Abstract:

Five types of sand-conglomerate fanbodies,including alluvial fan, fandelta, coastal submerged fan, steep-slope deep water turbidite fan and slump turbidite fan,are developed on the northern steep-slope belt of Dongying depression. From the marginal salient to the basin's hydrocarbon-generating center, the oil reservoirs in these sand-conglomerate fanbodies are successively the stratigraphic-lithologic reservoirs,structural-lithologic reservoirs and lithologic reservoirs.In the steep-slope belt,the 4th member and 3rd member of Shahejie Formation are excellent source rocks,with a maximum thickness of 4000m, where the type I-Ⅱ kerogen are present.The organic-carbon content for both source rocks ranges from 0.5 to 3.5 percent.Oil and gas were moved into the fanbodies,developed on the middle-upper parts of steep-slope belt,through the composite conduit system consisting of faults,sand layers and sequence boundaries,which is characterized by stepped migration in vertical and lateral transformation.The oil reservoirs in the fanbodies experienced the hydrocarbon-charging stages corresponding to the deposition periods of Dongying,Guantao and Minghuazhen Formations.The reservoiring process,however,occurred mainly during the deposition of Guantao and Minghuazhen Formations.The dynamic process of oil and gas accumulation can be summarized as the reservoiring model of the fault terrace type of the sand-conglomerate fanbodies in steep-slope belt.

Key words: steep-slope belt, sand-conglomerate fanbody, reservoir type, reservoiring dynamics, reservoiring model, faulted basin