Sedimentary Facies Of Eogene Sha3 Member To Dong3 Member In The East Depression, Offshore Liaohe Basin

To better understand sedimentary facies development in rift basin setting, The space-temporal distribution of depositional system is demonstrated using core, wireline log, 3D seismic data in the east depression of the offshore Laiohe Basin.Firstly, based on detailed core observation, facies marks are summarized, which are obtained from direct observation of the characteristics of lithology, sedimentary structure, ichnology and indirect inferences from well-log and seismic reflection. Through the identification of facies marks and anylysis of sedimentary facies cross section, fan delta, braided delta, delta, lacustrine, sublacustrine fan, turbidite fan, beach-bar have been delineated in the east depression of the offshore area.Secondly, through the analysis of single well section and well-to-seismic section and based on the comprehensive analysis of seismic reflection, conglomerate, sandstone thickness and heavy mineral, three main provenance areas are analysed which are eastern uplift, central low-uplift and northern area.Inview of the shortage of well data and uneven distribution of well location, seismic data are fully utilized to analyze the sedimentary facies. Based on the reliable internal reflection texture and external shape, seismic facies are divided and named. In the study area, seven seismic facies are identified, including mat-shaped, foreset, wedge shaped, filling, divergent, mound and hummocky seismic facies. In addition, a series of geophysical methods are adopted such as seismic attributes, neural network multi-attribute analysis, and waveform analysis which get a good result in the sedimentary facies analysis.Lastly, through the analysis of single factor with synthesize factor drawing, ancient sedimentary environments are reconstructed under the sequence stratigraphic framework. In the plane, the sedimentary facies show dissymmetric features. In Yannan Fault and footwall of Gaizhoutan Fault, sublacustrine fan, fan delta and braided delta are dominant facies. And in the north of study area, delta and fan delta are main facies. In the central depression, profundal and turbidite fan are developed. In the vertical view, the sedimentary facies change from sublacustrine fan, fan dalta which present high hydrodynamic conditions to braided delta, delta which present low hydrodynamic condition. The main elements controlling the distribution of sedimentary systems are the structure, paliegeomorphy and paleoclimate.