The service environment of oil and gas gathering pipelines becoming more and more complex and harsh, resulting in frequent failure, which not only causes the loss of oil and gas resources, but also the environmental and safety issues. Therefore, this paper focuses on the internal corrosion characteristics and most concerned issues of the oil and gas gathering pipelines and its mitigation measures. Firstly, several typical corrosion-induced failures of oil and gas gathering pipelines are introduced, moreover, the internal corrosion characteristics and advanced understanding of corrosion causes and mechanisms are analyzed. Then, internal corrosion control techniques including inhibitor, coating, clad pipe, non-metallic pipe, and life extension techniques including PE pipe insertion lining repair, air pressure extrusion coating repair, local repair and reinforcement were introduced.
The exploration and development of oil and gas resources towards the direction of ultra-deep, low permeability, and unconventional in China.1 In addition, some oil and gas fields have developed into the middle or late stage, the application of various EOR technologies, such as acid fracturing, CO2 flooding, air foam flooding and polymer flooding, resulting in the service environment of oil and gas gathering pipelines becoming more and more complex and harsh, such as high temperature, high pressure, high H2S/CO2, Cl− and bacteria, corrosion failures became one of the biggest challenges of oil and gas gathering pipelines.2,3
Oil and gas gathering pipelines are the connecting line between each unit of oil and gas field ground system, which characterizes by widely distributed, long distance, complex structure with different pipe diameters, and the transportation medium is highly corrosive, therefore, the corrosion failure of oil and gas gathering pipelines frequently occurred. Based on the material type, the oil and gas pipelines can be categorized as metallic pipe (carbon steel, stainless steel, etc.), non-metallic pipe (glass fiber reinforced plastics (FRP) and flexible composite pipe), and composite pipe (metal-metal, metal-nonmetal, and nonmetal-nonmetal). Coating and inhibitor are widely used in oil and gas gathering pipelines due to most of them are carbon steel.4 According to statistics, 90% and 97% failures of oil and gas gathering pipelines in A and B onshore oilfield are caused by corrosion, and nearly 50% failures of subsea pipelines in C offshore oilfield are caused by corrosion. The "Qingdao Crude Oil Leaking and Explosion Accident" resulted from corrosion failure, which happened on November 22, 2013, has once again sounded the alarm for the safety production and operation of the oil and gas industry.5 It is worth noting that the corrosion failure of oil and gas pipelines is not only the economic problems causing oil and gas loss, but also the environmental and safety issues, therefore, the protection of oil and gas pipelines corrosion has attracted unprecedented attention. 6,7