Analisis Geofisika Dalam Pemodelan Statik Pada Formasi Gumai Cekungan Sumatera Selatan
Erwin, Lutfi Fauzan
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South sumatera basin has one of the highest oil and gas production in Indonesia with the dominant reserve accumulated at Talang Akar and Batu Raja Formation, but recent studies show that there is a new discovery in Gumai play. As we know that the production capacity of the reservoir highly depended on its geometry and petrophysical characteristics, therefore we need to build a static model of our reservoir. It is widely known that seismic inversion was able to help us to make predictions about lithology and porosity. In this study, seismic inversion was perform using three methods which are model-based inversion, linier programming sparse-spike inversion, and colored inversion. The results show us a high impedance anomaly forming a delta-front geometry and it is confirmed by the gross depositional environment map of Gumai Formation. Velocity model was made afterwards using velocity interval calculation and layer cake assumption to convert the data from time domain to depth domain for static modeling purposes. The last stage is static modeling to distribute reservoir characteristics and estimate oil reserve in target area. Lithology log from well data was distribute using sequential indicator simulation and porosity log was distribute using sequential gaussian simulation. Nine stock tank oil initially in-place (STOIIP) estimation by deterministic process are yields from combinations of well logs and impedance data. The results of STOIIP estimation values are ranging from 2.116.656 m3 to 16.666.996 m3.