Amounts Of Heavier Hydrocarbons Research Articles

Evaluating the total oil yield using a single routine Rock-Eval experiment on as-received shales

Shales in the early maturity and oil window stages contain a considerable amount of heavy hydrocarbons (S2oil) having strong interactions with kerogen/rock that make the accurate measurement of total oil (total extractable organic matter) more difficult from the routine Rock-Eval experiment. In this study, a fast method for evaluating the total oil yield using a single routine Rock-Eval experiment on as-received shales is proposed. First, the temperature threshold (TOK) of the S2oil and cracking hydrocarbons were determined by combining the pyrograms of the as-received shale with a solvent-extracted replicate. Then, the total oil yield was directly derived from the hydrocarbons evaporate at a temperature below than TOK in a routine Rock-Eval experiment. The results show that the TOK value is controlled by the sample’s maturity and pore structure. The higher the maturity, the larger the specific surface area and the smaller the pore size, the greater the TOK. A prediction model of TOK was proposed based on the sample’s production index (PI). The total oil yields estimated by the two methods of both the TOK prediction model and the average TOK value (465 °C) are consistent with those obtained by Jarvie (2012) using the thermal-extraction method with correlation coefficients of 0.983 and 0.9548, respectively. Compared with the previous methods, the single routine Rock-Eval experiment method proposed in this study is convenient and not requires an extraction experiment. In addition, there are archived routine pyrolysis data available that can be used to directly calculate the total oil yield based on the temperature threshold.

Modified product selectivity in Fischer-Tropsch synthesis by catalyst pre-treatment

Fischer-Tropsch Synthesis (FTS) yields a spectrum of products with carbon lengths of 1 to upwards of 100 units. In order to make use of the full spectrum of hydrocarbon fractions, particularly the heavier units, secondary processing is required. Modifying the FTS product distribution and catalyst activity in order to decrease the amount of long chain hydrocarbons (C25+) may allow significant simplification of FTS based processes. To this end we report the results of in-situ pre-treatment of alumina supported cobalt catalysts (Co/Ru/La – Al2O3) with acetylene in a fixed-bed reactor. It is postulated that acetylene dissociation and dehydrogenation resulted in the generation of carbidic and CxHy species on the catalyst surface. The formation of these carbonaceous species on different active sites of the catalyst surface following pre-treatment also significantly altered the FTS product distribution by affecting the extent and pathway of 1-olefin secondary reactions. It is thought that these changes resulted from decreased incorporation of 1-olefins in further chain growth and a decrease in secondary hydrogenation rate. The amount of heavy hydrocarbons (waxes) produced was reduced by more than two-fold.

Influence of Fischer-Tropsch synthesis (FTS) and hydrocracking (HC) conditions on the product distribution of an integrated FTS-HC process

The integration of Fischer-Tropsch synthesis (FTS) with direct hydrocracking (HC) was investigated in a two-stage reactor system, where the influence of FTS performance (concentration of residual H2 and CO as well as amount of heavy hydrocarbons) on HC was studied and the overall performance of the integrated process was analyzed regarding the liquid fuel (C5-C20) selectivity. Sufficient cracking of the C21+ fraction was achieved under FTS conditions and primary cracking was proven as dominant. Higher temperature has a positive effect on HC, but too high temperature would turn out to increase the C1-4 selectivity and a maximum of 70wt.% C5-C20 was obtained. The cracking of FTS hydrocarbons could be divided into two categories, cracking of heavy molecules via liquid phase and cracking of light molecules depending on gas phase. The cracking of lights was slightly suppressed when raising the H2 partial pressure, while the cracking of heavy molecules showed no response. Differently, an increase of the CO partial pressure obviously inhibited the cracking performance of both fractions. The wax flow rate study revealed a quite selective cracking of FTS wax, since the cracking of light hydrocarbons is partial pressure-limited. As long as enough wax covers the catalyst along the bed, a further increase in the catalyst amount has no effect on the final product distribution.

Soils and waste water purification from oil products using combined methods under the North conditions

Oil and gas production and transportation in Russia is increasingly moving to the north regions. Such regions are characterized by relatively low self-purification capacity of the natural environments from the contaminants due to slow character of the energy exchange and mass transfer processes. Off-shore field development in the Barents Sea and oil product transportation can result in contamination, as confirmed by the national and international practice of the developed oil and gas regions. The research aims at development of the soil bioremediation methods and industrial waste water purification contaminated by oil products in the north-western region of Russia. The dynamics of oil products carry-over have been investigated under the field model experiments in podzolic soils: gas condensate, diesel fuel and mazut from oil and the plants were selected for phyto-remediation of contaminated soils under high north latitudes. It is shown that soil purification from light hydrocarbons takes place during one vegetation period. In three months of the vegetation period the gas condensate was completely removed from the soil, diesel fuel – almost completely (more than 90%). Residual amounts of heavy hydrocarbons were traced, even 1.5 later. The following plants that were highly resistant to the oil product contamination were recommended for bioremediation: Phalaroides arundinacea, Festuca pratensis, Phleum pratense, Leymus arenarius. There has been developed and patented the combined method of treatment of waste water contaminated with hydrocarbons based on inorganic coagulants and local oil-oxidizing bacteria.

Conventional vs Sustainable Transportation Fuels for the Future

AbstractIt is clear that in the next ten years major changes will be required in our liquids for transportation energy scenario. These changes are driven by two major factors. The first is the desire to achieve 'energy independence' and the second is the desire to achieve an 'environmentally friendly' fuel supply. These two forces will dominate energy research and development in the near future. This presupposes that the lack of viable hydrogen storage materials and the long-range electric vehicle materials will continue to be limiting the hydrogen and electric vehicle technology. The DOE recently reported that the available amounts of heavy hydrocarbons (tars, coal and shale oils) in North America (United States, Canada and Mexico) are sufficient for 500 years at current rates of usage. However, these sources must be converted to liquid transportation fuels in an environmentally favorable manner. Also, promising sources of sustainable liquid transportation fuels maybe found in growing algae and converting the contained lipids to biodiesel. In this presentation we discuss recent development in both areas that promise a smooth transition from conventional to the use of sustainable transportation fuel sources.

Release of fossil methane from mineral soil particles, and its implication for estimation of methane oxidation in a mineral subsoil

In a preliminary experiment we found that methane evolved from a sandy subsoil during aerobic incubation of shaken soil slurries. In the study presented here the methane was found to be released from the sand particles by mechanical weathering, caused by the grinding effect of the shaking. Large amounts of gas (about 0.5 ml gas g−1 soil) were extracted by intense grinding of the soil in gas tight serum vials. Methane was the main hydrocarbon in the emitted gas, but also a considerable amount of ethane was present, as well as minor amounts of heavier hydrocarbons (up to C6). The δ13C-values of the emitted methane and ethane were −33 ‰ and −29 ‰, respectively. Together these results demonstrate a thermogenic origin of the gas. This paper also reports the results of an incubation experiment where possible methane oxidation was looked for. If a possible release of methane is not accounted for, methane oxidation may be overlooked, as illustrated in this paper. Methane consumption was detected only in soil from 40 cm, in contrast to soil sampled at 100 cm and deeper where a slight production was measured. When methane oxidation was inhibited by dimethyl-ether, a significant release of methane was seen. The release was probably caused by chemical weathering. When this methane release was taken into account, methane oxidation was found to be present at all measured depths (40 to 200 cm). Fertilization with urea inhibited the methane oxidation at 40 cm but not at deeper layers. It is hypothesized that ammonia oxidizing bacteria were the main methane oxidizers in this mineral subsoil (deeper than 1 m), and that oxidation of methane might be a survival mechanism for ammonia oxidizers in ammonia limited environments.

Natural-Gas Hydrates of Blake Ridge Region, Atlantic Continental Margin: ABSTRACT

A strong acoustic reflection that parallels the sea floor has been observed in seismic profiles collected over the Blake Ridge region, off the southeastern United States. This anomalous reflection occurs at a subbottom depth of 400 to 700 m in water depths of 750 to 3,750 m and has been mapped over an area of at least 80,000 km2. The reflection probably is due to the contrast between an upper high-velocity zone of sediment cemented by gas hydrates and an underlying low-velocity zone that does not contain gas hydrates. Coring by the Deep Sea Drilling Project (DSDP) has shown that gas hydrates are present in this region. During DSDP Leg 11, high concentrations of gas were observed; gas was composed mainly of methane of light carbon isotopic composition (< -70 per mil relative to PDB standard) accompanied by minor amounts of heavier hydrocarbons and carbon dioxide. DSDP Leg 76 confirmed that high concentrations of methane are present in sediment from this region. Conclusive evidence for gas hydrates was obtained when a vigorously outgassing sediment sample with a matlike layer of white crystals was recovered. The volume of gas released from this sample was about 20 times the volume of pore fluid, a result clearly indicating gas hydrate. Results obtained by using a pressure core barrel also indicate that gas hydrate is present. The molecular composition of the hydrocarbon gases and the isotopic composition of the methane suggest that the methane is of biologic origin. This methane, if trapped beneath the gas hydrate in reservoir rocks, could represent a significant resource. End_of_Article - Last_Page 1665------------