INTRODUCTION
Corrosion performance of the new generation of low carbon Cr-containing tubing has been assessed in the actual field conditions. The data is a clear illustration of the superior corrosion performance of these steels in CO2 containing production conditions. This is supported by extensive laboratory assessment of 3%Cr steels for both sweet and sour production and water injection applications. This paper covers field experience of 3%Cr tubing and the outcome of laboratory corrosion performance assessment. The superior resistance to CO2 corrosion, satisfactory SSC performance, improved corrosion in seawater injection conditions together with more than acceptable mechanical properties, make 3%Cr steel an extremely economical choice for the completion of producers and injectors and a major alternative to the existing steels.
The oil and gas industry is facing mounting pressure on many fronts, particularly development and production costs, and has certain goals to meet in the area of green operations in the face of restrictions on emissions. In these, appropriate and cost effective choice of materials is paramount to achieving operational success while realising economy and safety. The correct strategy in the choice of materials is becoming increasingly significant as the industry moves to harsher environments in deeper high pressure/high temperature wells, deep water and the need for virtual facilities with growing emphasis on the requirements for untreated water injection and low intervention.
Second to drilling cost, materials are the most costly elements of exploration and production (E&P) activities. The correct choice of materials while meeting environmental and safety constraints, reduces the significant impact of corrosion which remains a major operational obstacle to integrity management and trouble free hydrocarbon production [1,2]. The industry continues to lean heavily on the extended use of carbon and low alloy steels for both production and water injection applications. Water injection is a key consideration in reservoir management, increase production, safety and the environment. Carbon and low alloy steels have served the industry successfully. They are readily available in the volumes required and able to meet many of the mechanical, structural, fabrication and cost requirements. Their technology is well developed and they represent for many applications an economical materials choice. However, a key issue for their effective use is their poor corrosion performance which has led to severe failures, imposed cost penalty and undermined safety. Development of the new generation of low carbon 3%Cr containing steels has led to improving corrosion resistance of carbon steels enlarging the application regime of the conventional categories of carbon and low alloy steels [ 1,3,4].
