LAUSR

Tahe oil field is the first marine origin oil field in China, with proven reserves of 500 million tons. Given the important role of the paleogeomorphology in controlling the formation and distribution of karst reservoirs, this paper restored the pre-Carboniferous paleokarst landform in the major blocks of the Tahe oil field, via the paleogeomorphic genesis assembly method. First, four types of secondary landform units (karst platform, karst gentle slope, karst steep slope, and karst intermountain basin) were defined. Next, landform identification factors were added to these four types, to further divide the paleokarst landform into ten tertiary landform units. This enabled a more precise identification of the paleogeomorphic landforms. The karst development and the properties of hydrocarbon reservoirs in micro-geomorphic units were assessed. In addition, the relationship between petroleum production and geomorphology was analysed to robustly predict karst reservoirs in the Tahe oil field. The results show that karst develops differently according to the ancient landform units it developed from and that the current karst function is highly dependent on the precursor ancient landform. In addition, the morphology of the ancient landform significantly controls hydrocarbon accumulation, with oil and gas production being highly associated with the degree of karst development in each landscape unit. The research results indicate that the position of the slope in the karst hill and residual peak is favorable for future oil and gas exploration.