苏北盆地高邮凹陷阜宁组二段深层页岩储层地应力方向及主控因素

In-situ stress orientation and main controlling factors of deep shale reservoirs in the second member of Paleogene Funing Formation in Gaoyou Sag, Subei Basin

严泽宇 梁兵 孙雅雄 段宏亮 邱旭明

YAN Zeyu LIANG Bing SUN Yaxiong DUAN Hongliang QIU Xuming

中国石化 石油物探技术研究院有限公司, 南京 211103 中国石化 江苏油田分公司, 江苏 扬州 225009 东北石油大学 地球科学学院, 黑龙江 大庆 163008

SINOPEC Geophysical Research Institute Co., Ltd., Nanjing, Jiangsu 211103, China SINOPEC Jiangsu Oilfield Company, Yangzhou, Jiangsu 225009, China School of Earth Sciences, Northeast Petroleum University, Daqing, Heilongjiang 163008, China

苏北盆地高邮凹陷阜宁组二段页岩油资源量超7亿吨，但该区构造、应力双复杂的地质条件对页岩油勘探开发造成较大影响，尤其是现今地应力方向的认识不清，制约了水平井井组方案的部署和压裂方案的设计与优化。基于区域震源机制解、特殊测井和水平井压裂微地震监测等资料，结合波速各向异性、古地磁等实验测试分析资料，开展了各类地应力方向解释方法在深层页岩储层中的适用性研究，查明了花庄地区现今地应力的分布特征，并对其影响因素进行了分析。高邮凹陷阜二段现今水平最大主应力方向主要分布在40°—55°，平均方位角为45°，即现今水平最大主应力方向为NE向。平面上，研究区地应力方向与大区域上应力方向具有较小的应力偏转，主要受构造格局的影响；此外，断层附近存在应力扰动带，扰动带内应力偏转较为明显，扰动带的宽度与断层的断距和延伸长度成正相关。通过对比分析，认为微地震监测、诱导裂缝/井壁崩落、岩心实测、阵列声波各向异性的适用性逐级降低，阵列声波测井中的波速各向异性受平面上岩相相变的影响较大。结合地应力方向解释结果、天然裂缝优势走向，建议该区水平井的部署方位为SE155°—SSE170°。

The shale oil resources in the second member of the Paleogene Funing Formation in the Gaoyou Sag, Subei Basin exceed 700 million tons. However, the complex geological conditions of both its structure and stress significantly impact the shale oil exploration and development in this area. In particular, the lack of clarity regarding the present-day in-situ stress orientations constrains the deployment of horizontal well groups and the design and optimization of fracturing projects. In this study, the applicability of various methods for interpreting in-situ stress orientations in deep shale reservoirs was investigated based on data from regional focal mechanism solutions, specialized logging, and microseismic monitoring of horizontal well fracturing, as well as the experimental analysis such as velocity anisotropy and paleomagnetic tests. The distribution characteristics of the present-day in-situ stress in the Huazhuang area were identified, and their influencing factors were analyzed. The results indicated that the present-day maximum horizontal principal stress direction in the second member of the Funing Formation mainly ranged from 40° to 55°, with an average azimuth of 45°, indicating a northeastward orientation. In the planar view, the in-situ stress orientation in the study area exhibited minor stress deviations on a larger regional scale, mainly influenced by the structural patterns. Furthermore, stress perturbation zones were found near faults, where stress deviations were more pronounced, and the width of these perturbation zones was positively correlated with fault displacement and extension length. Comparative analysis suggested a decreasing applicability of microseismic monitoring, induced fractures/wellbore collapses, core measurements, and array acoustic anisotropy. Specifically, the velocity anisotropy in array acoustic logging was significantly influenced by lithological phase transitions on a planar scale. Based on the interpretation of stress orientations and the dominant trends of natural fractures, the recommended horizontal well deployment azimuth for this area is SE155° to SSE170°.

国家自然科学基金面上项目 42072155;中国石化科技开发部项目 P23189;中国石化科技开发部项目 P24207;中国石化江苏油田分公司科研课题 JS24038;

https://doi.org/10.11781/sysydz2024061187