Geomechanical Characterization of Naturally Fractured Formation, Montney, Alberta

摘要

The integration of geomechanics, geology and reservoir engineering is required to maximise production from unconventional naturally fractured reservoirs. In these reservoirs, fluid flow, especially to production wellbores, can change as reservoir conditions change as fluids are injected to the reservoir. Therefore, an accurate prediction of natural fracture network, initial in-situ stresses and the rock properties is needed to optimize stimulation treatment in naturally fractured unconventional reservoirs. Furthermore, in most unconventional reservoirs, hydraulic fracturing is required to enable sufficient fluid mobility for economic production and it is critical to understand fracture network connectivity, extent, and interaction of natural fractures within the system. Although the technology has greatly improved in the past decade to enhance production, predictive geological-geomechanical models barely exist for optimization of these recovery processes. In research described here, a case study on the geomechanical and geological characterization of an unconventional reservoir is presented with focus on how the natural fracture orientation can change the generated fracture network. The results show less deviation from the original fracture orientation with the smaller angle between the natural fracture and hydraulic fracture, and then resulting fracture geometry is closer to a planar geometry. The larger the angle, the greater the chance of the hydraulic fractures intersecting natural fractures and the greater the diversion of the fracture path along the natural fractures and the more complex the network. Also, the greater the stress anisotropy, the more likely a hydraulic fracture crosses a natural fracture. A three-dimensional calibrated mechanical earth model was constructed by integrating both petrophysical, geological, and geomechanical data in the study area. A detailed workflow was developed to reduce the uncertainty in the geological and geomechanical parameters used to design hydraulic fracturing operations and improving the prediction of the final stimulated fractured volume.