National Oil and Gas Assessment
A map showing oil and natural gas production in the Continental United States.
The 1995 USGS National Oil and Gas Assessment Team concluded that most of our Nation's future energy supply will come from known U.S. oil and gas fields, from newly discovered natural gas deposits, and from imported oil.
The 1990 Clean Air Act Amendments, and concern about greenhouse gas emissions have introduced a sense of urgency to identify the Nation's remaining deposits of clean-burning natural gas. As a result, the USGS has initiated a new national assessment that focuses on the Nation's natural gas endowment and the potential of additional reserves of oil and gas from existing fields in the United States, exclusive of Federal waters.
National Petroleum Reserve - Alaska
The North Slope of Alaska is thought to have the greatest remaining oil potential of any onshore area in the United States. The USGS is conducting an intensive examination of its geology and petroleum potential with current research focused on conventional oil and gas resources of the National Petroleum Reserve-Alaska (NPRA) on the western portion of the North Slope.
A map of Alaska showing the location
of "National Petroleum Reserve - Alaska".
A map of northern Alaska showing the locations
of NPRA and ANWR, the "Alaskan National Wildlife Refuge".
The same team of USGS scientists that produced the assessment of the Arctic National Wildlife Refuge (ANWR) 1002-area has been working in the NPRA for the past three years and four field seasons and will build on the findings of that assessment. While the petroleum geology of the NPRA is similar to that of ANWR 1002 area, it is important to remember that NPRA is 15-times the size of the 1002-area. Energy resources from the North Slope are important to the Nation's energy supply and resources in NPRA are a major focus in Alaskan land management decisions.
A picture of the NRPA area looking very similar to a more southern wetland.
The goal of the project in the NPRA is to:
- improve our understanding of the origin, habitat, and abundance of Alaskan petroleum
- improve estimates of undiscovered oil and gas resources.
The NPRA assessment project is a multidisciplinary framework geologic investigation that applies the latest concepts of basin analysis, sequence stratigraphy, fluid-flow modeling, petroleum systems, geochemistry, structural and geophysical analysis. The area provides a unique opportunity to examine outcrops of the rock units that contain the largest petroleum accumulations and potential in the Nation.
Field Studies in NPRA
Field-based geologic studies fill a critical need for potential field interpretations of seismic data and provide opportunities to examine stratigraphic, structural, geochemical, bio-stratigraphic, and geo-chronologic sequences of depositional systems in Northern Alaska. The opportunity to test interpretations made from seismic data and to verify geologic concepts significantly improves models for hydrocarbon source and migration, trapping mechanisms, reservoir quality, and timing of generation and migration for the North Slope.
Fieldwork in Alaska is expensive because of its remote location, poor access, and the vast size of the region. Helicopters and supporting field camps in remote areas are required to efficiently transport scientists to locations for field investigations. Field studies have resulted in understanding the depositional systems of the Colville basin in eastern NPRA and the foothills region to the south.
A helicopter, having landed in a remote NPRA location, with a USGS Scientist gathering his field study equipment.
Two USGS researchers conducting field research, walk the beach at Skull Cliff, Alaska.
Petroleum Geochemistry Studies
An image of oil stained grasses at the Fish Creek seep.
Petroleum geochemical studies of oils, gases, seeps, and stained reservoir rocks, and source beds provide the key links of source, carrier, and trap in a petroleum systems approach to resource analysis. Petroleum-stained rock units were identified in many outcrops where they had not been previously identified. These findings are essential for assessing undiscovered oil and gas resources in NPRA and have received a great deal of interest from the petroleum companies active in exploration in the North Slope. The objectives are to:
- Define the petroleum sources, migration pathways, and potential reservoir charge within and adjacent to NPRA.
- Characterize background levels of organic compounds is surface occurrences of petroleum to define natural levels of potentially hazardous compounds that are naturally introduced to the Arctic ecosystems of Alaska.
Data Rescue for NPRA
The USGS is also nearing the completion of data rescue and archiving activities in the NPRA. These data sets were compiled during two government oil and gas exploration programs in the NPRA: one by the U.S. Navy in the 1940's and 1950's, and the other by the Navy and the USGS in the 1970's and 1980's. The Energy Program has devoted significant effort to organizing the data and making the data digitally available. More than 14,000 line miles of seismic and related geophysical data, logs and other records from 126 drill holes, and special studies of geochemistry, paleontology, and reservoir rocks are being transferred to more durable and accessible digital formats from aging tape media. The USGS is collaborating with the Alaska Division of Geological and Geophysical Surveys, the Bureau of Land Management, and U.S. Forest Service on projects in the NPRA.
Outreach Efforts
The USGS scientists have briefed DOI representatives and BLM office in Anchorage on the status and condition of existing (government drilled) wells in the NPRA. Our scientists have also briefed the Anchorage BLM and Minerals Management Service office on the status of the assessment and have made a commitment to early sharing of the assessment results with BLM to assist in their oil and gas lease-sale preparation process. The assessment of the NPRA is on schedule and USGS plans to complete the assessment by summer 2002.
Central Alaska
Central Alaska is a remote and sparsely populated region that includes mountainous areas underlain by rock of Precambrian to Mesozoic age, and lowlands underlain by mostly non-marine deposits of Cenozoic age. The region occupies an area of about 30,000 square miles; major landowners in this region include Federal government, State, and native corporations and villages.
No petroleum production has occurred in central Alaska, and only about a dozen exploratory wells have been drilled. The 1995 USGS assessment concluded that there may be potential for natural gas accumulations in mildly deformed, coal-bearing strata of Cenozoic age. The Cenozoic basins are almost entirely unexplored. In addition, un-metamorphosed Paleozoic and Mesozoic rocks in some areas may also have oil and gas resource potential. These potential sources of energy may in the future supply energy to remote Alaskan communities that currently import their energy needs at considerable expense.
USGS focus is on the large Yukon Flats basin, where according to current schedule, the actual assessment will be conducted during the latter part of FY 2002. Thus far, the efforts have been on identifying and gathering all available geologic, geophysical, geochemical, and historical information related to petroleum resources in central Alaska, and on establishing contacts with potential collaborators, including BLM, potential contributors of data, and potential clients.
