Triaxial Induction Applications In Difficult And Unconventional Formations Available to Purchase

Multiarray triaxial induction tools have the potential to revolutionize the petrophysics of thin-bed formations as well as to give geologists a powerful measurement of dip. Both of these applications are very dependent on the ability to extract the needed parameters from the triaxial raw data. Because of the need for relatively fast turnaround time for the answer, 1D inversion algorithms have been the method of choice since the introduction of these tools. However, the world is far from one-dimensional. Standard measures of the quality of the inversion, such as the misfit, are not capable of distinguishing the several sources of error, especially when the formation is not 1D. By incorporating a zero-D inversion into the workflow and looking at the rate of change of the continuous dip from that product, we can see immediately if the formation is 1D or not. This can be used to drive a multiple-input log quality indicator. In addition, the choice of regularization terms is extremely important to make sure that the answer is well behaved in non-1D formations. The regularization terms include smoothing and terms to make sure that the unknowns are within the allowable physical range. Finally, a reference term is included to make sure that the solution is not too far from a reference model, which is usually a reasonable first guess. Combined with the new log quality displays, the enhanced regularization gives good inversion results along with flags of formation zones that are outside the 1D assumptions of the inversion. The sensitivity of the zero-D dips to resistive fractures extends well beyond the borehole, even to fractures that do not intersect the borehole. Finally, in a geology application, use of the higher-resolution zero-D dips clearly define faults and structure that were not visible on seismic data.