ABSTRACT
Oryx Energy has been drilling horizontal wells in the Pearsall Field of South Texas since 1985 and stimulating a number of these wells since 1989. Until 1992, stimulation techniques included acid washes, acid fracs and high rate water fracs. In 1992, Oryx Energy stimulated wells with high injection rate water fracs with varied success and high costs. A new stimulation method for these horizontal wells was desired to improve the degree of stimulation and reduce costs.
In 1992, a horizontal well was stimulated with a propellant gas fracture tool in an attempt stimulate the well in a method that would be cost competitive and have better results than the water fracs. The process permits simultaneous initiation of numerous multi-oriented fractures. The gas fracture propellant tool was designed to create fractures into the formation down the axis of the wellbore that are more or less perpendicular to the existing natural fractures. This treatment, while not economically successful, did result in sustained increases of oil, water and gas. This showed that the stimulation was successful in connecting some lesser depleted fracture intervals with ones that were producing before the treatment.
This paper reviews the results of Oryx Energy’s propellant gas fracture stimulation treatment of a horizontal well with 1028’ of 4 1/2" O.D. propellant in a 5 1/2" carrier run in an openhole wellbore. The job design, problems encountered, and results are reviewed in this paper.
