Development of Novel Nanodetectors in Drilling Fluids To Identify the Contribution of Different Producing Zones in Naturally Fractured Carbonate Reservoirs: From the Laboratory to Field-Level Implementation

Abstract

The objective of this research was to develop and incorporate nanodetectors (NDs) in drilling fluids to identify the contribution of the different producing zones in naturally fractured carbonate reservoirs. The NDs were designed to interact with the crude oil and release the active compound that allows for fluorescence emission for surface detection. Novel nanocapsules based on carbon quantum dots (CQDs) were synthesized using various nanomaterials as the core and soy lecithin as the shell. Four CQDs were used: CQD green, CQD light blue, CQD red, and CQD dark blue. CQD red was discarded as a result of high retention in calcium carbonate, and encapsulation was performed with the others to form ND1, ND2, and ND4, respectively. The technology was assured through compatibility tests with reservoir fluids, static efficiency tests, and static retention. NDs had sizes smaller than 75 nm. Also, solubility tests showed that the active compound was released upon contact with oil-based systems. The characterization of the drilling fluids indicated that properties, such as the yield point and plastic viscosity, remained the same in the presence of the ND, which allows for its use under field conditions and secure wellbore stability. The technology was successfully implemented in a Colombian oil field. Filed results showed correlations between the gas profiles, brittleness of the zone, open fractures, and concentration of nanodetectors, which allows for the conclusion of the effectiveness of the nanostructures for the detection of naturally fractured zones of the evaluated wells.