1. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX 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

2. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX THE SPRABERRY AND DEAN FOMATIONS have been interpreted as low-stand, have been interpreted as low-stand, submarine-fan deposits, e.g., Handford submarine-fan deposits, e.g., Handford (1981); Sarg (1989); Tyler and others (1997) (1981); Sarg (1989); Tyler and others (1997) record terrigenous clastics transport record terrigenous clastics transport into the Midland Basin in the Early Permian into the Midland Basin in the Early Permian include hydrocarbon reservoirs that include hydrocarbon reservoirs that collectively contain >10 billion bbl OOIP collectively contain >10 billion bbl OOIP

3. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX SPRABERRY AND DEAN RESERVOIRS SPRABERRY AND DEAN RESERVOIRS Naturally fractured siltstones and sandstones Naturally fractured siltstones and sandstones Low matrix porosity (<10%) locally enhanced Low matrix porosity (<10%) locally enhanced by mineral dissolution or reduced by by mineral dissolution or reduced by quartz and carbonate cement quartz and carbonate cement <1 md matrix permeability <1 md matrix permeability >1 darcy fracture permeability >1 darcy fracture permeability

4. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX SPRABERRY AND DEAN RESERVOIRS SPRABERRY AND DEAN RESERVOIRS Low recovery (<10%) Low recovery (<10%) Short-lived wells are common, but some Short-lived wells are common, but some wells in waterflood areas have long wells in waterflood areas have long production history production history Under-pressured Under-pressured Collectively contain >10 billion bbl OOIP Collectively contain >10 billion bbl OOIP

5. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX From Tyler and others (1997) SPRABERRY AND DEAN FORMATIONS (LOWER PERMIAN, LEONARDIAN), MIDLAND BASIN GEOLOGIC SETTING AND REPRESENTATIVE OIL FIELDS

6. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX STRATIGRAPHIC COLUMN - CENTRAL SPRABERRY TREND From Tyler and others (1997)

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

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

9. DEPOSITIONAL SETTING

10. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX SPRABERRY FORMATION OPERATIONAL UNITS OPERATIONAL UNITS

11. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX AB 1 1’1’ 1’1’ W-E CROSS SECTION SPRABERRY AND DEAN FORMATIONS

12. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX A West East B CENTRAL SPRABERRY TREND From Tyler and others (1997)

13. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX From Tyler and others (1997) SAND DISTRIBUTION

14. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX SPRABERRY FORMATION SAND DISPERSAL PATTERNS From Tyler and others (1997)

15. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX UNUNITIZED AREA CENTRAL SPRABERRY TREND AA’ A A’ cross section line Central Spreberry Trend

16. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX CENTRAL SPRABERRY TREND UNUNITIZED AREA

17. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX UPPER SPRABERRY OPERATIONAL UNIT Iuc NET SANDSTONE AND SILTSTONE

18. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX Photograph, boxed, slabbed core R S T U R Sandstone bed in Sohio Petroleum Co. reports EXPLANATION

19. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX SUN, JALONICK 2 CORE FACIES

20. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX SUN, JALONICK 2 CORE FACIES

21. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX DEAN STRUCTURE -5,000 -6500 -6000 -4000 MIDLAND BASIN

22. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX DEAN FM. OPERATIONAL UNITS

23. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX DEAN FM. CROSS SECTIONS W E

24. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX 23145 W 891067 E' DEAN FM. - NORTHERN MIDLAND BASIN

25. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX DEAN FM. NET SAND UNIT 4 20 MIDLAND BASIN

26. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX CENTRAL SPRABERRY TREND DEAN FM. CROSS SECTIONS

27. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX DEAN FM. – CENTRAL SPRABERRY TREND 2314567 231456

28. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX SPRABERRY TREND DEAN FM. NET SAND UNIT 4 REAGAN CO GLASSCOCK CO MIDLAND CO UPTON CO 15 25

29. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX DEAN CORE FACIES ACKERLY-DEAN WATERFLOOD UNIT N. MIDLAND BASIN

30. E Guevara, Bureau of Economic Geology, PBGSP Annual Meeting, 2/27-28/06, Austin, TX DEAN CORE FACIES ACKERLY-DEAN WATERFLOOD UNIT N. MIDLAND BASIN