Pipeline corrosion is a challenging issue for oilfield operators. Growing global energy demand coupled with the relentless depletion of onshore and shallow water resources has driven the push towards the exploration of deepwater and unconventional fields. In many of these areas, sour gas is evident, a condition complicated by high-pressure, high-temperature (HPHT) environments which places severe demands on the corrosion resistance of infrastructure and equipment. Various methods to combat corrosion are utilized within the industry principally corrosion inhibitors and materials selection.
The use of well-planned and structured inspection, maintenance and repair regimes together with robust chemicals management can mitigate much of the impact of corrosive hydrocarbons. However, regulatory and environmental concerns have seen the replacement of some chemical preventative methods to those that are less toxic or perceived as less threatening to the environment.
A critical factor in the choice of preventative methods is that of Capex vs Opex. Chemical inhibitors are Opex intensive requiring frequent maintenance regimes. By contrast, assets with a longer design life may benefit from the use of CRA's (Corrosion Resistant Alloys) which reduce ongoing costs but substantially increasing initial Capex. DW's analysis of the CRA market indicates a growing adoption across upstream and downstream applications with overall spend increasing from $2.5bn in 2010 to $4bn in 2014.
As operators become more involved in corrosion prevention decisions, they face a number of challenges in juggling cost control and problems arising from corrosion. For the future, it seems larger Operators will assume a risk-averse stance on these matters. Adopting a long-term view on corrosion prevention will likely lead to increased utilization of Corrosion Resistant Alloys to reduce overall project costs.
