非零炮检距菲涅耳带研究

菲涅耳带是衡量地震横向分辨率的一个重要参数。对水平界面和倾斜界面两种情况下的非零炮检距菲涅耳带方程进行了理论推导,给出了相应的数值算例,指出了菲涅耳带在非零炮检距情况下表现为椭圆的性质,并对非零炮检距情况下地震绕射波能量的主要分布范围做了定量阐述。研究结果表明,炮检距是影响菲涅耳带椭圆大小和形状的主要因素,炮检距越大,椭圆面积越大,离心率也越大。界面倾角对椭圆大小和形状的影响相对微小可以忽略不计,但界面倾角却是影响椭圆中心位置偏离反射点程度的主要因素,倾角越大,椭圆中心在反射点下倾方向上偏离得越远。这一结论对于指导野外观测系统的设计和资料处理参数的选择都有积极的指导意义,同时也是对常规意义下菲涅耳带概念的扩充。

Study of non-zero offset Fresnel zone

Fresnel zone is an important parameter of seismic lateral resolution. The expressions of non-zero offset Fresnel zone for horizontal and dip reflectors were deduced. Two numerical examples illustrated the theoretical results, and the ellipse features of non-zero offset Fresnel zone expounded the distribution of the main energy of seismic diffracted waves quantitatively. The results show that offset is the main factor in changing the size and eccentricity of the Fresnel ellipse. But the influence of interface dip is relatively small and can be omitted. A considerable declinational departure of the ellipse's center from the reflection point may be caused by the reflector's dip, and the deflection grows rapidly with the dip increasing. These results can be used for guiding the design of field survey project and the parameter selection in data processing. It is also an expansion to the Fresnel zone in common sense.