Reservoir geometry, natural fracture networks and in situ stress directly impact on the planning and implementation of flooding operations. Image logs were acquired from two wells in Field A, the Cooper Basin, with three main objectives in mind: increase confidence on the distribution of oil reservoir sand prior to in-fill drilling; quantify natural fracture populations and assess their possible contribution to production from a tight reservoir, and; quantify the contemporary stress regime and consider its bearing on idealised flow direction.

Tectonic tilt and palaeocurrent indicators were identified in conjunction with natural fractures and in situ stress features from both wells. Palaeocurrent flow directions confirmed a dominant transport direction to the south. However, sediment transport within the Tirrawarra Sandstone reservoir is clearly to the northeast parallel to the strike of the Field A structure. This implies enhanced permeability parallel to this direction due to grain stacking.

Natural fracture density is more enhanced at the crest of the structure than the flanks and the dominant 065°N natural fracture trend is predicted to have greater hydraulic conductivity with respect to the in situ stress field.

The in situ stress field was determined to be strike-slip with σHmax oriented approximately 117°N defining a third permeability enhacement associated with Field A. Without further knowledge of the relative magnitudes of each of these permeability enhancements, it is recognized that EOR patterns planned in an east-west orientation will maximize flooding and sweep efficiency within the Tirrawarra Sandstone oil reservoir.

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