▎ 摘　　要

NOVELTY - Composition of matter comprises a core-shell quantum dot particle having an inorganic core (206) and an organic shell (204) and drilling fluid. USE - Composition of matter used for determining the drilling depth of various drill cuttings. ADVANTAGE - The composition of matter improves the stability of the quantum dots in harsh reservoir environments including high temperatures (e.g., over 100℃) and elevated salinities (more than 56,000 ppm and photoluminescence quantum yield of the quantum dots, exhibit fluorescent properties making suitable for detection using common analytical techniques. The quantum have a tunable fluorescence excitation wavelength, high quantum yield fluorescence, broad excitation spectra and remarkable colloidal stability. Thus, the returned drill cuttings to the surface may be identified accurately based on their depth of origin due to their fluorescent marker. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for preparing composition of matter, which involves introducing a core-shell quantum dot particle having an inorganic core and a polymer shell into a drilling fluid, circulating the drilling fluid through a well during a drilling operation that creates formation cuttings such that the core-shell quantum dot particle interacts with the formation cuttings, creating tagged cuttings; collecting returned cuttings from the circulating drilling fluid at a surface of the well, detecting the presence of the core-shell quantum dot particle on the returned cuttings to identify the tagged cuttings and correlating the tagged cuttings with a drill depth in the well at a time during the drilling operation. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic depiction of a core/shell quantum dot. 202Particle 204Organic shell 206Inorganic core