Rock Physics Analysis for Feasibility of Avo and Inversion Studies (2007)



Jabung Block, in the northern edge of the South Sumatra Basin, actively explored since 1993 and currently operated by PetroChina. More than 200 wells have been drilled, producing average of 60,000 BOEPD from multiple different reservoirs. The present block boundary remains 20% (1642 sqkms) of its original after the final relinquishment in 2003, adds challenges of exploration strategy having narrow and mature block. To overcome this issue, advance seismic approaches such as Seismic Multi Attribute, AVO, Inversion, and AVO-Inversion, should be applied instead of conventional interpretation. This technique can not be applied homogenously and should follow the characteristic of each field in different formation targets. The Rock Physics analysis has been investigated for feasibility reservoir as well as hydrocarbon characterization covers entire Jabung area. Rock physics analysis conducted by using electrical log data of around 50 assigned wells distribute and represent all different provenance area in the block. The study focused on lithology differentiation and hydrocarbon response to seismic data by deriving physical properties parameter from log data such as Impedance, Lame constant (Lambda and Mu), Bulk Modulus, Poisson Ratio, and Elastic Impedance in constant angle. Logs were cross-plotted to define facies correspond to reservoir/ or non-reservoir and correspond to hydrocarbon versus non-hydrocarbon. Hydrocarbon response analysis using by Zoeppritz equation was also applied to see AVO response. The result then mapped to see the Jabung reservoir (sand) distribution defined by rock physics parameter and AVO classes. The result shows that different field with different formation targets in Jabung Block may have different rock physics parameter. AVO responses are also unique in different provenance/ region. Study result will then assist exploration strategy of using this proper technique to define sand distribution and hydrocarbon response in seismic data out of existing fields. It has been applied to convince and rank potential prospects exist in the area.


Author : Woro Sutjiningsih, M. Noor Alamsyah, Lambok P. Marpaung, I Nyoman Suta, Tigor Siagian, Ari Subekti, Pandu Patria, Fatkhan