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An Analysis of Selected Acoustic and Electrical Images for the Discrete Fracture (DFN) in Essex County, Ontario


A number of historical horizontal and deviated wells were drilled in Essex County in the late 1990's. Several were wireline logged using the Circumferential Borehole Imaging Log (CBIL imager) to help understand the structural history of the Ordovician-aged Trenton Black River oil and gas bearing carbonates. Recent studies in Essex County and in the Dover region indicate that a fracture play could be linked to the structural history (i.e. Williamson & Andjelkovic, 2013) and to the hydrocarbon productivity of the region. (i.e. Andjelkovic et al., 2012 and Andjelkovic et al., 2013) Unfortunately, these studies introduced a bias of the fracture population data as the only wells analyzed were vertical, which introduced a geometrical error as the majority of fractures were also vertical, causing many fractures to be missed. The aim of this study is to tie the existing fracture population with the fractures identified on horizontal and inclined wells and to compare with the oil/gas production. A discrete fracture network (DFN) will be built to determine if pervasive regional fracture sets in the Trenton Black River (TBR) rocks could have a significant implication on the reservoir connectivity and consequently on hydrocarbon production. The constructed DFN model will represent fractures and faults as planar objects within the constructed 3D geological model of the Essex study area. Fracture sets will be tied to geomechanical or stratigraphic units. These fracture sets can be distributed stochastically or deterministically within the geological 3D grid. This phase of the study will involve assigning fracture properties such as fracture aperture and fracture permeability to the existing model. The constructed DFN model can be upscaled into a reservoir simulation grid, which can be applied to a “Dual Porosity” (DP) simulation case. Also, the study will indicate the importance of scale variance – from the scale of the core, through the scale of electrical/acoustic images to a more regional look of a discrete fracture analysis. Delineating fracture sets within DFN model with faults identified from the in-house 3D seismic data and high resolution aeromagnetic lineaments (Boyce & Morris, 2002) will help in understanding the changes in fracture trends and the associated oil/gas production within the Trenton Black River carbonates.