摘要
The tidal zones and shallow water areas of Liaohe are prospective for exploration,but are still under-explored and the hydrocarbon distribution has not been unveiled at present.Based on the previous study results and in combination with the specific geological conditions,the patterns of hydrocarbon enrichment are studied in this area.Three sets of sources rocks including the 3rd and 1st members of the Shahejie Formation as well as the Dongying Formation are developed in the Paleogene in the study area under control of structures and sedimentary evolution.These source rocks are featured by extensive distribution,large thickness and huge hydrocarbon-generation potential from the dominant hybrid-and humic-type kerogens.Oil and gas distribution patterns vary in different areas.The major controlling factors of hydrocarbon pooling from west to east are successively lateral migration,vertical migration,lithologic sealsing and vertical migration and accumulation in fault blocks.In addition,the types of oil/gas reservoirs change from oil reservoirs to gas reservoirs progressively from west to east.Three hydrocarbon pooling modes are recognized,namely the low(or normal) pressure fault terrace mode in the west,the high pressure compound mode in the midde,and the high pressure fault block mode in the east.The distribution and enrichment of oil and gas are mainly controlled by hydrocarbon kitchen,carrier system and reservoir quality.