Meeting the Challenges in Completion Liner Design and Execution for Two High-Rate Acid-Gas Injection Wells

摘要

Two high-rate acid-gas injection wells were drilled in the LaBarge area of Wyoming. These wells were designed for injection of up to 65 million scf/D of a mixture of 65% H_2S and 35% CO_2. The primary engineering challenges in well design, casing selection, and cementing of the injection strings, along with the related operational challenges for both wells, are discussed. Key drivers influencing zonal isolation, salt-zone loading, casing, and central-izer selection are presented. Casing selection was influenced by corrosive gas composition, high injection rates, and the potential for salt-zone loading. The use of SM-2550 tubulars, heavy wall casing for the salt loading, handling requirements, and centralizer selection are discussed. The primary driver in cement design was resistance to CO_2, because past work has shown little H_2S interaction with cement under these well conditions. A discussion of the development of a high-alumina cement system with low fluid loss to address CO_2 resistance and long liner length is coupled with the quality-control steps taken from the time of manufacture of the specialty cement to the final placement in the well. Also described is the development of an alternative portland cement system in which sized particles are included to dilute the cement and reduce total system permeability. The unique engineering solutions resulted in operational challenges with casing running, cementing materials, and equipment. A description of the location problems and the steps taken to resolve the issues is included.