摘要
合川地区须二段致密砂岩气资源十分丰富,但该区复杂地质条件对目前油气资源勘探开发造成了巨大影响,尤其是现今地应力方向认识不清制约了后期水平井部署和压裂改造的持续推进。基于波速各向异性、差应变及古地磁等实验测试分析,并结合特殊测井与微地震监测资料,开展了各类地应力方向测试与解释方法在致密砂岩储层中应用的适用性评价研究,查明了合川地区现今地应力方向的分布特征。结果表明合川地区须二段最大水平主应力方向主要分布在N103.1°EN134.3°E,平均最大水平主应力的方位角为N117.4°E,即合川地区须家河组砂岩现今最大水平主应力方向为NWW-SEE。平面上,地应力方向变化不明显,其较小的地应力偏转主要受沉积结构影响,而合川地区须二段致密砂岩均质性相对较强,各向异性偏弱,波速各向异性测试方法在该区无法适用。通过微地震监测和井壁成像测井评价地应力方向,认为差应变联合古地磁的实验测试结果与上述评价结果具有较高的一致性,故该测试方法更加适用于该区均质且各向异性较弱的砂岩地层。并结合地应力方向和裂缝优势走向等,建议水平井的部署方位为N40°E-N55°E。
The Hechuan area is rich in dense sandstone gas resources in the second member of the Xujiahe formation,and the complex geological conditions in this area have a great impact on the current exploration and development of oil and gas resources.One of the issues resulting from this complexity is an unclear understanding of how present-day in-situ stress direction restricts the later horizontal well deployment and the promotion of fracture transformation.Based on an analysis of wave velocity anisotropy,differential strain,and paleomagnetism,combined with special logging and microseismic monitoring data,the applicability of various types of in situ stress direction testing frameworks in dense sandstone reservoirs was evaluated,and the distribution of present-day in situ stress directions in the Hechuan area were determined.The results show that the maximum principal stress orientation of the second member of the Xujiahe Formation in the Hechuan area is mainly distributed between N103.1°E-N134.3°E,and the azimuth angle of the average maximum principal stress is N117.4°E;that is,the present-day maximum principal stress orientation of the sandstone in this area is NWWSEE.The change in the direction of the in situ stress in the plane is not significant,and its weaker in situ stress deflection is mainly influenced by the sedimentary structure.In the Hechuan area,the dense sandstone in the second member of the Xujiahe Formation is relatively homogeneous,and the anisotropy is weak;therefore,the wave velocity anisotropy test cannot be applied in this area.The experimental test results of differential strain combined with paleomagnetism are highly congruent with the results above.Therefore,the test more applicable to sandstone formations in this area,specifically the ones with a homogeneous and weak anisotropy,is microseismic monitoring and well wall image logging to evaluate the in-situ stress direction.Combined with the direction of the in situ stress and fracture development,the recommended orientation for horizontal well deployment is N40°E-N55°E.
作者
曹峰
何建华
王园园
邓虎成
徐庆龙
CAO Feng;HE Jianhua;WANG Yuanyuan;DENG Hucheng;XU Qinglong(College of Energy,Chengdu University of Technology,Chengdu 610059,China;State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China;Hainan Branch of CNOOC Ltd.,Haikou 570100,China;Exploration and Development Research Institute,Daqing Oilfield Company Ltd.,Daqing Heilongjiang 163000,China)
出处
《地球科学进展》
CAS
CSCD
北大核心
2022年第7期742-755,共14页
Advances in Earth Science
基金
四川大学深地科学与工程教育部重点实验室开放基金项目“深层复杂构造带页岩钻井地应力剖面扰动的力学机理及关键评价技术研究”(编号:DESEYU 202102)
四川省科技厅项目“基于多源数据驱动的深层页岩储层钻井地应力剖面智能构建技术研究”(编号:22MZGC0159)资助
关键词
地应力方向
古地磁测试
差应变测试
须二段
合川地区
In-situ stress orientation
Paleomagnetic test
Differential strain test
The second member of Xujiahe formation
Hechuan area
