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ABSTRACT: Reservoir characterization in Kaji-Semoga Field, South Sumatra, Indonesia, using seismic inversion and geostatistics

Tribuanawati, Dyah , P.T. Exspan Sumatera, Jakarta, Indonesia

An integrated reservoir modeling study of the Baturaja Limestone has been conducted using 2-D seismic data from Kaji-Semoga Field, South Sumatra, Indonesia, The work was designed to aid prediction of the lateral extent of the reservoir, to build a porosity model for use in flow simulation and reserve assessment and to evaluate uncertainty in reserve estimation. The method involved study of seismic attributes, followed by geological interpretation and Seismic Inversion modeling using wavelet estimation from a number of wells near the build-up. Several geo-statistical techniques for integrating well log porosity with quantitative average porosity derived from a constrained sparse spike inversion method were applied in the reservoir modeling.

The spatial distribution of porosity in inter-well regions has been estimated based on variogram ranges and azimuth. Continuous petrophysical properties within each facies type were determined by application of kriging and co-kriging mapping simulation methods. Co-kriging was initially tested on a numerically simulated reservoir model and compared with kriging, then a conventional least squares product technique relying only on local correlation between porosity and acoustic impedance was applied. As compared to kriging, the seismically assisted geo-statistical method detects subtle lateral variations in porosity that cannot be mapped from sparse well data alone.

The result of the study shows that if a reservoir is seismically resolved and properly imaged, sparse spike inversion can be used in conjunction with geo-statistical methods to obtain a more complete reservoir description.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia