EARLY DIAGENESIS AS A PRECURSOR FOR AQUIFERS IN CARBONATE ROCKS – PREFAB

Forty percent of the Earth’s population depends on carbonate aquifers for water supply. The goal of
PREFAB is to understand how carbonate aquifers develop and are further preserved following burial,
with a particular emphasis on the precursor role of early diagenesis. Two questions are at the core of
PREFAB: (i) how do porosity and permeability evolve during early diagenesis and (ii) how are they
further sustained over time considering mechanical compaction at depth? PREFAB will address these
questions through a unique investigation of the key factors conditioning the creation of porous and
permeable units in carbonate rocks. The novelty of PREFAB approach is the simultaneous synthesis
of analogous, controlled, carbonate microstructures with measurements of physical properties
evolution. This is achieved thanks to a new apparatus designed to simulate fluid-rock interactions in
the laboratory under temperature and stressfield in oedometric conditions, while measuring
deformation, porosity, permeability and ultrasonic velocities. By simulating diagenesis in the
laboratory through accelerated dissolution and mineral precipitation in a controlled environment,
PREFAB will isolate the effect of one specific microstructure relevant for understanding the role of
early diagenesis on aquifers: Early Cements. Triaxial mechanical testing of these lab-produced
samples will allow evaluating compaction during burial as a function of sediment type and diagenetic
alteration. By answering the fundamental question of carbonate aquifer creation and preservation,
PREFAB will provide new insights for research on groundwater resources, as well as more generally
resource management in carbonate rocks (e.g. geothermal, carbon storage, nuclear waste storage).