RESERVOIR CHARACTERIZATION IN KARANGBARU FIELD USING SIMULTANEOUS INVERSION

PROCEEDINGS JOINT CONVENTION BALI 2007
The 32^nd HAGI, The 36^th IAGI, and The 29^th IATMI Annual Conference and Exhibition

RESERVOIR CHARACTERIZATION IN KARANGBARU FIELD
USING SIMULTANEOUS INVERSION

Mualimin¹, Arif Prasetyo H², Rizaq Faidul H3

¹PT. PERTAMINA EP Region Jawa, Formerly Paradigm Indonesia.
²PT^. PERTAMINA EP Region Jawa,
³PT. Chevron Pacific Indonesia, Formerly Paradigm Indonesia on-site
PT. PERTAMINA EP Region Jawa.

EXTENDED ABSTRACT

Karangbaru Field is exploration field with respect to hydrocarbon exploration and exploitation, with 2 wells drilled to date. The fields has potential for additional gas reserves, although in more subtle traps with high risk.

The methodology integrates several processes-from seismic data acquisition through the three- dimensional visualization of the geo-bodies obtained by the simultaneous inversion of the data, using petrophysical information derived from the wells and rock model to predict the elastic properties. New 3D seismic was acquired to identify potential prospects. The design, acquisition, and processing parameters were determined by modeling the AVO response and geometry of possible reservoirs derived from VSP studies and well logs. The inversion process is carried out by inverting the prestack seismic data using a linear approach. These data have been reprocessed and prestack-migrated using a preserved amplitude sequence. The simultaneous inversion is based on the Fatti modification of the Aki-Richards equation, applied to seismic gathers with angles up to 30° . The inversion results such as P-impedance, S- impedance, and the Vp/Vs relationship transformed to the elastic attributes lambda-rho (ëρ), mu-rho (µρ) and Fluid Factor which are used to predict the distribution of sand geobodies through the volume, based on user-defined cutoff values of the ëρ and µρ parameters.

The integration of seismic, geologic, and data from existing wells is carried out through the simultaneous inversion of pre stack time-migrated data. The visualization of the geobodies with the attributes P-wave impedances, lambda-rho, mu-rho and fluid factor allows identification of optimum areas for future wells. The results have been used to define the locations of new development wells; this has decreased the risk associated with the search of additional gas reserves in the Karangbaru Field.