Hydrocarbon Character Research Articles

The influence of functional groups on the pyrolysis of per- and polyfluoroalkyl substances

Thermal treatment is a widely used remediation strategy for PFAS-contaminated materials such as soil, spent sorbents, and domestic waste. To better understand the effectiveness and environmental impact of thermal treatments for PFAS-contaminated materials, a fundamental understanding of PFAS thermal degradation mechanisms is required. This work aims to study the pyrolysis of six representative PFAS compounds, all of which have an eight-carbon length but with different functional groups. To assess the thermal stability and pyrolysis products of these six PFAS compounds, evolved gas analysis (EGA) was performed using thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) coupled with an infrared spectrometer (IR) and a mass spectrometer (MS), as well as pyrolysis-GCMS (Pyr-GCMS). The EGA data demonstrates that compounds with lower estimated vapor pressures were generally found to be more thermally labile, and the presence of an ionic bond necessitates higher temperatures for pyrolysis. Pyrolysis at 900 °C yielded a variety of fluorinated organic compounds at significant signals. Tetrafluoroethene constituted the majority of the Pyr-GCMS signal for all the compounds. Moreover, a significant fraction of detected products was unable to be identified, underscoring a need for better tools to help with the identification of unknowns. Pyrolysis can occur through random chain scission, scission of the functional group, scission of the terminal CF3 group, and HF elimination. Some compounds may undergo more complete beta-scission to produce smaller pyrolysis products compared to others. The presence of acidic protons within the functional group can help facilitate HF elimination, whereas the salt form of a PFAS compound is less likely to undergo HF elimination. Termination of radical intermediates can either be recombination with a CF3 radical or hydrogen abstraction (H-abstraction). Observed hydrogen-substituted products indicate that functional groups with higher hydrocarbon character may lead to more H-abstraction terminated products. Overall findings show that the functional group of a PFAS may decrease or increase its thermal stability and lead to different profiles of pyrolysis products.

Properties and Analysis of Liquid Alternative Fuels III: Vegetable Oils and Hydrotreated Vegetable Oils

The importance of alternative fuels and biofuels is constantly growing due to energy security, sustainability, and social responsibility. This article is another in a series of review articles designed to recapitulate information on the required properties of individual alternative fuels, their testing methods, and the significance of individual analyses. This article is focused on fuels based on vegetable oils and hydrotreated vegetable oils. Rapeseed oil is a triglyceride-based fuel that can be burned in modified diesel engines. Modification of the engine consists in the inclusion of preheating of the fuel or modification of the injection system, due to the high viscosity of this fuel. Rapeseed oil and vegetable oils in general have a higher oxygen content than conventional diesel fuels, which is associated with a lower energy content than that of diesel fuels. Compared to diesel, vegetable oils have a higher density, a lower cetane number, and a significantly higher flash point and viscosity. Vegetable oils also have low oxidative stability. Physical properties monitored in rapeseed oils include density, viscosity, flash point, and calorific value. From the chemical properties, the iodine number, acidity number, water content, calcium, magnesium, sulfur, and phosphorus are monitored. From the other properties, oxidative stability, ignitability, ash content, carbonation residue, content of impurities, and appearance are monitored for rapeseed oils. HVO is a high-quality fuel for standard diesel engines. Due to the hydrocarbon character of HVO, no engine modification is required. HVO has a very high cetane number, very good low-temperature properties, optimal viscosity, high flash point, excellent oxidative stability, and a very low content of undesirable contaminants such as aromatic hydrocarbons, sulfur, nitrogen, and oxygen-containing compounds. Compared to diesel fuels, HVO has a lower density. The observed qualitative parameters and testing methods are very similar to those of conventional diesel fuel B7. The main difference lies in the modified determination of aromatic hydrocarbons.

CONDUCTIVITY STUDY OF SODIUM BROMIDE AND SODIUM CHLORIDE SALTS IN BINARY MIXTURES OFAQUEOUS AND ORGANIC SOLVENTS

The effect of solvent composition on the conductivity behaviour of sodium bromide (NaBr) and sodium chloride (NaCl) salts in binary mixed aqueous and organic solvents was evaluated using conductivity measurement. The specific conductivities of the salts in methanol-water, ethylene glycol-water and ethylene glycol-methanol mixtures were determined at different solvent compositions (0, 0.1, 0.4, 0.7 and 1) and concentrations (0.01, 0.02, 0.03, 0.04 and 0.05 M) of the salts with JENWAY 4510 conductivity meter at room temperature. The results show that the conductivities of the solutions of both salts in the mixed solvent systems were higher at lower organic solvent compositions and gradually decreased with increasing composition of the solvents. It was also observed that conductivity decreased as the hydrocarbon character of the organic solvent increased in all the binary mixtures. These results have been discussed on the basis of free-ion and ion-pair interactions as well as other chemical and physical properties of the single component solvents.

Overview of HOMEChem: House Observations of Microbial and Environmental Chemistry.

The House Observations of Microbial and Environmental Chemistry (HOMEChem) study is a collaborative field investigation designed to probe how everyday activities influence the emissions, chemical transformations and removal of trace gases and particles in indoor air. Sequential and layered experiments in a research house included cooking, cleaning, variable occupancy, and window-opening. This paper describes the overall design of HOMEChem and presents preliminary case studies investigating the concentrations of reactive trace gases, aerosol particles, and surface films. Cooking was a large source of VOCs, CO2, NOx, and particles. By number, cooking particles were predominantly in the ultrafine mode. Organic aerosol dominated the submicron mass, and, while variable between meals and throughout the cooking process, was dominated by components of hydrocarbon character and low oxygen content, similar to cooking oil. Air exchange in the house ensured that cooking particles were present for only short periods. During unoccupied background intervals, particle concentrations were lower indoors than outdoors. The cooling coils of the house ventilation system induced cyclic changes in water soluble gases. Even during unoccupied periods, concentrations of many organic trace gases were higher indoors than outdoors, consistent with housing materials being potential sources of these compounds to the outdoor environment. Organic material accumulated on indoor surfaces, and exhibited chemical signatures similar to indoor organic aerosol.

Carbonyl Chalcogenides Clusters Existing as Disguised Forms of Hydrocarbon Isomers

<p>The 4n Series Method has been utilized to categorize, analyze and predict structures for transition metal carbonyl, borane, hydrocarbon and Zintl ion clusters. The method is being extended to study carbonyl chalcogenide clusters. Adequate examples have been given to demonstrate the application of the 4n series method to categorize clusters and where possible predict their possible skeletal structures. In this paper, the method is being applied to the study of carbonyl chalcogenide cluster complexes. What has been found is the striking structural similarity of a wide range of carbonyl chalcogenide clusters to those of corresponding hydrocarbon clusters. It was observed that when a derived hydrocarbon from a cluster, F<sub>CH</sub> = C<sub>n</sub>H<sub>q</sub>, is such that n<q, the cluster portrays structural similarity with an equivalent hydrocarbon. On the other hand when n>q, the ‘hydrocarbon character’ becomes reduced and the typical cluster tendencies increase. When n = q, the situation becomes more or less a borderline case. When q=0, then F<sub>CH</sub> = C<sub>n</sub>. When the series becomes bi-capped or more, then the equivalent carbon cations are obtained.</p>

Charging history of Paleogene deep gas in the Qibei sag, Bohai Bay Basin, China

The Qibei sag (QS), at the western region of the Bohai Bay Basin (BBB), eastern China, has made significant progress in the deep gas exploration recently, indicating that the deep gas reservoirs have good exploration prospects. The deep gas reservoirs within the second member of the Shahejie Formation of the Paleogene (E2s2) are buried at approximately 5000 m. The sources and hydrocarbon accumulation mechanisms were investigated by analyzing the regional structure, integrating geologic and geochemical parameters of source rocks and natural gas. Analyzing results show that, in the QS and adjacent areas (QSAA), three sets of source rocks (E2s1, E2s2, E2s3) were developed, which differ in organic chemical characters, but have abundant organic matters in fair-good standard. Affected by burial history, E2s3 source rocks have entered into the high mature-over mature stage and E2s1 source rocks are mainly in mature stage. The methane content of natural gas (78%∼91%), the methane carbon isotope value (−41.3‰∼−34.6‰) and the positive carbon isotope sequence (δ13C1<δ13C2<δ13C3<δ13C4) indicate that the deep gas is organic origin and mainly from thermogenic gas. The relationship between light hydrocarbon character parameters and thermal evolution degree indicates that the deep gas in the QS is mainly from E2s2 and E2s3 source rocks of the sag. Since the different hydrocarbon generation history, there exist two hydrocarbon accumulation periods in QS, and the early period is characterized by oil accumulation, which occurs at the shallows, such as the Binshen6 block; the late period is characterized by gas accumulation, which happens in the depth mostly, such as the Binshen22 block. The different hydrocarbon generation history results in the relative enrichment of gas in the depth and the phenomenon of oil–gas inversion.

Collisions of DCl with a Solution Covered with Hydrophobic and Hydrophilic Ions: Tetrahexylammonium Bromide in Glycerol

Gas-liquid scattering experiments are used to investigate interfacial interactions of gaseous DCl with liquid glycerol containing 0.03 M tetrahexylammonium bromide (THABr), an ionic surfactant composed of hydrophobic THA(+) and hydrophilic Br(-) ions. Surface tension and argon scattering measurements indicate that the surface of this solution is dominated by the hexyl chains of the THA(+) ion. The hydrocarbon character of the surface is further explored by comparing Ar and DCl scattering from the THABr solution and liquid squalane. We find that the addition of THABr to glycerol alters the reactivity of DCl in two ways: DCl molecules that land on the surface are more likely to desorb when THA(+) and Br(-) are present and are less likely to dissolve, but they are also more likely to undergo rapid, interfacial DCl --> HCl exchange. Similar trends are observed when THA(+) ions are replaced by Na(+) ions in a 2.7 M NaBr solution, even though THA(+) interacts weakly with glycerol OH groups and Na(+) binds strongly to them. These observations suggest that the THA(+) hexyl chains do not physically block DCl entry and that interfacial cation-OH bonding is not essential for promoting rapid D --> H exchange when Br(-)-OH bonding also occurs. The use of THABr confirms that ions in the top few monolayers, and not those deeper in solution, control DCl entry and rapid D --> H exchange.

Petroleum composition in the Cuu Long Basin (Mekong Basin) offshore southern Vietnam

The Cuu Long Basin (Mekong Basin) is a rift basin off southern Vietnam, and the most important petroleum producing basin in the country. However, information on petroleum type and characteristics has hitherto been largely unavailable to the public. This paper presents petroleum geochemical data on nine oil samples from four different producing fields in the Cuu Long Basin: the Dragon (Rong), Black Lion (Sutu-Den), Sunrise (Rang Đong) and White Tiger (Bach Ho) Fields. The oils are highly paraffinic with bimodal normal alkane distributions and show moderate pristane to phytane ratios and a conspicuous hyperbolic decrease in abundance with increasing carbon number of hopane homologues from C 30 to C 35. The TPP-index of Holba et al. (Holba, A.G., Dzou, L.I., Wood, G.D., Ellis, L., Adam, P., Schaeffer, P., Albrecht, P., Greene, T., Hughes, W.B., 2003. Application of tetracyclic polyprenoids as indicators of input from fresh–brackish water environments. Organic Geochemistry 34, 441–469) is equal to 1 in all samples which in combination with tricyclic triperpane T26/T25 ratios >1 and the n-alkane and hopane distributions mentioned above provide a strong indication of an origin from lacustrine source rocks. This is supported by the absence of marine C 30 desmethyl steranes (i.e. 24- n-propylcholestanes) and marine diatom-derived norcholestanes. Based on the overall biological marker distributions, the lakes probably belonged to the overfilled or balanced-fill types defined by Bohacs et al. (Bohacs, K.M., Carroll, A.R., Neal, J.E., Mankiewicz, P.J., 2000. Lake-basin type, source potential, and hydrocarbon character. An integrated sequence-stratigraphic–geochemical framework. AAPG Studies in Geology 46, 3–34). The oils were generated from source rocks at early- to mid-oil-window maturity, presumably Oligocene lacustrine shales that are present in the syn-rift succession. Oils from individual fields may, however, be distinguished by a combination of biological marker parameters, such as the oleanane index, the gammacerane index, the relative abundance of tricyclic terpanes, the proportions of diasteranes and 28-norspergulane, complemented by other parameters. The oils of the Cuu Long Basin show an overall similarity to the B-10 oil from the Song Hong Basin off northern Vietnam, but are markedly different from the seepage oils known from Dam Thi Nai on the coast of central Vietnam.

Reaction of cellulose–starch gel mixtures in water at high-temperatures and pressures for developing continuous batch microreactor systems

Cellulose–starch gel mixtures (4 wt% cellulose and 4 wt% starch gel) were mixed with water in a 9:1, water:organic, volume ratios and rapidly heated (ca. 20 s) to high-temperatures (ca. 520 °C) and high-pressures (ca. 800 MPa) in 0.04 μL microreactors to examine their characteristics and reaction products. Contents of the microreactors were observed during the heating with microscopy and residues were analyzed with chromatography and spectroscopy. At high water loading densities (ca. 980 kg/m 3), heating of either starch gels or cellulose–starch gel mixtures gave a light yellow colored liquid associated with 5-hydroxymethylfurfural along with solid products that had strong absorptions at 1630 and 1530 cm −1 associated with aromatic and polycyclic ring compounds. At low water loading densities (<700 kg/m 3), a brown colored liquid was generated that had an oil-like, paraffinic hydrocarbon character along with gases, but no particles were formed. The cellulose–starch gels studied in this work can possibly be used as feedstocks in continuous batch microreactor systems.

The Parent Hexacarbaborane arachno-C6 B6 H12 and a Methylated Pentacarbaborane arachno-CH3 C5 B7 H12 : Domains of Incipient Hydrocarbon Behavior within Borane Clusters.

Increasingly pronounced hydrocarbon character is exhibited by C6 H6 B12 , the first unsubstituted hexacarbaborane, and CH3 C5 B7 H12 , the first cluster pentacarbaborane. These compounds shed light on the structural dichotomy between open hydrocarbon skeletons and polyhedral borane frameworks for high-carbon carboranes.

Bis(5-carbomethoxy-1,3-phenylene)-30-crown-4: a macrocyclic monomer of predominantly hydrocarbon character

A general route to 5,5′-difunctionalized bis( m-phenylene) macrocycles ( 1) is reported. Bis(5-carbomethoxy1,3-phenylene)-30-crown-4 ( 1e) has been synthesized in one step from methyl 3,5-dihydroxybenzoate and 1,10-dibromodecane in the presence of sodium hydride in dimethylformamide. This monomer is suitable for synthesis of backbone polymacrocycles of predominantly hydrocarbon character.

1,1,1,4,4,4-Hexafluorbutane (R 356), a potential CFC substitute

As part of the world-wide efforts to limit the antropogenic depletion of the stratospheric ozone layer, there is an intensive search for substitutes for all chlorine-containing compounds used in refrigeration. Beside the H-CFCs with reduced ozone depletion potential (ODP), to date only perfluoroalkanes with a high greenhouse potential have been put forward as blowing agents in PUR rigid foams. We consider 1,1,1,4,4,4-hexafluorbutane (R 356) to be the better alternative than the above-mentioned substitutes. In spite of the C 4-carbon framework, the physical properties of hexafluorbutane are very similiar to those of R 11. R 356 is not combustible, nor is a gas-air-mixture explosive. Hexafluorbutane also seems to be well-suited from the ecological point of view: by definition, its ozone depletion potential is zero. Due to the partial hydrocarbon character, R 356 is rapidly decomposed in the atmosphere, and thus contributes only minimally to the greenhouse effect. A synthetic route is presented, and an overview given of properties of the technical application of R 356 in PUR rigid foam.

Naphthalenes associated with treated wastewater effluents in an urban national wildlife refuge

This project demonstrates the polynuclear aromatic hydrocarbon character of Jamaica Bay sediments and the wastewater effluents entering the Bay from four major water pollution control facilities. Jamaica Bay, is a part of the Hudson-Raritan estuarine ecosystem and is incorporated into the Gateway National Recreation Area. Jamaica Bay, because of its hydrological characteristics, affords a long residence time for introduced pollutants. This study was conducted to further characterize the PAH character of the wastewater effluents. These fused ring structures are of interest in that they represent the carcinogenic, mutagenic, and toxic components of petroleum compounds to marine organisms. Because of their high molecular weight, the solubility of PAH in water, is of a very low order. Consequently, in estuarine environments, PAH compounds will be found associated with suspended solids and sediments. Although PAH degrading microorganisms are known to occur in estuarine environments, the degradation rates of these compounds are very slow. Coupled with the low degradation rates and known carcinogenicity of many of these compounds, investigations have shown that fish and other organisms taken from areas with a history of oil contamination have been found to exhibit elevated levels of compounds which bioactivate complex PAH compounds into mutagens.

Paleostructural Control of Dakota Hydrocarbon Accumulations on Southern Moxa Arch, Southwest Wyoming and Northeast Utah: ABSTRACT

Production from the Lower Cretaceous Dakota Formation along the southern Moxa arch shows a number of anomalies in distribution and hydrocarbon character that can best be explained by complex interplay of the arch's depositional, structural, diagenetic, and thermal histories. The development of the Western Overthrust belt and its foreland basin largely controlled the orientation of the Dakota fluvial and deltaic systems. Differences in sandstone trends between the upper and lower Dakota resulted in different migration pathways an loci of oil and gas accumulations. Isochore mapping indicates that the onset of major structural growth of the Moxa arch began contemporaneous with deformation in the Overthrust belt during the Cretaceous Campanian. After early migration of hydrocarbons into the resulting structural/stratigraphic traps, subsequent diagenesis of Dakota sandstones, particularly in the downdip water legs of the reservoirs, effectively sealed the accumulations in their initial paleostructural position. Paleocene and Eocene structural compression reversed the original northward plunge of the arch and rotated it slightly to the east into its present structural configuration. Hydrodynamically driven convective heat flow has resulted in varying geothermal regimes within the area, increasing heat flow along most of the arch's crest, while cooling its southern portion. This phenomena has affected gas-oilmore » ratios and API gravities by enhancing or retarding thermal maturation of the trapped hydrocarbons.« less

Monterey Problems: Enhanced Mud-Logging Techniques Integrated with Rock Mechanics and Geochemistry for a Solution: ABSTRACT

Miocene Monterey Formation of southern California is an extremely complex lithological sequence. The delineation of producing intervals using wireline analysis is difficult at best as most production appears to occur from fractured intervals. Interpretation is also hampered by the extreme variability in lithological character and in hydrocarbon character (tar to gas). Recent studies using conventional and enhanced mud-logging techniques, including geochemistry, have demonstrated the applicability of good geological analysis in the delineation of producing intervals in the Monterey. The techniques utilized are based on the integration of surface-acquired geological and engineering data, MWD data, and geochemical data. Delineation of fractured intervals is accomplished through the integration of drilling response modeling and pulsed Nuclear Magnetic Resonance (pNMR) measurements of porosity on drilled cuttings. Delineation of potential producing intervals is accomplished by detailed hydrocarbon analysis (gas ratios, entrained gas, normalized gas, and geochemistry). In nonfractured intervals, permeability and irreducible water saturations can be estimated using integrated MWD and drilled cuttings (pNMR and sample examination) analyses. The use of this composite geological technique while drilling is illustrated by several examples. The techniques described can be applied to wildcat wells in the Monterey without the need to develop empirical relationships for specific fields.

Evaluation of a thermionic detector for capillary supercritical fluid chromatography of nitrated polycyclic aromatic compounds

AbstractA thermionic detector was evaluated for capillary supercritical fluid chromatography of polar nitro‐containing polycyclic aromatic compounds (nitro‐PAC). Three modes of detector operation were studied. The best performance was obtained using a nitro‐selective mode of detection. Although linearity was confined to a narrow range for a given source current, the sensitivity was excellent; 20 pg injected for p‐nitrophenol gave a signal‐to‐noise ratio of 3. Conventional thermionic detection also produced good sensitivity; however, serious baseline drift was observed at high operating temperatures using density programming. A third mode, flame thermionic detection, was not acceptable because of low sensitivity. A number of nitro‐PAC were successfully chromatographed using density programming at 101°C. Hydroxynitropyrenes, nitropyrene quinones, and 9‐hydroxy‐2‐nitrofluorene, which could not be eluted in capillary gas chromatography, were successfully chromatographed here. Retention of these compounds increased sequentially on 50% n‐octyl‐, 5% phenyl‐, and 25% biphenyl polysiloxane stationary phases, respectively. Stationary phase interactions appeared to be more a function of the polar functional groups on the aromatic rings than of the hydrocarbon character of the compounds. Solute solubility in the mobile phase and volatility were additional factors contributing to the elution of these molecules. Finally, these results were used to identify a number of nitro‐PAC in a polar subfraction of a diesel particulate extract.

Mutagenicity and chemical characterization of two petroleum distillates.

To investigate if the Salmonella/microsome assay could reliably screen complex petroleum samples for their carcinogenic potential, two high boiling (700-1070 degrees F) petroleum distillates with known activity in a dermal carcinogenesis bioassay were fully characterized with respect to their hydrocarbon composition and polynuclear aromatic hydrocarbon (PNA) content and assayed for mutagenic activity. Mutagenicity assays were also carried out on the aromatic hydrocarbon aggregates separated from these oils by adsorption chromatography. The composition of the distillates differed substantially, and reflected the fact that they were derived from crude oils that were extremely divergent in hydrocarbon character. Both the distillate and aromatic samples consistently induced a very slight increase in revertant TA98 and TA100 colonies; however, an increase of 2-4-fold over background was observed when the S-9 concentration was increased 5-10 times that of the standard assay. The maximal response was less than that expected from the samples' known PNA content and observed potency in the dermal carcinogenesis bioassay. In the Salmonella/microsome assay, all samples inhibited the mutagenic activity of added benzo[a]pyrene. Discordance between the magnitude of the samples' mutagenic activity and their known PNA content may be related to direct or indirect inhibition of sample PNAs by other components of the complex petroleum fractions. Observed inhibitory effects support the use of elevated S-9 concentration in the in vitro assays assessing the carcinogenic potential of petroleum-derived materials.

Interpretation of Hydrocarbon Shows Using Light (C1-C5) Hydrocarbons: ABSTRACT

Mathematical treatment of light hydrocarbons (C1-C5) in the interpretation of hydrocarbon shows has been attempted by many authors. The methods so far developed have been used on specialized grids and can only be used for a few readings per grid. A study of a large number of mud logs from many different geologic environments was conducted to compare hydrocarbon shows to various ratios of C1-C5 hydrocarbons. The aim of the study was to produce a method of interpretation of reservoir hydrocarbon character using C1-C5 gas shows that would be relatively simple to calculate, plot, and interpret. The method also had to be easily integrated with other reservoir character plots and logs such as mud logs and wireline data; hence it had to be plotted on a depth log while not losing any interpretational value. From this study, a new method of mathematical treatment was evolved End_Page 484------------------------------ which can be performed at the wellsite during drilling, and by study of the relationship of the ratios, initial evaluation of the reservoir characteristics is possible. End_of_Article - Last_Page 485------------

Anatomy of Texas Oil: ABSTRACT

Approximately 153 billion bbl of in-place oil have been discovered in Texas oil reservoirs. Characterization of 500 of the largest of these reservoirs (those that have cumulative oil productions of more than 10 million bbl) on the basis of geologic and engineering parameters, facilitates the grouping of Texas oil reservoirs into families or of similar reservoir geology and common engineering and production attributes. Basic data for each reservoir were tabulated from information in the hearing files of the Texas Railroad Commission and other public sources. Thirty variables were examined for each reservoir. Oil plays were characterized in terms of: (a) reservoir genesis, (b) petrophysical properties of the reservoir, (c) trapping mechanism, (d) drive mechanism, (e fluid properties, (f) volume of in-place oil, (g) recoverable reserves, (h) calculated oil recovery efficiency, and (i) End_Page 560------------------------------ reservoir management practices and conventional well spacing. Most of the major Texas oil reservoirs can be grouped into 48 geological plays which account for 71% (32 billion bbl) of all Texas oil production. Twenty-one of the plays are located in a belt along the Texas Gulf coastal plain and in the East Texas basin. Mesozoic and Cenozoic sandstone reservoirs deposited in fluvial-deltaic and strandplain systems dominate over fluvial sandstones and carbonate reservoirs. The remaining 27 plays extend westward from north-central to west-central Texas. Dolomite is the prevalent reservoir lithology with sandstone and reef-associated limestone being more abundant than chert, conglomerate, and nonreef associated limestone. Reservoir genesis in the north and west Texas plays is diverse and includes a spectrum of clastic depositional environments from fan and fan delta to slope and basin systems. Carbonate reservoirs have been interpreted as open and restricted shelf deposits, platform margin-assoc ated banks and reefs, and deeper water atoll and pinnacle reef systems. Unconformity-related reservoirs in west and east Texas, such as the prolific East Texas field, are grouped into two plays regardless of the depositional history of the reservoir. Recovery efficiencies of the Paleozoic north and west Texas plays are considerably lower than those of the coastal plain and east Texas plays. The effects of drive mechanism, lithology, permeability, API gravity, and viscosity on reservoir performance are well known. An additional important control on recovery efficiency that has been emphasized by this study is reservoir genesis. Although productivity can be modified by extremes in permeability or hydrocarbon character, it otherwise follows predictable trends based on the known geologic complexity and heterogeneity of the depositional system of the reservoir. End_of_Article - Last_Page 561------------

Phase behavior of alcohol-hydrocarbon-brine mixtures

Ten monohydric alcohols (methanol through tert-amyl alcohol), representing a class of amphiphiles that contrast surfactants which efficiently solubilize hydrocarbon and brine, were mixed with equal volumes of hydrocarbons and brine of various salinities. The resulting multiphase mixtures were examined for the number of coexisting liquid phases and the partitioning of the alcohol among them. The patterns of phase behavior are similar to those observed with amphiphiles classified as surfactants. The dependence on salinity, hydrocarbon character, and temperature is similar also. The patterns of phase behavior in the alcohol systems may be characteristic of all amphiphile--hydrocarbon--brine systems. 5 figures, 5 tables.