RIASSUNTO
ABSTRACT
Corrosion control of heavily fouled systems poses a significant challenge for integrity management programs. In cases where deposits build up in pipelines, or within pits, it is virtually impossible for a corrosion inhibitor to penetrate the deposit and impart inhibition at the underlying surface. The inhibitor simply adsorbs onto the deposits while corrosion continues unabated at the metal surface. The research presented in this paper extends our earlier work into the development of multifunctional corrosion inhibitor products that are extremely effective at removing pipeline deposits and mitigating corrosion. The focus of this paper is the development of a new formulation containing a patent-pending corrosion inhibitor active that exhibits these properties, in addition to meeting the most stringent environmental regulations governing the use of production chemicals in the North Sea.
INTRODUCTION
Over the past 150 years of oil production, there have been few times that maintaining production has been as critical as it is today. With the oil price riding at all time highs and the world?s demand unrelenting, it is critical for companies to maximize their production. Any downtime results in deferred or lost production depending upon the accounting method employed by the leaseholder. Maintaining the integrity of production infrastructure is obviously critical to maintaining production. However, if the integrity of the system cannot be maintained the impact on the safety of personnel, the environment and ultimately the company?s license to operate can be catastrophic. Furthermore, operational and capital expenditures required to maintain the asset can quickly exceed budgetary levels. One of the biggest integrity management challenges facing the industry today is maintaining the integrity of lines that contain significant quantities of oily deposits. These deposits, affectionately known in the industry as ?schmoo?, often contain appreciable quantities of corrosion byproducts, biomass, sand and clays.1 This forms a physical barrier that retards the diffusion of the inhibitor to the pipe wall. Furthermore, these solids often have a strong affinity for corrosion inhibitors and can significantly reduce the in-situ inhibitor availability (ISIA).2,, 3,, 4 Generally, the composition of the matter that settles out of the bulk fluids forms an ideal environment to grow bacteria. The metabolic byproducts of these bacteria can be extremely corrosive. This process, known as microbiologically influenced corrosion (MIC), has been recognized as a significant problem in the industry for many years.5, 6 In many cases, these deposits are not easily removed from a pipeline due to the absence of pig launchers and receivers. Even in cases where maintenance pigs can be run, often the debris in a pit cannot be removed and corrosion still occurs under this material at the base of the pit. Recently we published our extensive work into the development of a new-patented chemical technology that is effective in heavily fouled systems.7 This multifunctional product is highly effective at mitigating corrosion from both CO2 and H2S dissolved in the production fluids, and microbially influenced corrosion (MIC). The key attribute of the product is that it is highly effective at removing problematic schmoo deposits from the surface of a line, thereby allowing the inhibitor to adsorb at the surface and mitigate corrosion. This technology has been proven in the field and is being used globally to successfully control corrosion in heavily fouled systems.