December 4, 1997

Harken Southwest Corporation of Irving, Texas, completed the horizontal drilling in a well designated Mule 31-K-1. The well is located in the Navajo Nation and is producing 149 barrels of oil per day. The new well is a sidetrack of the discovery well, drilled in 1991, which was shutin after producing only 283 barrels of oil. Total horizontal displacement is 939 feet in a northwest direction.

The new well is part of a $5 million project funded by the U.S. Department of Energy with the Utah Geological Survey as prime contractor. The project is designed to increase oil reserves and production from small fields throughout the Paradox Basin region using new techniques such as horizontal drilling. Harken, the Survey's industry partner, is the field operator.

In horizontal drilling, the drill bit is manipulated so that it turns to enter the reservoir approximately perpendicular to vertical. The horizontal well then acts as a drain to more efficiently pull oil and gas from the reservoir, thus increasing production without having to drill new vertical holes. In the Paradox Basin, most oil is produced from small, reef-like mounds that formed in a shallow, warm sea 320 million years ago.

Because of their limited size, these fields usually consist of from one to five vertical wells. Often, several dry holes are drilled in an attempt to determine the limits of these ancient mounds. However, by using horizontal drilling technology developed over the past 10 years, wells can penetrate a greater section of oil-bearing rock. Production is increased, meaning more oil is recovered at a lower cost. One horizontal well may produce as much as four conventional vertical wells, and the environmental impact to the surface area is significantly reduced.