicated that Talang Akar formation ware passed late oil generation stage and generated with oils to convert dry gas with the result % Ro is 2 %. The hydrocarbon explosion got result from transformation ratio model that source rock unit have probably completed all potential hydrocarbon since Pleistocene that in regional Sumatra has even inversion stage.