Fracture propagation and reservoir permeabiity in limestone-marl alternations

• Applicant: Professorin Dr. Sonja Philipp
• Subject Area: Palaeontology
• Term: from 2009 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 133348776

Layering is a common feature of many sedimentary rocks (which host most fluid reservoirs of petroleum, gas, ground and geothermal water) because of depositional changes (stratification), and diagenetic processes. Mechanical layering, where the mechanical properties change between layers, may coincide with changes in grain size, mineral content or facies. In this project we explore how mechanical layers relate to sedimentary layers in limestone-marl alternations. We investigate the effects of mechanical layering, primarily the stiffness (Young’s modulus) of the host rock, on the emplacement and geometries of extension and shear fractures. The main aims are to: (1) define a minimum marl thickness for fracture arrest in limestone-marl alternations (depending on Young’s moduli contrasts, fracture type, and loading), (2) determine which sedimentological parameters are needed to define a mechanical facies of limestone-marl alternations, and (3) improve our understanding of the effects of fracture propagation on fluid transport and flow channelling in limestone-marl alternations. The project combines quantitative field studies, laboratory analyses (to obtain mechanical, mineralogical and petrographic rock properties), and advanced numerical modelling on the mechanics of fracture emplacement and fluid transport in order to predict more accurately fracture propagation and permeability development in fluid reservoirs.

• DFG Programme: Research Grants