Three pre-Tertiary source rock sequences are developed in Jiyang depression

including Lower Paleozoic carbonates

Upper Paleozoic coal measures and Mesozoic Jurassic coal measures

of which the Upper Paleozoic coal measures are the best.Therefore

gas reservoirs that have been generated and reservoired indigenously should be taken as the main targets of exploration in pre-Tertiary in Jiyang depression.Focus should be put on the Upper Paleozoic petroleum system

with considerations being given to Mesozoic petroleum system.The geologic features and reservoiring history of Gu-1 gas reservoir in Gubei area indicate that formation of gas reservoirs characterized by being generated and reservoired indigenously has largely depended on the development of the Upper Paleozoic source rocks

large anticlinal traps and good timing of source-reservoir-cap rocks in the deep sag area.Comprehensive evaluation of the distribution of favorable source rocks

reservoir and seal conditions and trap types indicates that there are 7 favorable exploration prospects in the Upper Paleozoic in Jiyang depression

including Gubei

Gunan

Luojia and Guojuzi in Zhanhua sag

Jinjia and Linfanjia in Dongying sag

and Chexi in Chezhen sag

and 4 less favorable prospects

including Chengdong and Yinan in Zhanhua sag and southern slopes of both Dongying and Huimin sags.