The purpose of this study is to construct a core- and log-based rock-mechanical model of thin-bedded sands and shales. The study area is North LaBarge field, Wyoming, where rocks of the Cretaceous Mesaverde Formation produce hydrocarbons from low-permeability, thin-bedded (0.5-10 in; 1-25 cm) sands and shales. Hydraulic fracturing is necessary to obtain production from this reservoir.

For roughly 90 ft (27 m) of core, permeabilities and p- and s-wave velocities were measured every 0.5 in (1.2 cm) using probe-type devices. Laboratory results were converted to subsurface conditions using pressurized core plugs, a full-waveform sonic log, and a density log. The resulting rock-mechanical model provides a detailed stress profile which can be used as input into computer models which predict fracture height. Such models generally use bulk-rock properties in which fracture heights are overestimated because the models do not take into account the ability of thin shales to impede fracture propagation.

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