RIASSUNTO
ABSTRACT:
Parameters, their corrosion forms and mechanisms that are important in defining the deepwater environment in relation to the reliability of offshore and subsea facilities have been studied. The aim of this research is to provide baseline information for predicting deepwater corrosion behaviour and its design-oriented solutions. Experimental results of two major case studies, namely a pioneering deep ocean studies performed by shallow, and deep, waters exposures and computational modelling of seawater resistivity changes on impressed current cathodic protection system, were analytically reviewed. Whereas analysis of the former case study identified different material responses indicating five forms of corrosion which initiated electrochemically and propagated in a localized manner by general corrosion, embrittlement, or dissolution mechanisms, the latter confirmed marked water resistivity influences on the cathodic protection system. Various prominent parameters associated with the observed forms and mechanisms of the corrosion process, or which are significant in determining the durability of subsea structures in the ocean as a function of the efficiency of protective coating and cathodic protection, were identified.
INTRODUCTION
In recent years, there has been a rapid increase in deepwater production sector worldwide, perhaps driven by the security circumstances in most countries; increasing demand for, and dependence on, oil and gas revenue; maturing of established hydrocarbon extraction basins and growing need to overcome depleting reserves. The trend of future exploration and development activity is moving towards deeper waters (beyond 8202.1ft or 2500m) and very aggressive environments. It becomes imperative then to deal with the important human and technical hazards associated with the operations to guarantee the increased life of the asset; effective realisation of both regulatory compliance and revenue targets (production at greater flow rates and in sufficient volumes) as well as promotion of Health and Safety at work.