This paper presents the first application of metal expandable frac packers for multistage acid fracturing (MSF) completions. This technology significantly reduces deployment risk commonly associated with openhole (OH) MSF completions with the ability to rotate while running in hole without any risk of premature expansion or compromising integrity of the sealing mechanism. Additionally, it improves efficiency of fracturing operations in tight gas reservoirs with the ability to expand to larger borehole diameters than is possible with current isolation packer technologies.
The overall deployment method for this technology is similar to traditional openhole multistage fracturing completions that are industry standard. The main difference is that the isolation packer used is expanded by pressure to mechanically deform the metal sleeve to provide sealing against the open hole. The technology comprises an innovative material and design that can hold high differential pressure at high reservoir temperatures while maintaining permanent isolation in a relatively compact element length. The metal expandable frac packer completed an extended qualification process, including American Petroleum Institute (API) testing, to fulfil deployment and acid fracturing completion requirements.
The outcome was an overall successful deployment and stimulation operation of multistage completion with the metal expandable frac packer. The metal expandable frac packer provided the ability to deploy the lower completion in difficult wellbore conditions with ability to rotate. The metal expandable frac packer is set with pressure; therefore, there is no waiting time to have full differential pressure capabilities for the fracturing operations. This technology provided a flexibility factor for packer placement as the metal expandable packer technology can hold its rated pressure at larger borehole diameters. Since the mechanism of the metal packer is expansion by inelastic deformation, the metal expandable sleeve conforms perfectly to the geometry of the borehole, providing a highly reliable seal for high pressure fracturing operations. Through a complete diagnostic process, it was confirmed that the metal expandable packers successfully isolated each stage of the stimulation treatment.
Metal expandable frac packers unique testing was conducted in the laboratory and in field to qualify the technology with special focus on the chemical composition for the fluids encountered for the deployment, stimulation, and production environments including high concentration acid fracturing applications. The metal expandable sleeve technology utilizes a unique double-sleeve system for pressure compensation to enhance the sealing integrity of MSF stimulation operations and truly provide 10,000 psi under API 19OH V1.