Definition of a wet hydrogen sulfide environment

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1. International definition of wet hydrogen sulfide environments: The NACE MR0175-97 standard \"Materials for Oilfield Equipment Resistant to Sulfide Stress Cracking\": (1) Acidic gas environment: Total gas pressure ≥ 0.4 MPa, and H2S partial pressure ≥ 0.0003 MPa； ⑵Acidic multiphase system: When the crude oil being processed contains two or three phases (oil, water, gas), the conditions can be relaxed to: total gas pressure ≥ 1.8 MPa and H2S partial pressure ≥ 0.0003 MPa ； When the gas phase pressure ≤ 1.8 MPa and the H2S partial pressure ≥ 0.07 MPa ； Or the H2S content in the gas phase exceeds 15%. 2. Definition of a wet hydrogen sulfide environment in domestic settings: \"An environment with both water and hydrogen sulfide is considered a wet hydrogen sulfide environment when the partial pressure of hydrogen sulfide is 0.00035 MPa or higher, or when there is liquefied petroleum gas containing both water and hydrogen sulfide and the hydrogen sulfide content in the liquid phase is 10×10-6 or higher.\" 3. Ionization of hydrogen sulfide: In a wet hydrogen sulfide environment, hydrogen sulfide undergoes ionization, which renders the water acidic. The dissociation reactions of hydrogen sulfide in water are as follows: H2S = H+ + HS- (1) HS- = H+ + S2- (2)