Jurassic hydrocarbon accumulation period division in Huanjiang oilfield: evidence from fluid inclusions

This study provides a detailed description and quantitative analysis of Jurassic hydrocarbon inclusions in the Huanjiang area in the Ordos Basin through fluid inclusion analysis and homogenisation temperature measurement, revealing the hydrocarbon filling process and accumulation stages of the sandstone oil reservoir. The results show that oil pool of the Yan'an Formation is generally accumulated with mature and highly mature hydrocarbon, with the later one being the main period, and is characterised by filling sequence from bottom to top. Each layer exhibits obvious characteristics of two stages hydrocarbon filling, with the oil pool forming period being the Early Cretaceous, and the main filling period being the middle to late Early Cretaceous, which is basically consistent with the main hydrocarbon accumulation period of the basin. This indicates that the western margin thrust structure is dominated by uplifted, while the source rocks have not undergone further subsidence for hydrocarbon generation and expulsion. [Received: May 7, 2024; Accepted: June 14, 2024]