Rock mechanical properties of Jurassic underburden at Valdemar

The pore pressure generation due to conversion of clay minerals under the Danish oil and gas reservoir Valdemar is studied. The structural change from smectite to illite under high temperature and stresses implying collapse and release of inter-layer water seems to be of great importance to oil migration from a potential source rock. The structural development may be caused by volume-constant flow of the clay shale under very low effective pressure. And the release of gas and oil to be caused by internal hydraulic fracturing during this process.
The research project intends to intergrate the knowledge in a number of geosciences to the benifit of understanding very important reservoir mechanisms. Rock mechanics, structural geology, clay mineralogy and -chemistry, and geotechnical modelling of porepressure development seem to be key points for the oil maturing and migration from Jurassic clay shales, which then is contained in the Lower Cretaceous reservoir at Valdemar. Preliminary results were presented at the Fifth Nordic Symposium on Petrophysics, August 19-20th 1999, Copenhagen, DK.
The study is presumed to be finalised in March 2000 and the results will be published as part of the on-going Energy Research Programme PRIORITY.