Sequence Stratigraphy Research And Prediction Of Favourable Zones Of Es₁-Es₂in North Raoyang Sag

Acording to the data related to cores,drilling, logging and seismic, with the theoreticalbasis of high-resolution sequence stratigraphy as directors,the sequence of study area can bedivided into2mid-cycles and14short term cycles, corresponding to the three-ordersequences and four-order sequences(parasequence sets).On the base of the sedimentary faciesanalysis of single well and combining with the characteristics of logging curves and thetesting results, braided river delta and lacustrine are identified in the isochronal.They can besubdivided into5types of subfacies (braibed river delta plain, braibed river delta front,formerbraibed river delta,shallow lacustrine and semi-deep lacustrine subfacies) and12types ofmicrofacies (braided channel,between distributary channel,flood river,swamp, distributarychannel,estuarine sand bar, sheet sand,distal bar,between underwater distributary channel,sandbeach bar,carbonate bank-dam,lacustrine mud). The indicators of sub and micro sedimentaryfacies were systematically summarized.Through the analysis of single factor maps, such as the sand thickness contour map andpercentage of sandstone contour map,combined with the analysis of logging curves shape,sedimentary facies maps of parasequence sets are worked out.Through the analysis ofreservoir lithologic and physical property characteristics of different reservoir sandbodies,combined with the analysis of sand thickness and percentage of sandstone, the sandbodies of underwater distributary channel is the best reservoir,which has mediumporosity,permeability and appropriate sand thickness,percentage of sandstone.The sandbodies of braided channel and estuarine bar is the second best reservoir.The sand bodies ofsheet sand,turbidite and carbonate bank-dam is the third best reservoir.Through the analysisof the source-reservoir-cap combination relations and data of the testing results,favourable zones are predicted.During the period of LST and HST,the sand bodies of braided channel,estuarine bar and sheet sand distributing along the area of Gao yang,Da Bachi-BoShizhuang,Nan Mazhuang and Guo Jiazhuang can form stratigrahpic and lithologicreservoiris which are the most favourable zones.During the period of TST,sandy beach bar,carbonate bank-dam of shallow lacustrine distributing along the gentle slop belt and theRenqiu ancient raised area, turbidite of semi-deep lacustrine distributing along the Renxi andMaxi subsags can form lens reservoir which are the favorable exploration areas.