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The geothermal reservoir Groß Schönebeck- on the way to power production
in the North German Basin -
G. Zimmermann, U. Trautwein, H.-G. Holl, S. Köhler, B. Legarth, A. Saadat, H. Winter & E. Huenges
outline
- introduction- proppant frac treatment 2002- massive water frac treatment 2003 I + II- flow-back test 2003 I + II- conclusion and outlook
geothermal reservoir Groß Schönebeck
technology development forgeothermal power production
1. milestone january 2001:• temperature > 150 °C• depth > 4 km
2. milestone march 2002: • flow rates > 25 m³/h
3. milestone december 2003:• flow rates > 50 m³/h• prod.-index > 10 m³/(h MPa)
4. next step:• 2. well (doublet system)
geology of the Central European Basement
Paris
Bruxelles
London
Munich
Praha
Warszawa
Berlin
Hamburg
Kobenhavn
NEGB PTNWGBNEB
DB
North Sea
Baltic
Sea
Rotliegend
Tornquist zone
VariszicanbeltVariszican Deformation front
Caledonian Deformation front
Caledonides &older massifs
Precambriancrystallinebasement
Alps
Rhenohercynian
Saxothuringian
Moldanubian
Alpi
ne
front
0 100 200 km
after Ziegler 1990, Bertelsen 1992, Plein 1993, Beneck et al. 1996
drill site Gr Sk 3/90
lithology, porosity and permeabilityD
epth
(m)
0
500
1000
1500
2500
3000
2000
3500
4000
CenocoicCretaceousJurassic
Triassic
Zechstein
Rotliegend
Depth 4294 m
Sandstone ConglomerateSiltstone Volcanics
3900
4000
4100
4200
Depth 4240 m (1990)4294 m (2000)
Zechstein
Mellin
Peckensen
Eldena
Rambow
Havel
0 10 20
POROSITY (%)
0,001 1 1000PERMEABILITY (mD)LITHOLOGY
n = 200
Sandstone ConglomerateSiltstone Volcanics
3900
4000
4100
4200
Depth 4240 m (1990)4294 m (2000)
Zechstein
Mellin
Peckensen
Eldena
Rambow
Havel
0 10 20
POROSITY (%)
0,001 1 1000PERMEABILITY (mD)LITHOLOGY
n = 200
hydraulic stimulation of sandstones February 2002
qi
pwhpat
Open Hole Packer
7“ Liner
3 ½“ Fracstring
9 5/8“ Casing
5“ Fracstring
p,TMemory Fracinterval5 7/8“
OH-Interval
3874 m
4294 m
2309 m
Sand Plug
Expansion Joints
dzdpRRf
dzdpslurry
concept:
• open-hole stimulation
• high-viscous fluid(HTU-Gel + citric acid)
• proppant
result:
• increase of productivity
• not sufficient for economics
Legarth et al., Geothermics, 2003
SH:18,5°±3,7
Holl et al. EAGE, 2004
dept
h[ m
]
cumulative flow [ m3/h ]
logging after stimulation sandstones
flow back test march 2003
0
5
10
15
20
25
30
0 5000 10000 15000 20000 25000
time [sec]
flow
[l/s
]
0
20
40
60
80
100
120
140
160
180
head
pre
ssur
e [b
ar]
head pressure
flow
productivity indexPI = 3-4 m³/(h MPa)
FMI measurements after 1. waterfrac treatment
Holl et al. EAGE, 2004
dept
h[ m
]
4127
4128
perforated liner installed beneath 4135 m
massive waterfrac treatment fall 2003
production test Groß Schönebeck 1.12.03
production test (flow back) december 2003
0
0,2
0,4
0,6
0,8
1
1,2
0 500 1000 1500 2000time, min
flow
, m³/m
in
0
20
40
60
80
100
120
head
pre
ssur
e, b
ar
flow
pressure
production test (flow back) Groß Schönebeck 1.12.03
fracture closureat 96,5 bar
80
85
90
95
100
105
110
115
120
26500 28500 30500 32500 34500 36500 38500 40500 42500
time, s
head
pre
ssur
e, b
ar
0
0,2
0,4
0,6
0,8
1
1,2
flow
rate
, m³/m
in
PI > 14 m³/h MPa PI < 14 m³/h MPa
flow back test december 2003
0,8
1
1,2
1,4
1,6
2,7 2,9 3,1 3,3 3,5 3,7 3,9 4,1 4,3
log time (sec)
log
(diff
eren
tial p
ress
ure
(bar
))
bilinear flow ( ~ t0,25)
formation linear flow (~ t 0,5)
fractureclosure
according to Cinco-Ley & SamaniegoSPE 1981
Conclusionlearning curve „enhancing productivity“
Primary testJan. 2001passive
sandstonefracFeb. 2002gel and proppant100m3
40 l/s
waterfracFeb. 2003water4000 m3
25 l/s
waterfracNov./Dez. 2003water10000 m3
40 l/s (80 l/s)
fracfluidvolumemax. rate
prod
uctiv
ity in
dex
[ m/h
MP
a ]
3
15
10
5
conclusion and outlook
- increase of productivity- no sustainable PI -> tie-back with proppant
- use this well as injection well- design of 2nd well for doublet system