LIVIU DUMITRACHE, IULIAN NISTOR, SILVIAN SUDITU, ANA MARIA BADEA DETERMINING WATER VAPOUR PHASE EQUILIBRIUM COEFFICIENTS AT DIFFERENT TEMPERATURES FOR GAS WELLS In the course of gas production from reservoirs across the world, salt precipitation from the reservoir water is observed to an increasing extent as recovery progresses. This phenomenon, likewise, occurs during the injection of dry gas into porous aquifers. Salt deposits can form in the production string, in the perforation zone as well as in the area of the reservoir surrounding the well <1>. A better understanding of salt precipitation phenomena along with the conditions under which this takes place is needed for a better productivity control <2>. Simulating the process and taking actions as necessary may reduce or even eliminate the necessity for down-hole fresh water washes and, in turn, minimize the overall production losses. Input for this simulation are also the Water-Vapour Phase Equilibrium Coefficients. This article presents a methodology on how to obtain these coefficients for different temperatures using commercial simulators.