Metal-reducing microorganisms reduce a variety of metals in metabolic processes coupled to the oxidation of organic compounds. These bacteria play an important role in the biogeochemical cycling of metals and organic matter in anaerobic aquatic and sediment ecosystems. It has been proposed recently that metal-reducing microorganisms also are active in deep subsurface environments such as petroleum reservoirs. Only two metal-reducing bacteria have been isolated from petroleum reservoir fluids, Shewanella putrefaciens and Deferribacter thermophilus. This project studied the occurrence and distribution of metal-reducing microorganisms in petroleum reservoirs. The research focused on the isolation, characterisation and identification of anaerobic bacteria from petroleum reservoirs that were capable of reducing metals and the potential roles of these isolates in the microbial ecology and biogeochemical cycling of petroleum reservoirs. Petroleum reservoirs were selected for this study on the basis of physio-chemical conditions such as temperature, salinity, pH and the presence of organic and inorganic compounds, that were likely to provide a suitable environment for anaerobic bacteria capable of reducing metals. Factors such as the stratigraphic features of the sedimentary basin, age of reservoir and past oil field practices also were considered in choosing the reservoir for study. Seven petroleum reservoirs in the USA and Azerbaijan were chosen for extensive investigations. The physico-chemical conditions in these reservoirs varied substantially. A systematic study of the production water from these petroleum reservoirs revealed a consistent presence of iron- and manganese-reducing microorganisms. It was found that salinity and temperature play a significant and defining role in the occurrence and distribution of these metal-reducing microorganisms. Biotic metal reduction was detected from production waters from all but one of the oil wells sampled. It was significant that the water from this well (Neftcala #1074) was the most saline (78 g/l NaCI). Metal-reducing activity was detected at temperatures up to 70°C. Two pure cultures, strains RED1 for Redwash petroleum reservoir (USA) and NEF1 from the Neftcala petroleum reservoir (Azerbaijan) were isolated and characterized. The strains had diverse physiological and metabolic properties including the ability to oxidize a wide range of carbon compounds and reduce a variety of metals. Their temperature, salinity and pH optima varied markedly. Phylogenetic analyses of the 16S rRNA of strain RED1 showed that the strain represented a new species of a new genus in the domain Bacteria. The bacterium most closely related to strain RED1 is the fermentative Fe(III)-reducer, Pelobacter acetylenicus (similarity value, 92.8%). Strain NEF1 possesses a unique combination of phenotypic traits and a low mol % G+C. From preliminary analyses and comparative biochemistry, NEF1 appears to be a novel metal-reducing bacterium of the Flexistipes group. The bacteria isolated in this study were able to grow at temperatures and salinities consistent with the reservoir from which they were isolated. This indicated that petroleum reservoirs are a new source of physiologically diverse, novel, metal-reducing microorganisms. The bacteria isolated also demonstrated a number of characteristics that would enable them to survive and persist in extreme subsurface conditions and develop a selective ecological advantage in petroleum reservoir environments. Significantly, the metal-reducing bacteria isolated were able to utilize an array of metabolic products produced by bacteria indigenous to petroleum reservoirs. This has resulted in a new proposed model for the ecological succession of bacteria in petroleum reservoirs.

Thesis (Ph.D.)--University of Oklahoma, 2004. / Title from title screen (viewed on Dec. 7, 2007). Title from document title page. Includes bibliographical references. Available in PDF format via the World Wide Web.

Thesis (Ph. D.)--University of Wyoming, 2006. / Title from PDF title page (viewed on Dec. 20, 2007). Includes bibliographical references (p. 208-216).

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This study proposes two methods, (1) a probabilistic method based on historical oil prices and (2) a method based on Gaussian simulation, to model future prices of oil. With these methods to model future oil prices, we can calculate the ranges of uncertainty in traditional probability indicators based on cash flow analysis, such as net present values, net present value to investment ratio and internal rate of return. We found that conventional methods used to quantify uncertainty which use high, low and base prices produce uncertainty ranges far narrower than those observed historically. These methods fail because they do not capture the "shocks" in oil prices that arise from geopolitical events or supply-demand imbalances. Quantifying uncertainty is becoming increasingly important in the petroleum industry as many current investment opportunities in reservoir development require large investments, many in harsh exploration environments, with intensive technology requirements. Insight into the range of uncertainty, particularly for downside, may influence our investment decision in these difficult areas.

This report studies the application of carbon nanomaterials as a novel type of tracer in detection of residual oil. The carbon nanomaterials studied include oxidized carbon black (OCB) coated with different molecular weight polyvinyl alcohols(PVAs). Transport studies are conducted using columns packed with ground core materials, with synthetic seawater as the carrying fluid. Compared to lower molecular weight PVA-functionalized OCBs, the breakthrough of PVA(50K)-OCBs is less sensitive to aging and temperature; therefore, PVA(50K)-OCBs are chosen as nanoreporters to sequester chemical tags. Two different tags, 14 C labeled 2,2',5,5'-tetrachlorobiphenyl(PCB) and triphenylamine, are tested in the experiments. Efficient transport of tags through oil-field rocks and selective release when rocks contain oil are demonstrated. The kinetics of PCB adsorption is studied to better understand correlation between PCB release and oil content. A linear relationship between residual oil content and PCB release is found in flow-through experiments.

The fouling characteristics of a desalted crude oil were investigated in a systematic investigation. There are two main parts in this study, the dry bulk tests (dehydrated crude oil) and the wet bulk tests (to which desalter brine was added). Three barrels of desalted crude oil provided by Amoco Oil Company were studied. For the dry bulk tests, no brine was added to the crude oil. The effects of fluid velocity and surface temperature on fouling were investigated. The higher the surface temperature the greater the fouling was observed. Fouling decreased with an increase of fluid velocity. Fluid velocity had a stronger effect on fouling at low surface temperatures than at high surface temperatures. It was also observed that the fouling behavior of crude oil depended on small difference in composition. The threshold surface temperatures for the initiation of fouling were 400-450 °F (3.0 ft/sec), 525-550 °F (5.5 ft/sec), 550-600 °F (8.0 ft/sec) and about 600 °F (10.0 ft/sec) for Barrel No. 2 and Barrel No. 3. For Barrel No. 1 however, the threshold surface temperatures were about 550 °F (3.0 ft/sec) and 600 °F (5.5 ft/sec). For the wet bulk tests, a certain amount desalter brine (weight percentage = 0.8%) was added to the crude oil for each run. The effects of fluid velocity, surface temperature and the presence of brine on fouling were investigated. Higher surface temperature enhanced fouling considerably. Fouling was reduced as fluid velocity was increased. It was shown that brine had a strong effect on fouling. No fouling occurred for velocities of 5.5 and 8.0 ft/sec at a surface temperature of 350 °F which was a condition for which an aqueous phase was present and the salt remained in solution. Significant fouling occurred for velocities of 5.5 and 8.0 ft/sec at a surface temperature operated at a low 400 °F (Tb = 300 °F) which was a condition for which the aqueous phase at the heat transfer surface was dissolved or boiled to extinction and the salt was deposited on the heat transfer surface. / Graduation date: 1991

Petroleum coke (petcoke) has been burned at kraft pulp mills to partially substitute for natural gas and fuel oil used in lime kilns. Due to the high vanadium and sulfur contents in petcoke, there had been concerns over the impact of burning petcoke on kiln and chemical recovery operations. Laboratory studies were performed to examine the fate of vanadium and sulfur in lime kilns and chemical recovery cycle. The results suggest that most of the vanadium in petcoke quickly forms calcium vanadates with lime in the kiln, mostly 3CaO•V2O5. In the causticizers, calcium vanadates react with Na2CO3 in green liquor to form sodium vanadate (NaVO3). Due to its high solubility, NaVO3 dissolves in the liquor circulating around the chemical recovery system. V becomes enriched in the liquor, leading to vanadium build-up in the system. The S in petcoke would stay in the reburned lime, lower the lime availability, increase SO2 emissions from the kiln stack, alter the S balance, increase the liquor sulphidity, and potentially contribute to ring formation in the kiln.

Petroleum coke (petcoke) has been burned at kraft pulp mills to partially substitute for natural gas and fuel oil used in lime kilns. Due to the high vanadium and sulfur contents in petcoke, there had been concerns over the impact of burning petcoke on kiln and chemical recovery operations. Laboratory studies were performed to examine the fate of vanadium and sulfur in lime kilns and chemical recovery cycle. The results suggest that most of the vanadium in petcoke quickly forms calcium vanadates with lime in the kiln, mostly 3CaO•V2O5. In the causticizers, calcium vanadates react with Na2CO3 in green liquor to form sodium vanadate (NaVO3). Due to its high solubility, NaVO3 dissolves in the liquor circulating around the chemical recovery system. V becomes enriched in the liquor, leading to vanadium build-up in the system. The S in petcoke would stay in the reburned lime, lower the lime availability, increase SO2 emissions from the kiln stack, alter the S balance, increase the liquor sulphidity, and potentially contribute to ring formation in the kiln.

The system studied in this thesis is called the Low Rise Return system and uses a partly filled marine drilling riser with a variable mud level which is used control the bottom holes pressure.Initially main components of the Low Riser Return System are listed and explained. Then the performance characteristics of the system are explored. Level movements in riser during level increase and decrease at constant mud pump rates are explained along with the effect of mud pump rate on maximum level increase and decrease rates.A simple simulator is then presented that calculates the bottom hole pressure when pump rates are changed. The simulator includes a function that enables it to simulate lost circulation scenarios.The simulator is used to simulate some preferred scenarios. First a pressure increase and decrease at constant mud pump rates are simulated. Then it is shown how a faster pressure decrease can be achieved by temporarily lowering the mud pump rate. Next simulations are shown where changes in mud level are used to compensate for changes in equivalent circulation density as mud pump rates are changed. Finally simulations are run that demonstrate how mud level can be reduced to cure lost circulation scenarios. Results and lessons learned are then discussed.