Integrated Carbonate Reservoirs
Studies - Linking Static and Dynamic Models to Expand Evaluation
Validity in
Space and Time
By
Jean-Remy Olesen1, Andrew Carnegie2
(1) Schlumberger Logelco Inc, 11728 Maadi Cairo, Egypt (2) Schlumberger Oilfield Services, Abu Dhabi, United Arab Emirates
The permeability distribution of most carbonate reservoirs is extremely
heterogeneous and profoundly affects the reservoir
behaviour when subjected to
rapid fluid withdrawal. Variations in rock texture,
diagenetically
altered
layers, secondary porosity, solution channels, faults or fractures, all
contribute to the complexity of the fluids flow and the
reservoir
pressures
distribution.
In carbonates, conventional open-hole petrophysical logs do not provide
enough permeability information to allow the building of a realistic reservoir
model. Recent developments in the fields of electrical conductivity and NMR
images
evaluation
are now providing a much clearer picture of the permeability
distribution. Other recent developments in the interpretation of cased-hole
pulsed neutron spectroscopy data in carbonate reservoirs allow the accurate
evaluation
of depletion profiles in cased hole.
The knowledge of the permeability profile acquired in newly drilled in-fill
key-wells can be extended through the evaluation
of depletion profiles in
selected cased hole wells and this can be further extended to field-wide
permeability mapping through fast, efficient, geo-statistical techniques
integrating 3-D surface seismic if available, open-hole, cased-hole and
production log data with historical well performance data.
Geo-statistical tools were used to match observed water breakthrough and to
predict future water breakthrough. They are based on proportion curve analysis
and on a network approach which is guided by some simple physical rules. It
allows one to detect or exclude specific high permeability paths, such as faults
interpreted from seismic or diagenetically
altered layers detected from open
hole or production data.
An application of this integration is presented in a typical carbonate
reservoir
.