ABSTRACT:

Hydraulic fracturing is a commonly used technique to stimulate hydrocarbon production in low permeability formations. In cased hole completion, perforations act as a connection between the wellbore and the formation. Since perforations are the points at which the induced fractures initiate and propagate, and the path for hydrocarbon transportation from the targeted formation to the wellbore, they have major influences on production rate. Near wellbore problems such as T-shaped fractures, multiple parallel fractures, sand production, tortuosity, and reoriented fractures have been observed in different cases due to the fact that different perforations parameters were not properly designed. Fracture geometry is directly influenced by orientations of perforations. The objective of this study is to numerically simulate the hydraulic fracturing lab experiments which were done on 10cm mortar samples from a perforated tunnel. Lattice numerical simulations, which is based on the physics of granular material, were used in this study. The model uses the Synthetic Rock Mass (SRM) approach to model hydraulic fracture propagation. The numerical model was built based on the rock properties and stresses applied to the rock in the lab and the perforation geometry was also added into the model similar to the lab conditions. The geometry of the fractures initiated from the perforation tunnels showed reasonably good match with the lab observations. The simulations were repeated with different orientations for the perforations with respect to the in-situ stresses. The results showed the that fracture tortuosity will be apparent when deviating the perforation from the optimum direction, i.e. minimum stress direction in this example. The results will be presented and interpreted.

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