Study On The Sedimentary System In The Upper Sha2 Member In Chezhen Depression

Upper Shahejie2 Member is the main purpose exploration layer in the Chezhen Depression. Based on the theory of sequence stratigraphy and integrated previous research papers, from the regional geological ,this paper will use as much information of well logs, seismic and cores data as possible to do some research on the sequence stratigraphy and sedimentary faces of the upper Shahejie2 Member.Study suggest that the Upper Shahejie2 Member can be divided into one 3rd order sequences and two 4th order sequences. The fourth sequence are named sequenceâ… and sequenceâ…¡from the bottom to the up. The fourth sequence are distributed widely in the Chezhen Depression, and can be compared very well.There are four depositional systems in the Chezhen Depression: beach and bar deposition system,delta deposition system, fan-delta deposition system and shore-shallow lacustrine deposition system.A series of delta depostional system are distributed on the southern gentle slope of Chezhen depression. Fan-delta depositional system are distributed in the northern of the Chezhen Depression. Beach and Bar deposition system and deposition of littoral- shallow lake system, mainly located in the central belt depression.During the sequenceâ… sedimentary times, deposition of a relatively limited scope, Chexi sag and Dawangbei sag are together except Guojuzhi sag. Sequenceâ…¡deposition time,the depression was together enough.The Chezhen Depression which was filled with sand was mainly due to the control of the following elements: first : the overall depression was in a relatively shallow body of water, rapid changes in lake level, provided the impetus for widespread conditions second:Yihezhuang and Chengzhikou salient provide a rich source for the depression; third: subject to the control of the ancient base-level cycles, the development of depositional systems and the well-preserved;Based on distribution of Chezhen depositional system, combined with the type of oil and gas reservoirs,the study suggest that the potential for the future exploration to find structure-lithologic, lithological - such as subtle reservoir formation dominated. Chexi sag and Dawangbei sag exploration focused on the lower part of sequenceâ… and upper sequenceâ…¡.Guojuzhi sag mainly concentrated in the upper fouth sequencesâ… and the lower part of sequenceâ…¡.