摘要
ZDSD-1孔是"大陆科学钻探选址与钻探实验"项目在罗布莎铬铁矿区科学钻探实验区部署的第三口科学钻探孔,终孔深度1 486.86 m,全孔实施了连续取芯和综合地球物理测井作业。采集到的超声成像测井资料包含丰富的井壁地质特征信息,对裂缝、破碎带识别和构造应力场分析具有重要作用。通过对超声成像测井资料的研究,在超声成像测井图上裂缝多表现为宽度变化明显的暗色条带特征;破碎带多表现为杂乱的暗色或黑色斑块,地层破碎严重时则呈大段的暗色或黑色条带;井壁崩落表现为一组近180°对称分布的暗色或黑色垂直条带或斑块。通过对20组井壁崩落方位的统计,推断ZDSD-1孔现今最大水平主应力方位为40.3°~218.4°。
Drill Hole ZDSD-1 is the third scientific drilling hole in the Luobusha chromite deposit,belonging to the " continental scientific drilling: site selection and pilot hole" project,and its final depth is 1486.86 m. The drill hole implemented continuous coring and conducted geophysical well logging.The ultrasonic image logging data contained a mass of information about the borehole wall geological features,which played an important role in the identification of fractures,fracture zones and the analysis of tectonic stress field.Using the ultrasonic image logging data,the authors found that most fractures exhibit the form of dark stripes whose width changes obviously,the fracture zones in most cases exhibit littery dark patches,while they assume a large area of dark stripes where the strata are broken seriously,and the borehole breakouts exhibit a pair of symmetrical dark straight stripes or patches spacing 180 degree.Through the statistics of the orientation for 20 pairs of borehole breakouts,the authors infer that the orientation of the maximum horizontal principal stress for drill hole ZDSD-1 is 40.3° ~ 218.4°.