Casing/cementing/zonal isolation

Use of Biodegradable Materials During Refracturing of a Horizontal Well

One approach to refracturing involves the use of mechanical diverters such as perforation balls and rock salts, which may be useful for one stage; however, cessation of pumping operations results in these diverters falling out of the perforations or dissolving.

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Fig. 1—Before treating the fourth stage, the diverter batch had a 3,000-psi pressure spike when entering the perforation clusters.

One approach to refracturing involves the use of mechanical diverters such as perforation balls and rock salts, which may be useful for one stage; however, cessation of pumping operations results in these diverters falling out of the perforations or dissolving. In this paper, a new approach is presented that uses degradable materials. These materials can be tailored to plug perforations on a temporary basis but degrade over time depending on formation temperature.

Introduction

There are several operational approaches to refracturing wells, some of which require sealing off existing zones and losing the previous-fracturing-treatment production, while others require installing sophisticated downhole tools. These include sliding-sleeve systems, coiled-tubing tools, and perforation-squeeze systems (please see the complete paper for details of these approaches). A simpler approach, considered a proven method of sealing perforations and zones, is the use of mechanical diverters.

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