| Title | Development of Diverter Systems for EGS and Geothermal Well Stimulation Applications |
|---|---|
| Authors | Daniel BOUR, Yini NORDIN, Jeff WATTERS, Joy SUTTON, Kyle COMBS, Allen APHBLETT, Peter ROSE |
| Year | 2012 |
| Conference | Stanford Geothermal Workshop |
| Keywords | EGS, stimulation, diverter, multiple-zone, degradable, non-damaging, reservoir, optimization, completion, DOE |
| Abstract | In the creation of an EGS system the reservoir rock must be stimulated to allow for circulation of fluids from the injection well to the production wells. Key to optimizing an EGS system is the creation of multiple stimulated fractures from one wellbore. This has proven to be a difficult task as most EGS injection wells are completed open hole and there are few mechanical tools or systems that can reliably provide the needed hydraulic isolation in a geothermal environment to do multiple zone stimulation. The development of diverter systems was undertaken to overcome the problem of hydraulic isolation and multiple zone stimulation. Diverter systems were developed specifically for open hole application under geothermal well conditions. One of the performance parameters that were set for diverter development was a material that would remain intact during stimulation treatment and then dissolve into non-damaging degradation products after the stimulation. This makes it possible to apply this technology without the need for a drilling rig during or after the stimulation. The elimination of a drilling rig greatly reduces the cost of stimulation treatments as well as significantly reduces the risk of damaging the well during the process. Included in this work will be an explanation of how particular diverter systems were developed and why they were chosen over other chemical systems. Test methods for development will be described along with test results from a number of materials evaluated for this application. Also, degradation versus temperature data, decay kinetics results, and laboratory fracture sealing tests will be provided. Some brief description of the successful application of diverters in field applications will also be provided along with description of planned future development. This work has been funded in part by DOE Grant DE-EE0002795, “Temporary Bridging Agents for Use in Drilling and Completion of Engineered Geothermal Systems.” |