Refracturing or restimulation of existing producing wells is an economical option for increasing production when compared to new drills. However, stage isolation during restimulation of horizontal laterals can be a challenge, especially in wells with extended laterals and many perforated zones. This paper presents six case studies utilizing mechanical isolation technology for restimulation.

In some cases, existing wells may not have been effectively stimulated. Slimhole reentry systems have been successfully utilized to achieve mechanical isolation in horizontal laterals. This paper describes slimhole tool systems, the process of their installation, and the limitations. In order to evaluate refracturing success, initial post-fracture production of each well in the study is compared to post-refracture production data. The six case studies covered are from five different producing formations, covering locations in Alberta, British Columbia, Colorado and Texas.

This paper shows that slimhole refracturing technology is an effective method for restimulation. Stage isolation in existing producing wells can be reliably achieved using mechanical packer systems. In one of the Canadian examples, a producing well in the Montney formation in British Columbia was restimulated after more than three years on production. The resulting production increased from about 175 Mscf/D to a stabilized production rate of 700 Mscf/D more than 20 months after the restimulation. In San Juan County, Colorado monthly BOE increased 79 times after five months and in Limestone County, Texas monthly BOE increased 2.5 times after five months. In the Alberta Glauconite formation, production one year following restimulation resulted in over 435 MMscf of additional gas recovered.

Mechanical isolation packers are a viable and effective alternative to temporary isolation techniques for extended horizontal wellbores. Multiple formations, both oil and gas in United States and Canada are used as examples. Long term production is now available to validate refracturing benefits using slimhole systems that provide mechanical isolation.

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