PP–PS Joint Inversion Applied to 2D–3C High Resolution Seismic Data – A Case of Junggar Basin, Northwest China

For exploration in the Chepaizi area, Junggar Basin of Northwest China, lateral lithologic variations due to deltaic and fluvial sediments present major challenges to the characterization of oil sand reservoirs. The major oil reservoirs exist in so-called “sweet spots”. However, conventional P wave is not able to effectively distinguish true “bright spots” from false ones, which leads to high drilling risk. For example, a strong reflection amplitude is observed in the target layer for Che89, a highly productive oil well drilled in 2006. But only a few wells drilled on a similar reflection response turned out to be successful commercial discoveries. It is widely believed that not only the fluid content, but also lithologic variations, have led to such misleading outcomes. Effectively locating the hydrocarbon distribution by eliminating the impact of lithologic variations could be the key for successful oil exploration. In order to better characterize the reservoirs, PetroChina Xinjiang acquired a high resolution 2D-3C seismic line in 2007, intersecting two existing wells, Che89 (good producer) and Che97 (dry well), by employing DSU3 digital sensor units with advanced MEMs accelerometer technology. Both high-resolution amplitude-preserving processing and PP-PS joint inversion were employed for reservoir characterization.