Performance Evaluation of Eco-Friendly PPDs Synthesized from Natural Sources for Enhancing the Cold Flow Behavior of Waxy Crude Oil

Summery Waxy crude oil faces significant flow assurance challenges due to wax deposition, leading to poor cold flowability and complex rheological behaviour. Wax deposition in crude oil pipelines increases pumping costs, reduces flow capacity, requires frequent cleaning, causes shutdowns, raises maintenance expenses, and leads to financial losses from supply disruptions, and infrastructure repairs. In order to address these issues, pour point depressants (PPDs) are crucial processing aids that alter the wax crystallisation process and enhance crude oil flow. However, conventional PPDs are expensive and non-biodegradable, which renders projects unprofitable and cause environmentally risky. Natural-based PPDs are investigated in this study as affordable, environmentally friendly substitutes. Application research on biodegradable PPDs in field crude oil is limited, especially in Indian field crude oil. Therefore, current research focusses on the synthesis of new biodegradable polyethylene glycol fatty esters using stearic acid [Polyethylene glycol stearate (CONPPDS)] and lauric acid [Polyethylene glycol laurate (CONPPDL)] along with cobalt oxide nanoparticles synthesized through green synthesis as eco-friendly PPDs to combat wax deposition issues. The relative effects and efficacy of PPDS and PPDL on flow assurance were assessed by employing pour point, wax deposition, DSC, and rheological studies that included viscosity, yield stress, and rheomalaxis. Impacts varied as well because the chain lengths of synthesized PPDs varied. Using microscopic examination, the mechanism of interaction between PPDs and wax particles was also investigated. The addition of PPDL and PPDS lowers the pour point of waxy crude oil by 15°C and 18°C, respectively, at a minimum concentration of 300 ppm. Viscosity reduction was observed by 91% to 98%, and over 70% decrease in yield stress at 40°C, ensuring smoother pipeline transportation. The wax deposition was sufficiently reduced by more than 80%, suggesting less agglomeration of wax crystals Biodegradability and toxicity tests, conducted using OECD standards, confirmed that the PPDs are biodegradable and non-toxic. Our bio-based PPDs offer a cost-effective, eco-friendly alternative to commercial PPDs for real-field applications like field of ONGC, OIL etc. Efforts are underway to implement these findings in ONGC operations. Future research will optimize natural PPD formulations, conduct large-scale field trials, and assess economic feasibility, advancing sustainable flow assurance solutions for waxy crude oil.