The Distribution Character and Development Model of Hydrocarbon Source Rocks of Lower Palaeozoic,the Eastern North China

Researching the hydrocarbon source rocks of Lower Palaeozoic in North China is very important to the pre-Tertiary oil-gas strategic precinct.From the point of view of sedimentology,the type,quality evaluation,genesis and development model of hydrocarbon source rocks in the study area were analysed according to the statistics of parameters TOC(%),S1+S2 and bitumen A.The research shows: there are preferable hydrocarbon source rocks in the Lower-Majiagou Formation,the Upper-Majiagou Formation and the Fengfeng Formation of Ordovician,whose mean TOC values are 0.183%,0.21% and 0.181% respectively;The high quality hydrocarbon source rocks develop in Lower Cambrian and distribute in the limited region,whose mean TOC value is 6.46% and max TOC value is 11.2%.According to the rock types,the hydrocarbon source rocks in North China can be divided into two series,the claystone type source rock in Lower-Cambrian and the carbonatite type source rock in Lower-Middle Ordovician.The genesis of hydrocarbon source rocks lies on sedimentary environment: claystone type source rock develops in the shallow-sea continental shelf and carbonatite type source rock is controlled by the tidal flat and restricted platform.The study of spatial distribution rule of hydrocarbon source rocks finds that Hefei basin is the potential developed region of claystone type source rock and Dongpu depression,Linqing depression and Jizhong depression are the ones of carbonatite type source rock.These results can provide a lot of effective geological information of the pre-Tertiary oil-gas strategic precinct in the eastern North China.