潜山裂缝储层地震多尺度裂缝带预测方法研究

Seismic prediction method of multi-scale fracture zone for buried-hill fractured reservoir

现有潜山裂缝储层地震预测主要描述地震视野下(数十至千米)某一特定尺度范围的裂缝带特征,为进一步突破地震裂缝预测尺度,综合描述太古界潜山裂缝储层多尺度特征,结合地震预测与模型表征发展地震多尺度裂缝带预测方法:(1)综合基于叠后地震的高陡“断缝体”刻画属性(描述大尺度裂缝带)、叠前AVO梯度方位各向异性预测属性(描述中小尺度裂缝带),利用Contourlet变换方法实现属性融合,作为断裂发育强度指导场.(2)对断裂发育强度指导场利用Hough变换方法进行矢量化提取,同时结合井筒FMI测井裂缝方向、地震叠前各向异性预测方位属性,建立断裂发育方向指导场.进一步根据矢量化提取结果,基于断裂带长度与数量服从幂律分布关系,统计分形维数.(3)结合发育强度指导场、发育方向指导场与分形维数,利用分布函数随机过程实现地震多尺度裂缝带预测.其中裂缝带分布位置以发育强度指导场为约束,利用泊松过程实现;裂缝带长度服从指数分布,并利用分形维数约束;裂缝带方向服从Fisher分布,并利用发育方向指导场约束.该方法应用于渤海M气田,预测的大尺度裂缝带与区域储层品质地质认识一致,中小尺度裂缝带与井区裂缝发育特征及生产测试较为一致,指导了M气田开发井优化,证实该方法具有一定实用意义.

The currently fracture prediction methods mainly focus on describing the fracture zone within a specific scale,we develop a new method to predict the multi-scale feature zone of buried-hill fractured reservoir.Firstly,we exploit the post-stack seismic structural attribute and pre-stack AVAz attribute respectively predict the large-scale and middle-scale fracture zone,and use the high-order wavelet transform to get a multi-scale merged attribute as the fracture intensity field.Secondly,we extract the fracture lines from the merged attribute using the Hough transform method,and by using the FMI logs to constrain the orientation of the predicted fracture,we establish a fracture orientation field.Besides,based on the power-law distribution relationship between the length and amount of the fracture,the fractal dimension is estimated.Finally,based on the fracture intensity field,fracture orientation field and fractal dimension,we exploit the distribution function and stochastic process to predict the multi-scale fault zone.The position of fracture zone is constrained by the fracture intensity field and realized by Poisson process.The length of fracture obey exponential distribution and constrained by the fractal dimension.The direction of the fracture is constrained by the fracture orientation field and obey Fisher distribution.The new method is applied in M gas field,Bohai Bay Basin,and the predicted large-scale fracture zone is consistent with the regional reservoir quality,and the middle-scale fracture is consistent with the production test data.The results is used in optimization of the designed development wells,and to some extent confirms the practical significance of the proposed method.