C. Li, Chengchi Wang, Panpan Chen, Yawen Jing, Dongrui Su, Guixin Yu, Mingxuan Li
Laser Raman spectroscopy is a promising technique for real-time oil and gas detection in drilling fluids during drilling operations; however, the distribution of crude oil and its coupling with Raman spectral responses under varying temperature conditions remain insufficiently understood, which limits its quantitative applications in downhole environments. This study investigates the temperature- and concentration-dependent behavior of crude oil in oil-containing drilling fluids and develops a quantitative analytical method based on Raman spectroscopy for geological guidance. Crude oil is modeled as dispersed droplets within a continuous fluid phase, and Raman spectra are collected under different temperature and concentration conditions to establish a quantitative relationship between spectral intensity and crude oil concentration. Results show that crude oil exists as dispersed droplets whose size decreases with increasing temperature, accompanied by an increase in interfacial visibility, while higher concentrations lead to a more uniform volume distribution at constant temperature. Raman shifts within 1000–3000cm$^{-1}$ effectively characterize crude oil, with a dominant peak at 1519cm$^{-1}$, and a positive correlation between peak intensity and crude oil concentration is observed, particularly at elevated temperatures. Based on this relationship, a quantitative model for crude oil detection is established. The proposed method enables accurate real-time identification of oil-bearing formations with minimal influence from concentration variation or formation thickness, providing theoretical support and practical guidance for the application of Raman spectroscopy in LWD systems and improving drilling precision and reservoir evaluation efficiency.