Abstract: This paper presents briefly the geological features,describes the turbidite and its sequences and styles and studies the sedi-mentary facies and microfacies of the upper part of the Shasi member in six wells in Bonan sag. It is demonstrated from lithology of deepwater, rock structure of density flow origin, grain distribution of turbidite origin, seismic and well logging responses and proper formingconditions that under the background of the deep lacustrine and semideep lacustrine facies deposits develops sublacustrine fan and farglutinite lens. .

Key words: Shengli oilfield, sedimentary sandbody, turbidite deposit