【作者】 朱四新；

【导师】 王绪本；

【作者基本信息】 成都理工大学 ， 固体地球物理学， 2011， 博士

【摘要】 琼东南盆地深水区低幅构造是深水勘探的有利区带,因为此区域紧邻油源、有良好的油气运移通道、区域盖层发育。但由于此区域独特的地形地貌特征、特殊的沉积环境和沉积过程造成地震波传播速度横向变化剧烈,再加上缺乏高品质地震资料和实钻井资料,这些因素综合引起叠加速度拾取精度低、层速度求取困难、时深转换误差大、PSDM很难在此区域得到一个好的应用效果。针对这些问题,本论文研究的内容是:○1常规速度求取方法基本原理及适用性分析研究;○2研究在QDN三维靶区得到一个好的叠加速度场的基础上,如何通过速度求取及校正技术研究得到一个准确的深度域的层速度场;○3研究在QDN二维靶区得到一个好的PSDM成像效果基础上,得到一套适合此区域的PSDM应用技术流程。○4通过研究二、三维靶区的速度场,得到琼东南盆地深水区的速度规律。相应的技术思路为:在三维低幅构造横向速度变化剧烈研究靶区,在对常见速度求取方法及其缺陷分析的基础上,主要针对常规的基于水平层状介质、横向速度均匀假设的DIX公式求取层速度结果不可靠、从而导致时深转换深度域剖面构造形态严重畸变这一问题,应用基于井-震结合的双层模型三维射线追踪相干反演的速度求取与速度校正技术,较好地消除深水区水深变化、地层速度横向变化等因素引起的构造畸变影响,得到了一个准确的深度域层速度场。在二维PSDM应用研究中,结合本地区速度研究认识,基于前人研究经验,开拓性地应用趋势速度法建立PSDM速度模型,开展PSDM处理研究,避免了常规时深转换法对地层的扭曲,深度剖面恢复了真实的地质深度和形态,取得较明显的成像效果。PSDM处理消除了水深变化、崎岖海底及地层速度变化等因素对下伏地层的影响,上超、前积沉积特征清晰,深度剖面断面清楚、基底轮廓更加清晰,恢复古地貌,基本落实了凹陷地层结构和基底的埋深;莫霍面构造形态及深度合理;落实了低幅构造,为低幅构造勘探提供了依据。在速度规律研究中,使用了水深校正技术、交汇分析、等厚地层速度分析、沿层速度剖面等多项技术组合的创新思路,取得了该区地层速度结构、影响主因以及水深的影响认识。本论文在总结国内外速度研究及PSDM应用研究相关最新科研成果的基础上,以地球物理学、地质学、测井学理论为指导,结合研究区地质概况,取得以下几点创新性研究成果:(1)采用层约束下的模型差值方法,考虑大断层影响,用井震联合建模解决井震速度的剪刀差问题。(2)通过对基于双层模型的三维射线追踪相干的速度求取及速度校正技术进行研究(①基于射线追踪理论,适于任何产状;②避开Dix公式的应用;③非双曲线理论假设),既解决了单层反演速度精度不够,又避免了逐层反演误差积累、速度修正难的问题,较好地消除了深水区水深变化、地层速度变化等因素引起的构造畸变影响。(3)基于前人研究经验及本地区速度研究认识,开拓性应用趋势速度法建立PSDM速度模型,开展PSDM处理研究,取得较好的成像效果。(4)应用水深校正技术、交汇、层剖面等多项技术综合分析琼东南盆地地层速度规律,得出此区域地层速度变化主要受水深、埋深影响,局部受岩性变化影响,横向速度变化剧烈。(5)建立了一套适合琼东南盆地深水区特殊地质条件的速度分析和时深转换成图方法技术流程。更多还原

【Abstract】 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:①The adaptive analysis of section general geology and the basic principle for routine velocity obtain.②How 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.③Researching 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.④Getting 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(①based on the ray tracking, applicable to any attitude of stratum;②avoid the application of Dix formula;③nonhyperbolic 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.更多还原