Abstract
The environmental fate of specialty chemicals is now being addressed. Water soluble corrosion inhibitors which might find their way into the ocean, navigable waters, or sensitive land areas should have acceptable environmental properties. This paper outlines laboratory investigation and field evaluation methodology for assessment and improvement of these properties.
Since nearly all corrosion inhibitors used in petroleum recovery operations are blends, this investigation focused on solvents as well as active components. The following protocol was typically used in this investigation.
Potential components were first corrosion tested in simple kettle tests using weight loss and linear polarization for evaluation. Interesting candidates were then subjected to Microtox evaluation; this is the least time consuming of environmental evaluations and gives general prediction of toxicity. Candidates which still showed promise were often blended and tested in kettle corrosion tests. Surviving candidates and blends were then subjected to EC50 tests using Skeletonema Costatum.
Candidates which still showed promise were next subjected to biodegradability testing. Solvents of interest and commercially available inhibitors were also tested by EC50 and biodegradability methods. At this point many of the blends were evaluated as corrosion inhibitors in a laboratory flow loop.
Potential components were first chosen from commercially available compounds, then from synthesized compounds with varying degrees of oxyalklation. These were often combined with other environmentally acceptable components known to act synergistically to inhibit corrosion.
The final series of laboratory tests involved vapor pressure, environmental acceptability of vapors, and octanol/water partitioning of blends. The surviving blends were field tested first in oil wells using simple batch methods, then in continuous injection situations. This paper summarized the results of these tests plus some information for recent commercial applications.
