Geochemical characteristics and accumulated process of heavy crude oil of Chunguang oilfield in Junggar Basin, China

Chunguang oilfield is a new focus of the exploration in Junnggar Basin with the heavy crude oil distributing in Jurassic, Cretaceous and Tertiary strata. Based on the analysis of the geochemistry and fluid inclusion in the reservoirs, the source, accumulated period and process of the heavy crude oil reservoir has been investigated. The results indicate that the heavy crude oil can be divided into three types based on the degradation and sources. The heavy crude oil was mainly derived from the Permian source rocks, and latterly mixed by the heavy crude oil generated by the Jurassic source rocks. The accumulated period of the heavy crude oil has two stages. One was ranged from Cretaceous to Paleogene and the heavy crude oil was sourced from Permian source rocks of the Shawan depression and latterly mixed by the heavy crude oil generated by the Jurassic source rocks. The second period was from Neogene to present and the heavy crude oil was mainly derived from the Jurassic source rocks. Combined with the geological evolution, the heavy crude oil accumulated process has been recovered.