Biodegradation2004

1
Biodegradation-2004
Oil/Gas
MIXING/RECHARCHING MAJOR FACTOR
Mineralogy!
Nutrients N,P,K ?

Oxidant O2 , SO4-- Mn4 CO2 Fe H2O
Tltlt80C
Degraded Oil/Gas Progressive Loss of
hydrocarbons production of CH4,, acids,
phenols, high MW compounds
Reduced Oxidant CO2 CH4 H2O, S-- Mn2 Fe

MEA
Organisms isolated
Degradation fluxes10-4 kg/ m2 / year.
Economically significant
destruction levels(10-50)
2
Head et al, Nature, 2003
3
Zengler et al(1999)
Head, Jones , Larter Nature 426, 2003
4
Pre Drill Fluid property Prediction
API, viscosity, TAN
Mixing
degradation
Oil Charge
5
Frigg Field
SEAL LEAKED
Frigg field and a Viking Graben black oil
charge. Viking Graben Petroleum sourced at Ro
0.8-0.9. 1. Current reservoir at 61C and
198.5bar Gas Volume as of charge 26.2 2.
Reservoir at 50C and 149bar
Gas Volume as of charge 42.3 Thus the trap
would have a significant gas cap under all
conditions.
Dry Gas Cap 95C1 iC4/nC4gt2, 0.3CO2 degraded oil
Degraded oil leg
Degraded residual oil column
Larter et al(1999)
6
Frigg Field
SEAL LEAKED
Frigg field and a Viking Graben black oil
charge. Viking Graben Petroleum sourced at Ro
0.8-0.9. 1. Current reservoir at 61C and
198.5bar Gas Volume as of charge 26.2 2.
Reservoir at 50C and 149bar
Gas Volume as of charge 42.3 Thus the trap
would have a significant gas cap under all
conditions.
Dry Gas Cap 95C1 iC4/nC4gt2, 0.3CO2 degraded oil
Degraded oil leg
Degraded residual oil column
Larter et al(1999)
7
Viscosity vs. Biodegradation II
Koopmans et al(2001)
8
Predicted Downhole Viscosity Profiles
Viscosity (cP)
Viscosity (cP)
Viscosity (cP)
0
5000
10000
15000
0
10000
20000
30000
0
10000
20000
-1700
-1720
-1740
-1760
Depth (m)
-1780
-1800
-1820
-1840
9
Zengler et al(1999)
Head, Jones , Larter Nature 426, 2003
10
This distribution of predicted viscosity or API
gravity across a field or the probability of
finding API gravity lt18 in a field. Bacchus 2 and
Permedias MPath will deliver the next generation
of predictive tools