UC San Diego
Investigations Supporting the Development of a Downhole Energy Harvesting System
- Author(s): Kjolsing, Eric
- Advisor(s): Todd, Michael D
- et al.
Hydrocarbon well operators deploy downhole reservoir monitoring equipment in order to optimize the rate at which hydrocarbons are extracted. Alternative power sources are sought that could be deployed in these harsh environments to replace or supplement standard power sources currently in use. To this end, four investigations were performed to support the design of such a device. In the first investigation base assumptions used in the preliminary design of an electromagnetic energy harvester were shown to be in doubt, implying that the expected power output would not meet initial projections. In the second investigation a parametric study was performed to understand how high uncertainty variables affect the natural frequency and damping ratio of a producing hydrocarbon well. In the third investigation a structural housing was designed to satisfy American Petroleum Institute load cases. Using finite element models and standard tube/casing geometries, design pressures were iterated until a permissible housing design was achieved. This preliminary design provided estimates of the radial width and volume in which energy harvesting and storage elements may be situated. In the last investigation two software programs were developed to estimate the energy that might be harvested from user specified harvester configurations. The programs are dependent on user input production tube accelerations; this permits well operators to use well-specific vibrational data as inputs to generate well-specific energy output estimates. Results indicate that a downhole energy harvesting tool is structurally feasible under reasonable operating conditions but conclusions regarding power output may only be made if actual downhole accelerations are known.