(84am) Sustainable Detection of Oil at Well Site: High Contrast UV Fluorescence Imaging System for Pixel-Level Detection of Oil-Bearing Rock Cuttings

In this work, we introduce an economical ultraviolet (UV) fluorescence imaging system for accurate detection of crude oil in rock cuttings. Our basic idea is grounded in the past fluorescence applications in petroleum applications (e.g., prospecting and exploration). Visible fluorescence is initiated by electron energy absorption when excited by UV radiation. Photons of UV radiation collide with the electrons promoting electron excitation from the ground level to a higher energy level (excited state). Subsequently, the electronic energy is released through fluorescence during deactivation back to the ground state. Unsaturated organic structures which contain pi (Ï€) electrons such as aromatics and conjugated polyenes are primarily responsible for the crude oil fluorescence.

Crude petroleum oils are complex mixtures of organic compounds, including saturates, aromatic, polar, and asphaltene. Most downhole spectroscopic fluid measurements are costly and tedious. They are particularly challenging due to the simultaneous presence of varying amounts of gases (CO2, CO, O2, N2, and H2 CH4, etc.). Our work is motivated by the long-standing need of acquiring surface measurements at the well-site as part of the mudlogging activites. This capability can bring huge gains by enabling automation and optimization of the complete workflow based on rapid measurements on each single drilled cutting.

Fluid analysis as part of mud logging workflow can be vital for the first indication of the potential success. Common mudlogger spectroscopy tools are based on Infrared (IR) measurements. However, IR is limited by challenges of overlapping of absorption bands and saturation of the signal due to the high absorptivity of crude petroleum. On the other hand, efforts on advancing the fluorescence-based methods have considered two performance criteria: high sensitivity and faster measurements. Unfortunately, the UV fluorescence inspection that has been used for the past 60 years (for detection of crude oil during mud-logging) does not score well on either criterion. The legacy detection system, called Fluoroscope, provides an eyepiece window to view the interaction of high-power UV radiation and drill cuttings, but it suffers from low robustness and bulky apparatus. The fluoroscope typically provides weak contrast images which are of limited use for reliably applying modern machine learning tools for detection of oil in drilled cuttings. Besides, UV radiation and mercury-based bulbs pose high health and safety risks for the operator. Hence, our claim is that the fluoroscope system is not suitable for integration into automated workflow at well sites. Our proposed UV imaging system targets these bottlenecks and breaks the fixedness of traditional technology.

Our device systematically addresses abovementioned pain points of the conventional oil-show equipment Fluoroscope by improving the safety of user and environment and enabling high-quality data acquisition and integration of measurements for rocks and fluids. More broadly, our UV fluorescence imaging system crucially supports a highly sophisticated quantitative imaging toolbox. The main features enabled by our system include: 1) single pixel-level quantification of oil bearing cuttings; 2) correlative imaging based on merging the white light and UV images for estimation of percent oil bearing cuttings; and 3) Machine learning for rapid oil detection.