Abstract

A new chemical treatment has been developed to stimulate problem sandstone formations. This treatment is designed to overcome a commonly observed problem in which wells initially respond to matrix acidizing but show rapid production declines following treatment. These rapid declines are generally attributed to migration of clays and other fines. The treating fluid, which slowly generates hydrofluoric acid, reacts more slowly than conventional Mud Acid and thus penetrates a greater distance into the formation before spending. The fluid also acts to stabilize clays and other fines by chemically fusing them to the sand grains. The chemistry of this system is entirely different from that previously reported in the literature.

The effectiveness of this stimulation and clay control method is demonstrated by core test studies. The control mechanism is illustrated by scanning electron microscope studies and x-ray analyses of treated clays. Preliminary field test results are also presented.