Source Kitchen Characterization and Petroleum Accumulation in Songliao Basin, Northeastern China

Feiyu Wang¹, Xiongqi Pang², Zihui Feng³, Wei Fang⁴, and Jingkun Li^4
1 Petroleum University of China, Beijing, China
² Key Laboratories for Petroleum Formation Mechanics, Chinese Ministry of Education, Petroleum University, Beijing, China
³ Daqing Oilfield CO, Daqing, China
⁴ Research Institute of Exploration and Development, Daqing Oil Field Inc, CNPC, Daqing, China

The Songliao basin represents a typical nonmarine basin, where the giant Daqing oil field is the most important oil-production area in China. The Songliao basin experienced two obvious different tectonic evolutionary stage and formed two source rock assemblages: (1) late Jurassic to early Cretaceous Hauterivian rift stage, composed of volcanic and volcaniclastic rocks, alluvial and lacustrine sediments, predominated with gas-prone coal measures source rocks; (2) early Cretaceous Barremian to late Cretaceous Mastrichtian depression stage, lacustrine environment prevailed and formed widespread organic matter-rich mudstones of the Qingshankou(K2qn) and Nenjiang(K2n) Formation, thickness of balck mudstone range 60-80m and 110-250m respectively. According to geochemical, petrological screen and organic facies analysis, the prime organic-rich interval of the Qingshankou(K2qn) and Nenjiang(K2n) Formation were related to the algae blossom and anoxic events when stratified water body existed. The maturity distribution and evolution of source rocks are delineated using Trinity and Genesis software based on the stratigraphic architecture data,two hydrocarbon kitchens and super-petroleum system have been identified and described, the first is Qingshankou(K2qn) mature source kitchen, the second is late Jurassic to early Cretaceous overmature coal and terrestrial source kitchen distributed in separated rift minibasins. Nenjiang(K2n) Formation source rocks only have a minor contribution to petroleum accumulation because its immature or marginal mature phase. Oil accumulation were found both in positive and negative structural feature areas in the Qingshankou(K2qn) source kitchen distribution area because of its high source potential index, especially the discovered oil reserve of stratigraphic pools in negative structural feature areas cumulated about 2 billon ton in past twenty years. The natural gas from late Jurassic to early Cretaceous overmature gas-prone source kitchen became prospective during the past few years following discovery of a few middle size humic-type gas fields and delineation of the enormous gas reserves in the volcanic and volcaniclastic rock reservoirs.