渤南洼陷井-震速度误差分析和速度模型的建立及应用

高精度速度场的建立对渤南洼陷隐蔽油气藏勘探十分重要。综合大量测井、测试和地震资料，分析和讨论了测井、VSP和地面地震速度间的差异;利用VSP测井优化技术，对叠前偏移速度做了标定和校正，在此基础上对离散速度数据进行空间插值，获得了全区地震层速度、均方根速度三维数据体。不同类型速度资料的对比分析表明，研究区浅层的井孔速度大于井旁地震层速度，中、深层则呈现正好相反的特点;浅层速度弥散、深层介质的各向异性是导致井、震速度误差的主要原因。利用VSP速度对地震层速度的局部误差进行闭合差校正，经空间插值后建立的全区速度模型可从任意方向切片观察速度空间展布。三维速度资料为研究渤南洼陷整体的地层密度、压力系数等岩石和流体参数的空间展布和结构特征提供了可能。

Seismic velocity is one of the most important parameters for subtle reservoir exploration in Bonan Sag.The difference among logging,VSP and ground seismic velocity are analyzed and discussed based on a large amount of logging,testing and seismic data.On the basis of analysis for discrete velocity in target area,a method with VSP logging optimum technique is proposed to calibrate and correct prestack migration velocity, and the 3D data volume of seismic interval velocity and RMS velocity is obtained.Comparison between different types of velocity data reveals that,velocity obtained from borehole is larger than seismic interval velocity in the upper stratum,of which the fact is opposite in the middle and deep stratum.Velocity dispersion of upper stratum and rock anisotropy of deep stratum could explain the cause of the logging and seismic velocity error.The local error of seismic interval velocity is conducted mis-tie correction by using VSP velocity.By spatial interpolation,we get an overall velocity 3D model and it offers a comprehensive understanding of velocity distribution at any direction slice.3D velocity data reveals an overall variation view of formation density,pressure parameters and some other spatial distribution as well as structural characteristics of rock and fluid.