Foam Fracturing in the Uinta Basin — A Field Study of the Dakota and Wasatch Formations

Abstract

The Dakota and Wasatch formations of the Uinta Basin in northeastern Utah and northwestern Colorado have been historically difficult to clean up following a fracturing treatment. Recovery of normal water-based fluids has been averaging 20 to 30%, with much rig time spent in swabbing before the wells were put on production. Because of low recovery and the potential for clay problems, a number of techniques and fluids were tried without any significant improvement. Since these formations were very low in permeability, .05 to .2 md, deeper penetration through fracturing remained a high priority for treatment success. To achieve this penetration, relatively large volumes of treating fluids were needed. Foam fracturing was then instituted as a means of controlling the amount of water put into the formation. The first treatments were relatively small and sand concentrations of two pounds per gallon were the maximum that could be achieved. The results were encouraging enough to warrant the continued use of foam as a fracturing fluid. With the advent of equipment to achieve higher concentrations of sand at the formation and better materials to stabilize the fluid itself, foam fracturing matured into a much more viable means of treating both formations. The immediate advantages of foam are obvious. There is 65 to 75% less water put into the formation that has to be recovered and the possibility of damage due to swelling or migrating clay is reduced. The reduced damage is the result of smaller volumes of water and easier handling, of clay control agents, KCl and/or chemicals. A very important aspect of this technique is a faster and improved cleanup, which can be attributed to less water, more energy and lower hydrostatic head.