It has been 10 years since the presentation of ‘Wireline logging for deepwater geohazard assessment’ (Digby, 2002) given at the 5th International Conference of Offshore Site Investigation and Geotechnics (OSIG). This paper compares the state of wirelining logging for geological site investigation then to now, and the improvements made as a result of the lessons learned over the past decade. In those 10 years there has been a gradual improvement in the equipment available and a refinement of the methods used to improve the percentage of borehole logged through-the-bit. In addition, a number of new developments are on the horizon which will further widen the availability of high-quality geophysical borehole data in the shallow section of deepwater prospects. The most significant advance, however, has not been operational improvements, but in the understanding of how to use the wireline data to allow the best integration of the geophysical and geotechnical data sets routinely acquired for geohazard assessment.
Wireline logging and related techniques (such as logging while drilling (LWD)) are widely used in virtually every field of geological site investigation involving boreholes. The techniques, of course, were first developed in the oil exploration industry, where the techniques still reach their greatest sophistication and widest range of use. The geotechnical investigations offshore for field development only have this data if clients are already aware of significant problems to the development that conventional drilling and sampling cannot readily define. Geotechnical investigations are often carried out in very shallow depths for anchor emplacements and pipe line manifolds, etc., that may only require investigation to 30m or less. Many companies and geotechnical specialists are unaware of the benefits that can result from high-resolution, high-quality borehole geophysics, or of the fact that it is available for offshore geotechnical investigations.
