North Carolina Natural Gas? East Coast Triassic Rift Basins Opening Up

Among the myriad of prospects being hawked at Summer NAPE in August, one stood out if for no other reason than its sheer uniqueness. Summer NAPE is now known more specifically as NAPE South, so it was no surprise that the exposition’s offering was weighted heavily toward Texas, Louisiana and New Mexico prospects, with a few Rocky Mountain opportunities thrown in for good measure. And then there was North Carolina, a non-producing state with just 128 wells drilled to date. What was North Carolina doing there? In a few words, promoting the state’s potential for shale gas and coalbed methane.

North-Carolina-Natural-Gas-East-Coast-Basins
Image Source: http://pubs.usgs.gov/fs/2012/3075/fs2012-3075.pdf

North Carolina Natural Gas?

Dr. Jeffrey C. Reid, senior geologist of energy and minerals at the North Carolina Department of Environment and Natural Resources, was on hand to discuss the results of a USGS study released in 2012 (USGS Fact Sheet 2012-3075) that assesses a number of Mesozoic basins on the U.S. East Coast. Among those studied were two Triassic rift basins that lie within North Carolina’s boundary — the Deep River and Dan River basins – concluding both have the potential for commercial gas production. Reid told a NAPE audience that until recently virtually no one knew of the existence of these rift basins. They were formed during the breakup of the Panagea supercontinent in the Permian to Early Jurassic, when strata were deposited in fresh-water, narrow lakes similar to African rift valley lakes. These basins are also comparable in scale to the rift basins in East Africa.

North-Carolina-Natural-Gas-Triassic-Paleogeography
Image Source: http://www.searchanddiscovery.com/documents/2011/10366reid/ndx_reid.pdf

And now, according to Dr. Reid, is an excellent time to explore these basins as the current state law in North Carolina allows for the drilling and stimulation of vertical exploration wells. Wells drilled under these rules will be grandfathered into the new oil and gas rules that are currently under consideration. Some 126 new rules and the repeal of 10 others are being proposed, which would result in a considerably more stringent environment than the one under the current rules. Four public hearings were held in August and September across the state, which not surprisingly were largely attended by vocal anti-fracking crowds. The period for written comments ended on September 30. These comments will be considered before the rules are presented to the General Assembly, which next meets in January 2015. Before these rules take effect, however, the current moratorium on horizontal drilling and fracking will be lifted 61 days after the General Assembly approves them.

The Deep River Basin

So this presents a window of opportunity for explorers. Viewed as the more prospective of the two basins, the Deep River Basin is a 150-mile northeast-southwest rending basin that runs through the center of the state, encompassing parts of Durham, Orange, Wake, Chatham, Lee, Moore, Montgomery, Richmond, Anson and Union counties. It has a steeply dripping eastern border fault, and is comprised of three sub-basins, which have about 7,000 feet of Triassic strata including a source rock (the Cumnock Formation) and seal (the Sanford Formation. The Cumnock includes a organic-rich black shale up to 800 feet thick that extends across some 59,000 acres at depths of less than 3,000 feet in the Sanford sub-basin. The middle of the three sub-basins, the Sanford is primarily found in Lee and Chatham counties, which of course are most likely to be the focus of any horizontal drilling and fracking. The USGS mean estimate is 1.66 Tcf gas and 83 million barrels of natural gas liquids. Two shut-in wells have 0.21-0.23% helium as well. There is also potential for both coalbed methane and shale gas.

North-Carolina-Natural-Gas-Mesozoic-Basins
Image Source: http://www.ces.ncsu.edu/files/library/53/NCGS_OFR_2009-01_20090709-2.pdf

Eight oil and gas exploration wells were drilled in the Lee County portion of the Sanford sub-basin between 1974 and 1998, starting with Chevron’s V. R. Groce #1. That 5,348-foot basement test had several oil and gas shows, thick gassy coals and organic shales, and low porosity and permeability sandstones. A decade later, Seaboard Exploration & Production drilled Butler #1 to a total depth of 4,538 feet. This Lee County well was acidized and fracked and flowed low rates of gas and condensate before being plugged and abandoned. The last wells drilled in the county were by Amvest in 1998, the Simpson #1 and Butler #3 which flowed gas despite unsuccessful fracking attempts.

In 2010, there was a small flurry of leasing in Lee County, but less than half of those contracts remain in effect and the ones that are expiring are generally not being renewed. So in addition to the leeway presented before new oil and gas legislation takes effect, there is also open acreage to be had.

The Dan River Basin

The second basin in North Carolina assessed by the USGS to have technically recoverable, undiscovered resources is the Dan River Basin in north-central North Carolina that extends some 40 miles through Stokes and Rockingham counties into southern Virginia, where it is called the Danville Basin. While even less explored, based on data submitted to the USGS it is believed to have mean undiscovered resources of 49 Bcf of gas with no natural gas liquids.

North-Carolina-Natural-Gas-Triassic-Rift-Basins
Image Source: http://portal.ncdenr.org/c/document_library/get_file?uuid=9a3b1cc1-484f-4265-877e-4ae12af0f765&groupId=14

For further information, contact Dr. Jeffrey C. Reid at (919) 707-9205 or jeff.reid@ncdenr.gov

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Anne Leonard

Anne Leonard is Regional Manager of Northern Latin America at Drillinginfo International. She has been reporting on exploration and production for more than 30 years. She began her career in Denver covering the Rocky Mountain Region, and has spent the last 10 years covering the international arena, with a particular focus on Latin America, Africa, Western Europe and the Far East. Anne received her Bachelor of Arts in Journalism from the University of Nebraska.