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火山岩地层裂缝发育、裂缝发育程度是制约产能关键因素.裂缝是怎样影响地层横向的地震成像效果,并具有什么独特的地球物理反射特征,是人们一直关注的重点.本文设计不同类型含裂缝地质模型,结合不同岩性实验室测试参数将地质模型转化为地球物理模型,采用计算精度高的交错网格高阶有限差分法,开展不同裂缝模型地震波场特征正演模拟研究,对比分析含裂缝和不含裂缝地层波场传播的特征和成像剖面特征,以及含裂缝和不含裂缝全弹性波场的频率域特征变化,指导火山岩地层中裂缝的识别和预测.研究表明,含裂缝地层产生强散射波场,裂缝散射波振幅与裂缝数量、速度差有关;发育裂缝的火山机构,散射波场与其他波场(如反射波场、透射波场等)叠加、干涉相互作用,造成波前面出现断断续续的现象,在成像地震剖面上裂缝形成断续反射,且火山岩地层中裂缝散射波主频高于地层反射波的,裂缝发育地层具有高频段振幅明显增强的特征.
The development of fractures in volcanic strata and the degree of fracture development are the key factors restricting productivity.However, how fractures affect lateral seismic imaging of strata and have unique geophysical reflections has been the focus of much attention recently.In this paper, different types of fractured geological models , Combined with different lithology laboratory test parameters to transform geologic model into geophysical model. The staggered-grid high-order finite difference method with high accuracy of calculation was used to study the modeling of seismic wave field characteristics in different fracture models. The characteristics of the wave field propagating in the fractured strata and the characteristics of the imaging profile, as well as the characteristics of the frequency domain including the fractures and the full elastic wave field without fractures, guide the identification and prediction of fractures in the volcanic strata. The results show that strong scattered waves The amplitudes of the scattered waves in the field and the cracks are related to the number of cracks and the velocity difference. The volcanic structures and scattering wave fields of the fractures overlap with other wave fields (such as reflected wavefield and transmitted wavefield) and interfere with each other, resulting in intermittent Phenomenon, fractures form intermittent reflections on imaging seismic sections, and in volcanic formations Slit scattered waves reflected waves of higher frequency, fractures formation has significantly enhanced the amplitude of the high frequency characteristic.