kelessidis_sgem_drill_fluids
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DRILLING FLUID CHALLENGES FOR
OIL-WELL DEEP DRILLING
Vassilios C. KELESSIDIS
Technical University of Crete
Mineral Resources Engineering
SGEM 2009
Albena, June 14-19, 2009
Research aim
�Develop smart drilling fluids
�Adaptable to harsh conditions
�Have available techniques for optimal
measurements of fluid properties, particularly
rheologyrheology
�Develop hydraulics models for pressure drop
prediction along the wellbore
�Better understanding efficient cuttings
transport in a multiphase environment
22
The problem
�Drilling depths, total (>7000 m) and water (~ 3000m) depths, are ever increasing
�High pressures (>2000 bar) and high temperatures (>3000C) are encountered
�Narrow pressure tolerances
Harder rock is encountered, lower drilling �Harder rock is encountered, lower drilling rates
�Demand for better drilling fluids, avoid problems -understand behavior in such hostile environments
�Hydraulic programs for complex rheology
33
Drilling fluid challenges
ROLE
�Hydrostatic pressure
�Cuttings transport
�Cooling the bit
�Wellbore stability�Wellbore stability
CHALLENGES
�High T,P � stable density and rheology
�Measurements at downhole conditions
� Predictions of downhole conditions
�Stability of additives
�Appropriate rheological models66
Barite sag – solution ?
841.0
*116.0
85.4
=
=
=
n
sPaK
Pa
bariteAPI
yτ
854.0
*076.0
92.0
=
=
=
n
sPaK
Pa
baritesizedmicron
yτ
Rheograms for micron sized barite
1010
Conclusions
�Demand for more energy � challenge to oil industry, deeper waters and deeper wells
�Extreme environments � better drilling fluids
� Improved drilling techniques, Managed � Improved drilling techniques, Managed Pressure Drilling, narrow pressure margins
�Good and representative rheological models for the complex fluids
�Model of choice – Herschel-Bulkley, hydraulics modeling is needed
1111
Conclusions�Take into account effects of temperature and
pressure
�Modeling for predicting temperature and
pressure downhole
�Rheological measurements at downhole �Rheological measurements at downhole
conditions
�Development of additives that withstand
extreme conditions
� Leading to ‘smart’ drilling fluids, adopting to
particular environment1212
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