Applications of chemostratigraphy in a characterization of shale gas Sedimentary Microfacies and predictions of sweet spots-taking the Cambrian black shales in Western Hubei as an example

Exploratory research was conducted in this paper on the correlation of chemical elements with sedimentary microfacies and shale gas sweet spots through cluster analysis, factor analysis, and so on, using a large amount of geochemical data of elements obtained from shale gas exploration of the Cambrian Niutitang Formation in Western Hubei. This paper screened the chemical element associations and parameter systems that can reflect sedimentary microfacies and sweet spot evaluations, proposed a classification method for the chemostratigraphic facies of shales, and finely depicted the sedimentary chemical microfacies of the shales in the Cambrian Niutitang Formation. A chemostratigraphic lithofacies paleogeography map of SQ1 (the first sequence strata) in the Cambrian Niutitang Formation in Western Hubei was compiled. Sweet spots were predicted and evaluated, and favourable areas were predicted, thereby providing important support for making a breakthrough in the exploration of the Cambrian shale gas in the Yichang area. Chemostratigraphy has a higher precision and a low characterization cost of reservoir sedimentary microfacies; especially in areas lacking drilling data and seismic data and having a low exploration degree, chemostratigraphy is an important means for identifying of shale sedimentary sequences and predicting shale sweet spot sections.