|
NPR-A: Almost 100 years of exploration continues
Kristen Nelson PNA News Editor
It has been almost 100 years since the first geologic exploration of northern Alaska — conducted by the U.S. Geological Survey in 1901 — correctly surmised the presence of a sedimentary basin beneath the North Slope.
Such publicly funded exploration continues to play a role in North Slope exploration, and will continue to play a role for years to come, Fairbanks geologist Charles G. (Gil) Mull of the Alaska Department of Natural Resources Division of Geological and Geophysical Surveys said in January in a talk prepared for the Alaska Geological Survey.
Mull, who has worked in Alaska since 1961 and in the North Slope and Brooks Range area since 1963, said DGGS anticipates “that the long-term collaborative interaction between the public and private sectors in hydrocarbon exploration in northern Alaska will continue for a number of years.”
Early exploration in the area now known as the National Petroleum-Reserve Alaska was by the government. The USGS conducted a 1901 reconnaissance on the North Slope and published the results of a 1919 privately funded expedition.
Enough evidence of oil was found that the area now known NPR-A was set aside as a petroleum reserve in 1923, and systematically explored by the USGS between 1923 and 1926.
The possible need for fuel during World War revived interest in the reserve, and although the war ended before exploration could begin, the U.S. Navy and the USGS explored in the area from 1945 to 1953, with surface geological parties, geophysical programs, core holes and relatively shallow test wells. Stratigraphic and structural framework delineated The public contribution to understanding NPR-A was not just exploration and drilling. More important than the wells, Mull said, “was the delineation of the stratigraphic and structural framework of the Brooks Range and North Slope by a close-knit group of USGS geologists, some of whom continued their studies on the North Slope until very recently.”
A second generation of geologists, he said, has built on the work of the original group and continues working today at USGS and at the Alaska Division of Geological and Geophysical Surveys. All of the information from work in the 1940s and 1950s was published by the USGS, and, Mull said, “was of immeasurable value to the next wave of explorers who came with the oil industry in the early 1960s, in the exploration program that culminated in 1967 in the discovery of the giant Prudhoe Bay field by ARCO and Exxon.”
The 1970s saw a third wave of exploration in the petroleum reserve. The Navy, with Husky Oil as its contractor, drilled a test well at Cape Halkett. After Congress transferred the reserve to the Department of the Interior in 1977, the USGS, again with Husky Oil as prime contractor, shot an extensive reconnaissance seismic grid and drilled a number of test wells for stratigraphic information in NPR-A.
The only significant discovery was the Walakpa gas field south of Barrow, but “the program resulted in a large database, all of which is in the public domain,” Mull said.
There were four federal oil and gas lease sales in the NPR-A between 1982 and 1984, with 1.4 million acres leased but only one well drilled.
On the state side, the Alaska Division of Geological and Geophysical Surveys began a series of field mapping projects in 1983, in and adjacent to NPR-A. “This program,” Mull said, “in collaboration with the USGS, continues to the present day but in recent years has been hampered by limited DGGS funding for petroleum-related projects.”
Since 1996, a consortium of ARCO Alaska Inc., Anadarko Petroleum Corp., BP Exploration (Alaska) Inc., Phillips Petroleum Co., the Arctic Slope Regional Corp., the North Slope Borough, the Alaska Division of Oil and Gas and USGS have funded DGGS field studies and analytical work on the North Slope.
Mull said that “the studies indicate that hydrocarbon source rocks, reservoir rocks and traps have a high probability of occurrence in the subsurface of the western part of the North Slope. Evaluation of the probability of their occurrence together in any given area awaits further exploration and ultimately the drill.”
Currently, Mull said, there is interest in the NPR-A area because of the ARCO Alaska and Anadarko Petroleum discovery and development of the Alpine field east of NPR-A and the upcoming Bureau of Land Management oil and gas lease sale in the northeastern corner of NPR-A.
The Division of Geological and Geophysical Surveys, pending availability of funding for field operations, and the U.S. Geological Society, are both planning field programs in northeastern National Petroleum Reserve-Alaska this summer, he said. Those studies, Mull said, will concentrate primarily on mapping and on facies studies in deltaic sandstones of the Nanushuk group and related outer shelf to turbidite sands within the prodelta Torok formation.
The USGS is also funding a DGGS mapping project to the east in the Sagavanirktok quadrangle, bisected by the trans-Alaska pipeline.
Longer range, Mull said, DGGS wants to prepare a modern geologic map of the entire North Slope in electronic format. That project, he said, is subject to the availability of funds and computer personnel.
The map would be at a uniform scale with modern stratigraphic nomenclature and would include all available mapping, including contributions from industry. Mull said that maps of some areas of the North Slope are 50 years old and include “a wide variety of structural annotation and stratigraphic names, some of which have been long abandoned.”
The proposed electronic format map, he said, “will be of use for the long period of exploration that is likely to occur in NPR-A regardless of the inhibiting effect of sometimes low oil prices.”
| 