Greater Sierra (also called Helmet Area) is a large oil and gas field in northeastern British Columbia, Canada.

It is east and north from the town of Fort Nelson, extending to the Alberta and Northwest Territories borders (150 and 130km respectively).

[2] Major projects tap in the large gas reservoirs hosted in Mississippian and Devonian limestones such as the Jean Marie Member of the Redknife Formation.

Horizontal drilling and hydraulic fracturing techniques are used to extract the gas from the low permeability shales.

Companies with large interests in the area include Canadian Natural Resources and Petro-Canada.