Variability and Main Controlling Factors of Hydrocarbon Migration and Accumulation in the Lower Paleozoic Carbonate Rocks of the Tazhong Uplift, the Tarim Basin, Northwest China

Figure 10

Hydrocarbon transport modes inside and outside the carbonate source rocks in the Tazhong Uplift. (a) Modes of hydrocarbon transport inside the source rock. The source rocks of the Yurtusi Formation in the Lower Cambrian Series supply the hydrocarbons. The hydrocarbon accumulations of the lower assemblage are controlled by tectonic lithologic traps, and those of the middle and upper assemblages migrate vertically via the No. 1 Fault Zone and strike-slip faults. The hydrocarbon transport capacity of the No. 1 Fault Zone is related to the fault displacement and that of strike-slip faults is related to the multistage fault superposition pattern. The overall hydrocarbon enrichment in the northern area is higher than that in the southern area. (b) Mode of hydrocarbon transport outside the source rock. The hydrocarbons come from the northern Manjiar Sag. The hydrocarbon accumulation of the lower assemblage is controlled by tectonic lithologic traps. Affected by the No. 1 Fault Zone, the hydrocarbons of the middle and upper assemblages change their flow direction to migrate vertically and accumulate along the No. 1 Fault Zone; they then accumulate in the karst fracture cavity development area of the middle and upper assemblages.