Disputas: Manzar Fawad

Prøveforelesning

Bedømmelseskomité

Professor Andrew Aplin, School of Civil Engineering and Geosciences, Newcastle University
Professor Ivar Brevik, Department of Earth Science, University of Bergen
Professor Leiv-J. Gelius, Department of Geosciences, University of Oslo

Leder av disputas:  Professor Jan Erik Weber

Veileder:  Jens Jahren og Jan Inge Faleide

Sammendrag

Loose sediments like sand and mud compact as a function of increasing burial depth in sedimentary basins producing sandstones and mudstones. Sediments and sedimentary rocks are made up of grains of varying size, shape, sorting, packing and composition. These different grain-scale properties influence the resulting pore space reduction and the propagation of ultrasonic velocities during sediment compaction. This PhD project has contributed to quantification of the influence of grain-scale properties based on experimental laboratory testing of different sediments. The results from the experiments have been used to generate empirical equations linking the different parameters. The results from the experimental tests and the derived empirical equations can be used to predict porosity velocity properties of rocks buried shallower than approximately 2000 meters in a normal sedimentary basin.

Sediment compaction is an important process in nature. Compaction can be both mechanical and chemical. Mechanical compaction results from stress increase due to the weight of the sediments deposited above. Chemical compaction on the other hand results from cement precipitated in between the sediment grains. In this PhD project, mechanical compaction of sediments has been studied. Research on compaction of sediments is relevant for production of fluids from the subsurface like groundwater and petroleum. The amount of these fluids present at depth is a function of the rock porosity or rock volume not occupied by minerals. Understanding compaction processes better increase our ability to predict the amounts of these fluids at depth. In more detail, compaction of sediments results in squeezing the particles closer together pushing out water from the pore spaces between the particles. The grain-scale properties like particle size, shape, sorting, packing and composition vary depending upon the environment where the sediments are deposited. Petroleum exploration in sedimentary basins utilizes sound waves to acquire sub-surface images (seismic imaging). In the laboratory, the seismic sound waves are mimicked using ultra-high frequencies. This doctoral thesis combine the results of experimental compaction resulting in reduction of pore spaces and the behavior of ultrasound velocities controlled by the grain-scale properties to better understand compaction processes in natural settings.

Kontaktperson

For mer informasjon, kontakt Anne Innes.