Estimation of the spatial distribution of fluid permeability from surface and tomographic GPR data and core, with a 2‐D example from the Ferron Sandstone, Utah

Abstract

Reservoir analogs provide detailed information that is applicable to fluid transport simulations but that cannot be obtained directly from reservoirs because of inaccessibility. The Ferron Sandstone of east‐central Utah is an analog for fluviodeltaic reservoirs; its excellent outcrop exposures are ideal for detailed study. Ground‐penetrating radar (GPR) data were collected in and between two cored boreholes and are used to build a 2‐D fluid permeability model in four steps. First, an anisotropic GPR propagation velocity model is obtained from traveltime tomography between two boreholes and between each borehole and the earth's surface. Second, the geometry of the sedimentological features is imaged by prestack Kirchhoff depth migration of constant‐offset GPR data acquired along a line between the two holes at the earth's surface. Third, a background permeability is assigned to each layer by interpolating the geometrical average of the measured permeabilities in each sedimentological element. Finally, the spatial distribution of flow baffles and barriers is estimated by calibrating the instantaneous amplitude and frequency of the surface GPR data associated with the mudstone layers in the boreholes via cluster analysis. The result is an integrated model that contains GPR velocity, lithology, and fluid permeability distributions. Low GPR velocities correspond to mudstones with low permeability. The main mudstone layers (potential barriers and/or baffles to fluid flow) do not appear to be continuous between the boreholes, which means that interpretations based on borehole data alone would overestimate element continuity and thereby underestimate effective permeability.

Digital Outcrop Models: Applications of Terrestrial Scanning Lidar Technology in Stratigraphic Modeling

“…Several research groups have been involved in taking outcrop data directly into the digital realm since the late 1990s. Various techniques have been explored, such as the use of (1) photogrammetry to build outcropbased seismic models (Stafleu et al 1996), (2) real-time kinematic global positioning systems or RTK GPS to trace bedding surfaces manually in conjunction with nonscanning (single-shot) laser surveying instruments (McCormick and Grotzinger 2001;McCormick et al 2000), (3) single-shot laser surveying of outcrop erosion profiles as a proxy for seismic impedance (Bracco Gartner and Schlager 1997a, 1997b, 1999Bracco Gartner 2000), (4) ground-penetrating radar (McMechan et al 1998;Loucks et al 2001;Hammon et al 2002;McMechan et al 2002;Dunn et al 2003), (5) photogrammetry and ground-penetrating radar combined (Pringle et al 2001), (6) ''photorealistic mapping'' Xu 2000;Xu et al 2000), or (7) lidar in conjunction with ground penetrating radar (Wizevich et al 1999;Bhattacharya et al 2000;Bellian et al 2004). Each of these techniques has its strengths and weaknesses for fast, accurate capture of stratal geometries and relationships.…”

Application of GPR in the study of shallow subsurface sedimentary architecture of Modwa spit, Gulf of Kachchh

“…A depositional (bedding) plane in sediments is a product of changes in sediment composition and changes in size, shape, orientation and packing of grains (Collinson and Thompson 1989). A number of studies have successfully shown relationship between the GPR reflections and sedimentary structures especially with the help of rigorously processed data (Annan 1999;Neal and Roberts 2000;Corbeanu et al 2001;Jol et al 2002;Hammon et al 2002;Buynevich and FitzGerald 2003;Neal et al 2003 andNeal 2004). The technique has been successfully employed using same GPR system in India wherein the correlations between the reflections and subsurface reflectors were established by trenching (Sridhar and Patidar 2005;Maurya et al 2006).…”

Tools and Techniques: Ground-Penetrating Radar

“…Because of similarities between acoustic and EM processing methods, seismic imaging techniques were initially used for the imaging of GPR data. Several approaches have been implemented in different domains: reverse time migration (e.g., Fisher et al, 1992a;Leuschen and Plumb, 2001), F-K migration (e.g., Bitri and Grandjean, 1998;Fisher et al, 1992b;Grasmueck et al, 1996Grasmueck et al, , 2005, Kirchhoff migration (e.g., Fullagar et al, 2000;Moran et al, 2000;Hammon et al, 2002), synthetic aperture radar (Gilmore et al, 2006), and prestack migration (Feng and Sato, 2004;Leparoux et al, 2001;Pipan et al, 1999).…”