Building an Oil and Water Partitioning Model for Corrosion Inhibitor Dosage Based on Novel Residual Technique

The partitioning behavior of corrosion inhibitor (CI) among different phases is a critical factor for successful application on carbon steel. Unreliable measurement of CI residuals can lead to inaccurate dosing, overtreatment, and higher operating costs. However, obtaining a reliable and accurate measurement of CI residuals can be problematic for both operators and CI suppliers. Traditional residual techniques usually involve complicated and tedious analytical procedures. These procedures may require dedicated benchtop instruments, which utilize a centralized laboratory to perform the analysis. Recently, a novel residual technique was developed based on a proprietary nanotechnology-based spectroscopy technique. The new technique involves a handheld instrument and allows rapid and accurate measurement of CI residuals in the water phase. In the current laboratory study, this technique was applied to build a model of the partitioning of a water-soluble CI between the oil and water phases at different water cuts. It was found that the CI partitioned in the water phase preferentially in all water cuts. A higher amount of CI partitioned in the water phase with decreasing water cut. The result of the study was a CI partitioning model to be used as guidance for CI dosage in the field.

In the production of oil and gas, corrosion inhibitor (CI) is usually dosed into multiphase flows (oil/water/gas).^1,2 The partitioning behavior of CI among the different phases is a critical factor for a successful application.³ Unreliable measurement of CI residuals can lead to inaccurate dosing, overtreatment, and higher operating costs. However, obtaining a reliable and accurate measurement of CI residuals can be problematic for both operators and CI suppliers. Traditional residual techniques usually involve complicated and tedious analytical procedures. In recent years, many techniques were employed to detect CI residuals in oilfield fluids, including methyl orange, ultraviolet spectroscopy (UV), chromatography, and mass spectroscopy.⁴ However, most of these techniques required tedious analytical procedures and/or a delicate benchtop instruments. In addition, the lack of portability made it impossible to perform real-time residual analysis and the high error rates made field investigations impossible.