Keywords: 
• Huabei areas /
• upper Palaeozoic /
• secondary hydrocarbon-generation /
• reservoir-forming conditions

Abstract: Huabei basin is an important hydrocarbon-generation area in East China. Source rocks in upper Paleozoic consist of coal-measure strata and dark mudstone. Because they were deeply buried and highly evolved and structural conditions are complicated after Paleozoic, there exists secondary hydrocarbon-generation in Carboniferous-Permian source rocks. Primary hydrocarbon-generation occurred in Yinzhi stage, while secondary occurred in Yanshan stage and Ximalaya stage. Source rocks distribute in Benxi Formation, Taiyuan Formation, and Shanxi Formation. And thickness in south and north areas is big while that in middle area is small. According to lots of parameters, source rocks are attributed to middle to good. Reservoirs exist in dolomite of lower Paleozoic and clastic rocks of upper Paleozoic. Primary pore poorly developed, so reservoir space mainly consists of secondary pore. And reservoir rocks are poor in physical properties, which are characterized by low porosity and low permeability. Carbonates in Fengfeng Formation, bauxite and bauxitic mudstone and overlying coal-measure strata in Benxi Formation, reddish purple mudstone and silty mudstone in Shiqianfeng Formation and lower Triassic are good cap rocks, which formed several reservoir-cap assemblages matching reservoir rocks. Traps are mostly fault anticline, fault nose and fault block. And they are good because they formed before hydrocarbon-generation period. Through analysis of reservoir-formed conditions, the formation of pools in Huabei basin mainly depended on the match of hydrocarbon-generation history, expulsion history and structural history and the preservation conditions of pools after their formation. So the future plays of the Huabei basin should be focused on the paleostructure and new structure formed Ximalaya stage where exist secondary hydrocarbon-generation.