Characteristics of hydrocarbon distribution and analysis of the main controlling factors for reservoir formation in the central and southern anticline zone of XH Depression

In order to clarify the main controlling factors for reservoir formation in the central and southern anticline zone of XH Depression, three typical oil and gas fields in the central and southern part, including T Gas Field, H Gas Field, and R Gas Field, were dissected. The results showed that the source and accumulation stage of hydrocarbons in the central and southern anticline belt were consistent, but there were significant differences in hydrocarbon distribution, mainly manifesting in three aspects: enrichment degree, vertical distribution horizon and plane occurrence location. The analysis believed that the main controlling factors causing the differences in hydrocarbon distribution were fault system, hydrocarbon source rock distribution, source-reservoir structural overlap relationship, and fault-sand coupling relationship. The difference of fault system determined the vertical distribution horizon of hydrocarbons and the differential enrichment degree inside the structure; the difference of maturity and thickness distribution of coal measure source rocks in Pinghu Formation determined the regional hydrocarbon enrichment degree; under the background of hydrocarbon accumulation outside the source rocks in Huagang Formation, the overlap relationship between the top surface structure of Pinghu Formation source rocks and the reservoir structure of Huagang Formation determined the local structural hydrocarbon accumulation intensity; and under the background of strong waterway in Huagang Formation in the central and southern part, the coupling relationship between faults and sand bodies determined the hydrocarbon accumulation scale of single layer.