Evaluation of Compatibility between Brine Packages and Materials for Tubing and Down Hole Equipment

The high-density clear brine, such as CaCl₂ has been widely applied in the oil and gas exploration field as completion or packer fluid, however, some failure cases of duplex stainless steels or super martensitic stainless steels in high density CaCl₂ brine have been reported. The effects of oxygen and/or production gas (CO₂/H₂S) contamination, or H₂S formation as decomposition products of NaSCN-type inhibitor have been discussed. In this study, the compatibility between brine packages and CRA materials used in the tubing and down hole equipment. The brine packages mean the brine and other additives like oxygen scavenger and inhibitor. The CRA materials evaluated in this study for tubing are super martensitic stainless steels and duplex stainless steels, and for down hole equipment are super martensitic stainless steels and austenitic precipitated hardened steels. The brines are NaBr, CaBr, ZnBr₂/CaBr₂/CaCl₂ and NaBr/KCl with the combination of inhibitor (amine base or NaSCN type). The SCC susceptibility for each CRA materials in each combination of brine packages was evaluated. The suitable combination for each CRAs and brine packages will be discussed.