Easy and Rapid Synthesis of Carbon Quantum Dots from Mortiño (Vaccinium Meridionale Swartz) Extract for Use as Green Tracers in the Oil and Gas Industry: Lab-to-Field Trial Development in Colombia

The main objective of this study is to develop nanotechnology-based materials, specifically carbon quantum dots (CQDs), as alternative nonpolluting, nontoxic, and easily manipulated tracers for the oil industry using an easy and rapid synthesis from Mortiño (Vaccinium meridionale Swartz) extract, a process that was evaluated in the laboratory and subjected to a Colombian oil field trial. The CQDs were synthesized using an easy and rapid microwave-assisted carbonization (MWC) methodology involving aqueous natural extraction in the presence of an organic nitrogen precursor. A displacement test at reservoir conditions in a porous media was used for evaluating CQDs retention, and a breakthrough curve with a CQDs saturation of around 1 pore volume injected was obtained, indicating that the CQDs could be completely removed from the porous media with null retention due to a poor interaction with the formation and preferential affinity to the aqueous phase. Fluorescence tests showed that quantification of the synthesized CQDs could be achieved for up to 1 ng L–1. Coreflooding tests at reservoir conditions were performed under two scenarios: (1) monophase coreflooding (the core was saturated with water) and (2) biphasic coreflooding (at residual saturation of crude oil). The results showed that the CQDS behave excellently within these outlines and are not affected by the presence of crude oil, obtaining a breakthrough that is almost ideal for a tracer. A CQDs field trial in Colombia was conducted by injecting 20 kg of the nanomaterial at a concentration of 500 000 mg L–1. The CQDs were analyzed in 10 producer wells, showing that they are useful as interwell tracers and the different interconnections between the different wells in the field were stablished. This study places the technology at a technology readiness level (TRL) of around 8, opens a broader landscape for the use of nanotechnology in the oil industry, and maintains Colombia as a pioneer in the application of nanoparticles and nanofluids under field conditions.