Dynamic
Characterization and Modelling of Polygonal Fracturing in a Carbonate Field in Abu Dhabi
Gouth, Francois1, Laure
Moen-Maurel2, Sabah Karim Aziz3 (1) Total EP, Pau, France
(2) Total, Pau, France (3) ADMA, Abu dhabi
An integrated fracture study has been
performed on a carbonate reservoir in the Middle East where a polygonal
fracture pattern with spacing of about 200m has been identified by the seismic.
All available data including well imagery, PBU, interference tests, PLT, MDT,
tracers and production data have been used to build a comprehensive conceptual
model that captures the triple porosity behaviour of the system: • Low
permeability matrix (~1mD). • Medium permeability diffuse
fractures (~10mD). • High permeability large-scale polygonal features (~100mD).
Diffuse fractures characterised by well imagery are dense enough on the crest
to form a connected network whereas on the flanks, test permeability is in line
with core data. Though the polygon features are seen on seismic throughout the
structure, PBU data suggests that their dynamic impact occurs on the crest
only. However, a material balance analysis confirms that the connected
accumulation extends toward the flanks suggesting some enhancement of
permeability likely related to the polygons. The conceptual fracture model also
allows a satisfactory match of the interference test data that could not be
obtained with a homogeneous model. A discrete fracture network (DFN) was used
to model the fracture system. A specific formulation has been developed to
calculate the equivalent permeability tensor associated with a polygonal
network. This was implemented in GoFraK, Total's in-house DFN software, which
was then used to generate input for simulations of reservoir performance at the
full field scale. This integrated study highlights for the first time the
dynamic impact of the polygons now seen, thanks to improved processing and
interpretation, on many Abu Dhabi fields