Williams, Kenneth E.1, Arkady
G. Madatov2 (1) Knowledge Systems, Inc,
An effective basin geopressure modeling
(EBM) concept for geopressure simulation is introduced that is several orders
of magnitude more rapid than conventional full-scale 3D grid-based modeling
with no loss in resolution or accuracy of the pore pressure analysis.
The EBM hydrodynamic modeling approach is
based on the identification of the interrelationships between the various
processes involved in the development, maintenance and dissipation of
overpressures. In addition to use in pre-drill pressure prediction, the
modeling also allows real-time updating of pressure predictions based on new
information acquired during drilling operations. The EBM approach has been
thoroughly tested and used in pre-drill pressure predictions for over 150
wells, and for real-time updating of more than 50 of those wells.
Reduction of model parameters to a
minimal but sufficient number of key variables allows significant
simplification of the background earth model. For example, the largest
uncertainty in pressure modeling is the permeability of the shale sealing
compartment units. EBM uses a specific surface area parameter directly related
to permeability and adjustable in calibration. Therefore the EBM calibration
strategy is based on the use of well data inversion. The relevant solution is
numerically stable within the range of reasonable model parameters and grid
properties.
The EBM concept incorporates both 1D and
2D approaches to overpressure modeling through geologic time and is shown to be
effective in accounting for the main overpressure generating mechanisms,
including 3D pressure communication phenomena.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California