基于随机缝洞介质理论模拟塔中北坡储层的地震响应

由于碳酸盐岩缝洞型储层自身的特点，岩石物理性质呈跳跃性变化，储集体形态变化也较剧烈，现有的随机介质模型并不适合对缝洞型储层的描述，且随机介质的非均匀尺度往往局限于水平方向和垂直方向，无法对地下任意方向的非均质特征进行描述。为此，在混合型自相关函数的基础上，通过引入方向因子给出了一种新的矢量自相关函数表达式，使产生的随机介质具有一定的方向性，在此基础上采用阈值截取法，通过给定缝洞发育的长、短半轴及局部发育密度构造具有不同统计特征的缝洞介质模型，实现了对不同尺度、发育密度、发育角度及不同充填速度的复杂缝洞的有效描述。结合塔中北坡实际钻井资料及测井解释成果，建立了符合该区实际地层结构的随机缝洞介质模型，利用非均匀介质条件下波动方程数值模拟，研究了不同参数情况下一间房组顶部储层的运动学及动力学特征。正演模拟结果表明，缝洞型储层发育尺度越大、发育密度越高及缝洞内充填速度越小，则对应T₇⁴界面波峰的反射能量越弱、低频特征越明显，从而为一间房组顶部缝洞型储层波场特征识别及储层预测提供了依据。在此基础上优选出对一间房组顶部缝洞型储层参数变化敏感的属性（均方根振幅及瞬时频率），大大提高了在界面强反射干扰下缝洞型储层预测的准确性。

Simulation of reservoir seismic response in the northern slope of the middle Tarim Basin with random fracture-cavern media model

In fractured carbonate reservoirs,rocks show discontinuous changes in physical properties and reservoir bodies vary significantly in shape.For this reason,existing random media models are incapable to simulate fractured carbonate reservoirs.Moreover,as random media exhibit heterogeneity only in horizontal and vertical directions,these models cannot describe heterogeneous characteristics of underground rocks in arbitrary directions.In this view,a new autocorrelation function is constructed by introducing a directionality factor into a mixed autocorrelation function,and the resulted random media will be directional.Based on this,fractured media models with different statistical characteristics are created by thresholding and designating the lengths of semi-major and semi-minor axes of fractures as well as local fracture density.These models can be used to effectively describe complex fractures of varying sizes,density,orientations,and filling rates.Then a random fractured media model is developed for the northern slope in the Tazhong Uplift using borehole data and results of well logging interpretation.After that,wave equation modeling for heterogeneous media is performed to investigate the kinematic and dynamic characteristics of a reservoir located at the top of Yijianfang Formation with different parameter values.The outcome of forward modeling suggests that as the fracture size and density increased,the fracture filling rate decreased,and the peak corresponding to the T₇⁴ interface shows a weaker reflected energy at low-frequency.This result provides a basis for analyzing wave field and characterizing fractured reservoirs at the top of the Yijianfang Formation.Furthermore,the most sensitive attributes to fractured reservoir variations such as root mean square amplitude and instantaneous frequency are extracted to improve fractured reservoir prediction in the presence of strong reflection interference from interfaces.