Lect3-Sequencestratigraphy-methodology探析.ppt

SEQUENCE STRATIGRAPHY;SEQUENCE STRATIGRAPHY;Seismic Sequence Stratigraphy;Seismic straitigraphic analysis;Identify bounding discontinuities on basis of reflection termination patterns and continuity;;Reflection termination: key to analyzing the the stratigraphic terminations, which can not be easily provided by outcrop and well data. Onlap offlap, downlap, toplap, erosional truncation, baselap ;;;;Downlap surfaces: develop during a transition from onlap to offlap. They typically develop above flooding surfaces and fan surfaces, as basin-margin depositional systems begin to prograde seaward.;Define geometries of genetic reflection packages that envelope seismic sequences and systems tracts（确定包括地震层序和体系域的成因反射组合）：层序内部反射组合的识别;Clinoforms(同倾进积体）: the dipping, prograding units. They lap out downward onto the downlap surface as lateral progradation takes place.;Seismic facies: an areally restricted group of seismic reflections whose appearance and characteristics are distinguishable from those adjacent groups characterizing different depositional environments. Various attributes may be used to define facies: reflection configuration, continuity, amplitude and frequency spectra, internal velocity, internal geometrical relations and external 3D forms. The objective of seismic facies analysis is to define the depositional environments, lithology, and the geologic history.; Common seismic facies: Simple reflection configuration: Parallel (even, wavy), subparallel, divergent. Complex reflection configuration: Disrupted, contorted, chaotic, lenticular, irregular, reflection-free, so on. Most common internal reflection patterns are progradational reflections, basically oblique and sigmoid (simple and complex), parallel, shingled, and hummocky clinoforms. ;;;Reflection character analysis-synthetic seismogram manufacture Through convolving the reflectivity determined from a sonic log in a well with the wavelet shapes extracted from actual seismic traces. ;;Procedure of seismic