Resistivity image log interpretation of Armour Energy's Cow Lagoon-1 well in the Batten Trough of the McArthur Basin identified conductive and resistive fractures and faults throughout the interval. The 423 fracture surfaces and 55 faults interpreted display a dominant strike direction approximately 150°N and secondary fracture populations striking east-west around 060°N. Two borehole breakouts were also determined from image logs and used to constrain the mean maximum horizontal stress direction to 133°N. Contemporary stress distribution in the well is variable and fundamentally linked to the elastic properties of the sampled stratigraphy. Both strike-slip and extensional regimes are represented by the data.

Fracture susceptibility models indicate that the minimum ∆P to initiate a fracture is relatively high in all formations and generally exceeds 25 MPa. This reflects high strength calculated for these units and implies that creation of new fractures under the contemporary stress conditions is unlikely. Reactivation of existing fracture planes is more likely, with minimum ∆P exceeding 7 MPa in each model generated. Observations imply that many of the fractures are optimally oriented to be open or hydraulically conductive in the far field stress field.

Fracture density was shown to vary across the interpreted interval and also strongly correlates with stratigraphy. Steeper bedding dips consistently correlate with an increase in fracture density. Fault count was attributed to the stress conditions and modes of failure. Low fault count correlates with tensile failure, whilst high fault count implies shear failure.

Systematic analysis of the Cow Lagoon-1 data concludes that NNW striking fractures are critically oriented for shear reactivation in the far field stress environment. Such fractures correspond with high fault density and preferentially occur within low strength, low Young's Modulus, low differential stress units.

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