Researchers at China University of Petroleum have provided comprehensive insights into the application of terahertz spectroscopy to characterize oil shale. At present, people's understanding of the oil generation potential of oil shale and the dynamic process of organic matter pyrolysis is still unclear, resulting in relatively slow progress in its development technology. Terahertz (THz) spectroscopy, as an emerging evaluation method in the field of oil and gas resources, has demonstrated research and application value in many aspects due to its fingerprint characteristics, low energy consumption, strong penetration, and wide frequency band.
"These applications include terahertz dating, terahertz exploration, crude oil identification, crude oil emulsion demulsification process, mode conversion of oil-water two-phase flow, depolymerization of crude oil in magnetic fields, PM2.5 monitoring and classification, etc." explained Professor Zhao Kun from the Beijing Key Laboratory of Oil and Gas Optical Detection Technology at China University of Petroleum (Beijing).
In order to meet the requirements for new theories and methods for efficient utilization of oil shale resources, Professor Zhao Kun of China University of Petroleum (Beijing) and his "Oil and Gas Optics" team recently reviewed the progress and challenges of terahertz spectroscopy in oil shale evaluation. Their research results were published in Volume 2, Issue 4, of "Energy Reviews" published in December 2023.
In this review article, the research team summarizes the application of terahertz spectroscopy in characterizing the anisotropy, organic matter distribution, cutin fingerprint spectrum, oil production, pyrolysis process, and terahertz wave absorption of oil shale. In addition, considering the actual future development of oil shale, they also proposed potential avenues for terahertz technology.
Utilizing the characteristics of terahertz waves, a new concept of thermal terahertz analysis was proposed and the pyrolysis model of cutin was rediscovered. Professor Zhao pointed out: "The most important discovery of terahertz wave exploration is that terahertz spectrum can be used to simultaneously characterize the main oil-producing areas and natural gas areas, which is difficult to achieve with other standard methods."
The characteristic absorption peaks of the stratum corneum in the terahertz range provide a new perspective for studying micron- and nano-scale stratum corneum. Since the anisotropic terahertz parameters are closely related to oil production, the researchers also achieved direct assessment of oil production without pyrolysis, thereby avoiding environmental pollution.
Professor Zhao emphasized: "Although important progress has been made in terahertz wave characterization of oil shale, the breadth and depth of research are still lacking, and many problems need to be solved urgently. In terms of practical applications, in-situ conversion is an inevitable trend for large-scale commercial development of oil shale in the future. Terahertz spectroscopy is expected to be implemented Real-time monitoring of the downhole cracking process and oil and gas productivity of oil shale. Terahertz waves are expected to become a sharp edge in overcoming the bottleneck of oil shale production after solving some specific problems such as high-power light sources, high-sensitivity detection, fast scanning imaging, micro-nano terahertz devices, and strong environmental adaptability.