Publications

The Abadi gas field in Masela PSC Block, West Arafura Sea was discovered in 2000 and total seven wells were drilled until 2008. For the purpose of reservoir characterization works, a rock physics modeling was applied to the seven wells in the Abadi gas field. P-wave velocity (Vp) and S-wave velocity (Vs) from sonic-log is available in all the seven wells in the field. But from the quality check of sonic-log measurement, it became apparent that Vp and/or Vs reading has significant error in some intervals due to the bad borehole effect. It was also shown that calculated Vp/Vs ratio from sonic-log measurement does not have enough accuracy for the reservoir characterization work. The objective of the rock physics modeling in this study is to detect and edit bad sonic-log velocity data, and to estimate Vp, Vs and Vp/Vs logs with more accuracy, which identifies quantitative relationships between the seismic properties and the petrophysical properties of the reservoir rocks. In this study, velocity of Quartz and Clay in the modeling parameter were optimized to prioritize the match with core velocity and the correlation trend shown in the cross plots of the sonic-log properties versus petrophysical properties. As a result, modeled velocity logs were constructed, which was more consistent to the petrophysical properties. Especially the correlation between modeled Vp/Vs and core Vp/Vs showed significant improvement from the measured sonic-log. In addition to this, mud filtrate invasion correction was applied by the rock physics modeling and the response of velocity by changing the pore fluid can be evaluated quantitatively. The results of the rock physics modeling in this study, especially precise Vp/Vs prediction, is effective and useful for simultaneous AVA inversion works and 3D rock property prediction.