Interpretation of hydraulic fracturing pressure in low-permeability gas formations

The interpretation of hydraulic fracturing pressure was initiated by Nolte and Smith in the 1980s and remains qualitative. An accurate interpretation of hydraulic fracturing pressures, during injection and after shut-in, is critical to understand and improve the fracture treatment in low-permeability gas formations such as tight sand and gas shale. It would provide additional information about the wellbore and better understanding of the reservoir. In this paper, new models for the accurate calculation of bottomhole treating pressure based on surface treating pressure were first developed. This calculation was determined by incorporating hydraulic pressure, fluid friction pressure, fracture fluid property changes along the wellbore, proppant effect, perforation effect, tortuosity, effect of casing, rock toughness, thermal effect, and pore pressure effect on in-situ stress. New methods were then developed for more accurate interpretation of the net pressure and fracture propagation. The models and results were finally validated with field data from tight gas and shale gas reservoirs.