Sedimentary Characteristics of  Sublacustrine Fan in Weixi’nan Sag of Beibuwan Basin

Key words: 
• Weixi&rsquo /
• nan sag /
• sublacustrine fan /
• sedimentary characteristics

Abstract: On the basis of integrated analysis of core, well logging, seismic and grain size probability curves data, sedimentary characteristics of sublacustrine fan in Liu-1 Formation of Weixinan sag is comprehensively studied. Sublacustrine fan is characterized by the Bouma sequence implying typical turbidite, it is classified into two types of powerful hydrodynamic sedimentation and weak hydrodynamic sedimentation. For depositional texture, sublacustrine fan features grain distribution character of typical turbidite deposit in terms of grain size probability curves and C—M map, moreover, it contains large numbers of turbidite deposit structures. Sublacustrine fan is resulted from the condition of cliffy paleolandform and abundant sedimentary  supply, and formed at the location of deep water lacustrine area of fault slope-break zone or syndepositional structural slope-break zone. The sublacustrine fan formed from deep lacustrine, trap condition is excellent, a  near source rock, hydrocarbon source is abundant, easily forming hydrocarbon reservoirs, already  obtained commercial oil-gas flow in numbers of drilled well, and have great exploration foreground.