Testing an Innovative Technique of Media Filtration to Improve Quality of Produced Water

The objective of this project is to improve the quality of produced water at an oil & gas production site. This paper will give the results of pilot tests of Veolia's technology, which uses coalescence and filtration to remove hydrocarbons and solids from produced water. The media is regenerated through a backwash process. The pilot test was conducted on-site in January 2025. The CoafilTM technology was tested using a pilot unit of 25 L/h. This technology was selected to achieve very low discharge concentrations of hydrocarbons. Test 1 involved using fine media (0.5 - 1 mm) in a single-stage mode, expecting low oil in water (<30 mg/L) at the feed. In this study oil in water (OIW) was measured as Total Petroleum Hydrocarbons (TPH) using an Infra-Red analytical method (NF M07-203). The test lasted approximately 108h and showed that a single column loaded with fine media could eliminate almost all hydrocarbon suspended droplets from the water. The TPH concentration at the pilot's outlet generally ranged between 0 and 1 ppm using online analyser (Video imaging Particle Analysis), while laboratory values showed results ranging from 1 to 6 mg/L. Test 2 examined two columns in series using coarse and fine media (0.7-1.7 / 0.5-1 mm) for further TPH removal. This test lasted approximately 60h and demonstrated that the series configuration positively impacted the pilot outlet quality, with TPH concentrations close to 0 mg/L according to the online JORIN analyser, and laboratory concentrations ranging from 1 to 5 mg/L. Both tests revealed that the Media filtration technology can give consistent results between 1 and 5 mg/L TPH when applying 2 filters in series, whereas the online analyser (using Video imaging Particle Analysis) gave outlet results below 1 mg/L. This discrepancy arises because the laboratory oil in water method measures Total Petroleum Hydrocarbons (TPH), which include dispersed oil but also some apolar soluble hydrocarbons which are not removed by filtration. It is expected that 1 to 5 mg/L are dissolved Hydrocarbons. Operational challenges include the effectiveness of backwash procedures and media saturation at the pilot scale. Accurate measurement of concentrations close to 1 mg/L at laboratory requires a lot of attention at every analytical step as the limit of quantification of the Infra-red method is close to the values measured at the outlet of the system. In conclusion, the pilot tests demonstrated that the tested media could effectively remove suspended hydrocarbons and solids from the water. However, dissolved hydrocarbons are not removed by filtration and will appear in the analytical results in outlet concentrations ranging between 1 and 5 mg/L, depending on the analytical method used. This technology is considered an innovative and relevant technology when the produced water requires a very good water quality for sea disposal or reinjection.