Fracture identification by reflected guided borehole radar waves

Summary

Reflected guided borehole radar waves can be observed when a borehole radars (BHR) is either suspended by a conductive communication cable or run in a borehole filled with saline water. They are often referred as unwanted contaminations to the conventional BHR surveying and should be avoided or suppressed. However, as a type of reflected waves, they contain geological information about the surroundings of the borehole and can be used to recognise geological boundaries such as lithological interfaces and fractures intersecting the borehole. The guided BHR reflections have different phase characteristics for stratigraphic boundaries and fractures. The reflections from both sides of a fracture have the same phase, whereas the reflections from both sides of a stratigraphic interface have opposite phases. Such characteristics enable us to differentiate fractures from bedding boundaries down the borehole using the borehole guided waves. This is demonstrated by both synthetic and real field data.

• fracture identification
• borehole radar
• guided wave