3D Geologic Modeling and Fracture Interpretation of the Tensleep Sandstone, Alcova
Anticline, Wyoming
Nathaniel J. Gilbertson, Geology & Geological
Engineering, Colorado School of Mines, 1516 Illinois St, Golden,
CO 80401,
phone: 303.549.4626, [email protected] and Neil F. Hurley, Dept. of Geology
& Geological Engineering, Colorado School of Mines, 1516 Illinois St, Golden,
CO 80401.
Alcova Anticline is a Laramide-age structure on the southeast margin of the Wind River basin,
central Wyoming.
The Pennsylvanian Tensleep Sandstone, a prolific
oil-producing reservoir in the Rocky Mountains,
occurs at the core of the exposed anticline. The North
Platte River cuts across the axis of the anticline, resulting in
two near-vertical walls of Tensleep Sandstone, approximately
500 m wide, 100 m tall, and separated by 140 m. High-resolution (1-2 cm) Lidar scans of the two walls were acquired to study the
frequency and orientation of fractures in the structure. The Lidar survey at Alcova was
designed to collect sufficient data points to resolve fracture planes ≥1
m2 in area. Additionally, high-resolution photomosaics
were draped over the data set. The Lidar
dataset has been processed using various decimation approaches. Fracture
planes have been detected using automated and handpicking approaches. One goal
of the study is to populate a 3D geologic model with a fracture network, based
on outcrop work. The 3D geologic model, which is built from serial cross
sections, is constrained by GPS measurements of key formation contacts in the
study area. Extracted fracture data from the Lidar
dataset determine the parameters used to seed the fracture generating
model. A further goal of this study is to provide input into a reservoir
model of Teapot Dome anticline, an analogous Tensleep reservoir and a proposed CO2
sequestration site.