Abstract

Catastrophic failures of drill pipes have to be prevented from occurring during drilling operations of oil and natural gas wells. We are investigating mechanisms of crack propagation in ultra-high strength low alloy (UHSLA) martensitic steel drill pipe under cyclic stress as functions of pH, H2S concentration and temperature in simulated production fluids. These fluids are deaerated 5%NaCl solution buffered with NaHCO3/ CO2 in contact with 0.83 kPa H2S. Microscopic investigations of the pre-cracked fatigue crack growth specimen surfaces were performed after corrosion fatigue tests in neutral pH solution at 20 and 2000C, respectively. These investigations revealed that the environment temperature affected not only the crack propagation mode but also the general corrosion behavior. This paper discusses effects of the production fluid temperature on fatigue crack growth rate (FCGR) at ?K=11 MPavm for UHSLA steel. Post-corrosion fatigue surface characterization methods, such as optical and scanning electron microscopies, were used in this study.

Keywords:
drillstring design, corrosion inhibition, materials and corrosion, pipeline corrosion, production chemistry, drill pipe selection, h2s management, steel, permission, well integrity
Subjects:
Drillstring Design, Production Chemistry, Metallurgy and Biology, Pipelines, Flowlines and Risers, Drill pipe selection, Materials and corrosion, Well Integrity, Subsurface corrosion (tubing, casing, completion equipment, conductor), Corrosion inhibition and management (including H2S and CO2)
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2015. NACE International
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