断裂带内部结构特征及其与油气运聚关系

Internal structures of fault zones and their relationship with hydrocarbon migration and accumulation

含油气盆地中断层的发育及其内部结构的变化对油气运聚成藏具有很大的影响。在前人研究的基础上,结合断裂带野外划分,综合运用地震、钻井、成像测井等资料对断层进行了定性的内部结构划分和常规测井刻度标定,总结测井响应特征,并运用指示曲线计算法和交会图法对其进行定量分析。结果表明断裂带主要由位于中部的滑动破碎带和其两侧的上、下盘诱导裂缝带等具有不同变形和物性特征的结构单元组成,而且断裂带内部结构具有明显的时空差异:时间上,同一断裂不同地质历史时期内部结构存在差异;空间上,断裂带具有横向上的不对称性、垂向上的分层性和走向上的分段性。正是这些差异引起断裂带内部不同结构单元物性的非均质特点,致使断裂带对油气的输导和封堵能力也存在时空差异。

Development of faults and their internal structure changes exert great influence on oil-gas migration and accumulation in hydrocarbon-bearing basins. Based on previous studies and fault outcrop observations,the present study integrated the division of fault zones with the information on seismic,drilling,imaging logging,etc. to qualitatively classify internal structures of faults,calibrate conventional logging scales and sum up logging response characteristics. Quantitative analyses were carried out on internal structures by means of instruction curves and intersection mapping. The result revealed that fault zones were mainly composed of structural units with different deformation and properties in the central sliding breaking zones and the induced fracture zones on both the upper and lower plates,and there existed distinctly temporal and spatial differences in the internal structures of fault zones. Temporally,internal structures were different for the same fault but at different geological periods; spatially,fault zones had horizontal asymmetry,vertical stratification and segmentation along fault strike. These differences are just what that caused the heterogeneity of physical properties of different structural units within fault zones,which then makes temporal and spatial differences in abilities of hydrocarbon transporting and sealing by faults.