Accumulation model based on factors controlling Ordovician hydrocarbons generation, migration, and enrichment in the Tazhong area, Tarim Basin, NW China

摘要

The hydrocarbon accumulation model of Ordovician reservoirs in the Tazhong area, Tarim Basin, was investigated based on the analysis of the key factors controlling hydrocarbon generation, migration, and enrichment process and history. The results show that the hydrocarbon generation processes are controlled by Cambrian-Lower Ordovician and Upper Ordovician source rocks distributed in the Tazhong area and the Manjiaer Sag. Vertical hydrocarbon migration distance is controlled by the vertical source-reservoir distribution, faults, and caprocks. Structure played a major role in the lateral hydrocarbon migration along NW-SE direction. Lateral migration pathways were governed by unconformities, transport faults, and reef-beach body reservoirs. A part from the sedimentary control, hydrocarbon enrichment is controlled by recent tectonic events. The hydrocarbon charging points refer to the intersection of northeast- and northwest-trending faults. Two types of hydrocarbon accumulation models could be retained, (a) mixed-sourced area model, in which the hydrocarbons are sourced from both the Tazhong area and the Majiaer Sag, and (b) single-sourced area model, in which the hydrocarbons are only sourced from the Tazhong area itself.