摘要
为克服各向同性和VTI介质逆时偏移方法对复杂地质构造成像的局限,研究了TTI介质拟声波逆时偏移方法.首先从精确的TTI介质频散关系出发,引入一个各向异性控制参数σ,推导了新的二阶耦合TTI介质拟声波方程,以保证波场延拓的稳定性;然后引入波场的伪速度分量,推导了等价的一阶拟声波方程.相比于规则网格有限差分法,交错网格有限差分(SGFD)法能够有效地压制数值频散,模拟精度更高;因此利用高阶SGFD法求解TTI介质一阶拟声波方程,构建逆时偏移所需的正向和逆时波场延拓算子,并应用归一化互相关成像条件实现精确的TTI介质逆时偏移成像.最后,简单讨论了伪横波的产生机制,并给出了伪横波的联合压制策略.模型试验结果验证了方法的有效性和稳定性.
In order to overcome the limitations of isotropic and VTI reverse time migration（ RTM） for imaging the complex geological structure,TTI pseudo-acoustic RTM method is studied. Starting from precise TTI dispersion relation,a new second-order coupled TTI pseudo-acoustic wave equations are acquired by introducing an anisotropic control parameter to ensure the wave-field propagation stable; and then the equivalent first-order pseudo-acoustic wave equations are deduced through introducing the pseudo-velocity components of wave-fields. Compared with the regular-grid finite difference method, the staggered-gird finite-difference（ SGFD）method is more accurate with weaker numerical dispersion. Thus,we apply the high-order SGFD method to solve the TTI first-order pseudo-acoustic wave equations, constructing the forward and backward wave-field extrapolators,and then the normalized crosscorrelation imaging conditionis are used to implement accurate TTI reverse time migration. Finally,the cause of pseudo-q SV wave is discussed briefly,and we present the joint suppression strategy of pseudo-q SVwave. The model tests show the validity and stability of the proposed method.
出处
《地球物理学进展》
CSCD
北大核心
2016年第1期396-402,共7页
Progress in Geophysics
基金
国家高技术研究发展计划(863)(2011AA060301)
国家自然科学基金(41204086
41374122)联合资助
关键词
TTI介质
拟声波
逆时偏移
稳定性
伪横波
控制参数
TTI media
pseudo-acoustic wave
RTM
stability
pseudo-q SV wave
control parameter
