全方位局部角度域叠前深度偏移在复杂构造成像中的应用  

Application of full-azimuth local angle-domain prestack depth migration to complex structure imaging

作　　者：王江[1] Wang Jiang(Exploration and Development Research Institute,PetroChina Daqing Oilfield Company,Daqing,Heilongjiang 163712,China)

机构地区：[1]中国石油大庆油田有限责任公司勘探开发研究院

出　　处：《天然气勘探与开发》2022年第2期22-30,共9页Natural Gas Exploration and Development

基　　金：国家重大科技专项“大型油气田及煤层气开发”(编号:2011ZX05001-001-004)。

摘　　要：大杨树盆地构造活动具有多期建造和改造的特点,导致其构造复杂、断裂发育、地层非均质性强,体现在地震采集资料上就是地层速度横向变化大,地震资料信噪比低、致使构造精确成像困难。为此,尝试应用全方位局部角度域叠前深度偏移技术来解决这些问题:①采用全方位角成像偏移+多方位层析深度域速度建模;②进行关键参数(偏移孔径、反假频参数、最大倾角和最大开角)的优选;③进行倾角道集镜像加权叠加精细构造成像。应用结果表明:①全方位局部角度域叠前深度偏移在陡倾角的复杂构造区,能够使反射波归位准确、绕射波收敛合理;②在浅层全方位反射角道集角度范围宽、信噪比高,有利于浅层速度建模与模型优化,通过对倾角道集进行镜像加权得到的镜像倾角道集不但反射能量强,而且消除了散射和绕射能量;③在相同速度模型下,在陡倾角成像方面,全方位局部角度域偏移方法的成像精度比Kirchhoff偏移更具优势,不但复杂构造带能够精细成像,地震资料分辨率和信噪比都得到明显提高,地震数据频带由8~78 Hz拓宽到5~88 Hz。Dayangshu Basin has experienced multi-phase construction and transformation by tectonic movement,bringing about complex structure,developed fault,and heterogeneous strata.From seismic acquisition data,both great lateral variation of interval velocity(making accurate imaging difficult)and low signal-to-noise ratio(SNR)are represented.So,a technology of full-azimuth local angle-domain prestack depth migration was attempted to address the mentioned problems.Specifically,full-azimuth migration imaging and multi-azimuth tomography were combined for depth-domain velocity modeling,key parameters(such as migration aperture,anti-aliasing parameters,maximum dip angle,and maximum opening angle)were optimized,and mirror-weighted stacking on dip-angle gather was adopted for fine structure imaging.Results show that the full-azimuth local angle-domain prestack depth migration can make reflected wave restore accurately and diffracted wave converge reasonably in complex structural zones with steep dip.The reflected-angle gather in shallow interval is featured by wide angle range and high SNR,which is conducive to velocity modeling and model optimization.The mirror-weighted dip-angle gather is good in strong reflection energy,and also avoids scattering and diffraction energy.With the same velocity model,the full-azimuth local angle-domain migration is superior to Kirchhoff migration in accuracy of steep-dip structure imaging.It may not only realize fine imaging on complex structural zones,but also provide seismic data with much higher resolution and SNR.In addition,the frequency band expands from 8-78 Hz to 5-88 Hz.

关 键 词：局部角度域 偏移成像 复杂断裂带 倾角道集 反射角道集 大杨树盆地 

分 类 号：P631.4[天文地球—地质矿产勘探]