Solubilidades dos carbonatos de cálcio, estrôncio e ferro em condições de interesse do processo de regeneração do monoetilenoglicol

Abstract

The oil industry is constantly facing problems related to the production of natural gas. During the process, when water from the reservoir itself, comes in contact with low molecular weight gases, a solid stable structure called natural gas hydrate is arranged and blocks the passage of the pipe. This is due to favorable conditions of low temperature and high pressure of the circulating fluid. The solution lies in the injection of chemicals into the production fluid. The monoethyleneglycol (MEG) is the most used hydrate inhibitor because it has no environmental impact, provides low operational cost since it presents viability of regeneration and presents chemical compatibility with the constituents of the production fluid. In order to study interest conditions for MEG regeneration process, procedures and experimental apparatus were applied to promote data whose inhibitor effects together with sodium chloride effect, temperature and CO2 partial pressure in aqueous mixtures containing carbonate salts, such as, calcium, strontium and iron, in excess, were analyzed. CO2 partial pressure ranged from 1,01 a 2,15 bar, temperature ranged from 5 to 50 °C, MEG concentrations swept the entire percentage range of mass percentage and sodium chloride was added at three concentrations: 0,17, 0,51 e 0,85 mol/kg. A modified analytical method has been specifically developed and applied in the presence of carbon dioxide. Through the data analysis, it was possible to conclude that increasing temperature and MEG concentration provide a decrease in carbonate salts solubility. It was also found that carbonate salts concentration increases with the increase in CO2 partial pressure and with NaCl presence. An empirical approach is applied to describe mathematically salts carbonate solubility under study in water considering the effects of CO2 partial pressure, temperature and NaCl concentration. Then, with the aid of Setchenov equation, the depletion with MEG concentration was expressed.