FROM THE BOREHOLE WALL INTO THE FORMATION – COMBINING BOREHOLE IMAGES WITH DEEP SHEAR WAVE IMAGING TECHNOLOGY
by Stefan Schimschal, Baker Hughes, a GE company
will be presented at 11:00 on Wednesday the 4 th of September, 2019, at the Solastranden Gård .
One major challenge of integrating borehole image and geophysical measurements is to bridge the gaps between their dissimilar horizontal and vertical resolutions and depth of investigation. Identifying and characterizing geological features like bedding contacts and fractures, by combining high-resolution Borehole Imaging (BHI) with Deep Shear Wave Imaging (DSWI) technology, helps to overcome this challenge. It reveal sub-seismic features in the reservoir section that ultimately lead to a more accurate structural model of the subsurface. In this paper, we present a case study showing the full integration of both imaging methods. Picked reflectors in the deep shear wave image allow correlation with corresponding geological features on the borehole image. Identifying the dip and azimuth of a reflector from the measured orientation of the corresponding feature on the borehole wall enables the rotation of the tool reference frame to be aligned with the sagittal plane from the deep shear wave image (i.e., the plane in which the reflection occurs. Note that the strike of the reflector equals the azimuth of the sagittal plane). With this borehole image-based adjustment the sagittal plane of the deep shear wave image is shown at its correct azimuth and therefore positioned “correctly” in the subsurface. Accordingly, our understanding and interpretation of the DSWI result improves significantly. Although this azimuth can also be obtained via the four component DSWI data (Tang 2004), this is not always as robust as the method proposed here. However, if possible, it is good practice to compare both methods, also because an “event” picked from a borehole image log does not necessarily have to coincide with a similar event in the DSWI image. The borehole image event may not continue away from the wellbore and/or the resolution of this borehole image event is far above the DSWI resolution.
Stefan Schimschal is a geophysicist working mainly on acoustic processing and application development. He started his career at Baker Hughes in 2013 at the acoustic group in the Celle Technology Center. Stefan holds a B.Sc. in geophysics and geoinformatics and a M.Sc. in geophysics from the TU Bergakademie Freiberg, Germany and has mainly worked on Seismic data processing during his Master times.