Drilling data - THN - 20120703 · Title: Microsoft PowerPoint - Drilling data - THN - 20120703...
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Geothermal Drilling Geothermal Drilling Tom Harding-Newman Energy Specialist July 2012 An analysis of global data
Transcript of Drilling data - THN - 20120703 · Title: Microsoft PowerPoint - Drilling data - THN - 20120703...
Geothermal DrillingGeothermal Drilling
Tom Harding-NewmanEnergy Specialist
July 2012
An analysis of global data
Agenda
• Background / context
• Defining success
• Highlights
� Success
� Capacity
• Factors affecting success and capacity
• Conclusions
2
Disclaimer
• The data presented here is based on a preliminary analysis
• Conclusions still need to be checked, verified, and peer-reviewed
• Do not quote or cite any findings• Do not quote or cite any findings
• This presentation does not claim to serve as an exhaustive presentation of the
issues it discusses and should not be used as a basis for making commercial
decisions
• Please contact me for further information and to receive the final version when
completed� [email protected]
3
Background
• The ability to accurately estimate drilling success rates increases confidence in
a geothermal project� Helps to quantify the expected risk
� Supports resource modeling assumptions
� Improves access to financial support
• Previously, there has been little historical record that can be used to justify
forecasted success rates� Well data is often confidential, proprietary information
� No central database
� Local databases may be incomplete, giving an inaccurate picture
• We’d like to quantify the drilling risk, and assess what factors affect the risk
and by how much
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A summary of available data
• The database covers:
� 14 countries
� 57 fields
� 2,613 wells, thought to represent ~70% of all commercial wells drilled around the world
• 7,700MW installed in the fields in the database, compared with 10,700MW installed worldwide• 7,700MW installed in the fields in the database, compared with 10,700MW installed worldwide
• Categories of data include
� Completion date
� Well status
� MW capacity of wells
� Depth
� Resource type
� Geology type
� Production casing size
� Pumped and re-drilled status
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Data compiled by GeothermEx
Quantifying geology and resource types
Geology type
Code Description
1Granitic / higher-grade metamorphic
Tertiary and older volcanic/volcaniclastic -
Resource type - enthalpy
Code Description Temperature
1 Non-electric <100oC
2 Very low temp. 100oC to 150oC
3 Low temp. 150oC to 190oC
We have attempted to categorize the geology and resource characteristics of the geothermal fields so that we may assess the impact on success rates
2volcanic/volcaniclastic - large-scale volcanic structures absent
3Younger volcanic/volcaniclastic - large-scale volcanic structures (volcanoes, calderas) preserved
4Sedimentary Basin - clastic, drilled above basement
5Sedimentary Basin - clastic, wells drilled into basement
3 Low temp. 150oC to 190oC
4 Moderate temp. 190oC to 230oC
5 High temp. 230oC to 300oC
6 Ultra high temp. 300oC +
7 Steam field 230oC to 240oC
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How to define success?
• There is no recognized basis for defining drilling success
• Any well that is drilled but isn’t used is unsuccessful, but what about partial
success?� Completely dry holes are rare
� Wells with low productivity may be pumped, re-drilled, or used for injection or observation
� Wells’ output may deteriorate over time, in which case, was it initially successful?
• Ultimately, success depends on the ROI of each well� Factors in cost of well and economics of power plant
� Hard to calculate on a well-by-well basis
� Availability of data
� MW output per $ of drilling cost may be simpler
• A simple MW threshold has been used in this analysis, where other data isn’t
available� Statuses of 12% of wells in database are unknown
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Phases of a project
• As a project develops, understanding
of the reservoir improves
• This aids in targeting of wells and
should improve the success rate
• A project can be split in to different 70%
80%
90%
100%
Cumulative average success
Success in Kamojang field, Indonesia
Exploration
Development Operation
• A project can be split in to different
stages:� Exploration
• Early stage drilling to establish reservoir characteristics
� Development• Drilling to reach planned capacity output
� Operation• Drilling to replace lost capacity
• Length of each stage will vary
between projects
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0%
10%
20%
30%
40%
50%
60%
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49
Cumulative average success
Well number
Exploration
Highlights
Stage Well numbers
Success rate
MW Capacity % re-drilledMode Average
Exploration <=5 59% 4 6.0 15%
Development >5,<=30 74% 2-5 7.3 14%
Operation >30 83% 3 7.5 18%Operation >30 83% 3 7.5 18%
OVERALL All 78% 3 7.3 16%
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• Success rate improves as the project progresses (learning curve)
• Capacity of wells does not significantly improve beyond the exploration
phase
• Re-drilling is equally common in each phase
Success
10
Evidence for the “learning curve” effect
• It is expected that well drilling
becomes more successful with more
wells drilled in a field� Each well drilled helps to refine
knowledge of the size and location of the resource
y = 0.07ln(x) + 0.4860%
70%
80%
Cumulative average drilling success
resource
• The available data supports this
theory� Success on the first well appears to be
about 50:50, on average
� Cumulative success rate rises rapidly in the first few wells
� The cumulative success rate continues to rise as later wells are consistently more successful
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y = 0.07ln(x) + 0.48R² = 0.99
0%
10%
20%
30%
40%
50%
60%
1 3 5 7 9 1113151719212325272931333537394143454749
Average success
Well sequence number
Exploration
Development Operation
Variations in success
• Developers and financers are not
just interested in absolute risk, but
also the risk variability
• The database suggests that most 10
12
14
Number of fields
Variation in success by field
• The database suggests that most
fields have an overall success rate of
over 50%, and 80-90% is the most
common� Implies new projects should expect
success rates above 50% but could be significantly higher
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0
2
4
6
8
<=30% >30%<=40%
>40%<=50%
>50%<=60%
>60%<=70%
>70%<=80%
>80%<=90%
>90%<=100%
Number of fields
Success range
Variations in success by phase
• There is a wide range of success
rates seen in the Exploration phase
=> no real way of assessing likely
success rate
40%
45%
50%
Variation in success by development stage
Exploration
• Success in the Development phase is
most frequently around 60-70%,
though also commonly above this
• Success in the Operations phase is
higher, normally 90-100%
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0%
5%
10%
15%
20%
25%
30%
35%
>=0%<=10%
>10%<=20%
>20%<=30%
>30%<=40%
>40%<=50%
>50%<=60%
>60%<=70%
>70%<=80%
>80%<=90%
>90%<=100%
% of fields
Success range
Development
Operation
Improvements over time
• Exploration appears to have become
more successful over the last 50
years� Possibly caused by better exploration
techniques
� NB. Wide variation in success rates in this 80%
100%
Success of wells by decadeExploration
Development
Operation
� NB. Wide variation in success rates in this stage makes averages potentially mis-leading
• No significant changes in success
rates of development wells over
time
• Operation wells appear to have
become less successful� Possibly caused by older fields being fully
exploited
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0%
20%
40%
60%
1960's 1970's 1980's 1990's 2000's
Success
Decade
Well capacity
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Distribution of well capacity
• Well capacity follows a positively
skewed distribution� Mode is 3MW
� Average is 7.3MW
� Skew is 1.64120
140
160
Distribution of well capacity
• A wide range of capacities are
possible� Maximum capacity of a single well in the
database is 54MW
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0
20
40
60
80
100
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
# of wells
Gross Capacity (MW)
Changes of capacity with project phase
• The distribution of well capacities is
similar in each stage of project
development� Do not expect improvements in capacity
of wells as a project progresses25%
30%
Distribution of well capacity
Exploration
• Exploration has a slightly higher
mode (4MW)
• In Development, 2-5MW are equally
common
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0%
5%
10%
15%
20%
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
# of wells
Gross Capacity (MW)
Exploration
Development
Operation
Improvement of capacity in a project
• There is very little improvement in
the capacities of wells as drilling
progresses� No learning curve
6.0
7.0
8.0
9.0
(MW)
Cumulative average capacity
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0.0
1.0
2.0
3.0
4.0
5.0
6.0
1 3 5 7 9 1113151719212325272931333537394143454749
Average capacity (MW)
Well sequence number
Impact of pumping on well capacity
• Only ~6% of wells are pumped� Pumps can only be used in a narrow
temperature range
• Pumped and non-pumped wells show
similar distributions
30%
35%
% of wells by pump status
Capacity distribution of pumped and non-pumped
wells
similar distributions� Pumped wells have a narrower range of
values
� Frequency of capacity of pumped wells has a strong peak at 3MW
• Due to costs, pumping is only used
where output would otherwise be
marginal or low� Not used to boost productive wells
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0%
5%
10%
15%
20%
25%
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
% of wells by pump status
Capacity (MW)
Pumped
Non-pumped
Factors affecting success
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Prevalence of well depths in database
• Wells are drilled at all depths from
100m up to 6km� Normally less than ~3.5km
• Frequency appears to generally rise 20
40
60
80
100
120
# of wells
Well frequency by depth
• Frequency appears to generally rise
up to 2,200m� Clear modes at 1,200m and 2,200m
• Most fields have wells drilled at a
range of depth
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0
100
300
500
700
900
1,100
1,300
1,500
1,700
1,900
2,100
2,300
2,500
2,700
2,900
3,100
3,300
3,500
Well depth (m)
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
Depth (m)
Field
Range of depths by fieldAverage depth
Impact of depth on capacity and success
• Might expect it to be easier to drill
shallow wells => higher success
• There does not appear to be any
correlation between well depth and 70%
80%
90%
100%
7
8
9
10
Average capacity (MW)
Average capacity and success by depth
success or capacity� Shallow wells not necessarily more
successful or more productive
• However, it is cheaper to drill
shallower wells, so a low
productivity well may be considered
successful if it is shallow/cheap� Cost factor is not picked up in our
definition of success here
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0%
10%
20%
30%
40%
50%
60%
70%
0
1
2
3
4
5
6
7
100
300
500
700
900
1,100
1,300
1,500
1,700
1,900
2,100
2,300
2,500
2,700
2,900
3,100
3,300
3,500
Success
Average capacity (MW)
Well depth (m)
Impact of casing size on capacity and success
• Larger casing allows greater flow
rates of fluids� Should allow greater well capacity
• There is no clear trend of increasing
capacity with increasing casing size
70%
80%
90%
100%
7.0
8.0
9.0
10.0
Average capacity (MW)
Frequency and capacity of wells by casing size
• Success is not clearly related to
casing size
• Casings between 200 and 350mm are
the most common
• When designing drilling program,
required capacity does not need to
be considered
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0%
10%
20%
30%
40%
50%
60%
70%
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
>=0<150
>=150<200
>=200<250
>=250<300
>=300<350
>=350<400
>=400
Success
Average capacity (MW)
Casing size (mm)
Geology and enthalpy
Average
capacity
(MW)
Geology code
1 2 3 4 5
Re
sou
rce
co
de
1
2 3.6
• Rock formation and enthalpy of the
resource should significantly affect
the productivity
• Expect capacity to increase with
Re
sou
rce
co
de 2 3.6
3 3.4 3.0
4 4.8 6.4 6.7 6.1
5 5.0 5.9 5.4
6 7.6 8.2
7 8.4 6.9
• Expect capacity to increase with
enthalpy� Enthalpy increases with resource code
• Expect rock formations with high
permeability to boost capacity� Especially old volcanic
• Capacity roughly follows
expectations
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Impact of geology on capacity and success
• Granitic rocks tend to have low
porosity/unpredictable permeability
(depending on fractures) and hence
capacity is low
• The cracks present in old rock formations
boost productivity70%
80%
90%
100%
7.0
8.0
9.0
10.0
Average capacity (MW)
Capacity and success by geology
boost productivity� Volcanic rock may be alternate layers of ash and
lava – permeability changes significantly between layers
• Basement rocks have similar permeability
to granitic, if cracks are lacking
• Geology does not appear to affect success
rates� Higher rate for Code 4 due to lower MW
threshold of success for some fields
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0%
10%
20%
30%
40%
50%
60%
70%
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
1 2 3 4 5
Success
Average capacity (MW)
Geology code
Impact of enthalpy on capacity and success
• Resource code is closely related to
enthalpy� Capacity should increase with enthalpy
• Capacity does generally increase
with resource code, but not strictly70%
80%
90%
100%
7.0
8.0
9.0
10.0
Average capacity (MW)
Capacity and success by resource type
with resource code, but not strictly� Estimations of resource temperature in
the exploration phase will be key in estimating future well capacities
• Maximum capacity of a well does
increase with resource code
• Success appears independent of
resource code
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0%
10%
20%
30%
40%
50%
60%
70%
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
2 3 4 5 6 7
Success
Average capacity (MW)
Resource code
Impact of re-drilling on capacity and success
• 16% of wells have been re-drilled
• Re-drilling does improve success� 77% of original wells are successful
� 87% of re-drilled wells are successful14
16
18
20
Variation in success rates of original and re-drilled wells
• Re-drilling tends to have almost
100% success, or 0% success,
depending on the field
• Re-drilled wells also tend to have a
higher capacity� 7.2MW for original wells
� 8.1MW for re-drilled wells
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0
2
4
6
8
10
12
14
>=0%<=10%
>10%<=20%
>20%<=30%
>30%<=40%
>40%<=50%
>50%<=60%
>60%<=70%
>70%<=80%
>80%<=90%
>90%<=100%
# of fields
Success rate range
Conclusions
• ROI is the best measure of drilling success, but is often not practical� Drilling cost per MW is easier, but just the MW output is normally used, irrespective of cost
� Assigning low productivity wells as injectors or observation wells complicates things further
• Overall, 78% of wells drilled were successful and the most common capacity is
3MW, though average capacity is 7.3MW� A strong learning curve is seen in success, but not in capacity, as a project progresses
� Success is very unpredictable in the Exploration phase� Success is very unpredictable in the Exploration phase
• Wells can be drilled to almost any depth (<5km is normal), though 2.2km is the
most frequent depth� Most fields have wells drilled to a wide range of depths
� Depth does not impact likely success or capacity
• Enthalpy and geology affect well capacity, but not success
• Re-drilling improves success and capacity
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Accessing the data
• The analysis is still being finalized
� The results presented here are based on a preliminary look at the data
• IFC will be releasing a report based on this data, and the data
itself, to the publicitself, to the public
� Expected to be in the next couple of months
• Please contact me if you would like to be kept up to date on
the release of the report and data
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ANY QUESTIONS?
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ANNEX – Individual fields
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Improvements in success and capacity
7
8
9
10
70%
80%
90%
100%
Cumulative average capacity (MW)
Field 1.1
32
0
1
2
3
4
5
6
7
0%
10%
20%
30%
40%
50%
60%
70%
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49
Cumulative average capacity
Success
Well number
Improvements in success and capacity
7
8
9
10
70%
80%
90%
100%
Gross Capacity (MW)
Field 2.2
33
0
1
2
3
4
5
6
7
0%
10%
20%
30%
40%
50%
60%
70%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
Gross Capacity (MW)
Success
Well number
Series1 Series2
Improvements in success and capacity
20
25
70%
80%
90%
100%
Cumulative average capacity (MW)
Field 2.8
34
0
5
10
15
0%
10%
20%
30%
40%
50%
60%
70%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Cumulative average capacity
Success
Well number
Improvements in success and capacity
7
8
9
10
70%
80%
90%
100%
Cumulative average capacity (MW)
Field 3.4
35
0
1
2
3
4
5
6
7
0%
10%
20%
30%
40%
50%
60%
70%
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49
Cumulative average capacity
Success
Well number
16
18
20
80%
90%
100%
Cumulative average capacity (MW)
Field 3.8
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0
2
4
6
8
10
12
14
0%
10%
20%
30%
40%
50%
60%
70%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
Cumulative average capacity
Success
Well number
