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Water production from shale oil and gas wells
Bing Bai
8/12/2013
Outline
• Wastewater characteristics• Wastewater production
• Vertical wells• Horizontal wells
• Sources of variability in water production volumes
• Water production prediction tools
Wastewater characteristics
• Frac flowback water– Fracturing fluids (15% – 40% recovery)– Water flows back after fracturing within 7 – 10
days– TDS: 30,000 – 200,000 mg/L– Chemical additives
• Produced water– Formation water + fracturing fluids– Water flows through the whole life time of well– High TDS– Oil & Grease and NORM
Wastewater production
• Vertical oil and gas wells• Arps Equation (Exponential decline) Q=Ae-kt
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
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2σ confidence interval
Average
Year
Wa
ter
pro
du
cti
on
, b
bl/
da
y/w
ell
Wastewater production
• Horizontal oil and gas wells• Arps Equation (Hyperbolic decline)
1 18 35 52 69 86 1031201371541711882052222392562732903073243413580
200
400
600
800
1000
1200
1400
1600
Time, days
Wa
ter
Pro
du
cti
on
, bb
l
Produced water (>164 days)
Transition water (31-163 days)
Frac Flowback (<30 days)
Wastewater production
• Horizontal well water production• Frac flowback water (30 – 35%)• Transition water (17 – 20%)• Produced water (53 – 55%)
10 15 20 25 30
0
10
20
30
40
50
60
70
80
90
100
Produced water
Transition water
Frac flowback water
Year
Pe
rce
nta
ge
, %
Water recovery ratio
• Frac flowback water: 21.75%• Transition water: 12.23%• Produced water: 28.26%(10 years) to 37.93% (30 years)
• Total water recovery ratio: 62.24% (10 years) to 71.91% (30 years)
DJ basin water production prediction
• Production per horizontal well• Flowback water: 13442.3 bbls (2137.2 m3)• Transition water: 8286.1 bbls (1317.4 m3)• Produced water: 10 year — 18766 bbls (2983.6 m3)
30 year — 26356.6 bbls (4190.4 m3)
• DJ basin water production prediction• Assume 1500 new horizontal wells are drilled each
year in DJ basin
• Water production volumes (DJ basin)• 30 day flowback: 20 million bbls (3.17 million m3)• 133 day transition: 12.4 million bbls (1.97 million m3)• Produced water: 10 year — 28.1 million bbls (4.47 million m3) 30 year — 39.5 million bbls (6.3 million m3)
• Total water produced from 1500 new horizontal wells in DJ basin
60.5 million bbls (10 year) — 71.9 million bbls (30 year) (9.61 million m3) (11.44 million m3)
DJ basin water production prediction
Sources of variability in water production volumes
Sources of variability in water production
• Temporal variability (decline curves)
1 19 37 55 73 91 1091271451631811992172352532712893073253433610
200
400
600
800
1000
1200
1400
1600
Time, days
Wa
ter
Pro
du
cti
on
, bb
l
Produced water (>164 days)
Transition water (31-163 days)
Frac Flowback (<30 days)
Frac floback Transition water Produced water
• Spatial variability (well location)• Formation, temperature, pressure, porosity
164179194209224239254269284299314329344359
0
5
10
15
20
25
30
35
40Produced water
Field AField B
Time, days
Wa
ter
Pro
du
cti
on
, b
bl
31 41 51 61 71 81 91 101 111121 131141 151161
0
20
40
60
80
100
120
140
160
180Transition water
Field AField B
Time, days
Wa
ter
Pro
du
cti
on
, b
bl
1 4 7 10 13 16 19 22 25 28
0
200
400
600
800
1000
1200
1400
1600Frac flowback
Field AField B
Time, days
Wa
ter
Pro
du
cti
on
, b
bl
Sources of variability in water production
Time periodArea A(bbl)
Area B(bbl)
Two tail t-test(p value)
Frac flowback 14069.96 12279.41 0.03
Transiton water 8286.1 8290.74 0.94
Produced water 4496.6 4517.34 0.98
Total 26852.66 25087.49 0.54
• Wellbore length (frac stages)
Long: 38 stages (9500 ft/2900 m)Normal: 20 stages (5000 ft/1500 m)
0 50 100 150 200 250 3000
500
1000
1500
2000
2500
3000
Long
Normal
Time, days
Wat
er P
rod
uct
ion
, b
bl
Sources of variability in water production
Time periodWater production
(bbl)
Water production volume per stage(bbl/stage)
Two tail t-test(p value)
Long Normal Long Normal
Frac flowback 26130 13420 690 670 0.71
Transition water 14750 8340 390 420 0.66
Produced water 6520 3540 170 180 0.52
Total 47400 25300 1250 1260 0.51
Sources of variability in water production
• Type of frac fluid
Type I — Guar based fluid with basic pH
Type II —Non-guar based fluid with low pH
1 10 19 28 37 46 55 64 73 82 91 1001091181271361451541630
200
400
600
800
1000
1200
1400
Type I
Type II
Time, days
Wat
er P
rod
uct
ion
, b
bl
Sources of variability in water production
Time period Type I Type IITwo tail t-test
(p value)
Frac flowback 8802.49 7954.57 0.44
Transition water 5408.55 3442.38 0.046
Total 14211.04 11396.95 0.04
• Frac water source
Recycled: Recycled produced water (recycle ratio 1/7)
Non-recycled: Fresh water
Sources of variability in water production
1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 860
200
400
600
800
1000
1200
1400
Recycled
Non-recycled
Time,days
Wat
er p
rod
uct
ion
, b
bl
Time periodRecycled/Fresh Blend (1/7)
(bbl)Fresh Water
(bbl)Two tail t-test
(p value)
Frac flowback 7620.32 8281.41 0.63
Transiton water 1783 1984.87 0.52
Water production prediction tools
Water production prediction tool
• Excel based tool
• ArcMap based tool
Water production prediction tool
Thank you!
Questions?