1. 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

2. 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

3. 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 drillingHarder 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

4. Deep drilling challenges
44hard rock - wellbore stability - high P, T

5. MPD vs Conventional
55

6. Drilling fluid challenges
ROLE
Hydrostatic pressure
Cuttings transport
Cooling the bit
Wellbore stabilityWellbore stability
CHALLENGES
High T,P stable density and rheology
Measurements at downhole conditions
Predictions of downhole conditions
Stability of additives
Appropriate rheological models 66

7. Rheology, effect of pressure and
temperature
Low T
77
High T

8. Lignite additive for T control
88

9. ‘Flat’ rheology fluids
99

10. 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

11. Conclusions
Demand for more energy challenge to oil
industry, deeper waters and deeper wells
Extreme environments better drilling
fluids
Improved drilling techniques, ManagedImproved 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

12. Conclusions
Take into account effects of temperature and
pressure
Modeling for predicting temperature and
pressure downhole
Rheological measurements at downholeRheological measurements at downhole
conditions
Development of additives that withstand
extreme conditions
Leading to ‘smart’ drilling fluids, adopting to
particular environment
1212

13. Need to meet the challenge
1313