Derivative analysis for layer selection of geophysical borehole logs

Analysis of geophysical borehole data can often be hampered by too much information and noise in the trace leading to subjective interpretation of layer boundaries. Wavelet analysis of borehole data has provided an effective way of mitigating noise and delineating relevant boundaries. We extend wavelet analysis by providing a complete set of code and functions that will objectively block a geophysical trace based on a derivative operator algorithm that searches for inflection points in the bore log. Layer boundaries detected from the operator output are traced back to a zero-width operator so that boundaries are consistently and objectively detected. Layers are then classified based on importance and analysis is completed by selecting either total number of layers, a portion of the total number of layers, selection of minimum layer thickness, or layers detected by a specified minimum operator width. We demonstrate the effectiveness of the layer blocking technique by applying it to a case study for alluvial aquifer detection in the Gascoyne River area of Western Australia.