Structure- and Texture-Based Fullbore Image Reconstruction
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Structure- and Texture-Based Fullbore Image Reconstruction Tuanfeng Zhang1 Robert Laronga2
· Andriy Gelman3 ·
Received: 26 January 2016 / Accepted: 15 July 2016 / Published online: 2 August 2016 © International Association for Mathematical Geosciences 2016
Abstract Borehole image logs are produced by tools lowered into a well. Such logs provide oriented electrical and acoustic maps of rocks and fluids encountered in the borehole. Electrical borehole images, acquired in either water-based (conductive) or oil-based (nonconductive) muds, are generated from electrodes arranged in fixed patterns on pads pressed against the borehole wall. Depending on borehole diameter, gaps nearly always occur between pads. Because of these gaps, it is common to have nonimaged parts of the borehole wall. The existence of gaps in pad-based borehole images hinders efficient geological interpretation and accurate formation evaluation. A novel method to generate fullbore images combines an inpainting technique with FilterSim: a continuous-variable multipoint statistical approach. The inpainting algorithm detects dips and captures the trend of borehole image logs. The extracted smooth trend maps are fed into FilterSim to guide the construction of high-resolution textures that honor the original borehole image data, leading to seamless reconstruction of 360◦ fullbore images. The proposed method has been tested using various borehole image patterns and proves to be a reliable and robust way to perform fullbore image reconstruction. The reconstructed fullbore images facilitate improved visualization and interpretation of borehole image logs in various ways, including automated dip picking for fractures and bedding planes, thin-bed analysis in deepwater formations, complex heterogeneity analysis, and accurate porosity estimation in carbonates.
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Tuanfeng Zhang [email protected]
1
Department of Reservoir Geosciences, Schlumberger-Doll Research Center, Cambridge, MA 02139, USA
2
Schlumberger, South Dairy Ashford Road, Houston, TX 77077, USA
3
Department of Mathematical Modeling, Schlumberger-Doll Research Center, Cambridge, MA 02139, USA
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Math Geosci (2017) 49:195–215
Keywords Wireline borehole images · Image gaps · Fullbore images · Structures · Textures · Kernel regression · Inpainting · Multipoint statistics · FilterSim
1 Introduction Electrical imaging tools are widely used to log subsurface boreholes to locate and map the boundaries between rock layers (i.e., bed boundaries) and to visualize and orient fractures and faults (Gilreath 1987). Because these logging tools are pad-type devices with fixed arrays of electrodes, it is common to have gaps with missing information between the pads. A continuous-variable multipoint statistics (MPS) approach, FilterSim, has been used to fill the gaps with realistic statistically modeled images (Zhang 2006; Zhang et al. 2006; Hurley and Zhang 2011). The reconstructed fullbore images allow accurate formation evaluation, automated texture extraction, and reservoir heterogeneity quantifica
