Corrosion inhibitors injected into production fluids can be an extremely effective method of mitigating corrosion in pipelines. In many cases, the use of expensive alloys can be avoided if the appropriate corrosion inhibitor is utilized, saving significant capital expenditure. In some cases however, corrosion control in the infrastructure may deteriorate over time. This is often the case when significant quantities of oily solids accumulate in the pipeline. This material, which is affectionately termed 'schmoo', has the potential to adsorb a significant quantity of inhibitor and forms a safe haven for bacteria. This makes it extremely difficult, if not impossible, for even the best corrosion inhibitor to be effective.
Through measuring oil-water interfacial tensions and contact angles, the work of adhesion of an oil drop on a submerged carbon steel surface has been calculated in the presence of a series of corrosion inhibitors. A novel multifunctional corrosion inhibitor formulation has been developed that is extremely effective at removing oily deposits from the internal surface of pipelines. The effectiveness has been demonstrated in a series of dynamic 'schmoo' removal studies. The formulation is also shown to be an extremely effective corrosion inhibitor.
Results from recent field evaluations with this new product corroborate laboratory findings. The new multifunctional inhibitor is seen to exhibit superior inhibition performance to existing high performance products. Additionally, the product is shown to both prevent the deposition of 'schmoo' in a pipeline and remove it from a previously fouled system. The removal resulted in a significant increase in water injection rates and an associated increase in oil production.
We live today, in a world dominated by energy use. The world's population continues to increase, dramatic industrial growth is being experienced in India and China, and uncertainty over ultimate global oil and gas reserves have resulted in renewed awareness of the finite nature of one of our most important natural resources.1, 2 In order to meet this significant growth in demand, exploration is moving to uncharted ultra-deep water locations and production is being considered from locations previously considered to be off limits. Furthermore, much of the world's existing production infrastructure is operating well beyond its' original design life. This creates significant technical challenges in all areas of production, however, none is more challenging than that of preserving the integrity of the asset's infrastructure.
The use of corrosion inhibitor is often a key part of a successful integrity management program. Injection of a high performing inhibitor at the appropriate location and optimum dosage can be extremely effective at reducing the corrosion rate experienced at the pipe wall. It is not uncommon to reduce the natural corrosion rate in the system by >95%. Performance is typically determined in the field through the use of several techniques including electrical resistance probes, coupon measurements and inspection readings.3 In some cases however, the performance of a corrosion inhibition program can deteriorate over time. This is particularly the case in systems that have a tendency to accumulate significant quantities of solids.