BASIN-SCALE ROCK PHYSICS STUDY AND STOCHASTIC AVO MODELLING FOR THE DEEP WATER KUTEI BASIN (EAST KALIMANTAN – INDONESIA)

摘要

A rock physics study conducted on twenty two (22)rnwells from the deep water Kutei Basin (EastrnKalimantan – Indonesia) was carried out to analysernthe elastic properties on a basin-scale level andrngenerate stochastic AVO modelling for fluid andrnlithology prediction. The creation of an AVOrnreference model based on measured data is deemedrnof great importance for prospect generation deriskingrnof the field. The methodology consisted inrnthe execution of two phases. The first phaserninvolved the analysis and quality control of thernwell-log elastic properties distribution, thernidentification of six litho-fluid classes (normalrnpressure shales, brine sands, oil sands, gas sands,rnoverpressured shales and vulcanites) and fluidrnreplacement modelling to create different fluidrnscenarios for the sands. Then, depth trend analysisrnwas carried out well by well for each elasticrnproperty: density, P-wave velocity and S-wavernvelocity with variability and correlation analysisrnperformed. The second phase relied on the use ofrnMonte Carlo simulation to generate a large numberrnof elastic properties realisations for each litho-fluidrnclass and then calculate AVO intercept and gradientrnto be used for analysis. The study highlighted thatrnthe key factor driving the elastic behaviour is thernburial depth. Modelling the elastic behaviour ofrn“anomalous” lithologies (vulcanites andrnoverpressured shales), which are also present in thernbasin, allowed an understanding of their theoreticalrnimpact on the capability to discriminaternhydrocarbon bearing sands.