Petroleum systems of the Southwest Caspian Basin
- State Oil Company of Azerbaijan, Baku (Azerbaijan)
The Southwest Caspian Basin, located in offshore Azerbaijan, contains significant accumulations of oil and gas in Upper Tertiary siliciclastic sediments. The central basin contains up to 25 km of sediments. The relatively low geothermal gradients and low degree of compaction from rapid burial provide favorable conditions or the retention of hydrocarbons at relatively great depths. A variety of structural styles occur, ranging from anticlinal folds to monoclines, with various degrees of reverse faulting and brecciation. Molecular characterization of selected oil samples indicate most of the oils have been sourced form the same or similar facies; a Tertiary Type II, slightly calcareous, marine clastic facies. Insufficient organic-rich rocks are available for a reliable oil-source correlation. Examination of oil molecular characteristics, oil-oil correlations, molecular characteristics of key stratigraphic horizons, paleofacies maps, maturation, and potential migration pathways suggest the oil was not syngenetic but most likely sourced from deeper Oligo-Miocene or older marine shales. Compositional data for a single offshore gas sample suggest the gas is a mixture of low maturity Type III and biogenic. A multi-stage model of hydrocarbon emplacement for evolving structural traps has been postulated. The first phase of emplacement occurred in the Middle Pliocene when tectonic movement and significant subsidence initiated early trap/reservoir formation, migration, and hydrocarbon generation. Late Quaternary tectonic activity lead to the replenishment of older depleted traps, additional hydrocarbons for enhanced traps, and charging of new traps. In addition, late tectonic activity caused extensive redistribution of hydrocarbon accumulations, degassing due to breached faults, and destruction of selected oil pools.
- OSTI ID:
- 127316
- Report Number(s):
- CONF-950995--
- Journal Information:
- AAPG Bulletin, Journal Name: AAPG Bulletin Journal Issue: 8 Vol. 79; ISSN 0149-1423; ISSN AABUD2
- Country of Publication:
- United States
- Language:
- English
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