51315-5512-A Comprehensive Study of Titanium Alloys For High Pressure High Temperature (HPHT) Wells

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Product Number: 51315-5512-SG

ISBN: 5512 2015 CP

Author: Russell Kane

Publication Date: 2015

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This paper summarizes principal findings of a major experimental and analytical Joint Industry Program (JIP) research effort that developed corrosion data and analysis on Ti-alloys applicable to high pressure high temperatures (HPHT) wells. The range of test conditions included: simulated production environments with H2S CO2 chlorides and elemental sulfur and non-production environments (i.e. packer fluids and stimulation acids) and galvanic effects with other materials at temperatures up to 550 F (288 C). Included in this study were alpha-beta (?/?) and beta (?) titanium alloys with strength for use in downhole tubulars and associated equipment with yield strengths of 110 to 140 ksi (737 to 966 MPa) and in limited cases >150 ksi (1035 MPa). Most of the data development focused on the following alloys: Ti-6246 (UNS R56260) Ti-64 (Grade 5 - UNS R56400) Ti-64 ELI (Grade 23) and with additions of Ru or Pd (Grade 29 and Grade 24) Ti-TMZF (12Mo-6Zr-2Fe) and Ti-Beta C (Grade 19 - UNS R58640). Testing was based on the slow strain rate technique with a modified evaluation procedure from that given in NACE TM0198 and double cantilever beam (DCB) testing per NACE TM0177 Method D but under HPHT well conditions. In some cases where galvanic coupling was a potential issue SSR tests were also performed at room temperature following exposure under HPHT conditions. Packer fluid tests involved three primary fluid types: 16 ppg CaCl2/CaBr2/ZnBr2 13.6 ppg CaCl2/CaBr2 and 14.2 ppg CaBr2. Acidizing tests involved exposure to 10% acetic acid and a mixed acid environment consisting of 10% acetic acid and 10% HCl. The test results were used to define serviceability limits for specific alloy compositions based on different conditions of metallurgical processing and yield strength. For cases under galvanic coupling different behavior was observed for Ni-based alloy and steel couples. Results from the program were used to augment a proprietary oilfield material selection software system developed from earlier JIP efforts.Keywords: HPHT wells Oil & Gas production stress corrosion cracking hydrogen sulfide packer fluids galvanic slow strain rate