Study On The Seismic Geology Comprehensive Reservoir Prediction In Zhangdong Area Of Dagang Oil Field

Aiming at the following characteristics of oil and gas exploration in offshore area i.e.,the sparseness of wells,dominated by seismic data,we developed the ideas,the content,the method and the technology of"seismic geology comprehensive reservoir prediction technique". It is very important for the prediction and characterization of lithologic oil-gas reservoirs to carry on the synthesis study on sequence stratigraphy and seismic reservoir prediction in the guide of concept,model and understanding of geology.The sequences boundary surface of Paleogene sections of formation is identified based on the theory of sedimentology and sequence stratigraphy combined with seismic data,logging data,drilling core and other geologic information,and the Paleogene strata are classified as three 3rd-order sequences.Thus the framework of shahejie Member sequence stratigraphy is established at Zhangdong area. The sedimentary facies features and patterns,and the spatial and temporal distribution characteristics at the shahejie Member are invested and obtained the map of horizon and spatial position of favorable reservoirs based on the core description and the seismic data,geographic logging, well logging. The results suggests that the optimistic reservoirs should be the mouth bar in braid river the delta front facies of the Sha2 Member. The study of seismic geology comprehensive interpretation based on fine reservoir geologic characteristic description showes zhangdong structure is divided into north and south fault noses trap,which are divided into smaller fault noses by sublevel fault of NEE-EW trike direction.Faced with the characters of the Sha2 Member of the thin inter-beds,the paper applies analyzing the model experiment of the thin inter-beds of sandstone and mudstone.And correlative analysis on waveform of aim interval can realize inversion from seimic faice to sedimentary facies by combining with knowing of core facie,logging faice and the character of seismic reflect response.The study of the relationship between the frequency attribute character of seismic traces nearby well and sequence internal structures with time-frequency analysis technology showes formation of the frequency sequences have obviously corresponding relationship with medium-term and short-term sedimentary cycle. For the difficulty of small velocity differences between sandstone and mudstone,as well as their acoustic overlay,the reservoir property log rebuilding technique can upgrade reservoir prediction of the thin inter-beds.Seismic inversion result comformed to geologic understanding of reservoir evolution and the regularity of reservoir distribution.The comprehensive reservoir prediction which is union of multi-means such as seismic facies analysis,time-frequency analysis,spectral decomposition analysis,reservoir seismic inversion and hydrocarbon detection,with combination of analysis of oil type and its distribution,consideres that the optimistic reservoirs should be the mouth bar in the delta front facies of the Sha2 Member in the east of zhh6 fault nose and the north of z28x2 fault nose.