Research On The Reaction Law Of One Chem-thermogenic System And Its Applicability To Oil Fields

NaNO₂ and NH₄Cl chem-thermogenic system has been widely applied to oil production in China,such as plug removal and in-situ fracturing,etc.In this paper,based on experimental research,combined with numerical calculation method,the reaction influence factors and the temperature diffusion regularity of this system were studied.The corrosion characteristics and the compatibility with formation fluid were evaluated.Theoretically,with different concentrations of catalyst,the reaction process was accompanied by side reactions.The peak temperature increment increases at first and then decreases with the increase of catalyst concentration or initial reaction temperature and increases linearly with the increase of the reactant concentration.The parameters affecting the peak temperature increment are in the order of the reactants concentration,the initial temperature and the catalyst concentration.The corrosion of NaNO₂/NH₄ Cl system is mainly caused by the acid corrosion of hydrogen ion and the corrosion rate of steel under high pressure is higher than that under normal pressure.This system has good compatibility with common salt ions in formation water.when applied to alkaline formation the proportion of NH₄ Cl should be increased.In the sand-pack flooding experiment,with peak temperature increment as the main evaluation criteria,it is found that the effect of chemical Co-injection is better than that of chemical slug injection.During chemical Co-injection,the porosity and permeability of core is affecting the real velocity of the mixed chemical in the porous medium and thus affecting the temperature field.One numerical calculation method of temperature-field is proposed for field application.