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Sustainable drilling for oil and gas:challenging drilling environments demandnew formulations of bentonite based
drilling fluids
V. C. KelessidisTechnical University of Crete
http://[email protected] International Conference on Sustainable
Development Indicators in the Mineral Industry
17-20 June, 2007, Milos
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Summary of the presentation
• Introduction
• Energy Demand & Drilling environment
• Drilling fluids
• Demands for drilling techniques & drilling fluids
• Challenges for bentonite industry
• Summary / Conclusions
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Energy demand will continuously increase
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Where will thisenergy come from ?
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Mainly Oil – Gas - Coal
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Where the new
oil & gaswill come from ?
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Deep & Ultra-deep water !
‘hydrocarbon potential is not
considered adequate to give
any optimism for the deeper
waters providing substantial
additions to the reserves of exploitable hydrocarbons’
Wharman, 1978.
Transactions of the RoyalSociety of London.
How things change !
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Strong potential of subsurface oceanwaters ! (deep > 300 m)
>550%
~80%
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R.M. Slatt, Un. Oklahoma, 2001-02 AAPG DistinguishedLecture Series
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Fleet from one operator
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But all come at a price !
• US $ 10 – 50 million , single well– for 300 – 1500 m water depth
• US $ 3 – 9 million,
– for onshore (TD ~5000 m)– or offshore shallow water (TD ~ 6000 m)
• 50% costs for Drilling / tripping• 9.5% for Drilling Fluids (3rd largest)
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Cost distribution for deep drilling
drilling fluids
but many problems are drilling fluid related
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Drilling fluids
• the ‘blood’ of the well• cool & lubricate the bit
• transfer cuttings to surface
• apply hydrostatic pressure (safety)
• maintain stability of wellbore
INGREDIENTSwater oil (diesel or synthetic)bentonitepolymersmany – many additives
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Bentonite use in USA (USGS, 2005)
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
1996 1997 1998 1999 2000 2001 2002 2003 2004
M e t r i c t o n
s * 1 0 5
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
drilling fluids total bentonite % of total
Greece ~ 5%South Africa ~ 5%
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Drilling fluid costs
• 1990, total ~ 4.0 billion US $ (1996)
• per well, deep wells, 2006, 500.000$
• very difficult wells, reported savingsof up to 1.0 million US $
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Drilling fluids base, pros & cons
• Synthetic based muds, ~ 825 $ / ton– C14-C24, esters, ethers, poly-α-olefins
– beneficial but costly
– deep water, pressure margin very narrow– great chances for fracturing formations losses of very expensive fluids !
• Oil based muds, less expensive butenvironmental problems
• Water based muds, even lessexpensive
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Brownlee, J.K., et al., 2005. SPE 97590
HPHT Wells
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Challenges for drilling fluid industry
• Difficult well environment Hollisticapproach• flexible drilling fluids
• different formulations at differentdepth intervals• adjustable parameters• new additives
challenges for bentonite industry
find additives to expand operating range
of water based fluids
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Additives for bentonite fluids
• polymers• lignite
• expand operating range• in search for mechanism of operation
Representation of
adsorption of cationicsurfactants on bentoniteparticles (from Alemdaret al., 2000)
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Our recent work – Greek lignites
• methodology for lignite ‘activation’• techniques for measuring
performance
• excellent performance of most Greeklignites as HT additives
• stable slurries for– rheology and filtration control
– maintaining original core permeability
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Permeability of filter cake (1770C)
0.0
2.0
4.0
6.0
8.0
10.0
Β1 Β1 Β1-HYD Β1+Γ Β1+TH7 Β1+ΜΤ3 Β1+ΤΗ4 Β1+ΚΠ5
Permeability*103
(mD)
0.0
2.0
4.0
6.0
8.0
10.0
Β2 Β2+Γ Β2+TH7 Β2+MT3 Β2+ΤΗ4 Β2+ΤΗ4 Β2+ΜΤ6 Β2+ΚΠ5
Permeability *103
(mD)
aged
hydrated
+commerciallignite Greek lignites
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Rheological control with lignites
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
0.0 200.0 400.0 600.0 800.0 1000.0 1200.0
Shear rate (1/s)
S h e a r s t r e s s ( P a
)
H A A+G A+MT6 A+TH4 A+KP5 A+I1 A+PP2
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Retention of core permeability
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 0.1 0.2 0.3 0.4 0.5 0.6
Flow rate (ml/sec)
P e r m e a b i l i t y r e c o v e r y ( % )
A A+G A+MT6 A+TH4 A+KP5 A+I1 A+PP2
~ 100% recovery
~ 50% recovery
minimal damage
No 19, Aged+KP5
10
100
1000
100 1000 10000 100000
Time (sec)
P e r m e a b i l i t y ( m
D )
4=>8
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Summary
• Demand for hydrocarbons will be on the rise• > 1500 m water depth, > 6000 m wells• high and low temperatures• need for excellent performing fluids
• in search for flexible drilling fluids• WB fluids less expensive & environmentally
friendly
• bentonite additives can expand operatingranges
THE CHALLENGE ? focused
research and product development
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the challenge
is there !