Ichnological studies have been complementing sedimentological analyses in the exploration and production of hydrocarbons for some decades. Initially used as tool for facies interpretation, more recently ichnology has been applied to evaluate reservoir quality, predict and characterize source rock, constrain stratigraphic correlations, describe seal potential (e.g., unconformities) and to analyse the overburden. Ichnofabric analysis has proven to be an invaluable tool in core description and the interpretation of depositional environments. The identification of intervals with lowered bottom-water oxygenation by means of bioturbation combined with other proxies can aid in the identification of potential source-rock intervals. Likewise, various types of bounding surfaces can be recognized and described by their trace-fossil content. Discontinuity surfaces, omission surfaces and unconformities are hiatal surfaces with importance for sequence-stratigraphic interpretations. Together with sedimentary, diagenetic and structural features, ichnological heterogeneities may have a positive or negative impact on reservoir quality and connectivity, depending on the kind of involved burrows. This information is equally important for identifying suitable formations for safe CO2 storage. Advanced tools such as micro-CT scanning, thin-sectioning, digitalization and small-scale modelling are effective in ichnological analyses.
This workshop is designed as an introduction to the subject and covers major and relevant aspects of ichnology, with emphasize on well core. It will be delivered by a mixture of lectures, demonstrations and practical exercises. The following topics will be covered:
- Ichnological basics, principles and concepts
- Applications of ichnological studies
- Recognition of key ichnotaxa in core
- Interpretation of palaeoenvironments
- Ichnology in sequence stratigraphy
- Bioturbation and reservoir quality
- Core logging procedure
After an introduction to the subject and an overview of major fields of applications, the ichnofacies concept and the ichnofabric analysis will be outlined. A principle focus of the workshop is to recognize the most important and recurrent ichnotaxa in core sections. Integrated ichnological-sedimentological analysis leads to the interpretation of palaeoenvironmental conditions, including oxygenation, salinity, nutrition and sedimentary energy level. Selected core material is used to interpret sedimentary environments in continental, marginal-marine, shallow-marine and deep-marine settings of siliciclastic systems. In addition, the ichnology of chalk will be covered. Ichnological analysis is an important tool for sequence stratigraphy, and key stratal surfaces as well as bioturbation trends assist in such interpretations. Finally, bioturbation has an impact on reservoir quality, which is relevant for hydrocarbons, aquifers and CCS.