Railroad Valley is a graben block in the Basin and Range structural province. Topographically, it is basically flat with recent playa deposits on the surface. Two structural deeps exist in the valley. Five oil fields are associated with the northern deep. All oil fields are related to faulting.

Oil has been generated from Tertiary Sheep Pass and Mississippian shales. This generation is probably due to recent local heating of the valley by intrusive rocks. Temperature gradients are as low as 0.9°F/100 ft (16°C/km) to as high as 7.3°F/100 ft (133°C/km).

Eight million barrels of oil, with no significant quantity of gas, have been produced from the fields. The seals on the fields are imperfect and any gas generated, and much oil, has probably leaked into the overlying valley fill. Trap Spring and Eagle Springs fields are hydrostatically pressured whereas Bacon Flat, Currant, and Grant Canyon fields are overpressured.

The concept of immature source rocks occurring near a valley with high heat flow may improve exploration success.

End_of_Article - Last_Page 936------------