Borehole Image Tool Design, Value of Information, and Tool Selection
Javier O. Lagraba P., M. Hansen Steven, Mirano Spalburg, Mohammed Helmy, 2010. "Borehole Image Tool Design, Value of Information, and Tool Selection", Dipmeter and Borehole Image Log Technology, M. Pöppelreiter, C. García-Carballido, M. Kraaijveld
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Dipmeter and borehole image (BHI) logs supply geoscientists with highresolution records of rock properties and characteristics along the borehole wall. To maximize the value from borehole image logs, the objective of the project should guide the entire workflow from acquisition to processing, to the final interpretation. The planning stage of a logging run should start with an analysis of the information to estimate the monetary benefit of acquiring a BHI data set. Subsequently, tools can be selected which are capable of acquiring the data needed to answer the specific subsurface uncertainties of the project. This chapter outlines the operational principles and technical specifications of common imaging tools and their applications. The selection of the proper tool is influenced by aspects such as geological and petrophysical formation characteristics that can be resolved using either electrical or acoustic tools. Additionally, the well design influences whether a wireline or logging-while-drilling tool is the most practical logging solution. Drilling operations dictate the type of mud system being used, which is significant for determining which borehole imaging tool will be run, depending upon whether it was designed for oil-base or water-base mud.
Other criteria that influence the tool selection are borehole diameter, borehole deviation, required borehole coverage, borehole shape/rugosity, mud cake, borehole temperature, and borehole pressure. This chapter concludes with deliverables of image data at the well site and interpretation centers and their use for quality control.
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Dipmeter and Borehole Image Log Technology
Borehole imaging is among the fastest and most accurate methods for collecting high resolution subsurface data. Recent breakthroughs in acquisition, tool design, and modeling software provide real-time subsurface images of incredible detail, from the drill bit straight to a workstation. Associated interpretation workflows offer the high level of detail that is needed to make operational decision and to increase the predictability of subsurface models. Many exploration and production companies have acquired a wealth of dipmeter and image log data. The data are readily available and provide, for example the orientation of fractures and fluvial channels in space. Further applications of borehole imaging technology include matrix and fracture characterization, pore-type partitioning, geosteering, and in-situ stress determination. Exciting new applications are found in enhanced oil recovery, carbon dioxide sequestration, and geothermal projects. In addition, borehole image data are paramount to unlocking unconventional plays such as shale gas and coal-bed methane. AAPG Memoir 92 portrays key applications of dipmeter and image log data across the exploration and production life cycle. (Continued)