Study Of Velocity And Application Of Psdm For Low Amplitude Structure In Deep Water In Southeast Hainan Baisin Of South China Sea

The low amplitude structure in the deep water in Southeast Hainan Baisin of South China sea is the well zone for deep water exploration, it's because this zone near the petrol source,with well petrol escape route,and well developed zone cap-rock. However, this zone has peculiar topographic configuration,particular sediment surrounding and process; So the horizontal seismic wave change severe, additional, we lack the high quality seismic data and drilling data, as the result, these elements leads the superimposed velocity pick up with low quality,difficult to obtain the interval velocity,and the PSDM can't get a well result for application in this zone.This paper focus on four points as following:â‘ The adaptive analysis of section general geology and the basic principle for routine velocity obtain.â‘¡How to get an accurately depth interval velocity field through calibration and obtain of velocity based on researching the way to get an accurately superimposed velocity in the LinNan 3D target zone.â‘¢Researching the way to get a application path of PSDM suited LinNan 2D target zone based on I get the well result of PSDM imagery in this zone.â‘£Getting the rule of velocity in the abyssal zone of the southeast of HaiNan province through researching the velocity field in the 2D&3D target zone.In the 3D low amplitude and varied horizontal seismic wave target zone, aim to the phenomenon of routine way-DIX equation with the assumption that horizontal structure and constant horizontal seismic wave always leads to the obtain velocity uncertain, I adopt the 3rd cohere algorithm 3D raytracing velocity calibration and obtain based on the geometric pattern tensor, which is good at eliminating the impaction of abyssal zone,varied horizontal seismic velocity. Finally, I get a accurately depth interval velocity field.In the 2D PSDM researching, I add in the cognition of the velocity in this zone and stand on the predecessor's shoulders, reclaim the way of adopting tendency velocity to build the PSDM velocity model, start the research of PSDM. With this new way, the calculation avert routine time to depth conversion distort the layer, and the depth cut plane recovery the truth geography depth and structure, and get the obvious imagery effect.The PSDM eliminate the impaction of underlay layer for the varied depth,rugged sea floor and varied interval velocity, onlap-s tructure,clear foreset sediment structure,c lear sediment cut plane fractured surface,clear base ambitus,recovery the ancient landform,get the certain sunken structure and the depth of base and the Moho- boundary structure,depth justifiability; finally, the truth low amplitude structure supply the evidence for low amplitude survey.In the research of velocity rule, I adopt the abyssal calibration,convergence analysis,the same depth interval velocity analysis,lateral velocity cut plane and the related technique. Finally with these composition, I calculate the interval velocity structure,the affection element, and the realization of abyssal zone.This dissertation is based on the summarize of the latest research results at home and abroad, with sedimentology, petroleum geology, geophysics and borehole geophysics as the guide, combining the geological background of the research area,obtaining the following innovative research results:(1)Used several technologies,such as water depth revise,confluence,stratigraphic profile etc,to comprehensive analysis the law of formation velocity of Qiongdongnan basin.We learn that the change of formation velocity is mainly influnced by the water depth,cover depth,lithological change,and the horizontal velocity is changing dramatic.(2)Adopting Model-difference method under constrained stratum,considering the influence of interbedded sedimentation and megafault, deposited with correlation by well-to-seismic integration, to solve the price scissors problem of well-to-seismic velocity.(3)Research based on the velocity calculation of 3D ray tracking coherence of two-layer model and velocity correction(â‘ based on the ray tracking, applicable to any attitude of stratum;â‘¡avoid the application of Dix formula;â‘¢nonhyperbolic theory hypothesis),it not only solve the insufficient accuracy of monolayer velocity,but also avoid some problems,such as the accumulation of stepwise inversion error, the difficulty of velocity correction,it eliminates the influence of subsalt distortions which is caused by water-depth change, formation velocity,etc.(4)Based on the previous research experience and the cognition of speed in this region, we innovativly establish the PSDM speed model, develop PSDM processing research and obtain better imaging effect.(5)Establishing a set of technical processes which is suitable for velocity analysis of deep-water area in special geological conditions in Southeast Hainan Baisin of South China sea and Time-depth conversion mapping.