The Bakken reservoir development in Richland County, eastern Montana, has been a center of activity and has received significant attention in the industry since the first horizontal well was completed there in 2000. For one operator the initial completion program utilized cemented liners in the laterals in wells oriented to promote longitudinal hydraulic fractures. As discussed by Wiley, et al.,1  radioactive tracer logs indicated that there were often significant intervals, especially in the heel section of laterals that were not stimulated using this technique.

In late 2003, one operating company decided to attempt a refracture treatment in a well that showed long lengths of unpropped interval based on its tracer log. The approach was to emulate the completion technique then in use on new wells with uncemented liners. The result from this first refracture treatment was encouraging with a peak post-refracture treatment production rate in excess of the peak production rate after the original completion stimulation. As a result of this success, a refracture treatment program was initiated.

To date, all but one of the initial cemented liner wellbores have had refracture treatments pumped into them. The overall result has been an increase of over 1,300,000 stock tank barrels (STB) in the estimated ultimate recovery (EUR) for the wells in this program. Results showing the improved coverage from tracer logs will be presented along with examples of pre- and post-treatment production curves.

Over the course of this refracture treatment program, the fracture treatments have evolved. Treatment size has remained the same; however, the method of pumping the treatments has changed. This paper discusses how the refracture treatments were pumped and the results of the program.

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