Definition
Sour Service — Sour service refers to operations in wells containing hydrogen sulfide (H2S), where materials must be selected and controlled per NACE MR0175 / ISO 15156 to resist sulfide stress cracking and other forms of environmental embrittlement.
Also known as: sour service, H2S service, sour environment
What sour service means
Sour service describes any downhole or production environment where hydrogen sulfide is present in enough concentration to threaten steel by sulfide stress cracking (SSC). H2S dissolved in water generates atomic hydrogen that diffuses into high-strength steel and can cause sudden brittle failure under tensile stress. Because the risk rises with steel strength and hardness, sour-service applications restrict the metallurgy and hardness of the tubulars and tools used.
Whether an environment counts as sour, and how severe it is, is defined by the H2S partial pressure, in-situ pH, chloride content and temperature, following NACE MR0175 / ISO 15156.
How sour service is managed
- Material selection — steels qualified to NACE MR0175 with controlled hardness (often ≤ 22 HRC).
- Grade choice — sour-rated OCTG grades such as L80, C90 and T95 under API 5CT.
- Documentation — certification that each component meets the required sour severity.
Ignoring sour-service requirements risks catastrophic, brittle failure of the string.
Why it matters for rentals
For sour wells, rented tubulars, workstring and downhole tools must be certified for the specified H2S severity. See our workstring tubing and quality program, or contact us with your H2S data.