Chemical stratigraphy, or chemostratigraphy, is the technique of sediment characterisation and correlation using subtle variations in the elemental composition of the sediments. The technique relies upon the fact that even apparently homogenous sediments show changes in their chemical composition, these changes reflecting minor fluctuations in variables such as sediment source, facies, palaeoenvironment, palaeoclimate and diagenesis.
In recent years, chemostratigraphy has advanced from a tool to be used solely in sequences devoid of fauna and flora to a technique that is applied routinely in depositional environments from fluvial, through deltaic to deep marine. In addition to the laboratory-based field studies, recent advances in analytical instrumentation now allow deployment at wellsite to provide near real-time chemostratigraphy.
Chemostratigraphy can be applied to sediments of any age, of any lithology and from any depositional environment. More importantly, however, it can be applied to any sample, with the majority of our work being done on cuttings samples. As such, it is probably the most versatile stratigraphic tool available to the industry at this moment.