Introduction to the New Halliburton-Welex Dip Meter

Abstract

Abstract To provide a more detailed study of the structural conditions in a well, anew continuous dip meter tool is offered to the industry. The tool provides formore correlative points by improved pad design, use of a focusing currentresistivity measure, non-linear scales and rapid response galvanometers. A newtype of drift transducer gives direct readings of hole drift, and a constantvelocity coupling suspension eliminates "projection corrections." A techniqueof calibration eliminates errors of direction of 180 degrees and multiples of60 degrees. A method of presentation and a discussion of the interpretationnecessary to recognize faults, bars and unconformities is brieflydiscussed. Introduction In the early days of dip meter logging, only a few isolated stations werereported on a dip survey. The inadequacies of early tools, and, moreparticularly, inadequate calculations and interpretive techniques, gave theimpression to the industry that dip meter survey information was of smallutility. The experienced dip meter computer and log analyst, however, soonrealized that a wealth of structural information could be obtained from a dipmeter survey that provided sufficient information to allow computations atnumerous stations. It was recognized that errors due to erratic galvanometerresponse, tool rotation, "floating pads" and "projection corrections" or"pseudo azimuths" had to be eliminated. Theory Fundamentally, the Welex tool (Figure 1) operates on the sameprinciple as all dip meter tools; i.e.. three points defining a plane. Threeresistivity curves properly correlated provide these points when the positions of the point, are oriented in azimuth. The displacement of these points, properly corrected for the geometry of the bore hole, defines the plane inspace.