RESERVOIR CHARACTER IDENTIFICATION USING EXTENDED ELASTIC IMPEDANCE INVERSION IN “MR” FIELD, NATUNA BASIN

Abstract

Reservoir character identification is one of the key process in petroleum exploration. One of the petroleum exploration target is one of sedimentary formation in Natuna Basin, Udang Formation. Udang Formation at "MR" Field in Natuna Basin considered as a potential hydrocarbon reservoir. Through regional geology point of view, it consists of interbedded sandstone-shale with braided delta and lacustrine plain as depositional environment, which is a supporting proof of its potential as a reservoir. One of the method to analyze reservoir characteristic is through seismic inversion that modelled subsurface condition. Extended elastic impedance (EEI) inversion is one of inversion type that modify elastic impedance’s angle projection, so it could add more possibility of parameter covered in reservoir characterization. Inversion process use sensitive parameters that consist of mu-rho (rigidity) and lambda-rho (incompressibility). These two parameters used to show developed lithology characteristic at “MR Field” linked to hydrocarbon existence. Mu-rho with EEI (84°) and lambda-rho with EEI (336°) shows clear reservoir characteristic along the formation’s bed and the formation below and under it. Hence based on the result of EEI inversion, Udang Formation in “MR” Field has a good lateral spreading of high rigidity and low incompressibility that related to the presence of sandstone and possible to be taken as a sign of hydrocarbon presence.