Sour Service

Abstract

A multi-year joint industry program (JIP) has been completed involving an experimental testing program to evaluate the fitness-for-purpose of high-strength low-alloy steel coiled tubing (CT) in underbalanced drilling of sour oil and gas wells. The primary focus is the cold-worked material response to sour well conditions when subjecting the tubing to multiple cycles of plastic tension and compression strains in the range of 2% to 3%. The material performance and/or degradation...

Presentation Outline

  • Materials in sour HPHT environments
  • Testing standards and methodologies
  • Qualification program example - evaluation of coiled tubing materials forsour service
  1. NACE Proof Ring Test
  2. NACE Double Cantilever Beam (DCB)
  3. Slow Strain Rate Test (SSRT)
  4. Low Cycle Corrosion Fatigue (LCCF)
  • Summary and Conclusions

 

The Industry Challenge

HPHT wells often encounter sour and corrosive operating conditions where hydrogen sulfide, carbon dioxide and high salinity formation water can severely impact the integrity of premium casing and tubing connections. Existing testing facilities cannot simultaneously expose representative, large diameter specimens to the combination of chemical environment and loading conditions that occur in these wells.

The project will establish a new facility where large-scale, high load...

The Industry Challenge:

Oilfield equipment in sour service, where hydrogen sulfide is present, is susceptible to hydrogen embrittlement and stress corrosion cracking.

Complex operating conditions including multi-axis and cyclic loads make it difficult to predict how the effects of the sour environment could affect the pressure and structural integrity of the equipment.

Small-scale material tests, which are used to evaluate material performance in sour environments, typically do not reproduce the...