The Structure Subtly Interpretation And Reservoir Prediction Of The First Member Of The Kongdian Formation In Xiaoji, Cangdong Depression

Cangdong depression is the second oil-enriched depression and one of the most important field of oil and gas exploration and development in Dagang Oilfield. There are three petroleum systems, Shahejie formation, the second member of Kongdian formation and Paleozoic, in Cangdong depression. The exploration focuses on the main tectonic belt to find structural reservoir in early stage exploration. The study has been recealed that there are nine petroleum systems, Ordovician, Mesozoic, K3, K2,K1, Sh1, Sh2, Sh1 and Guantao formation. Seven oilfields, Zaoyuan, Wangguantun, Xiaoji, Duanliubo, Shenvshi, Yesanbo, Wumaying, have been found. There are 380 million tons petroleum geological reserves. K1 formation is the main oil-bearing series in Cangdong depression, and the exploration thinking of this formation is based on the tectonic features. Anticlinal reservoirs and fault nose reservoirs in the central uplift belt are the main prospecting targets. The exploration status showed that development degree of structural belts in Cangdong depression was high, so it is difficult to find new oil reservoirs with the guidance of structural exploration excepting for expanding reserves exploitation, and the mode of structural exploration should be changed.K1 formation was deposited in the shale zone of lake basin and distributed near the hydrocarbon source rock of K2 formation, so it is easy for large-area hydrocarbon accumulation. In order to guide the exploration of lithologic hydrocarbon reservoir, an integrated study has been being carried on Xiaoji area in Nanpi slope, including structure subtly interpretation, tectonic evolution, sedimentary background, multi-method reservoir prediction, and lithologic boundary recognition.