SPRABERRY AND DEAN SANDSTONES (LOWER PERMIAN, LEONARDIAN), MIDLAND BASIN, WEST TEXAS -

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

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 >10 billion bbl OOIP

SPRABERRY AND DEAN RESERVOIRS • Naturally fractured siltstones and sandstones • Low matrix porosity (<10%) locally enhanced • by mineral dissolution or reduced by • quartz and carbonate cement • <1 md matrix permeability • >1 darcy fracture permeability

SPRABERRY AND DEAN RESERVOIRS • Low recovery (<10%) • Short-lived wells are common, but some • wells in waterflood areas have long • production history • Under-pressured • Collectively contain >10 billion bbl OOIP

SPRABERRY AND DEAN FORMATIONS (LOWER PERMIAN, LEONARDIAN), MIDLAND BASIN GEOLOGIC SETTING AND REPRESENTATIVE OIL FIELDS From Tyler and others (1997)

STRATIGRAPHIC COLUMN - CENTRAL SPRABERRY TREND From Tyler and others (1997)

TUBB / DEAN / LOWER SPRABERRY STRATIGRAPHIC RELATIONSHIPS E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX QAd4871x

SPRABERRY AND DEAN DEPOSITIONAL SEQUENCES MIDLAND BASIN, WEST TEXAS E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX

DEPOSITIONAL SETTING

SPRABERRY FORMATION OPERATIONAL UNITS

1 W-E CROSS SECTION SPRABERRY AND DEAN FORMATIONS A B 1’ 1’

West East CENTRAL SPRABERRY TREND A B From Tyler and others (1997)

SAND DISTRIBUTION From Tyler and others (1997)

SPRABERRY FORMATION SAND DISPERSAL PATTERNS From Tyler and others (1997)

CENTRAL SPRABERRY TREND UNUNITIZED AREA A A’ Central Spreberry Trend AA’ cross section line

CENTRAL SPRABERRY TREND UNUNITIZED AREA

UPPER SPRABERRY OPERATIONAL UNIT Iuc NET SANDSTONE AND SILTSTONE

R S T U EXPLANATION R Sandstone bed in Sohio Petroleum Co. reports Photograph, boxed, slabbed core

SUN, JALONICK 2 CORE FACIES

DEAN STRUCTURE MIDLAND BASIN -6500 -6000 -4000 -5,000

DEAN FM. OPERATIONAL UNITS

DEAN FM. CROSS SECTIONS W E

DEAN FM. - NORTHERN MIDLAND BASIN E ' W 1 2 3 4 5 6 7 8 9 10

DEAN FM. NET SAND UNIT 4 MIDLAND BASIN 20

CENTRAL SPRABERRY TREND DEAN FM. CROSS SECTIONS

DEAN FM. – CENTRAL SPRABERRY TREND 1 2 3 4 5 6 7 1 2 3 4 5 6

SPRABERRY TREND DEAN FM. NET SAND UNIT 4 15 15 25 GLASSCOCK CO MIDLAND CO 15 UPTON CO REAGAN CO

DEAN CORE FACIES ACKERLY-DEAN WATERFLOOD UNIT N. MIDLAND BASIN

SPRABERRY AND DEAN SANDSTONES (LOWER PERMIAN, LEONARDIAN), MIDLAND BASIN, WEST TEXAS -