Design and Experimental Validation of a Unique Geothermal Downhole Valve for FORGE Project

Abstract

To control climate change, greenhouse gas emissions in the atmosphere must be lowered. In that respect, many countries have set a goal of net zero emissions and are focusing on renewable energy. Amongst the non-conventional energy sources, geothermal energy is the only one unaffected by any metrological and atmospheric changes and remains in operation mode most of the time. Moreover, power generation coming from geothermal energy has been increasing in recent years because new technology has been implemented to reach an acceptable production rate. Developing Geothermal wells puts the downhole tools in another load envelope compared to conventional oil and gas wells. In particular, high temperatures and combined mechanical and thermal cycles require a more detailed design and material selection. Nonetheless, this type of renewable source has many challenges to face. On one hand, drilling and completion operations costs are almost 50% of the budget, sometimes making the projects infeasible. On the other hand, the geothermal well's severe bottom hole condition (high temperature and pressure) creates problems for the bottom hole assembly. Zonal isolation requires dedicated tools capable of opening and closing repeatedly under the high-temperature conditions of a geothermal well. As part of the FORGE project, the OU and Welltec team have proposed a special downhole valve that uses metallic seals. This valve enables the closing and opening of the selected fracture interval and thus will enable accurate control of the fracturing process. Therefore, this paper presents an experimental test on a sleeve valve for completion and production operations specific to the geothermal well. This sleeve valve was able to endure the High-Pressure, High-Temperature (HPHT) testing conditions and was able to maintain its integrity. The detailed procedure and the result of the HPHT test will be presented in this paper.