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Institute for Energy Technology, PO Box 40, N-2007, Kjeller, Norway
Is 3-D basin modelling really necessary? The answer depends on the type of problem under consideration. The Institute for Energy Technology (IFE) 3-D Basin Simulator offers the possibility to investigate certain aspects of this issue. It is a prototype 1-D, 2-D or 3-D basin simulator for reconstruction of the time-dependent pressure and temperature evolution of compacting sedimentary basins. Comparison of results, from 1-D, 2-D and 3-D simulations confirms that there may be significant differences due to water flow and pressure behaviour. The advantage of 2-D simulations as compared to 1-D is seen in overpressured configurations where 2-D allows more realistic calculations, while 1-D is less predictable. When going from 2-D to 3-D advantages are evident in configurations with pronounced 3-D basin geometries in combination with rapid processes and overpressure. The differences in water flow velocities and consequently the pressure calculations, may be quite significant. The rates in 3-D may be several orders of magnitude higher than in 2-D due to lateral focusing effects, while the overpressure still remains high. One consequence is, for example, reduced compaction in 3-D as compared to 2-D, with notable effects on basin geometry and temperature evolution of individual layers. Temperature anomalies due to increased convection in 3-D seem to be of less importance, unless processes of lateral focusing of water flow reach extreme levels.
