RESEARCH Detergents Recover Oil Ethylene oxide-propylene oxide type detergent beats out most alkylphenols for low adsorbency honors U S I X G detergents to revive depleted oil wells by w a t e r flooding schemes m a y be more economical than has been thought. Reason: Nonionic detergents of t h e ethylene oxide-propylene oxide type aren't adsorbed as easily, or as much, on the inside surfaces of an oil well as are other nonionic detergents (ethylene oxide-alkylphenol condensates ). With t h e alkylphenols, adsorption could force detergent costs to run too high in relation to oil producing a n d processing costs. Research at the U. S. Bureau of Mines' petroleum experiment station at Bartlesville, Okla., shows that adsorption of ethylene oxicle-propylene oxide condensates might b e only one tenth that of the alkylphenols, H. Neal D u n ning and H. Roland Heydegger told t h e 33rd National Colloid Symposium in Minneapolis, sponsored by t h e ACS Division of Colloid Chemistry. W a t e i nuocling is used to displace oil in wells once considered worn out. At times, notes Dunning, only about one third of an oil reservoir can be tapped by conventional methods. T h e rest of
Pluronic H a s Lowest Adsorption Detergent
Adsorption in Water Micromoles per gram quartz
Pluronic L-64 Alkylphenols Octylphenol
Nonylphenol
0.225 10.0 6.1 4.4 18.8 12.0 8.7 6.5 3.6
9.7" 12
17 6.5 7.9 10.3 11.5 20
*Numbers denote ratio of moles of ethylene oxide to one mole of alkylphenol.
4 0
C&EN
JULY
6,
1959
it is held tightly on the sand and rock surfaces inside the well. In the past, such a well was considered depleted. But today, water p u m p e d into the reservoir displaces the adsorbed oil, can make t h e well a producing one again. Detergents are used because a detergent-water solution displaces the oil from hydrophobic surfaces more efficiently than does water alone. Also, d e tergents would permit using lower water pressures at less cost. The hooker, though, is that the detergent itself m a y be too readily adsorbed by the same surfaces. Thus, a high a n d uneconomical concentration of detergent would have to be used in a commercial operation. • R a d i o t r a c e r M e t h o d s Used. T h e specific detergent studied b y BuMines is Wyandotte's Pluronic L-64. General formula tor the JPiuromcs is H Ö ( C H40)m(CÄH„0)n(C2H40)I1H. The cendensed ethylene oxide portion of the molecule is labeled with carbon-14. Other nonionics are studied by spectrophotometries techniques. Since Pluronics have no groups that absorb energy in t h e visible or ultraviolet regions, they can't be checked this way. Solutions (10 to 1800 p.p.m.) of the tagged Pluronic L-64 are shaken with quartz for a day. Concentration is determined before and after shaking by measuring radioactivity with a GeigerMueller tube. Adsorption is calculated from t h e changes in concentration. Here's how Pluronic L-64's adsorption checks out. At lower concentrations, between 0 and 100 micromoles of detergent per gram of quartz, the adsorption curve rises steeply, then levels off. Beyond 100 micromoles, adsorption is practically constant until about 400. Then it apparently picks up again, says Dunning, although experimental errors ill *"V»i*f" ι·:ΐησρ nrp oiiif-F1! large since the increase in adsorption is so slight. Maximum adsorption is
0.225 micromoles per gram of quartz. • H i g h e r A d s o r p t i o n . With the al kylphenol detergents, adsorptions are m u c h higher. Maximums for these range from 3.6 to 18.S micromoles per gram, according to Dunning. Another measure of low adsorption: A molecule of t h e Pluronic takes u p an area of 2880 square Angstroms against 35 to 200 square Angstroms for alkylphenols. D u n n i n g emphasizes that these com parisons between alkylphenols and the Pluronic hold only for oil well flooding. For man\- other uses, h e says, the alkyl phenols are still the best detergents. L o w adsorption for the ethylene ox ide-propylene oxide condensate also means t h e solution moves more rapidly while it's working. Nonionic deter gents move through porous media much like they d o through a chromatographic zone. T h e front boundary of such a zone has self-sharpening tendencies; the boundary's front fights channeling, dif fusion, a n d a lack of equilibrium, all of which tend to decrease concentration. Low adsorption helps keep u p concen tration so the front moves along faster. W h y t h e low adsorption with the Pluronic? D u n n i n g says it may he due to t h e central location and large size of the hydrophobic polypropylene group in t h e molecule. W i t h other nonionics, the h y d r o p h o b i c alkylphenol is a small end group.
Red Polymer Work High U.S.S.R. rated equal to U. S. in polymer chemistry; em phasis on thermostable plastics JL H E big effort in Soviet plastics re search today is on thermostable poly mers—those w h i c h are stable u p to 6 0 0 ° C. for use in missiles, jets, and nose cones. And Soviet research workers have the potential to succeed. Soviet research in plastics is on a par with that in t h e U. S.; it's i n production w h e r e the Soviets fall down. The plas tics produced by the U.S.S.R. d o not match the quality of those made in the U. S. T h e s e are the opinions of Herman Mark, Brooklyn Polytechnic Institute. H e m a d e his comments a t a meeting marking the 40th anniversary of Foster Grant. Mark, a consultant for Foster Grant, returned from the U.S.S.R. in M a y (his second tour; t h e first took
