The Rocky Mountains are a growth engine for the nation's natural gas supply-the region's production jumped from 4.3 billion cubic feet (Bcf) per day in 1999 to 5.1 Bcf in 2001. Some of the key plays underpinning this impressive surge were spotlighted at the Colorado Oil & Gas Association's Rocky Mountain Natural Gas Strategy Conference in Denver recently. Roger Biemans, Denver-based president of EnCana Oil & Gas (USA), discussed his firm's involvement in Jonah Field, in the heart of Wyoming's Green River Basin. EnCana recently added to its holdings there with a $350-million acquisition from The Williams Cos. that included 600 billion cubic feet equivalent (Bcfe) of reserves, 135 million cubic feet (MMcf) of daily production and 16,000 net acres. EnCana's production from Jonah now stands at a hefty 400 MMcf per day. Jonah produces from overpressured reservoirs in the Lance formation; per-well ultimate recoveries range between 2.5- and 15 Bcf. Jonah contains some 10 trillion cubic feet (Tcf) of gas in place, and current reserves stand at 3 Tcf. The field is far from mature, contended Biemans: "Infill drilling will add at least another Tcf to that total." EnCana has been using such techniques as vertical seismic profiling and geostatistical modeling to aid its exploitation of Jonah's very discontinuous sands. "The challenge is to tap the undrained reservoirs-the smaller sand units are underexploited." Field extension to the northeast, where the sands are tighter and deeper, will also aid recovery, as will recompletions of bypassed pay and restimulations. Jonah, which currently makes some 600 MMcf per day, has the potential to produce 780 MMcf per day by 2006, predicted Biemans. Gary Nordloh, president and chief executive officer of Questar Market Resources, Salt Lake City, drew parallels between Jonah's established production and that emerging on the Pinedale Anticline. Located directly west of Jonah, the Pinedale produces from both the Lance and the deeper Mesaverde formation. Questar's Mesa acreage lies on the northern portion of the long, narrow anticline, a feature that covers four times the area of Jonah. (See "The Pinedale Anticline," December 2001, Oil and Gas Investor.) Questar drills four different types of wells at Pinedale, depending on the pressure regimes it expects and its combination of objectives. Costs for the wells range from $2.6- to $4 million. The traditional Lance objective yields average reserves of 5- to 6 Bcf per well, while the more exploratory Mesaverde contributes stand-alone reserves between 2- and 3 Bcf. Keys to success are the use of an effective well stimulation program and quick development of production infrastructure. The future appears rosy-by year-end, Questar expects to produce 100 MMcf per day gross from its 14,800 acres, and it has another 150 locations to drill on 80-acre spacing. The Pinedale Anticline, given its great size and promising results to date, has the potential to eventually rival Jonah's rates and reserves. A completely different group of fields on the eastern side of Wyoming is also adding to the Rockies' impressive growth in gas supply. Peter Dea, president and CEO of Denver-based Western Gas Resources, noted that coalbed methane (CBM) wells in the Powder River Basin were producing just 25 MMcf per day in 1996; today they produce 857 MMcf per day from 8,672 wells. Cumulative production totals 626 Bcf. The Wyodak coals are responsible for the majority of current production, but the future lies in the deeper Big George coals, said Dea. Four commercial pilot projects, operated by Yates Petroleum, Western Gas and Williams, Anadarko Petroleum and Devon Energy, presently make 33 MMcf per day from that objective. "The Big George now has 8.2 Bcf of cumulative production, a 300% growth in the last 12 months," said Dea. He estimated that the Powder's CBM play has only been 25% developed, and that production from the Big George will rise along the same slope as did that from the Wyodak. Indeed, predictions are that the Powder River Basin coals may one day produce more than the 8 Tcf that has flowed from the nation's premier CBM basin, the San Juan.