Study On Sequence Stratigraphy And Prediction Of Nonstructural Traps In Honglian-Shengbei Of Tuha Basin

Sequence stratigraphy has been applied in stratigraphy, sedimentology, basin analisis andprospect for energy sources and mineral because of its advanced method and concept systemand valid prediction since its appearance in 70's. Sequence stratigraphy is a jumped-upsubject coming from passive margins and has been introduced into China and appliedextensively in continental basin after years of research.Based on continental sedimentary basin sedimentology and theory and measures ofsequence stratigraphy, the paper is focused on the study on the core, logging, 3D and 2Dseismic data in Taibei Sub-depression, Tuha Basin. Starting with the study of sedimentologyon the key and new wells, normal pattern of sequence analysis and signature of sedimentaryfacies are established, every well position and contrast of wells in series analyzed as well.Main seismic profiles were detailedly interpreted, and its characteristics of sequenceboundary, signature of seismic facies and sedimentary facies analyzed, based on syntheticseismogram or data of VSP, then sequence stratigraphic framework and responsecharacteristics of sedimentary facies have been reasonably established. Sedimentary faciesand spatial distribution of sedimentary system have been studied by closing 3D and 2Dseismic interpretation. Subtle recognition, trace and contrast of the key boundary have beendone as well by analyzing seismic response terminal and log response pattern, which canoffer bases of sedimentology on 3D distribution of sedimentary sand and predicting favorablezone and the target of exploration.Taibei sub-depression is a second unit of Tuha basin which has been proved to beexciting and promising for oil-gas generation, in which Jurassic Kalaza Formation and thewhole Cretaceous are chosen as the study strata considering its structural geological character.5 sequences (Sq1, Sq2, Sq3, Sq4, Sq5) in Hongnan-Lianmuqin and 4 sequences (Sq1, Sq2,Sq3, Sq4) in Shengbei have been recognized according to regional geology and stratigraphy.The main sedimentary system includes fluvial, delta, alluvial fan and lake facies. We haveestablished an integrated stratum system with comparing the well in every field and seismicsection and educed the change of water-level, depositional character of sandstone and holisticcharacter of facies by the single well facies analysis and identification of sedimentary system.The research shows that Hongnan-Lianmuqin and Shengbei are characterized by severalprovenances, thin facies zone and many types of reservoirs. Through the cautious andprofound research on sequence stratigraphy, and comprehensive analysis for oil source bed,reservoir, cap-rock pattern and primary conditions of pool forming, three promising zones arepredicted.