Geological Reservoir Modelling in an Unconventional Play Setting, Sichuan Basin, China

Fluvial-lacustrine deposits of the Xujiahe Formation are the primary reservoir target for an ongoing appraisal project in the northwest Sichuan basin. The late Triassic clastics are comprised of six members T3x1 to T3x6. The amalgamated channel sandstone sections of the T3x2 and T3x4 members may form an “inefficient” Basin-Centered gas play charged from downdip source rock while the calcarenites, coaly shale, and calcareous siltstones of the T3x3 and T3x5/6 are possibly charged by local source rock. Static modelling helped to improve understanding of production history for un-fracced vintage wells and early production behavior of newly drilled appraisal wells. Well sector models (scale of ~1x1 km) were created for this purpose. The ability to predict areas with low water production is crucial for the economic feasibility of Xujiahe development. Water saturation versus porosity cross plots provided key input to saturation models in static models. The crossplot method tentatively helps predict well productivity but further calibration is necessary.