Influence of porosity and facies of Baturaja carbonate to the seismic wave velocity: case study of Tambun Field West Java

Abstract

The early Miocene Baturaja Formation is one of the most prolific reservoirs in Tambun Field, West Java. The hydrocarbon mostly comes from the Upper Baturaja Formation reservoirs. These carbonate rocks show some complex porosity, lithology and facies. This study includes detail relationship among reservoir petrophysics , elastic wave parameters, effect of water saturation, pore type and facies of Baturaja carbonate rock to the seismic wave parameter, such as compressional and shear wave velocity. Many data were collected and studies carried out to obtain detailed relationships between seismic attributes and petrophysical parameters of the Baturaja carbonate, such as: petrographic analysis, SEM image, detail core description, well logging data analysis and laboratory experimental of seismic wave velocities measurements in variation of overburden pressure, pore pressure and temperature. Some seismic wave parameters were simulated as close as possible to the reservoirs condition. The result shows that the seismic wave velocity in the Baturaja carbonate has wide value range, i.e: compressional wave velocity (Vp) ranges from 3300 to 4000 m/s and shear-wave velocity (Vs) from 1500 to 2000 m/s. Based on petrophysical data and seismic wave measurement, the total porosity is not the only main factor controlling elastic wave parameters, as a matter of fact, the pore type plays also important role. A plot of porosity versus velocity displays an inverse trend encountered in the zone B and D, for zone A and C the diagram are slightly scatter. It is shown also that there is strong relationship between seismic wave velocity and lithology facies, therefore this result proves that seismic waves can be applied to facies determination in carbonates of Baturaja formation.