Tim Carr - West Virginia University
Source Rock
Migration Route
Reservoir Rock
Seal Rock
Trap
Elements
Generation
Migration
Accumulation
Preservation
Processes
2
Reservoir Porous & Permeable Rock Suitable for Production Most Commonly Sandstone & Carbonate
What is the Volume of Hydrocarbons? Percentage of Pores versus Matrix Percentage of Pore Occupied by Hydrocarbons
Hydrocarbon Saturation
What is the Production Rate? Permeability – Ease of Flow
What is the Geometry of the Reservoir? Internal Geometry - Sweep External Geometry – More Hydrocarbons in Vicinity
Can We Provide Input to Models of the Reservoir? Static Geomodel Dynamic Fluid Flow Model Field Management & Enhancement
A “Container” From Which
Oil & Gas
Can Be
Produced
3
Primary (original)
Secondary (induced) (Generally more complex than
primary porosity)
4
Additional open space developed after
sedimentation: Cementation
Dissolution
Dolomitization
Fracturing
5
POROSITY IN SANDSTONE
MATRIX
FRAMEWORK (QUARTZ)
FRAMEWORK (FELDSPAR)
CEMENT
PORE
Note different use of “matrix”
by geologists and engineers 0.25 mm
Sandstone Comp.
• Framework
• Matrix
• Cement
• Pores
DISSOLUTION
PORE
FRACTURE
1. Primary and secondary “matrix” porosity system
2. Fracture porosity system
6
MORE POROUS LESS POROUS
7
Ohio Outcrop 8
Gloades Corner Reservoir, NY
9
Photo: J. Olson, UT Austin
10
11
Photo: J. Olson, UT Austin 12
Photo: J. Olson, UT Austin 13
Photo: J. Olson, UT Austin 14
(Smosna, 1996) (Gas Atlas)
Example of Fractured Carbonate Reservoir
Burgoon Sandstone
Formation
Green
brie
r L
imest
on
e
Big Lime
Big InjunLoyalhanna
Member
Gre
enbrier
Lim
esto
ne
Keener SS
Pocono Formation Pocono Formation
McCrady Formation
Upper
Member
Unnamed Shale
Sandstone
Upper
Member
Wymps
Gap
Member
Savage Dam
Deer Valley
Mauch C
hunk F
orm
ation
Maxville Limestone
Bluefield Maxton Sandstone Mauch Chunk
Pickaway
Taggard
Denmar
Reynolds
Member
Lillydale
Member
Hillsdale
PennsylvaniaEastern Ohio
Alderson
Union
Formation
West Virginia
Subsurface
Little Lime
Pencil Cave Shale
Northern West VirginiaSoutheast West
Virginia
Reynolds
Lillydale
Loyalhanna Limestone
MIS
SIS
SIP
PIA
N
MID
DL
E
LO
WE
R
AGE
UP
PE
R
Maccrady Fm
primary fault play target
15
Isopach of Union Oolite, Rhodell Field
Area
(from Gas Atlas)
study area
16
Sparks and Ayers, unpublished
CORE PLUG
17
3527’ scale in cm
ooids
3527’
intragranular porosity (blue)
1 mm
3527’
oolite rim (8% porosity)
sparry calcite (poor porosity)
2000’
200
0’
Scale:
Estimated Ultimate Recovery (EUR) Map
C.I. = 200 MMcf
21
2000’
200
0’
Scale:
UNION OOLITE
NET PAY ISOPACH
Porosity > 4%
C.I. = 4’
#5834
#5638
22
Cross-Section A – A’
A A’
0
-500
-1000
-1500
PILOT KNOB
ARISTA
NW SE
Scale:
500’
500
’
UNION
PICKAWAY
DENMAR
LITTLE LIME
PRICE
2000’
200
0’
A
A’ 23
DEPI #5834 (047-055-00238)
UNION OOLITE (Hanging wall)
UNION OOLITE (Foot wall)
PILOT KNOB THRUST FAULT
206’ OFFSET
OPEN FRACTURES 30 MMcf natural
50’
24
DEPI #5834 047-055-00238
FMI LOG
open fracture
drilling induced fractures
DEPI #5834 (047-055-00238)
SIDEWALL CORES
50’
PILOT KNOB THRUST FAULT 206’ OFFSET
26
OPEN FRACTURES – DEPI #5834 (FAULT ZONE)
Highly deformed interval Strike: NNE – SSW Dips: 30-50° 27
3446.5’ scale in cm
open fracture
28
300μm micritized ooids
3446.5’
open fracture
3446.5’
open fracture
authigenic, euhedral quartz crystals
3477’ scale in cm
calcite filled vugs & fractures
31
(after Nelson, 2001) no scale
UNION OOLITE THRUST MODEL WITH FRACTURE SWARM
UNION OOLITE
32
Avg Mcf/d
0
50
100
150
200
250
300
350
400
450
11/5/01 5/24/02 12/10/02 6/28/03 1/14/04 8/1/04
FAULT WELL PRODUCTION (outside Oolite trend)
DEPI #5834 (047-055-00238)
Lesser decline (reservoir production)
Steep initial decline (fracture production)
(30 MMcf natural)
33
How should we manage the field so as to maximize our investments?
Can we monitor how oil is being swept out of the reservoir?
What about injection wells and enhanced recovery?
Is there more oil in the vicinity – either at deeper depths or in nearby traps?
Can we contribute to a computer model of the field that matches existing production data? If so, we can test future recovery with different drilling scenarios. 34
Add reserves (volumes)
New discoveries
More from discovered producing zones
Additional producing zones
Get the most reserves at the lowest cost
Invest in the right basins
Drill in the optimum locations
Correctly assess what can be recovered
Avoid unnecessary wells 35
Modified from ExxonMobil 36
Courtesy of ExxonMobil
Geologic Model
Reservoir Simulation
Oil
Pro
du
cti
on
Production Time
HISTORY MATCH
Actual in Blue
Modeled in Red
37
Courtesy of ExxonMobil
An integration of all geologic, geophysical, petrophysical and interpreted or conceptual information about a reservoir into a single 3D numerical description of that reservoir
Structural Interpretation
Stratigraphic
Interpretation
Petrophysical Interpretation
Geophysical Interpretation
38
Courtesy of ExxonMobil
Each cell can be populated with rock & fluid Properties:
– Facies
– Porosity
– Permeability
– Fluid Saturation
– Etc.
1m
39
Courtesy of ExxonMobil
How do we use this information?
• Field development planning
• Field production optimization
• Reservoir surveillance
HistoryO
il R
ate
Time
Prediction
EOR
Infill Drilling
Oil
Rat
e
Time
Base Case
HistoryO
il R
ate
Time
HistoryO
il R
ate
Time
HistoryO
il R
ate
Time
Oil
Rat
e
Time
Prediction
EOR
Infill Drilling
Oil
Rat
e
Time
Base Case
Prediction
EOR
Infill Drilling
Oil
Rat
e
Time
Base Case
EOR
Infill Drilling
Oil
Rat
e
Time
Base Case
Time (yrs)
Oil
Ra
te
Time (yrs)
Oil
Ra
te
History
Oil
Rat
e
Time
Prediction
EOR
Infill Drilling
Oil
Rat
e
Time
Base Case
History
Oil
Rat
e
Time
History
Oil
Rat
e
Time
History
Oil
Rat
e
Time
Oil
Rat
e
Time
Prediction
EOR
Infill Drilling
Oil
Rat
e
Time
Base Case
Prediction
EOR
Infill Drilling
Oil
Rat
e
Time
Base Case
EOR
Infill Drilling
Oil
Rat
e
Time
Base Case
Actual
Modeled
40
Matrix Permeability
Fracture Permeability 41
Matrix Permeability
Fracture Permeability
Distributed Fracture Network
42
43
Take Home Ideas
Secondary Porosity Importance of Fracture Porosity
Permeability Ease of Flow Through a Rock
Related to Size of Pore and Pore Throats
Absolute and Relative Permeability
Volume of Hydrocarbons and Rate of Flow of Hydrocarbons Determines Economic Potential
Reservoir Simulation Develop Static Geomodel
Assist in Maximizing Profit
44
Assignments Reading for this week
Exploring for Oil and Gas Traps p. 17-22 & 38-43
Read Today in Energy for Tuesday (2/24) at http://www.eia.gov/
Be Prepared to Discuss in Class - Wednesday
Discussion Leader – Alexis Johnson
Test on Friday 2/27 During Class – Multiple Choice, True/False,
Short Essays