Reduction of Gross Rock Volume Uncertainty in a Salt Flank Structure Using Dipmeter and Image Log Data
Carmen García-Carballido, Adam Styles, Michael Pöppelreiter, 2010. "Reduction of Gross Rock Volume Uncertainty in a Salt Flank Structure Using Dipmeter and Image Log Data", Dipmeter and Borehole Image Log Technology, M. Pöppelreiter, C. García-Carballido, M. Kraaijveld
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Poor seismic imaging in the vicinity of salt domes is a well-known problem in major hydrocarbon basins such as the Gulf of Mexico and the North Sea. The consequence of poor imaging is volumetric and well targeting uncertainty. Structural interpretation of dipmeter and image logs is an essential technique to locally calibrate seismic maps and capture gross rock volume uncertainty.
Dipmeter and image log interpretation is based on the assumption that some beds, commonly low-energy deposits, were deposited horizontally. However, salt domes commonly develop at structural discontinuities, such as above basement faults or at breaks in depositional slope, so this assumption should be applied with caution. Core calibration and an appreciation of the structural history of the salt play are essential to arrive at meaningful interpretations.
The workflow described in this chapter is used to derive structural dips from dipmeter and logging-while-drilling (LWD) image logs for a typical salt flank play. This interpretation, complementary to seismic, is an additional calibration for local structure in poorly imaged areas. We show how structural scenarios were derived and reconciled with actual drilling results. This example demonstrates the usefulness of commonly run dipmeter, image log, and LWD data in calibrating seismic interpretations where seismic resolution is poor.
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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)