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Despite more than 60 years of production history, recovery of the more than 1.5 billion barrelsof oil in the Fullerton Clear Fork field, a shallow-water platform carbonate reservoir of EarlyPermian age in the Permian Basin of West Texas, remains a challenge. To develop a betterunderstanding of the distribution of the original hydrocarbon resource and to devise strategiesto recover the huge volume that still remains, we undertook a comprehensive, multidisciplinarystudy of the reservoir. Crucial elements of the study include (1) geological models of analogousoutcrops, (2) description of more than 14,000 ft of core, (3) new core data for rock-fabricanalysis, (4) analysis and correlation of more than 850 wireline log suites, (5) a 3-D seismicinversion porosity model, (6) a 35,000-acre (14,000-hectare) reservoir model, and (7) a 2,000-acre (800- hectare) flow simulation.
The study utilizes robust outcrop models as a key to proper interpretation of geological,petrophysical, and geophysical subsurface data sets. It demonstrates procedures for producingand utilizing a geologically constrained reservoir framework in reservoir modeling andsimulation. It shows the tremendous potential of iterative 3-D seismic porosity inversionmodels in defining porosity distribution. It illustrates the importance of a rock-fabric-basedapproach for defining porosity/permeability relationships. Finally, the study defines thedistribution of original and remaining oil volumes and provides insights into how theseresources may best be recovered.
INTRODUCTION
Cyclicity and Reservoir FrameworkCores and outcrops demonstrate a direct relationship between facies, cyclestacking, and porosity: high porosity is usually associated with grain-richfacies at cycle tops. This relationship forms a basis for the use of porositylogs in cycle correlation and flow-unit definition.
L 2.3 is a low-accommodation sequence in which cycles are characterizedby porous tidal-flat caps that are readily defineable and correlatable onporosity logs.
L2.2 and L2.1 comprise dominantly subtidal cycles whose tops are generallygrain-rich packstones. Note good correlation between high porosity andcycle tops and poor correlation to gamma-ray logs.
6700'
6750'
6800'
6700
6800
CGR
Low
er C
lear
For
k
L 2.3
SGR
L 2.2
GR
Neutron
Core
Density
Porosity (%)30 0
Peloid packstone
Peloid wackestone-packstoneSkeletal wackestone
Peritidal mudstone Ooid/peloid grain-dominatedpackstoneSiltstone/sandstone
Tidal flat
Tidal-flat-capped cycle
Lower Clear Fork L 2.3
CGR
Low
er C
lear
For
k
L 2.2
SGR
L 2.1
GR
Neutron
Core
Density
Porosity (%)30 0
L 2.2L 2.3
6850'
680
685
Peloid packstone
Peloid wackestone-packstoneSkeletal wackestone
Peritidal mudstone Ooid/peloid grain-dominated packstoneFusulinid wackestone-packstone
Tidal flat
Tidal-flat-capped cycle
Lower Clear Fork L 2.2
6950
Core porosity
Neutron porosity
Peloidal packstonePeloidal wackestone
Tidal-flat wackestone-packstone
Fusulinid wackestone-packstoneOncoid-fusulinid wackestone-packstone
Peloidal grain-dominated packstone
Tidal-flat cycle topSubtidal cycle top
GRPorosity (%)30 0
7000
6950
7000
Lower Clear Fork L 2.1Depth
(ft)
Stephen C. Ruppel, Rebecca H. Jones, F. Jerry Lucia,Fred P. Wang, Hongliu Zeng, Jeffrey A. Kane,
and James W. Jennings, Jr. SETTING
CA B
A B
Mineralogy and Controls of Porosity Distribution
Field Structure and Data
Type Log Seismic Architecture
Middle ramp and ramp crest subtidal, grain-rich facies L2.1 & L2.2 (Lower Clear Fork)
Inner ramp tidal flat, mud-rich facies L1 & L2 (Wichita & Lower Clear Fork)
Karst facies: L1 & L2 (Wichita)
A. Moldic ramp crest limestone grainstoneB. Peloid grain-dominated dolomite grainstone (interparticle pores)C. Peloid packstone (moldic and interparticle pores)
Polymict and monomict conglomerate and breccia locallypresent above and below L1/L2 sequence boundary.
Distal outer ramp clinoforms L1 (Abo)
Fusulinid-crinoid wackestone-packstone with interparticle pores
Proximal outer rampL1 (Abo); L2 (Lower Clear Fork)
Fusulinid wackestone-packstonewith moldic and interparticle pores
Reservoir architecture defined by 3-D seismic and outcrop dataL1: progradational, partly clinoformal; L2: largely aggradational and horizontal
Abo
Wichita
LCF
Tubb
L1
L3
West East
UCF
L2.0L2.1L2.2L2.3
A. Fenestral mudstone-packstone (fenestral pores)B. Laminated mudstone (fine- to micro-crystalline pores)C. Clay-rich organic-pond mudstone
Although mostly dolostone, the reservoir contains significant volumes of limestone whosedistribution is important for (1) defining reservoir architecture, (2) controlling fluid flow, and(3) understanding porosity development.
Sequence Stratigraphic Framework
C
GEOLOGICAL CHARACTERIZATION
Field structure is a function of Pennsylvanian block faulting. Thereis good evidence of continuing reactivation of some of faults duringand after Leonardian deposition.
-
-
-
-
0 8000 ft
UnitBoundary
C.I. 40 ft
CoreImage log
Well
Deep fault
3-DSeismic
FlowSimulation
Study
3-DInversion
Study
A
A'
Inner ramp tidal-flat facies withlocal pond facies
Outer ramp clinoformal,fusulinid-crinoid packstone-wackestone
Middle ramp peloid faciesInner ramp tidal-flat faciesOuter ramp fusulinid facies
Inner ramp tidal-flat-cappedsubtidal facies
Inner ramp tidal-flat facies
Wichita FaciesLower Clear Fork Facies
Abo Facies
Systems Tracts
L1
Abo
HFSL2.1
Low
er C
lear
For
kTu
bbW
ichi
ta
HFSL2.2
HFSL2.3
L3
HFSL3.1
Abo
Low
er C
lear
For
kTu
bbW
ichi
ta
HFSL2.0
6400
6950
7000
7050
7100
7150
7200
7250
7300
7350
GR POROSITY (%)10030 20 10 0 -10
6900
7000
7100
7200
7300
7400
7500
7600
Permeability(md)0.01
CORE
6800
7700
7000
7100
7200
7300
7400
7500
7600
GR N D
Northwest SoutheastDIP SECTION
GR P N DGR P N D
6550
6600
6650
6700
6750
6800
6850
6900
6950
7000
7050
7100
7150
7200
7250
7300
73507360.0
6400
6450
6500
6550
6600
6650
6700
6750
6800
6850
6900
6950
7000
7050
7100
7150
7200
7250
7300
7350
7400
7450
7500
SGR P N D
SGR P N D
SGR P N D
A A'
01000
Datum: Base of Sequence L3
CGR SGR PE Neu Den
Low
er C
lear
For
kW
ichi
ta
Abo
Tubb
HFS L2.1
HFS L2.2
HFS L2.3
Sequence/Cycle Tops6500
-3500
-4000
Depth(ft)
7000
Prod
uctiv
e In
terv
al
HFS L2.0
Peritidal/tidal flat Subtidal
L 3
L 2
L 1
Bureau of Economic GeologyJackson School of Geosciences
The University of Texas at AustinAustin, TX 78713-8924
Geographic Distribution of LimestoneL2.1 Lower Clear Fork L2.0 WichitaL2.2 Lower Clear Fork
Limestone abundant Dolostone L1 Wichita/Abo margin
Multidisciplinary Reservoir Characterization of a Giant Permian Carbonate Platform Reservoir: Insights for Recovering Remaining Oil in a Mature U.S. BasinMultidisciplinary Reservoir Characterization of a Giant Permian Carbonate Platform Reservoir: Insights for Recovering Remaining Oil in a Mature U.S. BasinSETTING GEOLOGICAL CHARACTERIZATION
Stratigraphy
SE
RIE
S
STA
GE
NEW MEXICO TEXAS
LO
WE
R P
ER
MIA
N
Leo
nar
dia
n
SUBSURFACE
Cle
ar F
ork
Gro
up
UpperClear Fork
WichitaGroup
San Andres
Glorieta
Yes
o
Paddock
Blinebry
Abo
Drinkard
Tubb
PLATFORM MARGIN
VictorioPeak
Cutoff
BoneSpring
San Andres
Tubb
Glorieta
LowerClear Fork
San Andres Leo 7-8
Leo 6
Leo 2
Leo 1
Leo 3
Leo 4
Leo 5
Wolf 3Wolfcamp Hueco HuecoWolfcamp
VictorioPeak
Glorieta
Abo
OUTCROP
SEQUENCE
Guad 1
PLATFORM AND MARGIN GUADALUPE MOUNTAINS/SIERRA DIABLOTexas - New Mexico
Ku
ng
uri
an
STA
GE
Geography
Fullerton Clear Fork field is one of the largest fields in the Permian Basin, covering anarea of about 35,000 acres (14,000 hectares). The field, which includes more than 1,200wells, contained between 1.5 and 2.0 billion barrels of oil at discovery.
KETCHUM MT.
DOVE CREEK
PAROCHIAL-BADE
HOWARD-GLASSCOCK
VAREL
REVILOLUCY
DIAMOND -M-
SHARON RIDGE
COLEMAN RANCH, N.
COLEMANRANCH
WESTBROOK, EAST
MIRIAM
P.H.D.
ROCKER -A-
GUINN
POST
WTG
SMYER
ROPES, E.
HARRIS
ROBERTSON, N.
RUSSELL
WASSON 72
OWNBY
PRENTICE
KINGDOM
SUNDOWN LEEPER
WARHORSE
BROWNLOVINGTON
MIDWAYDOUBLE A, SOUTHDOUBLE A
EMPIRE
BUCKEYEVACUUMCORBIN
HAL JAMAR
LEVELLAND
ANTON
ANTON-IRISH
RIDGE
HOOPLE
EDMISSON
KEYSTONE
KEYSTONE, SOUTH
EMPORER
MONAHANS, N.
DOLLARHIDEJUSTIS
FOWLER
TEAGUE
DRINKARD
OIL CENTER
METZ
PENWELL
C-BARMONAHANS
CRAWAR
SAND HILLS
MCKEE
BAYVIEW
SUN VALLEY, N.BROOKLAW
SUN VALLEY
BROWN & THORP
WENTZTIPPETT
UNION
FULLERTON
SHAFTER LAKE
DEEP ROCK
FUHRMAN SOUTH
NIX, SOUTH
BLOCK 12
MARTIN
TXL
MONUMENT BLOCK A-34
HOBBS
WEIR
SCAGGSHOUSE
BRUMLEY
GOLDSMITH
GOLDSMITH, W.
TURNER-GREGORY
EMBAR
JACKSON
CROSBY
DICKENS
KENT
SCURRY
LYNN
DAWSONGAINES
MITCHELL
GLASSCOCK
ANDREWS
MIDLAND
TOM GREENSTERLING
UPTON
ECTOR
TERRY
BORDEN
GARZA
MARTIN
HALE
LUBBOCKHOCKLEY
LAMB
CHAVES
EDDY
LOVING
REAGAN
CRANE
PECOS
WINKLER
COCHRAN
YOAKUM
WARD
IRION
LEA
HOWARD
MIDLANDBASIN
BLINEBRY
NORTHERN
EASTERN
SHELF
SHELF
DELAWAREBASIN
Fullerton Field
New MexicoTexas
CENTRALBASIN
PLATFORM
0 25 50 milesLeonardian shallow water carbonate reservoirs
RILEY, NORTH
FLANAGAN
WELTMER
WARREN
PADDOCK
ROBERDEAU, S.
BROWN & THORP,EAST
N
Mineralogy and geochemical data suggest that high-porosity trend in Wichita is the resultof early dolomitization along the outer tidal-flat margin. High-porosity trend in the LowerClear Fork is the result of early calcite stabilization along the platform-margin ramp crest.(Isotope data from this study and Kaufman [1991]).
Early Diagenesis and Structure Control Porosity Distribution
Later reflux dolomitization Early calcitecementation
andstabilization
Later reflux dolomitizationEarly seawaterdolomitization
andstabilization
L1 - L2 Wichita Platform L2 Lower Clear Fork Platform
B
L1 platformmargin
Core
Image log
Unit boundary
Low-porosity Wichitainner ramp tidal flat
High-porosity Wichitatidal-flat margin
Low-porosity Lower Clear Forkouter ramp subtidal
2.8 0/00 d18O
3.0 0/00 d13C
0.1 0/00 d18O
2.5 0/00 d13C
-3.0 0/00 d18O
4.0 0/00 d13C
2.5 0/00 d18O
2.6 0/00 d13C
NN
0
0 4 mi
6 km
High-porosity LowerClear Fork ramp crestLow-porosity Lower Clear Forkmid-ramp subtidalWichita/Abo inner/outerramp margin
1. Tidal-flat (mud-rich) limestones (L1/L2 Wichita) are low-flow baffles, whereas subtidal(grain-rich) limestones (L2 Lower Clear Fork) are high-flow zones.
2. Reservoir architecture in the poorly cyclic peritidal L1/L2 Wichita succession is best definedby limestone distribution (cycle bases).
3. Limestone is most common in the transgressive leg of the L2 sequence. This is consistentwith incomplete reflux dolomitization from an updip/upsection fluid source.
Stratigraphic Distribution of Limestone
Wic
hita
Low
er C
lear
For
kA
boTu
bbGR N D
GR N D GR N D GR N D GR N D GR N D
HFSL 2.1
L 1
HFSL 2.2
HFSL 2.3
West East
L 3
6450
6500
6550
6600
6650
6700
6750
6800
6850
6900
6950
7000
7050
7100
7150
7200
7250
7300
7350
7400
HFSL 2.0
L 2
6400
6500
6600
6700
6750
6800
6900
7000
7100
7200
7300
7350
6500
6550
6600
6650
6700
6750
6800
6850
6900
6950
7000
7050
7100
7150
7200
7250
7300
7350
7400
6450
6500
6550
6600
6650
6700
6750
6800
6850
6900
6950
7000
7050
7100
7150
7200
7250
7300
7350
7400
6450
6500
6550
6600
6650
6700
6750
6800
6850
6900
6950
7000
7050
7100
7150
7200
7250
7300
7350
7400.0
DolostoneLimestone100 30
0
ft m
0
Depositional Model
Inner ramp Rampcrest
Outer ramp
Slope –basin
Peloidwackestone-packstone Peloid/ooid
grain-dominatedpkstn-grnstn
Crinoid-brachiopodwackestone-packstone
Starve
d bas
in
Sabkha, tidal fla
t
Highly variableexposure-related facies
Buildupsand flanking
crinoid packstone
Middle ramp
Fusulinidwackestone-packstone
QAb3741c
Lagoon,
protected flat
Clinofo
rm sl
ope
(0.5-3
°), ra
re bio
herms
Bar-channel
HST
FACIES TRACTS
Outer ramp fusulinid wackestone-packstoneMiddle ramp grain-rich packstoneInner ramp amalgamated tidal flatInner ramp tidal-flat-capped wackestoneTidal-flat wackestone-siltstone
SEQUENCE STRATIGRAPHYHigh-frequencysequence
Compositesequence
L 1
HFS
Karst breccia andconglomerate
Reservoir interval
200 ft
Clinoformal, outer ramp fusulinid-crinoidwackestone-packstone
Sequence Stratigraphic Model
Abo
Wichita
LowerClearFork
TubbLandward Basinward
HFS 2.3
HFS 2.2
L 2
L 1
L 3
HFS 2.1
0
0 4 mi
6 km
0
0 4 mi
6 km
QAd4360x
BureauofEconomic
Geology