摘要
为研究鄂尔多斯盆地黄土塬区地震波的传播规律和噪声的产生机理,根据庆城北三维工区实际地表高程和速度结构,建立准确反映黄土塬区近地表结构的三维数字模型(速度和品质因子Q),以基于Q显式表达的黏滞声波方程为基础,采用坐标变换法实现起伏地表条件下的三维黏滞声波方程数值模拟。该方法可以将复杂近地表引起的近炮点强能量噪声和强衰减效应较客观地模拟出来,模拟结果与实际资料的吻合度较高。通过不同复杂程度模型的三维数值模拟和波场分析,厘清了黄土塬区地震资料近炮点强能量噪声和多次反射、多次折射的产生机理,并结合实际资料分析了黄土塬区不同位置(塬、梁、坡、沟)及不同炮点深度的波场特征差异,认为:沟中激发时,近炮点强能量噪声较弱,资料品质相对较好;随着炮点深度增大,信号的高频端成分逐步增加;黄土塬地区野外地震采集时,应避免在干黄土层中激发,尽可能选择胶泥层或更深层激发。波场分析结论对黄土塬区实际资料采集和处理具有一定的指导意义。
In order to study the propagation law of seismic waves and the generation mechanism of noise in the loess plateau,this paper establishes 3D realistic models(velocity and quality factor Q)of the loess plateau in Or-dos basin according to actual surface elevation and velocity structure of the Qingcheng North 3D work area.Then under the condition of undulating land surface,3D numerical modelling using the coordinate transforma-tion method is accomplished based on a viscoacoustic wave equation with explicitly expressed quality factor.This method can simulate the strong energy noise near the offset caused by complex near-surface and strong at-tenuation effects,and obtain simulation results similar to the real seismic data.Through wave field analysis of the numerical modelling results of the models with different complexity,this paper gradually clarifies the genera-tion mechanism of near-offset strong energy noise,multiple reflection and multiple refraction.Finally,this paper analyzes the differences in wave field characteristics at different locations(plateau,ridge,hillside,ditch)and at different source depth in the loess plateau area based on the numerical modelling and actual data.Analysis shows that when excited in the ditch,the near-offset strong energy noise is weaker,and the data quality is rela-tively good;As the source depth increases,the high-frequency component of the signal gradually increases;For real seismic data acquiring in the loess plateau,it is necessary to avoid excitation in the dry loess layer and try to excite in the clay layer or deeper layer.The conclusion of wave field analysis has positive guiding significance for real data acquiring and processing in the loess plateau.
作者
韩令贺
胡自多
狄帮让
徐中华
刘威
李翔
HAN Linghe;HU Ziduo;DI Bangrang;XU Zhonghua;LIU Wei;LI Xiang(National Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing 102249,China;Research Institute of Petroleum Exploration&Development-Northwest,PetroChina,Lanzhou,Gansu 730020,China;CNPC Key Laboratory of Reservoir Description,Lanzhou,Gansu 730020,China)
出处
《石油地球物理勘探》
EI
CSCD
北大核心
2024年第3期504-513,共10页
Oil Geophysical Prospecting
基金
中石油前瞻性基础性项目“海相碳酸盐岩成像理论与勘探技术研究”(2021DJ05)资助。
关键词
黄土塬
三维黏滞声波方程
数值模拟
品质因子
波场传播规律
loess plateau
3D viscoacoustic equation
numerical modelling
quality factor
wave propagation law
