分段生长模式下断层边部微幅度构造分析

Micro-amplitude structures near faults based on fault segment growth pattern

文中以松辽盆地杏北开发区F278b断层为例,优选Surfer软件6种插值方法,生成葡I11层构造等值线图。以三维地震精细解释为基础,读取线道号数据与断距数据,编制距离-断距曲线图,确定断层横向分段位置。以断圈形成机制为指导,寻找断层分段生长部位与断层边部的微幅度构造分布规律,统计发育微幅度构造位置的井与分段生长点附近井的砂地比,系统分析断层横向分段生长位置、地层能干性差异与微幅度构造的关系。研究结果表明:1)Surfer软件6种插值方法中,最小曲率法在断层边部、井位控制区域内部、边界部位等与实际情况相比较符合;2)断层下盘的微幅度构造与上盘的微幅度构造受断层横向分段生长影响,呈正弦曲线分布关系,交替出现;3)断层边部上盘负向微幅度构造处砂岩体积分数较高,下盘正向微幅度构造处与断层分段生长点附近砂岩体积分数比较低。

In this study, the Fault F278b in the north of Xingshugang development area, Songliao Basin was selected as the study subject. Six interpolation methods were optimized by Surfer, generating the structure contour map of PI1j layer. Based on fine interpretation of 3D seismic data, curves reflecting relationships between distance to fault and fault displacement were drawn to identify the fault cross segmentation location by reading the line track number and fault displacement data. Guided by the formation mechanism of fault traps, distribution laws of fauh cross segmentation grow places and micro-amplitude structures close to faults were summarized. Then ratios between sandstone and stratum thickness in wells near sectional growing places and micro-amplitude structures were counted to systematically analyze the correlation of fault cross segmentation location and stratigraphic competency difference with micro-amplitude structures. It is demonstrated that interpolation by the minimum curvature method in the fault edge as well as well-controlled areas and edges is the most consistent with the actual situation among six methods. Moreover, micro-amplitude structures in the footwall and hanging wall alternate in forms of sine curves due to the influence of fault cross segmentation growth. In addition, sand contents in the negative micro-amplitude structures in the edge of the hanging wall are generally high, while those in the positive micro-amplitude structures and near fault cross segmentation growth points are commonly lower.