Proactive management for long term integrity of pipeline assets
Threats to long-term operation due to corrosion can be reduced thanks to emerging technologies
Corrosion has always been a major threat to assets both on and offshore, yet it is often only as these assets age that the fight against corrosion becomes a priority to operators. To deliver enhanced long term integrity, operators must ensure that corrosion protection is an ongoing and proactive task, not a reactive one.
Over the last couple of decades, pipeline corrosion management has attracted ever-increasing attention due to a number of high-profile pipeline failures in the industry. Corrosion is an expensive business, and pipelines are increasingly subjected to attacks caused by transporting multiple products, empty periods during product changeover and below capacity flow through the pipelines. Pipeline failure can present a whole host of problems, from safety issues to the financial cost of total shutdown, which has highlighted the importance of risk assessment strategies and pipeline integrity management programmes.
Internal corrosion management typically involves monitoring a number of properties using coupon testing, residual inhibitor monitoring, corrosion rate probes and intelligent pigs, for example. These options are often combined to reduce corrosion and minimize the risk of integrity failure. Treatment of fluids to eliminate moisture, carbon dioxide, hydrogen sulfide, oxygen and solids levels in transported materials can also be implemented as part of an effective mitigation process. The use of special coatings, cathodic protection systems and chemical inhibitors can also be used in corrosion management strategies. The combination of these preventative methods, along with monitoring and inspection regimes, corrosion monitoring techniques, risk assessments and active maintenance programmes, comprise an integrated integrity management system.
One important component of corrosion management is the use of corrosion inhibitors, which form a protective barrier on vulnerable surfaces and protect infrastructure from corrosive attack. Organic, film-forming inhibitors are commonly used in the upstream oil and gas industry, which do not associate permanently. Instead, inhibitor stock in the bulk fluid must be present to maintain film integrity. The use of these corrosion inhibitors is generally considered costly, since treatment requires continuous injection or regular batching due to the large volumes of product constantly flowing through the process system or pipeline.
Laboratory testing can determine chemical dosage, however field conditions can differ significantly from those that can be set up in the laboratory, particularly with regard to pressure, temperature and the complex mix of treatment chemicals, solids, oil and water.
Furthermore, when systems change (for example with changing water cut, or wells being brought on or taken offline) dosage may need to be modified to remain optimal. A tool, which determines optimum dose onsite, would be advantageous to operators. The result would be improved integrity management, potential chemical savings and potential benefits with regard to oil in water separation, given the surfactant nature of the inhibitors.
An emerging solution
To help in the fight against pipeline and process equipment corrosion, LUX Assure, a chemical management specialist, developed CoMic. This is a corrosion inhibitor micelle detection technology that can be used in the field to provide effective and informed management for long-term integrity of aging assets.
As lifetime extension of offshore assets continues to be a growing concern for operators, products such as CoMic are necessary weapons against the hazards of aging infrastructure. As a product developed for the proactive management of process equipment and pipeline corrosion, it helps ensure optimal corrosion inhibitor usage.
The technology aims to provide a proactive and efficient way of managing corrosion and integrity. It does this by providing critical information to allow management to make informed engineering decisions, leading to proven results in operations, time and cost savings (which in many cases can be significant), whilst enhancing safety and reducing environmental impact.
CoMic ensures protection for assets as well as process optimization, prevention of emulsions which result in oil and water separation issues and potential savings in chemical usage. CoMic provides detailed information on corrosion inhibitor dose optimization based on micelle detection in oilfield fluids, and eliminates inaccuracies which can be caused by sample degradation. Regular testing, as part of an improved corrosion management system, offers an unprecedented understanding of equipment lifespan and provides significantly increased risk assurance for operators.
CoMic has been deployed on multiple assets in many countries around the world both on and offshore.
Case study – North Sea, U.K.
There are a cluster of oil and gas platforms in the North Sea connected by a diverse network of pipelines. Current monitoring technologies including electrochemical probe and coupon testing were deployed, and produced contradictory indications on the efficacy of corrosion inhibitor dosage on one specific pipeline. CoMic was then deployed to provide complementary information on whether corrosion inhibitor use was optimal.
LUX Assure carried out an initial laboratory assessment and observed typical film-forming behaviour for the inhibitor, with micelles detected in significant numbers once concentration reached the critical micelle concentration (CMC). However, CMC is a function of the specific environment, so the fluid has to be tested in the field if the analysis is to be accurate and useful.
Onsite, analysis of water from each end of the pipeline confirmed that the effective dose entering the pipeline wasn’t present at the exit. This suggested that either an increase in dosage was required, or that an alternative inhibitor should be used. The operator trialled a replacement inhibitor, with CoMic used to analyse two different dosage levels, helping define the optimum concentration of the new chemical. This delivered enhanced protection and assurance against corrosive attack.
Case study – Alaska
A major onshore production complex in Alaska runs three separate systems that deal with produced water and injected seawater. Uncertainty arose regarding inhibitor performance, and given the complexity and scale of the systems, integrity loss could have been very costly. LUX Assure contracted to carry out studies on all three systems.
The first system analyzed by CoMic had three interconnected production facilities distributed over a large geographical area, with each facility processing the output of numerous individual wells. Corrosion inhibitor was injected at each well site, with an extra boost added in one of the lines.
Analysis revealed significant differences across the system, with micelle levels above optimal at one facility, below optimal at another, and optimal at a third.
The CoMic analysis highlighted the potential benefits if inhibitor dosage were to be altered.
A return visit the following year showed optimal corrosion inhibitor levels throughout, suggesting that the company’s work helped avoid potentially expensive loss of integrity.