Oilfield corrosion test environments

NACE has develojjed several standards involving HT/HP corrosion testing. These have involved the laboratory simulation of two types of corrosive environments (1) Aqueous oilfield production environments containing corrosive acid gases (i.e., hydrogen sulfide and carbon dioxide) and water, and (2) nuclear reactor high-purity water environments. 

Oilfields in the North Sea provide some of the harshest environments for polymers, coupled with a requirement for reliability. Many environmental tests have therefore been performed to demonstrate the fitness-for-purpose of the materials and the products before they are put into service. Of recent examples [33-35], a complete test rig has been set up to test 250-300 mm diameter pipes, made of steel with a polypropylene jacket for thermal insulation and corrosion protection, with a design temperature of 140 °C, internal pressures of up to 50 MPa (500 bar) and a water depth of 350 m (external pressure 3.5 MPa or 35 bar). In the test rig the oil filled pipes are maintained at 140 °C in constantly renewed sea water at a pressure of 30 bar. Tests last for 3 years and after 2 years there have been no significant changes in melt flow index or mechanical properties. A separate programme was established for the selection of materials for the internal sheath of pipelines, whose purpose is to contain the oil and protect the main steel armour windings. Environmental ageing was performed first (immersion in oil, sea water and acid) and followed by mechanical tests as well as specialised tests (rapid gas decompression, methane permeability) related to the application. Creep was measured separately. 

Control of external corrosion of steel piping is generally achieved with coatings plus cathodic protection. Testing related to external environments (soil, seawater) to which oilfield piping may be exposed is handled ekewhere (see Section V of this manual). 

Slow Strain Rate Test Method for Screening Corrosion-Resistant Alloys (CRAs) for Stress Corrosion Cracking in Sour Oilfield Service Evaluating Elastomeric Materials in Sour Liquid Environments Evaluating the Compatibility of FRP Pipe and Tubulars with Oilfield Environments... 

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