Multidisciplinary Integration and Tools to Better Address the Utica Shale Stratigraphy, Rock Properties and Fraccability*

A series of horizontal and vertical wells in the Utica Shale of Quebec have shed new light on multidisciplinary approaches and tools for the evaluation of its stratigraphy, rock properties and ability to fracture. Two of the horizontal wells drilled are displayed in Figure 1. Method In horizontal wells, delineation of open fracture zones and faults has been achieved using gas chromatography. The combination of gas chromatography with image logs has demonstrated that wetter gas can be locally attributed to increased density of open fractures and not to a change in source rock maturity. These results led to fine-tuning the fracture design in such a way as to avoid areas of potential placement problems. Geomechanical modeling based on data from wells in the Saint Lawrence Lowlands in Quebec had predicted that an increase in pore pressure had the potential to change the stress regime from strike slip to thrusting, implying the possibility of limited height “pancake fractures” (Figure 2 from Brodylo et al. 2011). In one horizontal well, the close proximity of the borehole to a boundary between two rheologically different shale units was deemed susceptible to horizontal fracture propagation. The geomechanical model was correct as shown by some post fracture deformation of the 4” liner in the horizontal section caused by bed parallel shortening. As such, a borehole geometry that gently and gradually crosses stratigraphy should reduce the potential for casing deformation associated with horizontal fracture propagation. For various operational or economic reasons, a decision not to run wireline logs or not to monitor the stimulation with microseismic may be taken; this may have a substantial negative impact on our understanding of what happened during the hydraulic fracturing process. In one horizontal well in Quebec, the ease of placement in one particular fracture stage seemingly contradicted the petrophysical prediction. Log derived geomechanical properties of the Utica in the horizontal borehole indicated the presence of a less brittle facies where fracture initiation

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