Analytical treatment of oil field-produced water: a case study from Upper Assam Basin (India)

摘要

Large amount of water were produced during production of crude oil which contains contaminants in the form of both organics mainly hydrocarbons and inorganics. The produced water sample was diluted and analysed numerically which showed the presence of oil and grease, total suspended solid, total dissolved solid, turbidity and salinity, along with different ions such as fluorine, sodium, potassium, calcium, lithium, magnesium and heavy metals but the presence of nickel, molybdenum, copper and chromium has not been observed in the samples. These samples were further treated in the hollow fibre membrane set up by microfiltration, ultrafiltration and nanofiltration membranes respectively. After treatment in nanofiltration membranes, it was observed that there was a drastic change in turbidity, total suspended solid and oil and grease and all the parameters were found to be within range according to the central pollution control board of India. Later, the parameters were evaluated with ryznar stability index for aggressiveness of water, Langelier saturation index for scale and corrosion potential, ionic strength for concentration of dissolved chemical constituents and absorbance for the presence of pollutants. The trend of absorbance shows the decrease of pollutants present in produced water which can now be disposed into the environment without affecting it. The present approach of treating the oil field-produced water is safe and very easy to operate and large quantities of produced water can be handled at various installations and also, it will reduce the contamination at the subsurface without affecting the flora and fauna. The present approach is free from various chemicals otherwise normally used while treating oil field-produced water and also, it requires less time for completion of the whole process. The only limitation of this process is that certain quantity of distilled water has to be added for the treatment process.