Print this pageShale Dependent Sediment Compaction Model Implemented in a Pressure Basin Simulator; Effects from Geo-Model and Modelled Pressure Build Up?
Sediment compaction curves are extensively used in basin analysis to set up burial histories using back-stripping techniques and further relating porosity to depth or stress during fluid and gas migration. One difficult task has been to find proper values for the properties used in the compaction curves. The compaction properties not only control the porosity reduction, but also geo-mechanical properties and the geometry of the sedimentary layers of the basin. Burial history is thus a crucial input to basin models, affecting e.g. overpressure generation and fluid migration pathways.
Mudstones are the volumetrically most important rock types in sedimentary basins. A new compaction equation relating porosity versus depth has been developed by Fjær et al 2006. The method developed relates the compaction properties of a sediment layer to its shale content. The method has been tested on data from wells in different basins comparing calculated porosities with measured porosities (Lothe et al. 2008). This compaction equation has now been incorporated in an in-house overpressure simulator; Pressim. This simulator tries to capture the 3D flow pattern in the basin on a geological time scale and the resulting pressure distribution.
We will in this work carry out a study to see if the presented compaction relation would improve the geo-model used in the forward model, and thus improve the simulation results. This will be done by simulation test on a North Sea dataset where we try to match the simulated over-pressures with measured pressures from given well-data. We will also compare this method with other existing compaction relations (e.g. Sclater and Christie, 1980) within our simulator.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil