Use of Biodegradable Materials During Refracturing of a Horizontal Well

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. Traditionally, this is accomplished by pumping ball sealers or degradable balls in the fracturing fluid to seat on the perforations, diverting fluid away from the sealed perforations. Operationally, the perforation-ball method is very easily deployed, needing only a ball gun on the surface. These materials can also be pumped at designated times during the treatment. The main drawback of the method is the multizonal nature of wells. Constant pressure is needed to maintain the balls seated on the perforations; if at any point the treatment needs to be shut down (i.e., for equipment maintenance), these balls will unseat.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 171015, “Eco-Friendly Biodegradable Materials for Zonal Isolation of Multiple Perforation Clusters During Refracturing of a Horizontal Well: Case History From Marcellus Shale Hydraulic Fracturing,” by David Arnold, Anastasios Boulis, and Francisco Fragachan, Weatherford, prepared for the 2014 SPE Eastern Regional Meeting, Charleston, West Virginia, USA, 21–23 October. The paper has not been peer reviewed.
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Use of Biodegradable Materials During Refracturing of a Horizontal Well

01 May 2015

Volume: 67 | Issue: 5

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