Petroleum Traps

Most of the large volume of cmde petroleum consumed in the world is extracted from only a small fraction of the total number of oil fields discovered. The concentration of cmde petroleum in a few large fields is a consequence of the interaction of the geologic processes that create and trap petroleum. Even though commercial quantities of petroleum have been discovered in many locaHties around the world, there are enormous volume differences in fields present in a single region and in the total volume of petroleum present in different regions. 

Stratigraphic Traps. Petroleum geologists also seek another kind of trap, the stratigraphic trap, which results when a porous layer is pinched ... 

TVap Configuration of strata, such as an anticline, capable of trapping petroleum. 

Though no single theory has received universal acceptance, the last mentioned is one of the most popular. Perhaps an understanding of the mechanism is not too important. The significant fact is that gas chromatography can correlate kerogen in source beds with the trapped petroleum that once emigrated from them. 

Even if all of the elements described so far have been present within a sedimentary basin an accumulation will not necessarily be encountered. One of the crucial questions in prospect evaluation is about the timing of events. The deformation of strata into a suitable trap has to precede the maturation and migration of petroleum. The reservoir seal must have been intact throughout geologic time. If a leak occurred sometime in the past, the exploration well will only encounter small amounts of residual hydrocarbons. Conversely, a seal such as a fault may have developed early on in the field s history and prevented the migration of hydrocarbons into the structure. 

When we consider sources of methane we have to add old methane methane that was formed millions of years ago but became trapped beneath the earth s surface to the new methane just de scribed Firedamp an explosion hazard to miners oc curs in layers of coal and is mostly methane Petroleum deposits formed by microbial decomposi tion of plant material under anaerobic conditions are always accompanied by pockets of natural gas which IS mostly methane... 

Liquid-mtrogen traps Liquid oxygen Liquid petroleum gas... 

L. B. Magoon and W. G. Dow, The Petroleum System—Erom Source to Trap, AAPG Memok 60, American Association of Petroleum Geologists, Tulsa, Okla., 1994, 644 pp. 

Petroleum Recovery. Steam is iajected iato oil wells for tertiary petroleum recovery. Steam pumped iato the partly depleted oil reservoirs through iaput wells decreases the viscosity of cmde oil trapped ia the porous rock of a reservoir, displaces the cmde, and maintains the pressure needed to push the oil toward the production well (see Petroleum, enhanced recovery). Steam is also used ia hot-water extractioa of oil from tar sands (qv) ia the caustic conditioning before the separatioa ia a flotatioa tank (35). 

The ASME code requires every pressure vessel that can be blocked in to have a relief valve to alleviate pressure build up due to thermal expan sion of trapped gases or liquids. In addition, the American Petroleum Institute Recommended Practice (API RP) 14C, Analysis, Design, Installation and Testing of Basic Surface Safety Systems on Offshore Production Platforms, recommends that relief valves be installed at vari ous locations in the production system and API RP 520, Design and Installation of Pressure Relieving Systems in Refineries, recommends various conditions for sizing relief valves. 

Some petroleum geologists believe that there may be more methane trapped in hydrates than what is associated with natural gas reserves. However, as an energy source, there is considerable uncertainty whether this methane can ever be recovered safely, economically, and with minimal environmental impact. The Russians have experimented with the use of antifreeze to break down hydrates at some onshore locations in Siberia. But perhaps a more promising approach would be to pipe warm surface water to the bottom to melt the hydrates, with a collector positioned to convey the gas to the surface. Another approach might be to free methane by somehow reducing the pressure on the methane hydrates. 

C03-0150. A sample of a component of petroleum was subjected to combustion analysis. An empty vial of mass 2.7534 g was filled with the sample, after which vial plus sample had a mass of 2.8954 g. The sample was burned in a combustion train whose CO2 trap had a mass of 54.4375 g and whose H2 O trap had a mass of 47.8845 g. At the end of the analysis, the CO2 trap had a new mass of 54.9140 g and the H2O trap had a new mass of 47.9961 g. Determine the empirical formula of this component of petroleum. 

Acetylcyclohexanone. Method A. Place a mixture of 24-6 g. of cyclohexanone (regenerated from the bisulphite compound) and 61 g. (47 5 ml.) of A.R. acetic anhydride in a 500 ml. three-necked flask, fitted with an efficient sealed stirrer, a gas inlet tube reaching to within 1-2 cm. of the surface of the liquid combined with a thermometer immersed in the liquid (compare Fig. II, 7, 12, 6), and (in the third neck) a gas outlet tube leading to an alkali or water trap (Fig. II, 8, 1). Immerse the flask in a bath of Dry Ice - acetone, stir the mixture vigorously and pass commercial boron trifluoride (via an empty wash bottle and then through 95 per cent, sulphuric acid) as fast as possible (10-20 minutes) until the mixture, kept at 0-10°, is saturated (copious evolution of white fumes when the outlet tube is disconnected from the trap). Replace the Dry Ice-acetone bath by an ice bath and pass the gas in at a slower rate to ensure maximum absorption. Stir for 3 6 hours whilst allowing the ice bath to attain room temperature slowly. Pour the reaction mixture into a solution of 136 g. of hydrated sodium acetate in 250 ml. of water, reflux for 60 minutes (or until the boron fluoride complexes are hydrolysed), cool in ice and extract with three 50 ml. portions of petroleum ether, b.p. 40-60° (1), wash the combined extracts free of acid with sodium bicarbonate solution, dry over anhydrous calcium sulphate, remove the solvent by... 

The most common methods for trapping pesticide vapors from air use adsorbents. Common air sampling adsorbents include charcoal (derived from petroleum or coconut) and synthetic polymeric materials, such as cross-linked polystyrene and open-cell polyurethane foam. Charcoal has been used for the cumulative sampling of volatile... 

The purpose of alkali flooding (Jennings et al., 1974) is to introduce alkali into a reservoir where it can react with organic acids in the oil to produce organic salts, which act as surfactants. The surfactants (or petroleum soaps ) generated reduce the surface tension between the oil and water and this in turn reduces the level of capillary trapping of the oil. Thus, more oil is recovered because less of it remains trapped in the formation s pore spaces. 

CAFB [Chemically active fluidized-bed] A coal-gasification process intended for producing gas for power generation. Coal particles are injected into a shallow bed of lime particles that trap the sulfur dioxide. The bed particles are regenerated in a second fluidized bed, releasing the sulfur dioxide. Developed in the 1970s by the Esso Petroleum Company, UK, but not commercialized. 

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