Model for Fracture Stiffness Incorporating Surface Roughness Effects Based on Testing of Naturally Cemented Fractures

Natural fractures in fine grained carbonate reservoirs can modify reservoir behavior during hydrocarbon production because they increase both porosity and permeability of the host formation. These fractures, and their associated porosity and permeability, will respond to pore pressure changes associated with hydrocarbon production. The aim of this study is to evaluate this response using natural, partially cemented fractures. To this end a series of experiments was undertaken on fracture carbonate samples from Dry Canyon, NM. Fractures geometries were characterized via micro-CT imaging and petrographic analysis. Samples were then tested to determine their mechanical and hydraulic stress dependence. Results were fit with a semi-logarithmic closure model that relates fracture aperture change to applied stress and good agreement was found with the results of other studies. These findings support the use of this closure model in predicting the behavior of some naturally fractured carbonate reservoirs.