Performance Analysis of Novel Metal Expandable Openhole Packers for High-Temperature Geothermal Wells: A Case Study of Utah FORGE

Abstract

Achieving short- and long-term zonal isolation in geothermal wells has previously posed significant operational challenges, particularly during high-pressure hydraulic fracturing operations and ones with extensive temperature cycling. Conventional packer designs that rely on elastomeric sealing elements often fail under high-temperature and stress-corrosion conditions. Effective zonal isolation in these environments requires tools capable of sealing under the high-pressure, high-temperature (HPHT) conditions encountered throughout the well’s lifecycle. Welltec developed a novel downhole metal expandable packer (MEP) using non-elastomeric seals as part of the FORGE project. The University of Oklahoma (OU) conducted performance tests on these designs to enable precise stimulation control across multiple zones, ensuring they can withstand extreme geothermal well conditions. The assessment has focused on the performance of these innovative packers, with particular attention to their ability to endure HPHT loads over the well’s operational life. The challenges conventional openhole packers face in these environments have been reviewed with their limitations. Established packer calculations have been discussed regarding the forces acting among the tubing, packer, and casing interfaces. This study plays an important role in defining the operational envelope for multi-stage packers and predicting the packer performance during hydraulic fracturing operations in geothermal wells. Case studies have been done using casing and tubing design software to evaluate the safe operating envelope of these MEPs. Comparisons have been made between the currently proposed packers and a failed cased-hole packer in the FORGE Well 16A(78)-32 during the diagnostic fracture injection test cycles (DFIT). Evaluation has been conducted on the potential benefits and challenges of incorporating expansion joints and/or seal movement allowances in order to enhance the performance and reliability in geothermal well applications.