Umiat field contains the largest accumulation of oil discovered so far in Naval Petroleum Reserve No. 4 in Arctic Alaska. The Umiat anticline was tested with 11 wells; 6 produced oil in varying quantities. Behavior of the wells during testing was unpredictable. For example, one well was abandoned as a dry hole after all tests failed to recover any oil, yet an offset well, only 200 feet from the dry hole, produced 400 barrels of oil a day. The main oil reservoirs are less than 1,000 feet deep and are in the permanently frozen zone (permafrost). Reservoir pressures are low, and most primary production will be by expansion of gas-in solution in the oil. Because of the unusual reservoir conditions and the difficulties encountered in drilling and completing the wells, the Department of the Navy asked the Federal Bureau of Mines to make laboratory studies of the reserves and to determine the cause of the well plugging and to provide laboratory information, to be used as an aid in estimating oil recovery form frozen reservoir rocks under solution-gas expansion from low-saturation pressure conditions.