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Differentially protected 1,2-diols were synthesized by enantioselective aldehyde α-oxygenation followed by organomagnesium or -lithium addition. Contrary to a previous report, the resultant diols possess an anti configuration. Good selectivity was achieved regardless of the hybridization state of the nucleophile or the presence or absence of branching. This method was applied to short syntheses of all possible stereoisomers of two oxylipins from Dracontium loretense with incomplete stereochemical assignments. Spectroscopic comparisons between the synthetic and natural oxylipins led to unambiguous assignments.

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Short-hydrophobe surfactants based on cosolvent species have been studied as novel surfactants for enhanced oil recovery. The objective of this research is to investigate such simple surfactants as a sole additive that enhances the efficiency of oil displacement by creating low-tension polymer (LTP) fronts. This paper presents the potential enhancement of oil displacement efficiency by LTP flooding based on comprehensive experimental data, such as interfacial tensions (IFTs), surfactant partition coefficients, surfactant adsorption in a sandpack, polymer/LTP rheology, and sandpack flooding results. The optimal LTP identified was composed of 0.5 wt % 2-ethylhexanol-7PO-15EO in partially hydrolyzed polyacrylamide polymer solution, which reduced the IFT with heavy oil from 15.8 to 0.025 dyn/cm, without creating microemulsions. The surfactant adsorption in the sandpack was only 0.055 mg-surfactant/g-sand. Sandpack flooding results show that the LTP flooding achieved an incremental oil recovery in comparison to straight-polymer flooding. The oil recovery at 1 pore-volume injected (PVI) was 47% original-oil-in-place (OOIP) for the polymer flooding, 63% for the smaller LTP slugs (0.5 wt % surfactant for 0.1 PVI and 0.1 wt % surfactant for 0.5 PVI), and 70% for the larger LTP slug (0.5 wt % surfactant for 0.5 PVI). Fractional flow theory was applied to confirm that the IFT reduction by 3 orders of magnitude was conducive to a lowered residual oil saturation in LTP flooding, leading to a delayed polymer breakthrough and an increased oil cut thereafter in comparison to polymer flooding.

Summary Reservoir wettability plays an important role in waterflooding, especially in fractured carbonate reservoirs since oil recovery from the rock matrix is inefficient because of their mixed wettability. This paper presents the first investigation of amino acids as wettability modifiers that increase waterflooding oil recovery in carbonate reservoirs. All experiments used a heavy-oil sample taken from a carbonate reservoir. Two amino acids were tested, glycine and β-alanine. Contact angle experiments with oil-aged calcite were conducted at room temperature with deionized (DI) water, and then at 368 K with three saline solutions: 243 571-mg/L salinity formation brine (FB), 68 975-mg/L salinity injection brine 1 (IB1), and 6898-mg/L salinity injection brine 2 (IB2). IB2 was made by dilution of IB1. The contact angle experiment with 5-wt% glycine solution in FB (FB-Gly5) resulted in an average contact angle of 50°, in comparison to 130° with FB, at 368 K. Some of the oil droplets were completely detached from the calcite surface within a few days. In contrast, the β-alanine solutions were not effective in wettability alteration of oil-aged calcite with the brines tested at 368 K. Glycine was further studied in spontaneous and forced imbibition experiments with oil-aged Indiana limestone cores at 368 K using IB2 and three solutions of 5 wt% glycine in FB, IB1, and IB2 (FB-Gly5, IB1-Gly5, and IB2-Gly5). The oil recovery factors from the imbibition experiments gave the Amott index to water as follows: 0.65 for FB-Gly5, 0.59 for IB1-Gly5, 0.61 for IB2-Gly5, and 0.33 for IB2. This indicates a clear, positive impact of glycine on wettability alteration of the Indiana limestone cores tested. Two possible mechanisms were explained for glycine to enhance the spontaneous imbibition in oil-wet carbonate rocks. The primary mechanism is that the glycine solution weakens the interaction between polar oil components and positively charged rock surfaces when the solution pH is between glycine's isoelectric point (pI) and the surface's point of zero charge (pzc). The secondary mechanism is that the addition of glycine tends to decrease the solution pH slightly, which in turn changes the carbonate wettability in brines to a less oil-wet state. The amino acids tested in this research are nontoxic and commercially available at relatively low cost. The results suggest a new method of enhancing waterflooding, for which the novel mechanism of wettability alteration involves the interplay between amino acid pI, solution's pH, and rock's pzc.