North GOM Petroleum Systems: Modeling the Burial and Thermal History, Organic Maturation, and...
-
Upload
austen-lang -
Category
Documents
-
view
216 -
download
1
Transcript of North GOM Petroleum Systems: Modeling the Burial and Thermal History, Organic Maturation, and...
North GOM Petroleum Systems: Modeling the Burial and Thermal History,
Organic Maturation, and Hydrocarbon Generation and Expulsion
Roger J. Barnaby2006 GCAGS MEETING
• Evaluate source rock hydrocarbon potential and maturity– Smackover geochemistry (TOC, kerogen)– Model burial history – Model thermal history
• Model hydrocarbon maturation, generation and expulsion – Key controls– Timing and burial depths– Volumes of oil and gas
• Assess secondary hydrocarbon migration
Previous studies of northern GOM crude oils: composition, 13C,document Type II algal kerogen in Smackover major source
Objectives
SA
BIN
E U
PLI
FT
N. LASALT BASIN
MONROEUPLIFT
Primary control for basin modeling 140 key wells (red) 44 sample wells (blue) 30 additional wells being analyzed
50 mi
CRETACEOUS SHELF MARGIN
Burial History: Depositional and Erosion Events
Geological time scale: Berggren et al. 1995Formation ages: Salvador 1991 Galloway et al. 2000 Mancini and Puckett 2002; 2003 Mancini et al 2004
Smackover
Cotton Valley
Hosston
Sligo
MooringsportGlen Rose
Paluxy
Austin
Wilcox
Miocene
Oligocene
TuscaloosaWash/Fred
Midway
Jackson
Burial History
• Reconstructed from present-day sediment thickness after correcting for compaction
• Compaction due to sediment loading• Maximum paleo water depths < few 100 meters,
no correction for water loading– Paleobathymetry– Sea level through time
Porosity-Depth Relationships
0
5000
10000
15000
20000
0.00 0.10 0.20 0.30 0.40 0.50 0.60
porosityd
epth
(ft
)
Limestone
Sandstone
Shale
= 0 exp (-Kz)
Where: = porosity0 = Initial porosityK = compaction factorz = depth
Exponential Compaction
0
5000
10000
15000
20000
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70
porosity
dep
th (
ft)
Burial History: Decompaction
3
2
1
12
1
3
2
1y1
y2
y’1
y’2
t1Remove 2 & 3Decompact 1
t2 Add 2
Partially compact 1
t3Add 3
Compact 2 and 1
Present-daydepths
0
5000
10000
15000
20000
050100150200
Time (Ma)
Dep
th (
ft)
Compacted
Non-compacted
Burial History: Compacted vs Non-compacted
Lithology (Wilcox)
CALCULATE DECOMPACTION-lithology from digital logsEnd member lithologies-SS, SH, LS, ANHLog-derived lithology -mixture of end membersCompaction parameters formixed lithology – weighted arithmetic average
Lithology (Upper Glen Rose)
Smackover
Cotton Valley
Hosston
Sligo
MooringsportGlen Rose
Paluxy
Austin
Wilcox
Miocene
Oligocene
TuscaloosaWash/Fred
Midway
Jackson
Burial History
Smackover
Cotton Valley
Hosston
Sligo
Mooringsport Wash/FredGlen RoseTuscaloosa
Austin
Midway
Wilcox
Miocene
Oligocene
Jackson
2
Burial History
• Modeling formation temperature– Heat flow approach: temperature function of
basement heat flow, thermal conductivity overlying sediment
• Present-day heat flow– Well BHTs– Surface temp = 20oC– Thermal conductivity
• Porosity and lithology are major variables controlling thermal conductivity
• In-situ thermal conductivity computed by BasinMod
Thermal History
meter (103 . deg K)
T2, y2
T1, y1
= T2-T1 (103 . deg K)y2-y1 (meters)
W
meters2
Heat Flow
xW
TemperatureGradient
ThermalConductivity
Heat Flow Calculation
CalculatedHeat Flow = 50 mW/m2
BHTs
Calculated vs Measured BHTs
Thermal History: Paleoheat Flow• Constant vs. rift model
= 2.0
= 1.75
= 1.5
= 1.25
= 1.0
N. LA Beta1.25 ≤ ≤ 2.0
Nunn et al 1984 Dunbar & Sawyer 1987
170130026300
Moho Crust
Subcrustallithosphere
Aesthenosphere
= 230 km
120 km
= 1.25
= 1.5
= 1.75
= 2.0Dunbar and Sawyer 1987
Thermal History: Lithospheric Stretching
SA
BIN
E U
PLI
FT
MONROE UPLIFT
50 mi
17067006100
170612011700
170152087800
170152065500
170692007200
171190136200
170692023300
0
2000
4000
6000
8000
10000
12000
14000
0.10 1.00 10.00
%Ro (measured)
Dep
th (f
t)
Surface %Ro (expected)
17067006100
170612011700
Trend A
Trend B
Thermal HistoryLate K Igneous Event
Moody (1949)
Optimum match between BHTs and %Ro and modeled valuesusing rift model with Late Cretaceous thermal event
170670006100 (J-2)
Late K thermal event
Heat Flow History and Thermal Maturity, Monroe Uplift
6000 ft
Heat Flow: 170 Ma
Heat Flow: 119 Ma
Heat Flow: 95 Ma
Heat Flow: 17 Ma
• Thermal maturity (%Ro) calculated using kinetic model from LLNL• Standard type II kerogen • 1D steady-state heat flow at model base, heat transfer from conduction
Maturity Modeling
170692023300
Thermal History: Paleoheat Flow• Thermal maturity constrained by %Ro
170692023300
48 mW/m2, rift model, modeled maturity reasonably matches TAI and %Ro
171190164100
170152087800170812037000
170812042100
170692008800170692007200
Calculated %Ro vs. Measured
Present-day95 Ma
Smackover Maturity
Present-day
Hydrocarbon Generation & Expulsion
0
5
10
15
20
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 2.0 3.0 4.0
TOC (%)
N
Smackover: oil-prone Type II kerogen
TOC data updip wells onlyExtrapolated downdip
Ran models with range TOC
Pepper (1991)
OIL-WATER SYSTEMWATER-WET LITHOLOGIES
TY
PIC
AL
RE
SE
RV
OIR
S
OIL SOURCEROCKS
PHASESEQUALLYMOBILE
OILINCREASINGLY
MOBILE
WATERINCREASINGLY
MOBILE
0.7 0.4 0.0
RE
LA
TIV
E P
ER
ME
AB
ILIT
Y:
OIL
/WA
TE
R
OIL SATURATION
0.01
0.1
1
10
100
KSwirr
Ex: saturation threshold = 0.20
Oil Expulsion Volumetrics
109 bbls oil
Expulsed Oil Volumetrics
peak expulsion (108 to 103 my)(late Early Cretaceous)
TOC = 2 x RKZSaturation Threshold = 0.15
Constant heat flow (present-day)
Rift heat flowmodel
Primary gas
Secondary gas
Average GOR, North Louisiana = 12,500, up to 500,000 or more
Gas Generation and Expulsion
TOC = 2%, saturation threshold = 0.2, rift heat flow w/ K event
Expelled Gas (Primary + Secondary)
Timing of gas expulsion
Saturation threshold = 0.2TOC = 1%Heat flow model with rifting and late K event
0.00
0.20
0.40
0.60
0.80
1.00
020406080100120140
M.a.
Cu
mu
lati
ve
Ex
pu
lse
d G
as
Fra
cti
on
N. LA Petroleum System
E M L E L
Source Rock
Reservoir Rocks
Overburden Rocks
Generation-Expulsion
Salt
Uplift
Jurassic Cretaceous Tertiary
200 150 100 50
TimeScale Petroleum
Systems Events
Critical Moments
Secondary Migration
Trap
oilgas
Conclusions
• Geochemical data and basin modeling indicate that Smackover mature for oil and gas
• Peak oil expulsion late Early Cretaceous, persisted into Late Cretaceous
• Most gas is secondary• Peak gas expulsion early to middle Tertiary• Cumulative production accounts for less than
1.0% of total expulsed volumes of oil and gas– Estimates in published literature 1-3%