Effect of disjoining pressure on the onset of condensate blockage in gas condensate reservoirs

Abstract

An in-depth analysis was performed to investigate the formation of a condensate lens, as the primary stage of a phenomenon known as condensate blockage in gas condensate reservoirs. The lens formation is considered to be caused by the instability of the condensate film on the pore walls. Owing to the small sizes of the pores and low values of interfacial tension in gas condensate reservoirs, the stabilizing effect of the disjoining pressure may become more significant than the corresponding destabilizing effect of interfacial tension. To model this phenomenon, we employed the augmented Young–Laplace equation to determine the film pressure and subsequently, the film stability. Consequently, this analysis would incorporate the effects of interfacial tension, curvature, and the disjoining pressure on lens formation. The Scheludko dimensionless number, ξ, originally introduced by Gumerman and Gomsy [Chem. Eng. Commun. 2 (1975), 27–36], was used in order to compare the effects of the disjoining pressure and interfacial tension on the stability of the condensate film. The calculation results are provided for the Scheludko dimensionless number in the range 10−6 < ξ < 10−2. The selected range covers interfacial tensions between 0.01 and 0.25 (mNm−1) and the pore diameters between 0.2 and 10 (μm). We found that the critical film thickness required for lens formation, strongly depends on the dimensionless quantity when ξ > 10−5. For a typical value of ξ ≈ 10−2, the value of onset saturation for lens formation is found to be about 60%, whilst for much lower ranges, where the disjoining pressure has a negligible effect, the calculation results in a unique onset saturation of 13.5%.