Timing of Deep Gas Accumulation in Bonan and Gubei Areas of Jiyang Depression

The formation time and stage of the deep gas reservoirs in the Bonan and Gubei Areas of Jiyang Depression are ascertained by a set of analysis techniques,including the hydrocarbon generation history,fluid inclusion homogenization temperature,light hydrocarbon characteristic and structure movement analysis.Two periods of different original gas charging are established in the Gubei buried hill belt,coal-formed gas charging in late stage of Ng and oil-formed gas charging in middle stage of Nm.At the same time,there are two accumulation periods which include from late stage of Es1 to late stage of Ed and from the stage of Nm to nowadays in oil-associated gas reservoirs in Bonan sub-sag,the late stage accumulation plays an important part.There are different periods at different structure location and strata.The formation period of gas reservoir at downstructure location is earlier than that of gas pool at upstructure location.