Static Reservoir Model of Crevasse Splays in the Colorado River System, Salar of Uyuni, Bolivia
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Abstract
The Altiplano Basin (Bolivia) exhibits one of the best examples of dryland river systems with a low gradient, where it is possible to obtain field data to build 3D high-resolution geological models of different sediment bodies. This study presents the development and understanding of a 3D geological model for crevasse splays deposited in this kind of basin. The data used consists of sediments in-situ and remote sensing data (satellite images). The integration of field and remote sensing data shows that the grain size has a better correlation with the channels location than the RGBD information from the satellites images. Likewise, with the grain size model, it is possible to visualize that porosity is not highly affected by the clay content, and due to the small grains, the initial predicted porosity is around 49 to 56%, which can be reduced to values below 7% because of overburden. According to grain size and porosity, permeability is around 350 to 600 mD, due to grain size distribution at surface conditions. These petrophysical properties are appropriated for gas storage and they can accumulate up to 3 MSCM of gas reserves in one single crevasse splay. As observed in the field, crevasse splays are vertically stacked resulting in a high net to gross ratio, and increasing gas reserves up to 300 MSCM of gas in-situ, making these reservoirs an attractive target for exploration in fluvial systems.