The next iteration factor (NIF) method for calculating equilibrium conditions in subsurface waters, for the isolation of microorganisms from petroleum reservoirs

A mathematically simple program, based on the next iteration factor (NIF) method, of calculating species concentrations in the 10-component system Na-K-Mg-Ca-Sr-H-Cl-SO4-OH-HCO3-CO3-CO2-BO2-H2O is presented. This method does not have the programming and convergence problems associated with established methods based on Newton-Raphson and free energy minimization techniques. We developed the new program in order to establish the physicochemical conditions of extreme environments, such as petroleum reservoirs, in which resident microorganisms may exist. The knowledge of the conditions that we obtained from these calculations has led to the isolation of thermophilic bacteria and archaea not previously recovered from deep subsurface environments such as petroleum reservoirs.