Abstract:
The frontal uplift of Kuqa foreland basin is located at the southern end of the basin, which is rich in oil and gas resources. It is an important field for oil-gas exploration in Kuqa foreland basin. At present, oil and gas discoveries have been made in exploration of both marine cratonic tectonic strata and continental foreland tectonic strata in the lower and upper parts of the frontal uplift, respectively. The complex geological background leads to significant differences in oil and gas accumulation characteristics between the two sets of tectonic strata, thus restricting the further oil-gas exploration. Based on the data of drilling, rock thin section and source rock tests, reservoir property analysis, and hydrocarbon assay, this paper systematically investigates the oil and gas source, hydrocarbon accumulation period, oil and gas migration direction, and transport system characteristics of the western section of the frontal uplift of Kuqa foreland basin, and clarifies the hydrocarbon accumulation conditions of the western section of the frontal uplift. Further, in combination with the analyses of typical reservoirs, the types and distribution characteristics of reservoirs in the study area are determined. The findings show that:(1) The oil and gas in the western section of the frontal uplift of Kuqa foreland basin are mainly originated from the Triassic-Jurassic lacustrine source rocks and coal-measure source rocks in the northern part of the basin; (2) Mesozoic-Cenozoic sand body and tectonics co-controlled reservoirs and marine paleoweathering crust dominated buried hill reservoirs are developed in the study area; according to the differences of depositional setting and lithology, the latter can be further divided into marine carbonate paleoweathering crust type buried hill reservoirs and marine clastic paleoweathering crust type buried hill reservoirs; (3) Based on various hydrocarbon accumulation factors, the favorable exploration area of marine palaeoweathering crust buried hill reservoirs (Type I), that of the Paleogene basal sandstone sand body and tectonics co-controlled reservoirs (Type II), and that of the Cretaceous Baxigai Formation sandbody-structure co-controlled reservoirs (Type III) are optimized in the study area, aiming to provide theoretical guidance for further oil-gas exploration.