Deposition And Stratigraphic Sequence Development And Evolution Of Cretaceous Of The Southwestern Tabei Uplift And Potential Reservior Prediction

In view of the weak basic research and ambiguous understanding of the sedimentary evolution of the Lower Creataceous in the Tarim basin,the sequence stratigraphy and sedimentary facies are studied in the study area.based on comprehensive analysis of outcrops,cores,well logs,drilling and seismic data.The third-order sequence stratigraphic framework is established,and the time-space evolution pattern of the sedimentary system is analyzed.On the scale of the key zones,the sequence structure and sedimentary evolution are studied.The differences and similarities of the reservoir forming conditions are analyzed.On this basis,the optimum zones of lithologic-stratigraphic traps are predicted.The main results and achievement are as follows:With the comprehensive use of well drilling,logging and seismic data,under the guidance of sequence stratigraphy and modern sedimentology theory,identification features of all levels sequence boundary and its structure style of Kapushaliang group in the Lower Creataous of the Southwestern Tabei uplift are revealed.It can be divided into one second-order sequence and five third-order sequences and each third-order sequence is subdivided into two to three forth-order sequences or systems tracts.The third-order sequences are bounded by the edge of the basin unconformity.Based on the initial transgressive surface and the largest trangressive surface,the third-order sequences can be divided into lowstand systems tract and trangressive systems tract and high systems tract.The high precision fine time sequence stratigraphic correlation framework was studied,which provides new evdience for the prediction of the structural-stratigraphic traps.Meanwhile,a mathematical methods was utilized to achieve the quantitative analysis of high accuracy sequence stratigraphic framework and sedimentary cycles.The wavelet technology was applied to quantitatively analyze the correlation framework and depositional cycles of the Lower Cretaceous Kapushaliang group of the research area.The result is consistent with the actual geological understanding.Based on the study of sequences,the temporal and spatial evolution of the sedimentary facies is revealed.On the basis of well loggings,cores,seismic facies and seismic sedimentology,three kinds of sedimentary systems were recognized,namely the meandering river,meandering river delta and shore-shallow lacustrine.The composition and distribution of the sedimentary facies is studied.The lowstand systems tract are mainly of river and delta plain deposits,the high systems tract are mainly of river delta deposits,and the trangressive systems tract mainly developed delta front,predelta and the sand dam of the shore-shallow lacustrine.Combined with the basin paleostructure background and the distribution of oil and gas,the development pattern of the lithologic-stratigraphic traps is established,and the favorable zones for different tectonic units were predicted.The favorable reservoir sand bodies and the distribution of lithologic and stratigraphic traps are predicted to provide reference for the petroleum exploration.The favorable zones are around the two North-East strike-slip faults to find the structural-stratigraphic(lithology)combination traps.The favorable sandbodies are mainly delta front sandbodies and beach-bar sandbodies of shore-shallow lacustrine.