G. Alan Petzet
Exploration Editor
A group of independents has recompleted Shell Oil Co.'s Newporte field discovery well in far northern North Dakota for a sharply higher flow rate than the original 1977 completion.
The Renville County Cambrian Deadwood sandstone recompletion, averaging nearly 640 b/d of 33.7° gravity oil in the first 18 days on line, could open a new play spanning South and North Dakota and extending well into Canada.
It also might renew an old argument over whether Newporte field is a buried meteorite impact structure, or astrobleme. The new operator said much data run counter to the astrobleme theory and point toward a regional Williston basin stratigraphic play. The play appears to extend into adjacent Bottineau and Burke counties.
Recompletion details
The 9-11 EM Larson well, in the southwest quarter of 9-163n-87w, just south of the Saskatchewan-North Dakota line, had an initial potential of 127 b/d of oil from 5 ft of perforations in 60 ft of Cambrian aged Deadwood sand. The well was originally known as the 23X-9 Larson.
Shell plugged the well in October 1980. It had produced 7,022 bbl of oil since completion in December 1977.
A group led by Eagle Operating Inc., Kenmare, N.D., perforated 32 ft in the same Deadwood sandstone and have an IP flow rate of 1,025 b/d of 33.7° gravity oil with no water and 325 Mcfd of gas on a 24/64 in. choke with 700 psi FTP. Shut-in tubing pressure was 2,600 psi.
The perforations, at 9,552-60 ft, 9,564-68 ft, and 9,572-92 ft, were not stimulated.
The well produced 11,589 bbl of oil without water in its first 18 days on line. Paraffin cutting will be necessary. Gas analyzed 13% methane and 83% nitrogen.
The group includes Eagle, MFN Oil, Langdon, N.D., Fischer Oil & Gas, Grand Forks, N.D., Eisel Oil Inc., Boulder, Colo., Don Beckert, Dickinson, N.D., and SRG Inc., Englewood, Colo.
A budding play?
The group has acquired about 4,000 acres of leases in the play and probably will drill two offsets by yearend, said Jake Eisel, a Denver geologist.
The group became interested in Newporte because the discovery well was still flowing 30-35 b/d when plugged. The well had been drilled with salt mud and treated with hydrochloric acid.
The new group thought they might be able to reenter, acidize, and re-establish production at more than 100 b/d. Why Shell perforated only 5 ft of zone remains a mystery.
The new owners have also reentered Shell's Duerre well in the field but encountered mechanical problems. The group might attempt a short radius horizontal leg of about 500 ft in Deadwood there this summer.
Eisel said seismic acquired over a pinchout structure in Bottineau County appears identical to seismic obtained over the Newporte structure. However, at Newporte the central uplift feature characteristic of impact structures is absent.
J.H. Clement and T.E. Mayhew of Shell described Newporte in a 1978 Williston Basin Symposium presentation later published in these pages (OGJ, June 25, 1979, p. 165). They mentioned the astrobleme and several other theories on the field's origins.
Clement and Mayhew noted the Newporte discovery was 450 miles from Oregon Basin oil field in Wyoming, the nearest commercial production from rocks of near equivalent age or stratigraphic position at that time.
Eisel said Richardton field, a 1981 discovery in Stark County, N.D., that produced from Deadwood and overlying Ordovician Winnipeg, appears to be a similar feature and could indicate extension of the trend as far south as South Dakota.
With a very active horizontal oil play in Ordovician Red River and continued interest in Mississippian Lodgepole mound exploration, it has been difficult to imagine North Dakota becoming much hotter-until now.
Copyright 1996 Oil & Gas Journal. All Rights Reserved.
