Arctic National Wildlife Refuge, 1002 Area, Petroleum Assessment, 1998

ASSESSMENT RESULTS

The total quantity of technically recoverable oil within the entire assessment area is estimated to be between 5.7 and 16.0 billion barrels (95-percent and 5-percent probability range), with a mean value of 10.3 billion barrels. Technically recoverable oil within the ANWR 1002 area (excluding State and Native areas) is estimated to be between 4.3 and 11.8 billion barrels (95- and 5-percent probability range), with a mean value of 7.7 billion barrels (table 1).

Quantities of technically recoverable oil are not expected to be uniformly distributed throughout the ANWR 1002 area. The undeformed area (fig. 2) is estimated to contain between 3.4 and 10.2 billion barrels of oil (BBO) (95- and 5-percent probability), with a mean of 6.4 BBO. The deformed area (fig. 2) is estimated to contain between 0 and 3.2 BBO (95- and 5-percent probability), with a mean of 1.2 BBO.

Figure 5 shows the expected numbers of accumulations and volumes of technically recoverable oil relative to sizes of accumulations. Economic viability of an individual accumulation depends on the price of oil, availability of recovery technology, and the proximity of infrastructure (pipelines, etc.). An important threshold for economic viability is an accumulation size that is sufficiently large to warrant development, and, in the past, a minimum economic field size for the study area has been considered to be about 400 MMBO recoverable. In recent years, however, North Slope infrastructure has expanded and industry has applied innovative technologies to dramatically reduce costs. As a result, development of fields as small as 150 MMBO recoverable is occurring, even at relatively low well-head prices.

If one considers only the western part of the ANWR 1002 area-plays of the undeformed area (fig. 2)--and assumes, rather conservatively, a minimum commercially developable field size of 512 million barrels recoverable, then about 2.6 BBO is expected to be economically recoverable from about three accumulations (fig. 5; sum of resources represented by all accumulations larger than 512 MMBO). Furthermore, this part of the assessment area is relatively confined geographically, so that much smaller accumulations (as small as 100 MMBO) may be commercial if they can be developed jointly with other accumulations or as satellite fields. For the deformed area (fig. 2), considerable uncertainty exists about using a similar 512-MMBO minimum field size because this area is much farther from infrastructure. If a similar minimum field size is assumed, one would expect about 600 MMBO economically recoverable from one field (fig. 5).