Title: The Last Frontier
Author: Ira Pasternack
Publication: The Outcrop, June 2011, p. 12, 14-15
Article Type: President’s Column
During 1977-1978, I had the extraordinary good fortune to be a geological field assistant working on the North Slope of Alaska for the U.S. Geological Survey. The North Slope is the northernmost region of Alaska, and includes the foothills of the Brooks Range to the south and the coastal plain that extends north to the Arctic Ocean. It is one of the most remote areas of the United States with few year-round settlements and no paved roads.
The first geological reconnaissance study conducted in northern Alaska took place in 1901 (Schrader and Peters, 1904). As a result of this expedition, the areas along several rivers and part of the Arctic coastline were mapped and names were proposed for Paleozoic through Pleistocene rock formations that were encountered. Mapping in the region continued in 1904 when Collier (1906) worked the coastal areas from Cape Thompson to Cape Beaufort.
From 1906 to 1914, Leffingwell conducted extensive studies in the Canning River area and reported the occurrence of several oil seeps at Cape Simpson. Although the presence of the seeps had been known to northern Alaska explorers from about 1900 (Hanna, 1963), Leffingwell’s (1919) descriptions are considered to be the first scientific documentation of their existence.
The first northern Alaska expedition conducted specifically for the purpose of locating commercial petroleum deposits was that of Smith, Campbell and Steineke (Hanna, 1963). These men submitted two maps in 1921 while staking claim to the Cape Simpson oil seeps under the old mining claim laws for a company called North Star Oil Syndicate. Expeditions sponsored by other private-interest groups continued exploration of the region for petroleum occurrences during the next two years, but details of their work are highly fragmentary.
By 1923, the potential of northern Alaska as a petroleum province had become generally known. That year, in an effort to provide for possible future petroleum needs of the U.S. Navy, President Harding set aside a 37,000-square-mile portion of northern Alaska by Executive Order. This area was designated Naval Petroleum Reserve Number 4 (NPR-4), and it included all of the oil seeps reported up to that time. Private-industry groups would not return to explore the region for 35 years.
Shortly after the establishment of NPR-4, the Navy Department requested the U.S. Geological Survey to examine the area and report on its petroleum potential. From 1923 to 1926 USGS field parties traversed the Reserve along major rivers and mapped at reconnaissance levels (Smith and Mertie, 1930). This study concluded that Lower Cretaceous sandstones were the most likely to contain extensive oil pools because of their wide distribution and incorporation within numerous structural features and their proximity to potential oil source rocks.
The Navy Department showed little interest in NPR-4 until 1944, when exploration was renewed as a wartime measure. At the request of the Navy, the U.S. Geological Survey and Arctic Contractors, Inc. began another geological reconnaissance program, which also incorporated some geophysical surveys. These studies, generally known as the “Pet-4 program,” are summarized in Reed (1958) and included: (1) geologic mapping of much of the Reserve and adjoining areas, (2) almost 3,500 line miles of seismic data, and (3) gravity and aeromagnetic surveys of nearly the entire Reserve.
Concurrent with these studies, a drilling program consisting of 45 shallow core tests and 36 test wells was completed. The wells tested a total of 18 separate structures and resulted in discovery of an oil field (at Umiat with estimated reserves of 122 million barrels, Espach, 1951) and several possible gas fields (at Gubik, Barrow, Meade, Square Lake and Wolf Creek). The drilling, primarily targeting the Lower Cretaceous, demonstrated a general lack of reservoir-quality sandstones. The Navy suspended the Pet-4 exploration program on July 1, 1953.
In 1958, the Bureau of Land Management offered 5,200 square miles of land for public acquisition east of NPR-4 in the vicinity of the Gubik gas field. This land availability and discovery of a commercial oil field in southern Alaska during the previous year provided the incentive for industry to begin an intensive exploration program on the North Slope. During the summer of 1958, Sinclair Oil Company operated the first industry-sponsored geological field party on the North Slope since 1923. By 1960, five other major oil companies also were operating field parties on the North Slope.
During 1963 and 1964, Sinclair and British Petroleum drilled the first industry exploration wells on the North Slope. A total of seven shallow wells were drilled to test several anticlines which had been defined by surface geologic work and by seismic surveys. None of the wells was successful. Industry activity on the North Slope tapered off over the next several years, as the results of other wildcat wells also proved discouraging.
When ARCO-Humble spudded the Prudhoe Bay State No. 1 well on April 22, 1967, it was among the last of the oil companies’ remaining operations on the North Slope (Sweet, 2008, p. 200). The well, testing pre-Cretaceous reservoirs near the crest of a large, seismically defined anticlinal structure, penetrated more than 400 feet of gas column. ARCO-Humble completed a delineation well, the Sag River State No. 1, 7 miles to the southeast of their discovery in July 1968 to confirm the magnitude of the field at Prudhoe Bay. Prudhoe Bay is estimated to contain recoverable oil reserves of between 13 and 15 billion barrels, making it the largest oil field in the United States and North America.
Following the tremendous discovery at Prudhoe Bay, industry’s hopes for finding commercial petroleum deposits on the North Slope were revived and exploration activity intensified. Interest in the petroleum potential of NPR-4 also was renewed, and when the energy crisis of 1974 occurred, the Navy Department decided to resume studies there. On June 1, 1976, jurisdiction of NPR-4 was transferred from the Navy Department to the Department of the Interior, and the area was re-designated as the National Petroleum Reserve in Alaska or “NPRA.”
During the summer field seasons of 1977 and 1978, the U.S. Geological Survey conducted a study of the depositional environments and reservoir potential of the Lower Cretaceous Nanushuk Group in and adjacent to NPRA. Under the direction of Project Chief Dr. Thomas Ahlbrandt, field parties measured and described in detail 33 surface sections totaling 82,000 ft in thickness (Ahlbrandt, et al., 1979; and Huffman, et al., 1985).
Each field party consisted of at least two geologists for safety reasons (grizzly bears posed an ever-present hazard). One geologist described the outcrop, while the other recorded notes on a standardized form at a scale of 1 in = 10 ft. Paleontologists frequently worked with the field parties and their primary responsibility was to collect mudrock samples for microfossil evaluations.
One day, I was taking my turn writing notes while describing the easternmost measured section of the study called Marmot Syncline (Huffman et al., 1985, Fig. 1). Marmot Syncline is located in the foothills of the Brooks Range, and offered a commanding view of the tundra-covered coastal plain to the north dotted with numerous shallow lakes. Looking up from note taking, I happened to notice a moose circling around in one of the lakes. I grabbed a pair of field binoculars from my backpack to take a closer look at the moose and saw the reason the moose was circling. There were two wolves on the shore of the lake that were mirroring every move the moose made! I alerted the other geologists to grab their binoculars and we spent the next 20 minutes watching the drama unfold. The moose continued circling for awhile and then abruptly headed to the shore of the lake closest to a nearby river at a full trot. The two wolves were in hot pursuit and we all thought the moose wasn’t going to make it when suddenly the moose kicked one of the wolves with a hind leg. The injured wolf immediately went down, the other wolf gave up the pursuit, and the moose continued its trot to the river.
We came back to Marmot Syncline for several days to finish describing the 3500-ft-thick section and occasionally heard the sad howls of the injured wolf. I think that witnessing the wolves-and-moose encounter while working at Marmot Syncline was my most memorable experiences working on the North Slope, but was only one of many, many unforgettable experiences during my two summer field seasons there.
I want to thank Tom Ahlbrandt, Curt Huffman, Gil Mull, Susan Bartsch-Winkler, Gary Stricker, Dick Scott, Fred May and Jim Fox for letting me share in the wonderful experience of working northern Alaska together.
I also want to gratefully acknowledge Charlie Bartberger for the outstanding editorial help he has provided on all of the President’s Columns!
Ahlbrandt, T.S., A.C. Huffman, Jr., J.E. Fox, and I. Pasternack, 1979, Depositional framework and reservoir-quality studies of selected Nanushuk Group outcrops, North Slope, Alaska, in Ahlbrandt, T.S., ed., Preliminary geologic, petrologic, and paleontologic results of the study of Nanushuk Group rocks. North Slope, Alaska: U.S. Geological Survey Circular 794, p. 14-31. Downloadable from: http://ngmdb.usgs.gov/Prodesc/proddesc_24032.htm
Collier, A.J., 1906, Geology and coal resources of the Cape Lisburne region, Alaska: U.S. Geological Survey Bulletin 278.
Espach, R.H., 1951, Recoverable petroleum reserves in the Umiat structure, Naval Petroleum Reserve No. 4: U.S. Bureau of Mines Petroleum and Natural Gas Branch Open-file Report.
Hanna, G.D., 1963, Oil seepages on the Arctic coastal plain, Alaska: Occasional Papers of the Calif. Acad. of Sciences, v. 38, 18p.
Huffman, A.C., Jr., T.S. Ahlbrandt, I. Pasternack, G.D. Stricker, J.E. Fox, 1985, Depositional and sedimentalogic factors affecting the reservoir potential of the Cretaceous Nanushuk Group, central North Slope, Alaska and related rocks, central North Slope, Alaska, in Huffman, A.C. Jr., ed., Geology of the Nanushuk Group and related rocks, North Slope, Alaska: U.S.G.S. Bulletin 1614, pages 61-74. Downloadable from: http://www.dggs.dnr.state.ak.us/webpubs/usgs/b/text/b1614.PDF
Leffingwell, E. de K., 1919, The Canning River region, northern Alaska: U.S. Geological Survey Professional Paper 109, 251p.
Reed, J.C., 1958, Exploration of Naval Petroleum Reserve No.4 and adjacent areas, northern Alaska, 1944-53, Part 1, History of the exploration: U.S. Geological Survey Professional Paper 301, 192p.
Schrader, F.C., and Peters, J.W., 1904, A reconnaissance in northern Alaska across the Rocky Mountains, along Koyukuk, John, Anaktuvak, and Colville Rivers and the Arctic coast to Cape Lisburne in 1901: U.S. Geological Survey Professional Paper 20, 139p.
Smith, P.S., and Mertie, J.B., Jr., 1930, Geology and mineral resources of northwestern Alaska: U.S. Geological Survey Bulletin 815, 351p.
Sweet, J.M., 2008, Discovery at Prudhoe Bay: Hancock House Publishers, Blaine, WA, 312 pp. Website: http://www.hancockhouse.com/products/dispru_review.htm.