Genetic Analysis on Es4 Nature Gases in Northern Steep Slop of Dongying Depression——An Example of Well Fengshen 1

On the basis of composition natural gas,carbon isotopes and the potential hydrocarbon souzce rocks of Well Fengshen 1,the result of oil-source correlation shows that the gas generation is mainly the lower member of Es4 high and over-matured source rocks,perhaps it is mixed with hydrocarbon generated by the Ek2 source rocks.Based on the thermal experiment of crude oil from Well Wanggu 1,Well Boshen 6 and source rocks from Well Fengshen 1,Well Boshen 3 the discriminal indexes of natural gas generation types are established for Well Fengshen 1.Analysis of some methods such as gas composition,carbon isotope,light hydrocarbon and fluid inclusion illustrates that natural gas from Well Fengshen 1 is mainly attributed to kerogen-cracking gas and 10%～15% amount of oil-cracking gas.Study results show that the lower Es4 and Ek2 source rocks are the important natural gas source areas,and the sand body traps are the most important exploration targets in subsalt of Es4 of the northern steep slop of Dongying Depression.