Geochemical Transformation of Petroleum

Andreev, P.F.; Bogomolov, A.I.; Dobryanskii, A.F.; Kartsev, A.A.

doi:10.1016/b978-0-08-012450-6.50006-1

Cited by 7 publications

(5 citation statements)

References 1 publication

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“…The downward transition zone towards anaerobic, relatively reducing conditions (horizontal contours between about 500 and 700 m; Fig. 1) is defined by the penetration depth of dissolved molecular oxygen, which generally reaches no more than about 600 m (Andreev et al 1968). By extension, anaerobic/anoxic, relatively reducing diagenetic settings in mature sedimentary basins are common below the aerobic/oxygenated environments.…”

Section: Geological and Geochemical Boundary Conditionsmentioning

confidence: 99%

Magnetic mineral assemblages and magnetic contrasts in diagenetic environments — with implications for studies of palaeomagnetism, hydrocarbon migration and exploration

Machel

1995

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Magnetic mineral assemblages in diagenetic environments are governed by microbial and inorganic/chemical processes. Empirical evidence and thermodynamic modelling of diagenetic environments ranging from near-surface settings to depths of about 6-7 km suggests that microbial processes are very important in surface and near-surface diagenetic settings, whereas inorganic diagenetic processes dominate in most deeper subsurface diagenetic settings. In all diagenetic environments, molecular oxygen and hydrocarbons are important because they control which types of bacteria can thrive and because they drive various redox reactions via changes in the redox potential.Iron oxides, such as hematite and goethite, are stable under relatively oxidizing/aerobic conditions. With decreasing redox potential, i.e. under relatively reducing/anaerobic conditions, magnetite and pyrrhotite are the most important stable magnetic minerals, whereas hematite is unstable. Other magnetic minerals, such as greigite, may be important in some instances. Pyrite and siderite are also important because they may form at the expense of magnetic minerals. A significant decrease in the redox potential in diagenetic settings, via the invasion of hydrocarbons during migration or seepage from traps, for example, almost invariably results in diagenetic remagnetization. As a result 'positive', 'absent' or 'negative' magnetic contrasts are generated relative to the total magnetization (or remanence, or susceptibility) before such a decrease, depending on the relative amounts of magnetic to non-magnetic minerals formed and destroyed. Thermodynamic modelling further suggests that magnetic contrasts are more probable and tend to become more 'positive' with depth and with proximity to hydrocarbon pools. Any significant change in the redox potential is likely to cause magnetic contrasts via the formation or destruction of magnetic minerals, thus generating secondary (chemical) magnetization and resetting original detrital or bacterial magnetization. The predicted magnetic contrasts are also likely to form as a result of hydrocarbon migration, and it appears possible to delineate migration timing and pathways by geomagnetic methods. Hence the predicted magnetic mineral assemblages can aid in the interpretation of palaeomagnetic studies, particularly via the recognition and proper interpretation of remagnetization. Magnetic contrasts, measured from the air, at the surface or on drill core, can be used for hydrocarbon exploration in association with other exploration methods.

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Section: Geological and Geochemical Boundary Conditionsmentioning

confidence: 99%

Magnetic mineral assemblages and magnetic contrasts in diagenetic environments — with implications for studies of palaeomagnetism, hydrocarbon migration and exploration

Machel

1995

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“…Price (1973) concluded that deeply buried hot water at 150~ could dissolve large amounts of hydrocarbons. As the transformation of smectite to illite results in the production of large amounts of water at temperatures considered by many workers to be adequate for hydrocarbon generation (Colombo, 1967;Andreev et al, 1968;Kartsev et al, 1971 ;Yeroleyev, 1972), it seems likely that the process has often been important in primary oil migration.…”

Section: Introducyionmentioning

confidence: 99%

Diagenesis of Clay Minerals from Lower Cretaceous Shales of North Eastern British Columbia

Foscolos¹

1974

Clays and clay miner.

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Abstract--Clay minerals from shale outcrops of the Lower Cretaceous Buckinghorse Formation (4250 fl thick) were investigated in order to assess their degree of diagenesis and their oil-generating potential. Crystallinity index, sharpness ratio, per cent of illite which is the 2M polymorph and presence of discrete minerals have been studied in the whole clay fraction, while the very fine clay fraction has been subjected to X-ray diffraction, differential thermal, thermogravimetric, differential thermogravimetric, i.r. spectroscopy, surface area and chemical analyses. With information derived from these studies and from published data, a classification scheme was devised which relates variation of clay mineralogy to diagenetic stages and burial depth. Data on the < 2 #m size fraction show that the crystallinity index decreases while the sharpness ratio and per cent of illite which is the 2M polymorph increase with burial depth. Results on the <0.08/zm fraction reveal that a three-component interstratified clay mineral exists. In addition, Fourier transform calculations and chemical and physicochemical analyses indicate that both the ratio of the amounts of nonhydrated clays (illite) to hydrated clays and the K2O content of clays increase with burial depth: cation exchange capacity and surface area decrease with burial depth.

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“…1977). The thickness of this ‘aeration zone’ varies, but it can reach up to a depth of 600 m within regional aquifers (Andreev et al. 1968).…”

Section: Discussionmentioning

confidence: 99%

“…2003). It should be further pointed out that dissolved oxygen in groundwater can react with hydrocarbons inorganically (Andreev et al. 1968).…”

Section: Discussionmentioning

confidence: 99%

Evaluation of soluble benzene migration in the Uinta Basin

Zhang¹,

Person²,

Merino³

et al. 2005

Geofluids

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Field sampling and mathematical modeling are used to study the long-distance transport and attenuation of petroleum-derived benzene in the Uinta Basin, Utah. Benzene concentration was measured from oil and oil field formation waters of the Altamont-Bluebell and Pariette Bench oil fields in the basin. It was also measured from springs located in the regional groundwater discharge areas, hydraulically down-gradient from the oil fields sampled. The average benzene concentration in oils and co-produced waters is 1946 and 4.9 ppm at the AltamontBluebell field and 1533 and 0.6 ppm at the Pariette Bench field, respectively. Benzene concentration is below the detection limit in all springs sampled. Mathematical models are constructed along a northÀsouth trending transect across the basin through both fields. The models represent groundwater flow, heat transfer and advective/ dispersive benzene transport in the basin, as well as benzene diffusion within the oil reservoirs. The coupled groundwater flow and heat transfer model is calibrated using available thermal and hydrologic data. We were able to reproduce the observed excess fluid pressure within the lower Green River Formation and the observed convective temperature anomalies across the northern basin. Using the computed best-fit flow and temperature, the coupled transport model simulates water washing of benzene from the oil reservoirs. Without the effect of benzene attenuation, dissolved benzene reaches the regional groundwater discharge areas in measurable concentration (>0.01 ppm); with attenuation, benzene concentration diminishes to below the detection limit within 1À4 km from the reservoirs. Attenuation also controls the amount of water washing over time. In general, models that represent benzene attenuation in the basin produce results more consistent with field observations.

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Geochemical Transformation of Petroleum

Cited by 7 publications

References 1 publication

Magnetic mineral assemblages and magnetic contrasts in diagenetic environments — with implications for studies of palaeomagnetism, hydrocarbon migration and exploration

Magnetic mineral assemblages and magnetic contrasts in diagenetic environments — with implications for studies of palaeomagnetism, hydrocarbon migration and exploration

Diagenesis of Clay Minerals from Lower Cretaceous Shales of North Eastern British Columbia

Evaluation of soluble benzene migration in the Uinta Basin

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