Some thermodynamic aspects of petroleum recovery by methane pressurization

Abstract

In two previous papers (Cordeiro et al., 1973a, b ) a methane pressurization process was described by which the solubility of high molecular weight hydrocarbons in a solid phase could be enhanced within a liquid hydrocarbon phase by pressurizing the solid-liquid system with methane gas. This solubility enhancement was demonstrated to occur for two diverse hydrocarbon solids in the following prototype systems : System I: methane (gas) -normal decane (liquid) -normal dotriacontane (solid) System 11: methane (gas) -normal decane (liquid) -phenanthrene (solid) and some speculation was offered concerning the selectivity of aromatic vs. paraffinic solids of similar melting point under methane pressurization with n-decane being the liquid solvent in each case.In this paper, several thermodynamic aspects of the process are considered with respect to the Systems I and I1 and also System 111: methane (gas)-trans decalin (liquid) -normal dotriacontane (solid) the study of which has been recently completed. These experimental results are presented below. EXPERIMENT-SYSTEM IllAn experimental study of the phase equilibria behavior of the ternary system methane-trans decalin-normal dotriacontane was performed. The data was correlated with the Flory-Huggins model (Flory, 1942; Huggins, 1942) solely for the purpose of aiding the later thermodynamic analysis of the system with respect to process behavior. Our previous work (Cordeiro et al. 1973a) presents the equations of this model in detail. The model works as well as with System I, and better than with System 11, using the following partial molar volume and inter- where T is "K. The data are applicable in the range of 323-340°K up to pressures of 70 abn. These data were obtained from the following laboratory experiments, each of which was reproduced at least once.