Application of Fluorescent Tags for Drill Cuttings Depth Monitoring Using Hyperspectral Optical Devices

Accurate wellbore positioning and control of the directional drilling trajectory allow collision avoidance and proper target hitting [1]. Basic measurements while drilling, logging while drilling, in-hole gyroscope surveys, drill-pipe depth measurements, and other methods provide the data regarding well positioning, but with a degree of error and uncertainty. Accurate real-time monitoring of drilling depth and geological interpretation significantly improve geosteering to keep the well in the production zone becomes extremely essential [2]. Determining the depth of origin of drill cuttings with high precision during well propagation is a critical challenge to optimize well placement, improve drilling efficiency, detect oil-bearing formations and maximize hydrocarbon recovery. To achieve this goal, it has been proposed to use tracer materials that are periodically injected into the wellbore at programmed intervals during drilling and could mark formation cuttings at the bit site according to depth. The hydrodynamic circulation of the drilling mud to the wellhead would carry the tagged cuttings with the flow to the shale shakers, hydrocyclone systems and cuttings sampler, where the tagged pieces of formation would be separated and analyzed without contamination of the drilling fluid. Our study focuses on the design and development of fluorescent tags that can be detected by UV light and camera or hyperspectral optical devices combined with image recognition systems and engineering of the lab setup for this workflow. Fluorescent tags could be designed as a polymer matrix impregnated with various fluorophores with different fluorescent emission wavelengths, which could adhere to the cuttings when capsules bearing these tags are crushed over the formation with the drill bit.