Fracture Characterization andStructural Identification of CambayShale using short communication ofFMI* log

摘要

To reduce uncertainty and for avoiding drilling hazards, a thorough understanding of Cambay shale properties is desired. While drilling through Cambay shale differential pipe sticking problems are often encountered which maybe because of the fractures present in Cambay shale. Upper Cambay shale is more fractured, giving abnormal pore pressure while drilling. Engineers encountered many challenges in both acquiring adequate data and assessment of the fractures and faults in the borehole environment. FMI log helps us to overcome this problem and gives us a precise understanding of the borehole formation. This paper gives an idea of the fractures present, dip, strike and azimuthal properties, planar and cross bedding structures, faults and their orientations in both Upper and Lower Cambay shale by interpretation of FMI logs. From calliper log of Cambay shale it is evident that Upper Cambay shale has loose formations while the study of FMI logs indicates the presence of faults in both Upper and Lower Cambay shale. They are vertical in nature & drag component is more in Upper Cambay shale than in Lower Cambay shale. The validation of the interpreted data is done by drilling history, seismic data, mud logs, conventional logs and geological understanding of Cambay Basin. Such studies will help in developing future exploration strategies and designing of optimum well trajectory.