利用FMI资料分析塔河油田南部中—下奥陶统储层构造应力场

Analysis of the Lower-Middle Ordovician Reservoir Tectonic Stress Field Using FMI Data in the South of Tahe Oilfield

钻探结果表明,塔河油田南部地区上奥陶统覆盖区中—下奥陶统碳酸盐岩储层发育与分布明显地受断裂和裂缝控制。裂缝主要为构造开启缝,其次为钻井诱导缝,裂缝走向具有明显方向性,其形成与古构造应力场关系密切。利用大量中—下奥陶统钻井FMI资料进行裂缝识别、成因分类和走向统计分析,认为钻井诱导缝受现今构造应力场控制,构造开启缝主要受古构造应力场控制,裂缝走向与最大主应力方向一致。塔河油田南部地区诱导缝优势走向为北东向,现今最大主应力方向为北东向;构造开启缝优势走向主要有北北东向和北东东向两组,北北东向裂缝中可见充填缝,反映北北东向裂缝形成时间早于北东东向,其分别与加里东中期和海西早期的古构造应力场最大主应力方向相一致。

The drilling result shows the distribution and quality of Lower-Middle Ordovician carbonate reservoirs overlaid by Upper Ordovician in the south of Tahe Oilfield are mainly controlled by faults and fractures, with structural open fractures predominantly, drilling-induced fractures secondly. The fracture orientation is closely related to paleotectonic stress field. This paper employs a large amount of FMI drilling data to recognize and analyzes fractures orientation and their origin. It shows that drilling-induced fractures are controlled by present stress field, while the structural open fractures are controlled by paleotectonic stress field. The orientation of fractures is consistent with the maximum principal stress. The predominant orientation of drilling-induced fractures in the south part of Tahe Oilfield is northeast trend, present maximum principal stress is northeast trend, while the structural fractures predominant trend in north-northeast direction and north-east-east direction. Some of north-north-east trend fractures were filled, suggesting they formed earlier than north-east-east fractures and their forming time is corresponding to middle-Caledonian and early Hereynian paleo stress field respectively.