昭通地区现今构造应力场分布特征及成因机制

Distribution characteristics and genetic mechanism of present tectonic stress field in Zhaotong area

构造应力场研究对于油气勘探开发工作具有重要的理论与现实意义。为了更好地指导昭通国家级页岩气示范区的页岩气勘探开发工作,基于断层组合、叠加褶皱、钻井诱导缝走向、井壁坍塌方位等资料,应用构造解析与应力场数值模拟方法对该区现今应力场分布特征及成因机制开展了研究。研究结果表明:(1)该区现今最大水平主应力方向整体上为E—W,与局部应力场分布存在着差异,造成异常的原因主要是局部应力场分布受联合次生应力场的叠加作用控制影响;(2)青藏高原东部被印度板块挤出往东滑动推挤是该区现今构造应力场产生的主要动力来源,控制着其区域应力场方位;(3)该区局部地应力场受多组次生应力场联合控制,在南北向左旋与东西向右旋走滑力偶联合作用下,M工区现今最大水平主应力方位呈北东向,而在A井区东西两边的应力场联合作用下,其现今最大水平主应力方位呈北西向。结论认为,现今应力场分布特征及成因机制解析,为该区页岩气地质工程一体化的实践提供了技术支撑,对加快该区页岩气的产能建设起到了积极的推动作用。

The study of tectonic stress field has important theoretical and practical significance for oil and gas exploration and development.In order to better guide the shale gas exploration and development in Zhaotong national shale gas demonstration area,based on the data of fault combination,superimposed fold,drilling induced fracture strike,wellbore collapse orientation,etc.,the distribution characteristics and genetic mechanism of current stress field in this area were studied by using structural analysis and numerical simulation of stress field.The results show that:(1)the current maximum horizontal principal stress direction is E-W,which is different from the local stress field distribution.The main reason for the anomaly is that the local stress field distribution is controlled by the superposition of combined secondary stress field;(2)the eastern Qinghai Tibet Plateau is squeezed out by the Indian plate and pushed eastward,which is the main power source of the current tectonic stress field(3)the local stress field in this area is jointly controlled by multiple groups of secondary stress fields.Under the combined action of the North-South left-handed and the East-West right-handed strike slip couple,the current maximum horizontal principal stress direction of work area m is NE,while under the combined action of the East-West stress fields of well area a,the current maximum horizontal principal stress direction is NW.It is concluded that the analysis of current stress field distribution characteristics and genetic mechanism provides technical support for the practice of shale gas geological engineering integration in this area,and plays a positive role in accelerating the production capacity construction of shale gas in this area.