An evaluation of the effects of fracture diagenesis on hydraulic fracturing treatment

The rates and magnitudes of fracture diagenesis on commercially available proppants were determined from flow through experiments at difference stresses (depths) and temperatures and for hydraulically-open and –closed systems. A lumped-parameter conceptual model addressing diagenetic compaction is extended to accommodate the specific nature of the compaction of the designated proppant. Mechanisms include mineral dissolution, transport, and re-precipitation of the resulting products in the particle interstices, resulting in a loss of porosity in proppant packs. The model used recovered thermodynamic and kinetic data for mineralogical composition of available proppants within rigid walled hydrothermal and thermomechanical reactors. Under reservoir temperatures of 135 to 191^oC and stresses to 65.5 MPa, these ensemble data suggest that proppant packs may compact by up to 10%, resulting in porosity loss of up to 30%, and lose 75% of initial permeability. This may occur over a period of the order of 3 years. These predictions are consistent with observations from active wells where production may decrease to 10% over the period of a few years.