THE USE OF RAMAN SPECTROSCOPY IN ASSESSING THERMAL MATURITY OF THE CANEY SHALE IN SOUTHWESTERN OKLAHOMA, USA

Although organic-abundant oil-producing mudrocks have been researched in depth over the last 10 years, there remains a lack of understanding of one of their main elements: kerogen. There is particularly a need to better understand how kerogen can influence mechanical properties through understanding of its thermal maturity. Kerogen can have a fundamental influence on the development and spread of fractures in formations that contain significant amounts of this element. The Caney Shale is an organic-rich, often calcareous mudrock. Many studies have examined the impact that clay has on different kinds of shale productivity but there is currently no data reported on Caney shale in relation to its thermal maturity. The purpose of this research is to use Raman spectroscopy to assess the thermal maturity of the Caney shale and compare the results to vitrinite reflectance. A range of different geochemical screening methods can be used to assess thermal maturity. These include organic petrology and pyrolysis. This work seeks to identify a viable alternative method of measuring thermal maturity through the use of Raman spectroscopy, which represents a quick, non-destructive approach in comparison to the approaches that are traditionally used to determine how organic matter (OM) thermally changes. Raman can be employed to ascertain vitrinite reflectance equivalent OM maturity values to facilitate petroleum exploration, generate temperature data to support metamorphic research, and ascertain the highest temperatures reached in fault zones. Raman spectra of disordered organic matter D and G bands are acquired from the rock fragments without the requirement for prior sample preparation. It is possible for the thermal maturity parameters obtained from Raman spectra to differ significantly across distances of ≤4 μm within a given organic grain. The outcomes of this research highlight the substantial extent of chemical heterogeneity intrinsic within the organic matter that forms the rocks of interest. Furthermore, the use of 2D Raman mapping to study the spatial pattern of the Raman parameters can provide an indication that the structure of the organic matter is affected by the mineral surfaces that characterize the surrounding rock matrix.