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Interfacial Tension of the -Normal Decane System

G. L. STEGEMEIER SHELL DEVELOPMENT CO. JUNIOR MEMBER A/ME HOUSTON, TEX. B. F. PENNINGTON HUMBLE OIL AND REFINING CO. JUNIOR MEMBER AIME HOUSTON, TEX. E. B. BRAUER UNION 01 L CO. JUNIOR MEMBER AlME ABBEVILLE, LA. E.W.HOUGH* THE U. OF TEXAS MEMBER AlME AUSTIN, TEX. Downloaded from http://onepetro.org/spejournal/article-pdf/2/03/257/2157293/spe-327-pa.pdf by guest on 29 September 2021

ABSTRACT acid, tap and, finally, distilled water. Sub­ sequent cleanings were performed with re-distilled Interfacial tension divided by the difference in normal , which had an extremely low residue density between the and the vapor phases upon evaporation. Specific composition require­ was determined experimentally by the pendant ments necessitated a fairly precise sample intro­ drop method on several isotherms in the two phase duction - although, for a two-phase, two-component region below the critical point for the methane­ system, the composition of each phase is completely normal decane system. The density difference determined if pressure and temperature are con­ data of Sage and Lacey was used in the calculation trolled. of interfacial tension. Both interfacial tension and The normal decane was delivered into the evac­ and interfacial tension divided by density difference uated sample system as a liquid from a burette. were found to vanish at the critical point. Inter­ The methane was then introduced into the system facial tensions of less than one dyne/centimeter from a calibrated isothermal container, so that were observed as far as 1,000 pounds per square pressure differentials could be used to determine inch below the critical pressure. the amount introduced. High pressures were obtained by compressing the sample with a mercury injection EXPERIMENT AL PROCEDURE pump until the critical pressure was reached for The interfacial tension divided by the density the particular isotherm being studied. Experimental difference for the methane-normal decane system data were then obtained for specific pressures by was determined at the 100°, 130°, 160° and 1900P first decreasing the pressure slightly so that two isotherms, from pressures of about 1,000 psi to the phases would appear, and then photographing a drop critical pressure, which is more than 5,000 psi for at that pressure. Subsequent photographs were these isotherms. Particular emphasis was placed made at increments throughout the pressure range. upon the investigation at pressures slightly below Calculation of interfacial tension divided by the critical pressure where the interfacial tension density difference was made from measurements is less than 0.5 dyne/em. Volumetric properties in the two-phase region, including the critical pressures IS and temperatures, were taken from the work of Sage and Lacey. 1 \. The experimental pendant-drop technique used ~ ,. IOO-F - for the determination of interfacial tensions at high .~ • 13O-F ~i·F • '80-F pressures incorporated the ideas of Michaels and 110- • ItO-F - Hauser,2 Hough, et al,3 Walker4 and Heuer.S In 100 F~ addition, the technique for determination of extremely • 6 small interfacial tension by J ennings was utilized .. , 130·F in the region near the critical points. A detailed 160·F description of the apparatus is given in a disser­ · tation by one of the authors. 7 · Cleaning operations on the stainless-steel sample ~ !so. system included successive washings with chromic • " I f~O·F/' ~O-F • .... Original manuscript received in Society of Petroleum Engi­ PRESSURE [Plio] ""'" neers office Jan. 18, 1962. Revised manuscript received May 14, 1962. FIG. 1 - INTERF ACIAL TENSION DIVIDED BY DENSITY DIFFERENCE VS PRESSURE - METHANE- lReferences given at end of paper. NORMAL DECANE SYSTEM. ( *Presently on faculty of Mississippi State U., State College. SEPTEMBER, 1962 257 investigated in detail, and the isotherms and isobars are shown in Figs. 3, 4, 5 and 6. It can be seen 100~\1 0 .. f--+--+--+--1,1rl 180"F f--+--+--+----l--~-+-+--- from these plots that not only does the interfacial tension disappear as the critical point is approached, .-+--f---­ .100..- i 7~_+---+- -t--~-t__---j-~ • 130 '"F •.190..- ItO "F but also the interfacial tension divided by the ! . -+----+-- t----+~'\0+-- -+----+--t­ density difference. I'f--+--+--l--~+-~~,,~-+--+---+--+--· ~ I---~ I. f----+--f-- -+--t---t~-"\;I---t-· - - -~-t-----t---- \\l\ t t--- -- ~f- ~- - -+-- ~" --~ -- t-- r>... ______\\ Ii I\~ - ...... i 1.0 ''' \ o IOO·F '- \\ 6 130 ·f E 1.6 ~ a t$O·F - ~ • 190·F l ~ ~ 14 - \\ ------FIG. 2 - INTERFACIAL TENSION VS PRESSURE. \ ~ taken directly on the negatives. The tables of LLI 1.2 \ \\

ffi Downloaded from http://onepetro.org/spejournal/article-pdf/2/03/257/2157293/spe-327-pa.pdf by guest on 29 September 2021 Fordham8 and Mills 9 were used. The sample was It o 1\\ composed of Phillips research grade normal decane, ~ 1.0 \ ~ 99.35 per cent pure, and Phillips Btu grade methane, ~ \1\ "\ 99.4 per cent pure...... 0.8 \'~ Values of interfacial tension divided by density ~ 1\' difference, and of interfacial tension are plotted ~ 0.6 \ \\ for various isotherms in Figs. 1 and 2. Experimental

1500 9.76 9.88 9.77 2000 7.35 7.61 7.52 0.5 \ \\ - 5.50 5.50 100 ..- 2500 5.67 · 130 -r: 3000 3.66 3.51 3.75 1\\\ · 160"- 3500 2.40 2.43 2.41 · 190"- - 4000 1.43 1.41 1.38 \ \ \ 4200 1.11 1.08 1.03 0.4 ~ 4400 0.82 0.78 0.73 4550 0.539 \\ 4600 0.569 0.535 0.478 0.402 ,\\ 4650 0.513 0.479 0.419 0.339 4700 0.459 0.421 0.360 0.280 \ \ 4750 0.405 0.366 0.305 0.226 \ ~ 4800 0.353 0.312 0.251 0.177 4850 0.303 0.258 0.200 0.129 \ \ 1\\ 4900 0.254 0.206 0.149 0.085 4950 0.207 0.155 0.101 0.048 0.110 0.062 0.020 5000 0.163 0.2 \ \\ \ 5050 0.121 0.074 0.034 0.004 5072* 0.0 \ 5100 0.085 0.044 0.014 \\ 5150 0.055 0.024 0.002 5180** 0.0 o. I _\ \\,\ 5200 0.031 0.010 5250 0.012 5260*** 0.0 '0 5300 0.001 \~ \~ ~ 5310t 0.0 ~:~~~ 0 o * Critical pressure at 190 F. "-. '- ~ I+- ** Critical pressure at 160 0 F. 4400 4600 4800 5000 S200 *** Critical pressure at 130°F. PRESSURE (poia I t Critical pressure at 100°F. FIG. 4 - INTERFACIAL TENSION VS PRESSURE.

258 SOCIETY OF PETROLEUM ENGINEERS JOURNAL DISCUSSION OF RESUL TS

:s 2.0 Comparison of the methane-decane system to l 7 or butane7 indicates that the interfacial ~ I.B tension in a binary system increases much more E ...... ~ slowly as pressure is decreased below the critical, ~ than the single-component systems. For instance, ! 1.6 r-...... ~ "- at lOOoF a drop in pressure of more than 1,000 psi ~ z I-- '" results in an interfacial tension of only 1 dyne/em -...... ~ ~ 1.4 ...... , ~ for the methane-decane system, while about a i::: is ~ 150-psi drop below the critical would be required ,.. ~ 1.2 ~ ~ ~ I '-...... to increase the interfacial tension to 1 dyne/em ,l!l for propane or for . This is true for each '-..... ~ 1.0 ...... ~ ~ ~ '\ isotherm studied; hence, there appears to be a ~ ~ wide region of pressure and temperature in which ~ ~ .~ ~o Downloaded from http://onepetro.org/spejournal/article-pdf/2/03/257/2157293/spe-327-pa.pdf by guest on 29 September 2021 ~ 0.8 ""~ .~ 1\; the interfacial tension is quite low. The disap­ pearance of interfacial tension divided by density 0:~ I!! ~ ~~ ~~ difference at the critical point shows that the density !' 0.6 ,~ 1\\ difference becomes predominant over surface forces ~ ~"" ~o ",""- 1\\ in the critical region. Fig. 7 shows lines of constant 0.4 """'~ N~ e"\ ~\ 1\ "- ""- interfacial tension on a pressure-temperature plot. [\\ The shape of these curves in the vicinity of pure 0.2 ~ ~'\ 1\\ \\ r\'" decane is supported by calculations using the 1\\\ Weinaug and Katz equationlO and Sage and Lacey 0.0 ~ L0 ~ 1\\ \ 100 120 140 160 180 200 220 240 260 volumetric data'! TEMPERATURE [ ·F I The assistance of Grant in Aid No. 45 of the FIG. 5 - INTERFACIAL TENSION DIVIDED BY American Petroleum Institute is gratefully acknowl­ DENSITY DIFFERENCE VS TEMPERATURE. edged.

REFERENCES 1. Sage, B. H. and Lacey, W. N.: Thermodynamic Q.6 Properties of the Lighter Paraffin and Nitrogen, API, N. Y. (1950). ~

0.5 r-...... ~ "'" '\ t-... ~ ~ \ ...... Thil WofII "'" NcJturol Got SuppIJ HDndbook ~ '\ ~ ._o_~t.. "- I -.:=-...... KotIOarreICJtion - I \ \ I ~ 4800 ~ '" / -: "" ~ '\ \ I I ",~ , , \ I -...... , " "" \ \ .. 1 '\ ~ 4000 / -- , / "" I ,, \ \''\ , \ \ i\ I \ \ ~ I ~, , \ "" ~ \ 1\ 1\ I , , \ ~ I , "'" , \ ~ \ .. \ \\ ~ l\~\ ~ 0.2 ~ \ , \ 1\ 1\ ~ , \ \ "- I~ \ "'\ FO)\ , \ \ ~\~ , \ \ \ I , \ \ ~ , 1.5 \ ~ ~ \ Pn ~ , , l~ ! \ 1\ '\, ' I I , , \ \ \ \ l\\ , \ \\\ ".11 1\ \ I , \ ~ ~ \ o. ~ \ I , 1"'- ,r, \ \ \ , \ \ """- "'\ , , \ \ \\, I , \ \ \ , , , , \ I \ , K \ ~ ~ \ [\\ \ \ ~ "" !'-..o~" I'.... ~\ , \ ~ BOO " l\ 1\ \ \ \ '!'-.. \ \ \ ) \ \ \ \ \ \\ ~ \ k\\ \ o 8 ~ ~ ~ 1\\ \ ~ 100 140 180 220 260 300 --".V \~ ~ .2CO TEMPERATURE [·FI ·300 ·100 0 100 300 400 600 lStPERATURE ['F[ """

FIG. 6 - INTERFACIAL TENSION VS TEMPERATURE. FIG. 7 - PRESSURE VS TEMPERATURE.

SEPTEMBER, 1962 259 2. Michaels, A. S. and Hauser, E. A.: "Interfacial Very Low Interfacial Tensions", Rev. of Scientific Tension at Elevated Pressure and Temperature II. Inst,uments (1957) Vol. 28, 7.74. Interfac ial Properties of -Water Systems", Jou,. Phys. Chem. (1951) Vol. 55, 408. 7. Stegemeier, G. L.: "Interfacial Tension of Synthetic Condensate Systems", PhD dissertation, U. of Texas 3. Hough, E. W., Wood, B. B. and Rsasa, M. J.: "Ad­ (1959). sorption at H2 0 - He, -CH4, -N 2 Interfaces at Pressures to 15,000 psia", Jour. Phys. Chem. 8. Fordham, S.: "Calculation of Surface Tension from (1952) VoL 56, 998. Measurements of Pendant Drops", P,oc., Royal Soc. (1948) Section 194A. 4. Walker, J. W.: "Interfacial Tension of the -Water System", Master's thesis, U. of Texas 9. Mills, O. S.: "Tables for Use in Measurement of (1955). 1FT between with Small Density Differences", British Jour. Appl. Phys. (1953) Vol. 4, 247. 5. Heuer, G. J.: "Interfacial Tension of Water against Hydrocarbon and other Gases", PhD dissertation, 10. Weinaug, C. F. and Katz, D. L.: "Surface Tension U. of Texas (1957). of Methane·Propane Mixtures", Ind. Eng. Chem. (1943) Vol. 35, 239. 6. Jennings, H. Y., Jr,: "Apparatus for Measuring *** Downloaded from http://onepetro.org/spejournal/article-pdf/2/03/257/2157293/spe-327-pa.pdf by guest on 29 September 2021

260 SOCIETY OF PETROLEUM ENGINEERS JOURNAL