Study On High-resolution Sequence Stratigraphy And Sandstones Distribution Of The Upper Oil Layer Of Sha-2 Member Of Shahejie Formation In Chengbei Low Step Fault

Based on the theory and techniques of high-resolution sequence stratigraphy,the sequence stratigraphic framework and the rule of sandstores distribution of the Sha-2 member of Shahejie formation in the Chengbei Low Step Fault are identified.Trough the literature review,analysis and interpretation of drilling\logging data,a high-resolution sequence stratigraphic framework in this area is established.With the types of sedimentary facies and the distribution characteristics of the sandstores.Eventually,the targat area of the exploration and development are preidicted.In light of the high-resolution sequence stratigraphic method,the Sha-2 member of Shahejie formation is divided into 6 fifth-order sequences,which are named as sq1-6,sq1-5,sq1-4,sq1-3,sq1-2,sq1-1.In the contronal of the fifth-order sequences,the Sha-2 member of Shahejie formation also divided into 4 sands group,which named Es2s4,Es2s3,Es2s2,Es2 s.In the sands group,the layer is divided into 16 single layer,which named s4-4 s4-3 s4-2 s4-1 s3-4 s3-3 s3-2 s3-1 s2-4 s2-3 s2-2 s2-1 s1-4 s1-3 s1-2 s1-1.Through comprehensive analysis of core observation and drilling/logging facies,there are four sedimentary microfacies that are identified: underwater distubutary channel,mouth bar,sheet sand and underwater distributary bay.Combined with sand body thivkness recoginzed the distribution characteristics of the sandstores of the Sha-2 member of Shahejie formation in contronal of the high-resolution sequence framework in the research area.In period Es2s4,the section developes a large scale underwater distubutary channel.it also develops turbidite volume in the north of the research area;In period Es2s3,the scale of the underwater distubutary channel was becoming smaller.the scale of the mouth bar was becoming larger;In period Es2s2,water significantly increases,the underwater distubutary channel was the most developed in the southwest.and the range expandes fauther more for the noutheast.it also develped mouth bar,but the scale is smaller than Es2s3;In period Es2s1,the provenance of the research area migration from south to north.but the main provenance is the south east,because of the large scale underwater distubutary channel in the east,Es2s1 period developes mouth bar and is located in front of the underwater distubutary.After comprehensive consideration of the sequence stratigraphic position,structure,the thickness of sandstores,sedimentary microfacies,combined with the Reservoir profile analysis,the favorable oil-bearing formations are Es2s4 and favorable sedimentary microfacies are underwater distubutary channel;the incline area in southeast and the Sliding zone of Chenghai39 are determined as the favorable exploration areas,Combined with the actual situation and the work need,deploy two wells in the favorable area.