复频条件下组合接收参数设计

Geophone array parameter design under multi-frequency condition

在低信噪比地区,检波器组合对随机噪声和规则噪声都具有压制功能,是提高地震资料信噪比的有效方法。传统组合参数设计技术隐含"地震波为某一频率谐波"的假设,未能综合考虑组内距、组合个数、加权系数、延时量四种参数,导致其低通滤波特征明显,AVO扭曲现象严重。文中剖析了复频条件下上述四种参数与组合方向因子的关系,给出理论信噪比计算方法;以该理论信噪比为目标函数,通过全局寻优设计最佳组合参数。经理论模型和实际资料验证,综合考虑四种影响参数的延时加权组合方法对线性噪声、随机噪声具有较强压制能力,同时其低通滤波效应和AVO扭曲现象得到削弱。

Geophone array is used to suppress random noises and regular noises and improve signal to noise ratio,especially in those prospects with low signal to noise ratio.Array parameter design is commonly performed under the assumption that seismic waves are harmonic waves at a specific frequency.Element interval,number of arrays,weighing factor,and time delay have not been taken into overall consideration;this results in significant low-pass filtering and distorted AVO effects.We discuss the relations among above 4 parameters and orientation factor at complex frequencies.To calculate the theoretical signal to noise ratio,we formulate an equation and then take it as the objective function for array parameter design through global optimization.As per model and field data tests,linear noises and random noises could be greatly reduced using the time-delay weighted arrays with above 4 optimized parameters;the behavior of low-pass filtering and AVO distortion could also be remedied.