A new recovery process for producing oil under both secondary and tertiary conditions utilizes the unique properties of micellar solutions (also known as microemulsions, swollen micelles, and soluble oils). These solutions, which displace 100 percent of the oil in the reservoir contacted, can be driven through the reservoir with water and are stable in the presence of reservoir water and rock. Basic components of micellar solutions are surfactant, hydrocarbon and water. They may also contain small amounts of electrolytes and co-surfactants such as alcohols. The specific reservoir application dictates the type and concentration of each component. A salient feature of the process is the capability for mobility control. Micellar solution slug mobility, by way of viscosity control, is made equal to or less than the combined oil and water mobility. Mobility control continues with a mobility buffer that prevents drive water from contacting the micellar solution. Laboratory and field flooding have proven that the process is technically feasible and that surfactant losses by adsorption on porous media are small. Introduction Projects are under way to recover the maximum amount of oil under the most favorable economic conditions. New techniques are being developed to increase oil recovery. Polymer solutions are becoming an important means of controlling mobility in a waterflood. Thermal methods such as in-situ combustion and steam injection are being used in reservoirs containing highly viscous crudes. Surfactant flooding is receiving attention as a method of reducing interfacial tension to increase recovery. Exotic recovery processes have been considered primarily for secondary operations. Economics are unfavorable in most cases for tertiary recovery. Studies at the Denver Research Center of the Marathon Oil Co. have led to a new oil recovery method. Micellar solutions (sometimes called microemulsions, swollen micelles, and soluble oils) are used to recover oil by miscible-type waterflooding. Basically, these solutions contain surfactant, hydrocarbon, and water. The method can be used in either secondary or tertiary operations.

High-resolution proton magnetic resonance spectra have been determined for the dimethylcyclohexanes and several related hydrocarbons between —130° and 130°C. All of the compounds which should undergo rapid ring inversion at room temperature produce spectra which change upon cooling because of ``freezing out'' of this motion. The assumption that appearance of the ring-hydrogen resonances as a relatively narrow band is invariably a symptom of rapid ring inversion is shown to be unfounded. Several of the ring spectra differ drastically from what is predicted using a bond-anisotropy model. A previously unrecognized effect must then make a significant contribution to the observed chemical shifts.

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Both traditional and DNA-based methods sometimes fail to differentiate between closely related strains of commercial interest in the brewing industry. The aim of this study was to compare species and sub species of Saccharomyces cerevisiae on the basis of their polar lipid chemistry using chromatographic methods. Six isolates were studied after propagation under batch conditions. Polar lipids were then extracted from lyophilised cultures and analysed by TLC in order to separate phospholipid families. TLC showed that the major phospholipid classes present were PC > PE > PG. Two unidentified phospholipids were found, one only in strain 34 /70. The major peaks detected by GLC were identified as methyl esters of palmitic acid and palmitoleic acid. The fatty acid composition of PC varied between strains and novel data on lecithin acyl constituents were observed. The polar lipid method succeeded in differentiating strain 34 /70 -one of the most commonly used brewer's lager yeast -from strain 34 /78 and other species tested. The presence of unusual polar lipids in Saccharomyces sensu stricto yeasts may be useful in distinguishing between other closely related strains.

Saccharomyces pastorianus syn. carlsbergensis strain 34/70 is well known to be the most used strain for lager beer production. The difference between this strain and very closely related strain 34/78 is the latter's greater flocculating character. This single physiological trait can cause technical difficulties in beer production. The aim of this study was to determine whether lipid analysis by a combination of thin layer chromatography (TLC) with electrospray ionization mass spectrometry (ESI-MS) could be used as a strain-typing technique in order to distinguish S. pastorianus syn. carlsbergensis strain 34/70 from strain 34/78. Both strains (34/70 and 34/78) were harvested after continuous culture under standard conditions. Polar lipids were then extracted from lyophilized cultures and analysed by TLC in order to separate phospholipid families. Phosphatidylethanolamine (PE) was extracted and investigated using ESI-MS, to gain further information on individual molecular species. Using TLC analysis, lipids were separated corresponding to standards for PE, phosphatidylcholine (PC), phosphatidylglycerol (PG), cardiolipin (CL), phosphatidylserine (PS), phosphatidylinositol (PI), phosphatidic acid (PA) and sphingomyelin (SM). ESI-MS of the PE band, separated by TLC, showed that electrospray mass spectra were highly reproducible for repeat cultures. Novel findings were that both brewing strains displayed major phospholipid peaks with m/z 714, PE (34 : 2) m/z 742, PE (36 : 2) and m/z 758, PE (37 : 1). However, strain 34/78 had additional peaks of m/z 700, PE (33 : 2) and m/z 728, PE (35 : 2). Strain 34/70 had an extra peak with m/z 686 PE (32 : 2). We conclude that combined TLC/ESI-MS can distinguish between S. pastorianus syn. carlsbergensis 34/70 and 34/78 and may be a useful typing technique for differentiation of closely related yeast strains. This novel approach may aid quality assurance and could be suitable for yeast collections and larger industrial companies.