Study On High-resolution Sequence Stratigraphy And Favorable Zone Prediction Of The Chang4-Chang6 In Huangling Area Of Ordos Basin

In this paper,a comprehensive application of high resolution sequence stratigraphy,sedimentology,reservoir geology theory and methods,through observation of field outcrop profile,core drilling,interpretation of logging data,analysis and identification of physical property of reservoir lithology,to finish the phase identification of Chang6—Chang4 of Yanchang formation of Huangling of the Ordos basin and to analysis the distribution of sedimentary facies,and predict favorable zones of oil and gas exploration in the region.By the study of the field section,core and logging data,and use of high-resolution sequence stratigraphy theory and technical methods,under the constraint of sequence stratigraphic framework,Chang6—Chang4 of Yanchang formation divided into 4medium-term base-level cycle interface,and divided Chang4+5 and Chang6 to 5 sand group(Bottom-named Chang6~3,Chang6~2,Chang6~1,Chang4+5~2,Chang4+5~1,),By comparing,established the sequence stratigraphic framework of Chang6—Chang4 of Yanchang formation.By comparing the whole region,analysis the focusing of key cross-sectional,and combined with core observation and drilling/logging data,summarized the longitudinal and transverse overlapping fashion evolution of stratigraphic sequence of Yanchang formation.Through heavy mineral analysis,particle size analysis of debris,flakes skeleton mineral analysis,and combining the background of ancient water flow of the Ordos Basin,consider that Chang6—Chang4 of Yanchang formation of Huangling of the Ordos basin unaffected by the main source of the northeast and secondary source of southeast.Through a lot of observation of outcrop and core description and the data of drilling/logging,successively according to the characteristics of the color of sedimentary rock,component,granule structure,sedimentary structure,authigenic minerals and paleontology etc.,to carry out the research on constraint in the sequence framework of sedimentary facies and sedimentary micro phase.Determineing the sedimentary environment of Chang6—Chang4 of Yanchang formation of Huangling is mainly deep lake facies and shallow lake facies,and mainly developed three types of sedimentary facies,respectively for the delta facies and sublacustrine fan facies and lacustrine facies.Summary the law of the development and evolution of Delta and sublacustrine fan facies.Based on the analysis of hydrocarbon accumulation conditions,favorable reservoir prediction and controlling factors of lithologic traps,Summed up that mainly developed delta front subaqueous distributary River,river mouth bar sand body and deep water gravity flow system of sublacustrine fan sand body type of Chang6—Chang4 of Yanchang formation of Huangling are the favorable areas for exploration of lithologic traps.Clarified the distribution law and main controlling factors of different types of reservoir sand bodies in sequence stratigraphic framework.The temporal and spatial distribution of favorable reservoir sand bodies in the sequence is analyzed.5 favorable zones for oil and gas exploration were comprehensively predicted,and the trap types and forming conditions of the main development of the favorable areas were analyzed.