上海地区浅部地应力测量及其构造地质意义分析

In-situ stress measurement in the shallow basement of the Shanghai area and its structural geological significance

通过水压致裂法与超声波成像测井法相结合的方法,对上海地区浅部(180 m深度范围)原位地应力进行了测量。测量结果表明:最大水平主应力值在9.54~12.91 MPa之间,最小水平主应力值在5.41~6.96 MPa之间,最大水平主应力方向为北西42°—62°,优势方位为北西,地应力结构为SH>Sh>Sv,可以反映区域构造应力场特征。依据区域内断裂空间分布特征和现今实测地应力结果综合分析认为,北东向断裂易于发生压性或压扭性逆断活动,断裂相对稳定;而北西向断裂易于发生张性或张扭性正断活动,在现今相对较高的应力水平状态下仍值得关注。测量结果可能对于揭示区域构造界线(江山—绍兴断裂)的走向有一定启示。

By the hydraulic fracturing method and the ultrasonic imaging logging method,in-situ stress measurement was carried out in the shallow basement(180 m depth range)of the Shanghai area.The measurement results show that the maximum horizontal principal stress is between 9.54~12.91 MPa,and the minimum principal stress is between 5.41~6.96 MPa.The maximum horizontal principal stress direction is NW420-620,the dominant orientation is NW,and the stress structure is S_H>S_h>S_v,which reflects the characteristics of the regional structural stress field.Based on the spatial distribution of the internal fractures in the area and the in-situ stress measurement results,the NE faults are prone to compressive or compression-torsional reverse faulting and the faults are relatively stable,while the NW faults are prone to tensile or tension-torsional positive faulting,which is still worthy of attention under the current relatively high stress level.At the same time,the in-situ stress measurement results may have guiding significance for the study of the structural boundary trend(the Jiangshan-Shaoxing fault)in this area.