Various types of fan delta systems have been developed in different evolution stages of faulted basin. Being controlled by the supply rate of sediments

expansion rate of available space and nature of lake basin's boundary fault

four types of fan deltas have been deposited in the 3rd member of Shahejie Fm(Es

3

) in Gubei oilfield. Retrograding fan delta has been deposited along with the transgression of the lake in the early and middle Es

3

;and the prograding fan delta has been deposited during the regression of the lake in late Es

3

.There are obviously different sedimentary characteristics

reservoir distribution and reservoir quality between the steep fan delta and the gentle one

the latter has better reservoir quality with an average porosity of 18.2% and average permeability of 293×10

-3

μm

2

because it has relatively shallow burial depth and weak diagenesis.In addition

the microfacies of sediments would also control the reservoir quality.The glutenites deposited in subaqueous distributary channels in front of the fan delta have the best reservoir quality with an average porosity and permeability of 20.5% and 350×10

-3

μm

2

respectively.The deep lacustrine dark-colored mudstones constitutes the major hydrocarbon source and cap rocks

and the glutenites deposited in front of the fan delta are relatively good reservoirs

which would constitute a good combination of source

reservoir and cap rocks. The Es

3

would

therefore

be the target of further exploration.