Abstract

This paper presents Shell Oil Company's experiences in stimulating producing, water injection, and water source wells on the Cedar Creek Anticline In Montana, using a blended HCL acid-Unibead* continuous diversion and stimulation technique. Wells not amenable to effective stimulation using conventional methods of zone isolation and acid placement because of problems in well mechanics are currently being stimulated using the continuous diversion and stimulation technique with favorable results. The use of surface blended mixtures of HCL acid and Unibeads to stimulate problem wells is considered to be more effective than the more widely used "slug-plug" diversion and stimulation technique, and to have wider application, especially for treating wells on the Cedar Creek Anticline.

The results of 30 treatments on producing, injection, and water source wells performed to date using the continuous diversion and stimulation technique are presented, along with the reasons for the use of this technique, observations made, conclusions reached, and recommendations for future use.

Introduction

Shell Oil Company began using a continuous HCL acid-Unibead* stimulation technique during December 1969 to acid treat impaired wells on the Cedar Creek Anticline in Montana completed in as many as 16 porous Silurian-Ordovician and 4 Mississippian carbonate intervals. Because of well mechanics, many of these wells were not amenable to effective stimulation using conventional methods of zone isolation and acid placement (such as a retrievable bridge plug and packer arrangement).

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