The main purpose of this project is to use the borehole acoustic televiewer to determine geological parameters from boreholes drilled site investigation of Keelung river Sihjiaoting flood diverted plan. Results of the televiewer were also compared with core interpretation.
The expected total drilling depth was 330 m in this project. Because 94BH01 borehole collapsed after removing the casing and the water level in the 94BH03 borehole was too deep, televiewer logging could not be done in these two boreholes. Logging of 3-arm caliper and borehole acoustic televiewer were successfully conducted in the remaining boreholes, 94BH02, 94BH04, 94BH05, and 94BH06. The total operating depth is 168.46 m.
With borehole acoustic televiewer, borehole trace and 360-degree unwrapped borehole image can be obtained. By imagine analysis, geological structures and fractures can be distinguished and the associated strike/dip information can be obtained for advanced structure and fracture statistic analysis. In order to estimate the applicability of borehole acoustic televiewer technique, the apparent dips defined by the conventional borehole interpretation and the dips calculated by televiewer analysis were compared in this project. With borehole acoustic televiewer, this project provides better understanding in detail about the geotechnical characteristics, including the location and strike/dip of existing structures and fractures, along the flood diverted route.