Prediction of Molecular Diffusion At Reservoir Conditions. Part 1- Measurement And Prediction of Binary Dense Gas Diffusion Coefficients

Abstract

Diffusion coefficients in binary dense fluid systems are measured and used along with data available in the literature to obtain a generalized correlation for predicting binary molecular diffusion coefficients in dense gases over a broad range of conditions. Introduction ATTEMPTS to quantify mixing phenomenal in porous media are often, encountered in design studies of processes(@ related to petroleum recovery. Dispersion, an important part of mixing phenomena, can be related to the distribution in travel times that results when a fluid passes through a porous media"1. On a micro-scopic scale, the two most important mechanisms con-tributing to dispersion are variations in velocity be-tween fluid elements flowing in neighbouring pores or groups of pores (often referred to as convective mixing) and molecular diffusion",', ". Although there is some controversy over the magnitude of convective effects, it has been thought that in vertical gravity-stabilized miscible floods, such as those carried out in the carbonate pinnacle reefs of Alberta, molecular diffusion played an important role in the mixing of the solvent bank with drive gas and oil('-,In other pro-cesses, such@h -as gas, solvent or C02 horizontal 'miscible floods, the effects of molecular diffusion are difficult to quantify, but are thought to be important in the recovery of non-flowing oil by mass transfer", ', "'. The estimation of molecular diffusion coefficients in low-pressure gases using .'the Chapman @@sk ?g Theory"." is adequate for a wide variety oi singie-Phillip M. Sigmund graduated from the University of Waterloo with a B.A.Sc. (c emical engineering) in 1963 and a M.A.Sc. (chemical en-gineering) in 1964. After obtaining his Pb.D. (chemical engineering) from the University of Texas in 1969, he joined the Petroleum Recovery Re-search Institute, where he is cur-rently employed as a senior research engineer.He has been involved in Institute research projects dealing _ with retrograde phenomena in porous media, diffusion and dispersion phenomena, hydrocarbon recovery from car-bonate reservoirs, and the use of CO, and SO, for en-hanc4@d oil recovery. Dr. Sigmund is a member of CIM, CIC, AIME and the Association of Professional Engineers of Alberta. 4a@ component and binary gases ... .... In liquids, the success of theoreticil models has been more limited, perhaps because of ilhe complex nature of molecular interac-tions in the liquid state. Nevertheless, except in the critical region, liquid diffusion coefficients can at present be predicted by empirical correlations, with sufficient accuracy for many engineering pur-poses"@ In the critical or dense fluid state, there are few exp@@rimental studies of diffusion coefficients inbinary mixtures. This has made it difficult t.o assess predictive t(@chniques, which have so far been tested largely on l-,he basis of self-diffusion data and are generally considered unreliable(',").The pres(@nt two-part paper describes Petroleum Re(!overy Institute work that was directed toward de-veloping improved predictive me...

Features of Convection and Diffusion in Porous Media for Binary Systems

“…This was done for two reasons: 1) to justify the use of the Boussinesq approximation in the range of temperature, concentration, and pressure expected in this study; and 2) to estimate the variation of the coefficients C w , C P , and C T in the x -z plane. We calculated C w , C P , and C T using the expressions presented in Reference (12) where the density, fugacity, and partial molar volume are calculated using the PR EOS and where the molecular diffusion coefficient and the thermal diffusion ratio are given by Sigmund (20) and Rutherford and Roof (21) , respectively. Figure 3 presents C w , C P , and C T contour lines for k = 1 md.…”

Numerical Modeling of Diffusion in Fractured Media for Gas-Injection and -Recycling Schemes

“…Most of the experimental data on diffusion coefficients are limited to binary or ternary mixtures (Cullinan and Toor 1965;Sigmund 1976aSigmund , 1976bRenner 1988;Leahy-Dios et al 2005). There are no measured diffusion coefficients for reservoir fluids.…”

Modeling, analysis, and screening of cyclic pressure pulsing with nitrogen in hydraulically fractured wells

“…To represent the component-mass flow from fractures into the matrix caused by compositional gradients, the molecular diffusion option for nitrogen (CMG 2013), which is a critical factor during the soaking period of cyclic pressure pulsing process, is activated. Sigmund correlation for molecular diffusion (Sigmund 1976) is used with a diffusion coefficient for nitrogen of 0.001 cm 2 /s, which is taken from the literature (Silva and Belery 1989) and validated with the ChapmanEnskog binary-diffusion theory (Marrero and Mason 1972).…”