Experimental Study of Near-Critical Behavior of Gas Condensate Systems

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractMuch special attention has been devoted in this paper to the near critical phenomena of gas condensate systems, including the critical points, bubble and dew point locus, dynamically optical phenomena, and especially the unusual phase transitions in near critical region.The experimental measurements are carried out during constant composition expansions in high-pressure PVT cell. The percentage-liquid volumes in near critical region are crossplotted to determine the critical points in pressuretemperature diagram. The reddish-brown color is observed in near critical regimes for the fluids due to the complexities of components.What most fascinated and surprised us is that unusual phase phenomena are unexpectedly observed in the nearcritical region. That is to say, during the constant composition expansion process the retrograde dewpoint phase change occurs twice above the critical temperature, and correspondingly retrograde-dew and normal-bubble point phase changes occur sequentially below critical temperature. In two cases, the first-appeared liquid at the bottom of PVT cell first disappears at the same lower-pressure during different temperature CCE processes. These unusual phenomena occur simultaneously for the same fluid at temperature high up to about 100ºC. As far as we know, this is the first report of such an observation in the literature. Introduction:As still deeper formations are drilled, more near critical fluids with some unexpected behavior are encountered 1-7 . The phase behavior of reservoir hydrocarbons has been studied and

Experiment and Simulation Study on the Special Phase Behavior of Huachang Near-Critical Condensate Gas Reservoir Fluid

“…Critical point, bubble/dew point curve, critical opalescence phenomena, and phase transition at critical region were tested. Test results indicate that two dew points occur at temperatures higher than critical point and transition between dew point and bubble point at temperatures lower than critical point, namely, transition from dew point into bubble point, and behaviors of synthetic fluid sample and real formation fluid sample at near-critical region are different: near-critical region of real formation fluid sample is wider and becomes wider when paraffin content in fluid is greater [7][8][9]. Parra and Remolina used synthetic 4-component nearcritical volatile oil fluid to study PVT phase behavior after injection of N 2 .…”

“…A. R. Bazaev and E. A. Bazaev reviewed the PVT parameters of some binary mixtures at the near-critical region and measured the PVT parameters of four groups of binary mixtures at near-critical region [4]. However, only a few scholars performed the phase behavior experiments and theoretical research on multicomponent mixtures at nearcritical region [5][6][7][8][9][10][11][12][13][14]. Yang et al measured PVT physical parameters, including deviation factor, bubble point and dew point at the critical region, critical point, volume fraction of liquid at the two-phase region, and density of gas and fluid phase, of real multicomponent formation fluid in reservoirs at the near-critical region through experiments [5].…”

The effect of gas-condensate reservoir depletion stages on gas injection and the importance of the aerosol state of fluids in this process

“…Thermodynamic or mathematical modelling of the reservoir (mostly based on equations of state) is commonly used for resolving these complex issues. Moreover, experimental determination and empirical correlations can be applied to improve the reliability of modelling Sun et al, 2012;Gozalpour et al, 2003;Jessen and Orr, 2004;Sadus, 1992;Shen et al, 2001). Using this approach, the authors performed a laboratory study to estimate the effect and mechanisms of gas-condensate reservoir depletion stages on the effectiveness of the gas injection method.…”

Phase Behavior and Physical Parameters of Natural Gas Mixture withCO2

“…The accuracy of PVT main parts satisfies the phase behavior experimental requirement of the synthetic gas sample with different CO 2 content [31].…”