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GCAGS Transactions

Abstract


Gulf Coast Association of Geological Societies Transactions Vol. 58 (2008), Pages 517-524

EXTENDED ABSTRACT: Imaging Digital Well Logs in 3D Virtual Reality:Investigation of Northern Louisiana Wilcox Fluvial/Coal Strata for Coalbed Natural Gas

Gary L. Kinsland1, Christoph W. Borst2, Jan-Phillip Tiesel2, James J. Willis3, and Catherine E. Bishop1

1Department of Geology, University of Louisiana at Lafayette, P.O. Box 44530, Lafayette, Louisiana 70504

2Center for Advanced Computer Studies, University of Louisiana at Lafayette, P.O. Box 44330, Lafayette, Louisiana 70504

3Odyssey International, L.L.C., 7190-C Cemetery Hwy., St. Martinville, Louisiana 70582

EXTENDED ABSTRACT

We have initiated an energy consortium, presently directed to the study of coalbed natural gas (CBNG) resources of the Wilcox strata of northern Louisiana. We are digitizing well logs, digitally mapping selected horizons and units, and developing a digital 3D geographical information system (GIS). About 800 geophysical well logs have been digitized in this area with most of them being the deepest wells that penetrated the stratigraphic interval of interest (Fig. 1).

This work was carried out within two different 3D software systems. One system was developed by the Center for Advanced Computer Studies (CACS) at the University of Louisiana at Lafayette, where several well logs were “hung” below a National Aeronautics and Space Administration (NASA) shuttle radar topography mission (SRTM) surface (Figs. 2-4). These data may be viewed and manipulated in interactive 3D environments, such as the total immersive space (TIS), a six-sided stereoscopic rearprojection system that provides a full 360° field of view. The TIS is in a 3D immersive visualization and high-performance computing center in Lafayette, Louisiana (Louisiana Immersive Technologies Enterprise [LITE]) (Fig. 5). The other software system is based upon Seismic Micro-Technology’s (SMT) VuPak. This system concurrently displays geophysical well logs and multiple interpreted horizons that are all displayed in 3D (Fig. 6). Presently, the geoscientist can interpret the data in 3D visualization environments; however, not in immersive environments such as the TIS. The interaction and interpretation in this system instead use the tools (keyboard and mouse) and commands familiar to SMT users.

In short, the CACS software system supports viewing, interaction, and interpretation of well logs in a totally immersive 3D environment, as interpretation tools continue to be developed. While the SMT system offers a wide range of features for interpretation, it is not yet adapted to totally immersive 3D interaction and display. CACS is developing an extended or combined system for viewing and interpreting 3D data in venues such as the TIS in LITE. The goal is to create a fully interactive 3D geographic information system (GIS) within which geologists can store, interact with, and interpret not only well logs, but also other data such as production histories, geochemistry, geophysics, etc. The authors are also developing new interactive visualization technology in their system (e.g., Best and Borst, 2008).

Figure 1. Distribution of digitized well logs in the northern Louisiana study area.

This proprietary software uses the open-source “VR Juggler” toolkit to manage a variety of interaction devices in diverse display environments (e.g., “fish tank” virtual reality with a pen-based device or an immersive projection system using inertial tracking devices). Another open-source toolkit—the “Coin3D” scene graph library—is used to create and handle high-level graphics objects. The resulting system is platform independent and has been used with a single-machine stereoscopic projection system as well as with multi-machine clusters such as for the TIS at LITE.

While the current work is focused on interpreting traditional wireline logs in the immersive environment, it is clearly a natural progression to integrate LWD (logging while-drilling) logs into the process as well, allowing for enhanced reservoir navigation, especially during drilling of lateral wells. This is especially true with regard to modern advances in wellbore imaging technology, with multiple petrophysical datasets now available as LWD azimuthal (360° coverage) logs, including for example azimuthal resistivity, high-resolution electrical (with cm-scale resolution) (Fig. 7), gamma ray, density (bulk density and delta rho), photoelectric effect, axial caliper, and acoustics. It is easy to envision working an area in an immersive environment using first available wireline logs and other datasets (e.g., seismic data) to develop a geological/petrophysical/

Figure 2. Two dimensional view extracted from the 3D imagery of the SRTM topography of a portion of the northern Louisiana study area. Elevation is color coded and directionally lighted. North is up and the area comprises one SRTM tile, i.e., one degree by one degree. At this scale, well symbols can barely be seen. SRTM data courtesy of the Jet Propulsion Laboratory (JPL, 2008).

Figure 3. (A) A portion of Figure 2 reoriented and enlarged. The well symbols are clearly visible and five wells are turned on (as indicated by the lighted box surrounding each well). The well symbols have the well logs hanging from them. The virtual “wand” allows well symbols to be selected (points to one well which is yet to be turned on). (B) Same view as in A with well log now turned on.

Figure 4. Perspective view of the bottom of the SRTM surface with some wells turned on and the spontaneous potential (SP) curves “hung” from the chosen wells.

Figure 5. Picture of interaction with the 3D data in the TIS. This picture is taken by a 2D camera with the sixth side of the cube open. Note that there is a double image of the data. These two images are seen as a volume filling 3D image by the operator, whose profile is seen to the far right, within the TIS. .

Figure 6. 2D image of three of our correlated horizons (top of the Midway, bottom of the Big shale, and top of the Carrizo sand) as presented in SMT's 3D VuPak software (a subset of the well penetrations is shown). The image encompasses the area of digitized wells in Figure 1.

geophysical model, then later integrating LWD data, including image logs, using fully immersive environments for model refinement and better wellbore guidance during drilling. We now literally have the capability to stand inside the wellbore while it is being drilled—we just need to be doing it.

We have conducted an extensive, but admittedly not exhaustive, survey of the literature, the internet, and individuals at academic institutions and petroleum companies. We find that there are immersive 3D systems being utilized to integrate and visualize large datasets (Halliburton, 2008) and to perform well planning (Terraspark, 2008); however, our development of an immersive 3D system within which well logs may be correlated and interpreted is, at least, very unusual if not unique.

The authors believe that visualizing and interacting directly in a 3D virtual reality space will lead to an understanding of the difficult-to-interpret fluvial Wilcox strata of northern Louisiana more quickly and thoroughly than is otherwise possible, paralleling their other experiences with such 3D environments (Borst et al., 2005, 2006; Kinsland et al., 2007a, 2007b).

Figure 7. 3D tube view of a modern LWD high-resolution electrical image log (data courtesy of Baker Hughes INTEQ), with perspective of being inside the wellbore. This figure represents a single-frame extraction from a composite movie sequence, simulating the while-drilling process and data stream. Subtle details become readily apparent with 3D visualization. For example, the lamination indicated by A exhibits a slight right-to-left tilt at shallower MD (outer circle). With continued drilling (toward small inner circle), the lamination first rises slightly upward from A to A’ within the wellbore, indicating drilling downsection, before dropping down relative to the wellbore, and eventually exiting the low side of the wellbore (position A”), indicating drilling upsection. The black stripes at center left and center right are a rendering issue and software limitation (a drawback of this particular commerciallyavailable software, which was not specifically designed for image log viewing). Integration and interpretation of similar azimuthal (image) log datasets, including interpretation while drilling, in the immersive environment is a natural progression of our current work using more traditional well logs.

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