SPRABERRY AND DEAN SANDSTONES

1
SPRABERRY AND DEAN SANDSTONES (LOWER PERMIAN,
LEONARDIAN), MIDLAND BASIN, WEST TEXAS - MATURE
PETROLEUM RESERVOIRS, SIGNIFICANT REMAINING
RESOURCES PBGSP Bureau of Economic Geology The
University of Texas at Austin
Edgar H. Guevara
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• THE SPRABERRY AND DEAN FOMATIONS
• have been interpreted as low-stand,
• submarine-fan deposits, e.g., Handford
• (1981) Sarg (1989) Tyler and others (1997)
• record terrigenous clastics transport
• into the Midland Basin in the Early Permian
• include hydrocarbon reservoirs that
• collectively contain gt10 billion bbl OOIP

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• SPRABERRY AND DEAN RESERVOIRS
• Naturally fractured siltstones and sandstones
• Low matrix porosity (lt10) locally enhanced
• by mineral dissolution or reduced by
• quartz and carbonate cement
• lt1 md matrix permeability
• gt1 darcy fracture permeability

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• SPRABERRY AND DEAN RESERVOIRS
• Low recovery (lt10)
• Short-lived wells are common, but some
• wells in waterflood areas have long
• production history
• Under-pressured
• Collectively contain gt10 billion bbl OOIP

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SPRABERRY AND DEAN FORMATIONS (LOWER
PERMIAN, LEONARDIAN), MIDLAND BASIN GEOLOGIC
SETTING AND REPRESENTATIVE OIL FIELDS
From Tyler and others (1997)
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STRATIGRAPHIC COLUMN - CENTRAL SPRABERRY TREND
From Tyler and others (1997)
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TUBB / DEAN / LOWER SPRABERRY STRATIGRAPHIC
RELATIONSHIPS
E Guevara, Bureau of Economic Geology, PBGSP
Annual Meeting, 2/27-28/06, Austin, TX
QAd4871x
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SPRABERRY AND DEAN DEPOSITIONAL SEQUENCES
MIDLAND BASIN, WEST TEXAS
E Guevara, Bureau of Economic Geology, PBGSP
Annual Meeting, 2/27-28/06, Austin, TX
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DEPOSITIONAL SETTING
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SPRABERRY FORMATION OPERATIONAL UNITS
11
1
W-E CROSS SECTION SPRABERRY AND DEAN FORMATIONS
A
B
1
1
12
West
East
CENTRAL SPRABERRY TREND
A
B
From Tyler and others (1997)
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SAND DISTRIBUTION
From Tyler and others (1997)
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SPRABERRY FORMATION SAND DISPERSAL PATTERNS
From Tyler and others (1997)
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CENTRAL SPRABERRY TREND
UNUNITIZED AREA
A
A
Central Spreberry Trend
A A cross section line
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CENTRAL SPRABERRY TREND
UNUNITIZED AREA
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UPPER SPRABERRY OPERATIONAL UNIT Iuc NET
SANDSTONE AND SILTSTONE
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R
S
T
U
EXPLANATION
R Sandstone bed in Sohio Petroleum Co.
reports
Photograph, boxed, slabbed core
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SUN, JALONICK 2 CORE FACIES
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SUN, JALONICK 2 CORE FACIES
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DEAN STRUCTURE
MIDLAND BASIN
-6500
-6000
-4000
-5,000
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DEAN FM. OPERATIONAL UNITS
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DEAN FM. CROSS SECTIONS
W
E
24
DEAN FM. - NORTHERN MIDLAND BASIN
W
2
3
1
4
5
8
9
10
6
7
25
DEAN FM. NET SAND UNIT 4
MIDLAND BASIN
20
26
CENTRAL SPRABERRY TREND DEAN FM. CROSS SECTIONS
27
DEAN FM. CENTRAL SPRABERRY TREND
2
3
1
4
5
6
7
2
3
1
4
5
6
28
SPRABERRY TREND DEAN FM. NET SAND UNIT 4
15
15
25
GLASSCOCK CO
MIDLAND CO
15
UPTON CO
REAGAN CO
29
DEAN CORE FACIES ACKERLY-DEAN WATERFLOOD UNIT N.
MIDLAND BASIN
30
DEAN CORE FACIES ACKERLY-DEAN WATERFLOOD UNIT N.
MIDLAND BASIN