Catalytic Activation of Ammonium Nitrate and Sodium Nitrite: Experimental, Modeling and Prediction of the Fracking Envelope in Low-Permeability Reservoirs with Light and Heavy Oils

The catalytic activation of thermochemical fluids or binary mixtures (BMs) based on ammonium nitrate and sodium nitrite was experimentally and numerically investigated as well as kinetically modeled. Experimental evidence in an autoclave reactor indicated an increase of temperature up to 242.5 degrees C and pressure up to 47.7 bar after the catalytic activation under standard conditions is accomplished. By means of the T and P growth and the observed reaction products (N-2, NO2, and H2O), the reaction kinetic constants along with its stoichiometry were established and later on validated with a numerical reactor model. Subsequently, field-scale numerical models evaluated the activation of the BM within different reservoir rock quality (porosity: 3-15% and permeability: 4.4-111 mD), fluid type (light and heavy oils), injection rate (1-3 m(3)), and initial reservoir pressure (85 and 150 bar). Poor reservoir quality and injection rate were observed as the dominant requirements to ensure a more aggressive reservoir fracking. They illustrated an exponential response on the peak pressure, particularly at porosity and permeability values <5% and <17 mD, respectively. The exhibited peak pressures in our models range from 108-389 to 144-392 bar, for the light and heavy oils, respectively. We found that these in situ pressures are substantially in excess in reference to the predicted fracking pressure of the studied reservoirs. This implies that the activation of the BM within the porous media is a promising reservoir fracking method. Moreover, its robust exothermicity surpasses the reported glass transition and melting temperature of certain asphaltenes. Our findings can provide meaningful understanding about the geology-injection requirements that can lead to fracking a given reservoir as well as its thermal development potential for well cleaning purposes when implementing BM for IOR applications.