Multistage Cementless Acid Fracturing in Sidetracking Slim Hole using Innovative Packers with Anti–Corrosive Thermo–Plastic Vulcanizates

Abstract

Abstract Most 5 1/2in-casing mature wells need to be re-fractured for improving the ultimate recovery. Over the last decade, operators focused on the sidetracking well completion for maximizing wellbore contact. Acid fracturing tend to be performed to treat the reservoirs and make fractures system more complicated as much as possible. The irregularity of slim hole has negative influence on the deploying of completion or fracturing assembly. Isolation tools are usually subjected to heavy corrosion caused by acid or proppant fluid. The 3 1/2in Open-hole packer-sleeve (OHPS) completion assembly including improved external casing packer (ECP) were proposed for sidetracking well completion. The water-swellable packers (WSPs) with anti-corrosive thermo-plastic vulcanizates (TPVs) was used as the alternative to current mechanical-set ECPs. The TPV matrix was prepared by physically blending high-strengthen carboxylated nitrile (XNBR) with polyamide (PA6). To improve the swelling performance, newly-developed Porous Super Absorbent Resin (PSAR) was mixed and distributed into XNBR/PA6 system. The new swellable TPV exhibits the advantages of high strength, anti-corrosive property and high reliability over traditional packing materials. The TPV material characterization and annular sealing test of 3 1/2in prototype was conducted in the lab. One 5 1/2in mature oil well was selected for field validation. One 3 1/2in OHPS string with four stages was successfully tripped into large-deviated slim borehole. During the stimulating operation, WSPs acted as effective barriers and any communications between stages did not occurred. It is concluded that the new OHPS using improved WSPs meet requirements of slim-hole sidetracking well completion and stimulation.