An Integrated Lithostratigraphic and Geomechanical Conceptualization of Dense Fracture Networks in a Shallow Paleozoic Dolostone

Fomenko, Andrey
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University of Guelph

A combination of detailed core logging and downhole geophysics (e.g., Gamma, Full Wave-form Sonic, ATV, OTV) was applied to an asymmetric trapezium of 5 vertical boreholes 75 m. deep and surrounded by 3 angled boreholes oriented 45°, 175° and 300°. Such approach was applied in order to capture the complexity of the discrete fracture networks of a Silurian dolostone at a 50x50 m site. The approach has shown to be effective for delineation of the laterally continuous major lithological and stratigraphic units defined by matrix properties and mechanical units defined by fracture intensity. Fracture intensity and orientation identified by core logging and borehole imaging (e.g., ATV, OTV) exhibited distinct variations across three major laterally continuous mechanical units that were not consistent with stratigraphic boundaries. These insights about the fracture characteristics were used to construct a discrete fracture network model to represent the investigated volume of the bedrock.

Hydrogeology, DFN, Fracture, Bedrock, Dolostone