The Mississippian Manning Canyon Shale, Soldier Canyon, Oquirrh Mountain, northern Utah. Photo courtesy of Tom Chidsey.
Considering that natural gas prices are at bargain basement levels and storage facilities are brimful, it would be easy to assume natural gas exploration is headed for a major hiatus.
The always-optimistic explorers continue efforts to find new supplies that will be needed when demand once again soars, triggering prices to move upward and storage levels to decline.
Utah is one of many areas where the drill bits are turning to tap into more gas, yet not ignoring oil.
“Most of the drilling activity in Utah is in the Uinta Basin, especially the eastern area, for Cretaceous Mesaverde and Tertiary Wasatch tight gas sands,” said AAPG member Tom Chidsey, petroleum section chief at the Utah Geological Survey (UGS).
“Tertiary Green River oil is the drilling target in the Monument Butte/Brundage Canyon area in the west-central part of the basin,” Chidsey continued, “and there’s activity in the Ninemile Canyon trend involving Tertiary, Cretaceous and older targets in the southern Uinta.
“Wolverine announced a second Jurassic Navajo sandstone oil discovery, Providence Field, north of their 2004 Covenant Field discovery in the central Utah hingeline thrust belt,” he added.
The 100-million-barrel Covenant Field find was a first in that it proved up oil in central Utah, which was a shocker to many industry veterans.
Shale Gas Potential
If it’s shale gas that presses your buttons, not too worry – Utah has that too.
If you’re not up to speed on the geological characteristics of the shale resources, there soon will be new info available, at least in two promising areas.
“The Survey is involved in two shale gas projects funded by the Research Partnership to Secure Energy for America,” Chidsey said.
“We just got funded for the second one, which is the Cretaceous Mancos Shale in the Uinta Basin area,” he said. “The other is emerging Paleozoic shale gas resources of the Colorado Plateau in central and southeast Utah.”
The good news is the results of the two projects will be available to all.
Shale gas reservoirs in Utah have tremendous untapped frontier potential, according to Chidsey. For example, he noted that existing gas production in the Uinta Basin could be greatly enhanced by the addition of gas reserves in the Mancos Shale.
In line with a number of emerging shale gas plays, the geologic and engineering insights for the Mancos are preliminary in nature.
In order to quantify these plays, however, accurate geologic and geophysical characterization must be integrated with reservoir specific engineering practices.
To achieve this, Chidsey noted the Mancos project will:
- Characterize the geology – including sedimentology, stratigraphy, organic, stable isotope and inorganic chemistry, natural fracture analysis, geophysical and 3-D seismic analysis – of the Mancos in the Uinta. The goal is to ID premium target zones and determine the resource potential.
- u Define the geologic parameters that determine various geo-mechanical properties, i.e., brittleness and susceptibility to fracing. Employ defined relevant geologic parameters to predict brittle areas along with Mancos shale gas prospectivity, from an engineering standpoint.
- Establish best drilling, completion and production techniques for specific target intervals, based on rock properties.
“The investigation will quantify and potentially lower the economic risk of exploration and development in the Mancos shale gas play,” Chidsey said, “encouraging larger scale commercial production.”
Project team members represent:
- The Utah Geological Survey.
- The University of Utah’s Energy and Geoscience Institute, departments of geology and geophysics, and chemical engineering.
- Halliburton Energy Services.
Chidsey noted that Questar E&P, Gasco Energy, Newfield, Wind River Resources and Pioneer Natural Resources will donate data. Many other Uinta Basin gas producers will participate as Advisory Board members, with some of these contributing data.
Unknowns and Objectives
In the Colorado Plateau and eastern Basin and Range provinces, Paleozoic shales are long recognized for their potential as source rocks for hydrocarbons that have migrated into other formations. Yet the shales haven’t been looked on as in-situ gas reservoirs, according to Chidsey.
These include the Manning Canyon/Doughnut and Delle Phosphatic shales of Mississippian age in north-central and western Utah, respectively, and the Pennsylvanian Paradox formation in the Paradox Basin in the southeastern part of the state.
“Shale beds within these formations are widespread, thick, buried deep enough to generate dry gas and contain sufficient organic material and fractures to hold significant recoverable gas reserves,” Chidsey noted.
“Exploratory efforts are just beginning to target these frontier gas shales – many in environmentally sensitive areas,” he added.
There are many unknowns about these shales, including the basic rock mechanic data. The distribution and thickness of the rocks are inadequately mapped, and the vertical succession and regional correlation of the Manning Canyon and Delle Phosphatic hasn’t been interpreted in a sequence stratigraphic framework.
Chidsey itemized the overall objectives and/or benefits of the current study:
- Identify and map the major trends for target shale intervals and identify sweet spots with the greatest gas potential.
- Characterize the geologic, geochemical and petrophysical rock properties of those reservoirs.
- Reduce exploration costs and drilling risk – especially in environmental sensitive areas.
- Recommend best practices to complete and stimulate these frontier gas shales to reduce development costs and maximize gas recovery.
All project maps, data reports and results will be publicly available and provided to both small and large operators via a proven technology transfer plan, according to Chidsey.