Development of a Cost-Effective Method for Oil-In-Water Analysis in Oil and Gas Field by Spectrophotometer Technique

Abstract Oil-in-Water (OIW) analysis is essential for environmental compliance and equipment protection in upstream crude oil operations. In most of Gas Oil Separation Plants (GOSPs), produced water contains varying concentrations of oil and grease, necessitating accurate, efficient, and sustainable analysis techniques. The current standard method—ASTM D8193-18—employs mid-infrared (IR) spectrometry technique, which involves significant solvent use, longer analysis time, and high operational costs. This study introduces a novel colorimetric spectrophotometric method using the spectrophotometer, developed as an alternative to conventional IR methods. Initial trials began by scanning across multiple wavelengths to identify optimal detection at 430 nm. Calibration was performed using prepared stock standards derived from both light and heavy crude oils collected from Water Oil Separation Plant (WOSP) samples. Cross-validation was conducted in multiple field laboratories using different oil types to confirm robustness and reproducibility. The method demonstrated less than 10% deviation from conventional IR results, while reducing solvent consumption by over 80% and analysis time by 70%. These results present a strong case for implementing this method as a standard practice in upstream water quality monitoring, aligning with sustainability objectives and circular economy initiatives.