REPRESENTATION OF A GROWTH FAULT IN A 2-DIMENSIONAL QUANTITATIVE MODEL

A growth fault in a north Indonesian basin has been modelled using the two-dimensional fluid flow/compaction model GEOPETII. The location of the fault and permeability for fluid drive are of primary importance in the fluid pressure distribution in the basin. Using multiple vertic al faults, simulations of the fault have been carried out, showing the importance of the growth history of the fault in influencing the exce ss pressure distribution. The simulations, which yield fluid pressure in agreement with the present-day observations, suggest that the fault has been dominantly closed to fluid flow since the time of its creati on. The modelling also led to the conclusion that the fault is not hyd rodynamically connected to the surface at the present day, but must ha ve been at some time in the past to remove the overpressures developed through undercompaction, which are due to the high sedimentation rate (of the order of 1000 m/Ma) characterizing the basin. Models using a single vertical fault suggest that the fault was open to fluid flow in a time interval ranging from 3.5 to 0.5 Ma.