Screening and Evaluation of Sorbents for the Detection of Oil Field VOC Microseepage

Geochemical exploration offers a cost-effective means of identifying subsurface oil and gas accumulations through the detection of volatile organic compounds (VOCs), which serve as markers of underlying hydrocarbon systems. These indicators may appear as visible macroseeps or as subtle microseepage, detectable only through advanced analytical methods. A widely used approach involves deploying specialized sorbent materials a few meters below the surface to capture VOCs, followed by gas chromatography–mass spectrometry (GC-MS) for analysis. Given the range of available adsorbents, selecting materials with optimal performance is critical. We developed a laboratory method to evaluate the adsorption affinity of various commercial and custom-made sorbents toward hydrocarbon mixtures, including nitrogen-, oxygen-, and sulfur-containing derivatives. Using natural crude oil in a simulated microseepage setup, we screened a library of sorbents to identify those most effective for capturing oil-related markers. The complexity of the VOC mixtures required advanced separation, for which we employed two-dimensional high-resolution gas chromatography with time-of-flight mass spectrometry (HR-GCxGC-TOF-MS). The screening revealed clear differences in sorbent performance based on analyte diversity and concentration, assessed through thermal desorption/HR-GCxGC-MS and BET surface area analysis. Two custom sorbents, composed of carbon nanomaterials, outperformed a commercial benchmark in both adsorption capacity and analyte diversity, making them strong candidates for future field deployment in surface geochemical exploration.