Effect of Completion Fluids on Well Productivity in Permafrost, Umiat Field, Alaska

Abstract

Introduction During the years from 1944 to 1953, the U. S. Navy conducted an extensive exploration program in U. S. Naval Petroleum Reserve No.4, northern Alaska, to determine the oil possibilities. The area was designated a petroleum reserve by the U. S. Congress in 1923 and consists of approximately 37,000 square miles. As a cooperating agency, the Geological Survey, U. S. Department of the Interior, made an extensive study of the area both in the field and in the laboratory, and reports have been published describing the general characteristics and geology of the region. The exploratory program included several test wells on the Umiat structure in the southeastern part of the naval reserve. Of the 11 wells drilled, some were productive and some were not, but oil-bearing cores or other indications of oil were obtained from all. Several types of drilling muds were used including fresh-water muds, salt-water muds, emulsion muds and oil-base muds. At the request of the navy, the Bureau of Mines of the U. S. Department of the Interior, cooperated in the program to obtain and study the cores and core data and to determine the best completion practice. Recently, information on these wells was removed from the restricted classification, and a study of the relation of completion methods and well productivity has been conducted so that the experience in this field may be made available. Physiography The Umiat field is located in the southeastern part of Naval Petroleum Reserve No.4 on the Arctic slope and lies entirely within the continuous-permafrost zone (as shown in Fig. 1). The Arctic slope is bounded on the south by the crest of the Brooks Range and on the north by the Arctic ocean. The Brooks Range, the Alaskan counterpart of the Rocky Mountains, encompasses several groups of rugged, glaciated mountains having a relief of 3,000 to 6,000 ft and maximum altitudes of 3,600 to 9,200 ft. Anaktuvuk Pass, at an altitude of 2,200 ft, is the highest elevation on the land route between Fairbanks and the Arctic plain.