--> Abstract: Railroad Valley and Adjacent Structures, Nevada: Analogues and Clues from the Flathead Valley, South-eastern British Columbia,; #90063 (2007)

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Railroad Valley and Adjacent Structures, Nevada: Analogues and Clues from the Flathead Valley, South-eastern British Columbia, Canada

 

Jones, Peter B.1 (1) Wedge Energy Inc, Calgary, AB

 

For more than twenty years, Railroad Valley, Nevada, was the site of some of the most prolific onshore oil wells in the U. S. A., Two neighbouring wells in Railroad Valley produced over 21 million barrels of oil, but ongoing exploration is severely restricted by lack and complexity of subsurface and surface data and uncertain structural relationships.

Comparable structural relationships occur in a simpler setting in the Flathead Valley, British Columbia, a half-graben in the Rocky Mountains, formed by the post-Laramide Flathead extensional fault. Paralleling the fault for more than 150 km south-eastward into northwest Montana, the Tertiary Kishenehn basin occupies the half graben, containing up to 3300 metres of Paleogene fine-grained lacustrine deposits and valley fill, overlying an irregular surface of Paleozoic carbonates and younger rocks. Fill includes reservoir-scale slide blocks of Proterozoic, Paleozoic, and Mesozoic carbonates and clastics, and oil seeps.

 

In the Flathead region, the Jurassic Fernie shale is a major detachment horizon separating overlying structures above from those below it, a function similar to that of the Mississippian Chainman shale of Nevada. Both units involve huge and anomalous thickness variations. The Flathead valley has the potential for discoveries comparable to those in Nevada, without the structural complexity that has hampered Railroad Valley exploration. The comparison can benefit exploration in both areas.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California