Sweet spots in Alberta’s Duvernay Shale natural gas formation harbor 9.6 billion bbl of liquid byproducts and premium light oil, according to a new marketable resources appraisal released Tuesday by provincial and federal earth-sciences agencies.

Recoverable supplies in the 130,000 square kilometer (52,000 square mile) formation add up to 77 Tcf of natural gas, 6.3 billion bbl of liquids and 3.4 billion bbl of oil, said the Alberta Geological Survey and National Energy Board.

“Estimates of marketable oil, gas, and natural gas liquids in this study could be conservative,” added the agencies.

Development remains in early stages across the formation, with a collection of large and small producers holding positions across the acreage. The Duvernay underlies about one-fifth of Alberta in a band stretching southeast from its northern boundary with British Columbia (BC) nearly to the Saskatchewan border.

The productive Devonian geological era resource pay zones are up to about one kilometer (0.6 miles) thick, one to five kilometers beneath the land surface. Numerous production firms are evolving Canadian adaptations of U.S.-born horizontal drilling and hydraulic fracturing to tap the formation, which was known but untapped before the advanced well technology emerged.

“As companies increasingly develop the Duvernay and improve well designs based on what they learn from early results, new wells could perform better than old wells and increase recoveries,” said the government earth-sciences agencies.

“Further, some areas in the Duvernay are less explored than other areas , such as the Duvernay’s east basin, and resources could be discovered in places that were thought to be not prospective.”

Current technical high-case forecasts of marketable Duvernay supplies rate its maximum potential production at 131 Tcf of gas, 10.7 billion bbl of liquid byproducts, and 5.6 billion bbl of oil.

The new appraisal rates the Duvernay as Canada’s second-richest shale deposit after the Montney Shale, which straddles northern BC and Alberta with estimated marketable resources of 449 Tcf of gas, 14.5 billion bbl of liquids and 1.1 billion bbl of oil.

A collection of large and small producers hold positions in the Duvernay, but it has not been developed as quickly as other targets in North America.