1. Bureau of Economic Geology APPLICATIONS OF 3-D SEISMIC TO EXPLORATION AND DEVELOPMENT OF CARBONATE RESERVOIRS: SOUTH COWDEN GRAYBURG FIELD,WEST TEXAS Stephen C. Ruppel, Yong-Joon Park, and F. Jerry Lucia Bureau of Economic Geology The John A. and Katherine G. Jackson School of Geosciences The University of Texas at Austin

2. Bureau of Economic Geology GEOLOGIC SETTING

3. 7 C N 1 G - J O W D E N O R T H R A Y B U R G A C K S O N 1 2 8 F N 2 V O S T E R A C U U M 9 9 S C 3 E - M O U T H O W D E N U N I C E O N U M E N T 3 1 0 W 4 K A D D E L L E Y S T O N E 1 1 D 5 M U N E A B E E C A R L S B A D 1 2 M E 6 M F C L R O Y I D L A N D A R M S 1 3 B L I G A K E 5 1 4 W O R L D 6 1 5 O L S O N G M U A D A L U P E T S N M E X 7 4 1 6 F A R M E R T E X A S 8 9 M i d l a n d S D I E R R A I A B L O 1 0 B a s i n 1 1 A M P A C H E T S D i a b l o 1 2 D e l a w a r e P l a t f o r m 1 3 B a s i n 1 6 1 4 0 5 0 m i F . S 1 5 T T O C K T O N Bureau of Economic Geology MAJOR GRAYBURG RESERVOIRS Permian Basin

4. GRAYBURG STRUCTURE South Cowden Field

5. W E Queen Fm. Q1 G4 G3 G2 G1 Guad San 13 Andres Fm. 50 ft Grain-dom. pack/gnstn Pel./skel. wacke/pkstn Siltstone Seq. boundary 0 Tidal flat Fusulinid wackestone High-freq. cycle ft 2000 0 Bureau of Economic Geology SEQUENCE ARCHITECTURE Grayburg Formation, South Cowden Field

6. 0 5 0 0 0 f t N 1 m 5 0 0 0 L a r g e - s c a l e a n h y d r i t e r e m o v a l ; c a l c i t e - l i n e d v u g s A l t e r e d a n h y d r i t e C o r e d w e l l s a n d g y p s u m Bureau N o d u l a r , p o i k i l o t o p i c a n d of Economic Geology O / W c o n t a c t v o i d - f i l l i n g a n h y d r i t e SULFATE DIAGENESIS South Cowden Grayburg Reservoir

7. Bureau of Economic Geology ANHYDRITE DISSOLUTION Grayburg Formation, South Cowden Field

8. N o . 1 3 - 1 1 N o . 9 - 1 7 N o . 8 - 1 2 Q u e e n N o . 6 - 1 6 N o . 6 - 2 0 G r a y b u r g N o . 7 - 1 N o . 7 - 4 O / W ( - 1 8 5 0 ) N o . 1 2 - 1 f t m 0 0 A b u n d a n t s u l f a t e , l o w p e r m . P a r t l y a l t e r e d s u l f a t e , g o o d p e r m . S u l f a t e a b s e n t , h i g h e s t p e r m . 5 0 0 0 f t 0 H i g h f r e q u e n c y s e q u e n c e 6 0 2 0 0 0 1 0 0 0 m C y c l e Bureau of Economic Geology PATTERNS OF SULFATE DIAGENESIS South Cowden Grayburg Reservoir

9. Permeability OWC kh < 100 kh 100 - 500 kh 500 - 1000 kh > 1000 Bureau of Economic Geology DISTRIBUTION OF PORE TYPES AND PERMEABILITY Pore Types OWC PILLARS

10. Permeability Cumulative Production OWC OWC PILLARS kh < 100 < 100 Mbbl kh 100 - 500 100-500 Mbbl kh 500 - 1000 500-1000 Mbbl kh > 1000 > 1000 Mbbl Bureau of Economic Geology PERMEABILITY AND PRODUCTION TRENDS UNDERPRODUCED AREAS

11. Bureau of Economic Geology 3-D INTERPRETATION OF STRUCTURAL SETTING

12. - 650 ms OWC - 700 ms - 750 ms - 800 ms 1 mile Bureau of Economic Geology SOUTH COWDEN FIELD STRUCTURETop Grayburg Moss Unit Two-way Travel Time South Cowden Unit

13. 500 ms 1000 ms 1 mile Bureau of Economic Geology 3-D SEISMIC STRATIGRAPHY South Cowden Field NW SE Yates Grayburg reservoir Queen Grayburg Lowstand wedge U San Andres Glorieta platform margin M L Clear Fork Moss Unit survey South Cowden survey

14. - 650 ms - 600 ms - 750 ms - 650 ms - 850 ms - 700 ms - 950 ms - 750 ms - 1050 ms - 800 ms 2 miles Bureau of Economic Geology DEVELOPMENT OF RESERVOIR STRUCTURE Top Clear Fork Structure Top Grayburg Structure Foster Unit OWC Moss Unit S. Cowden Unit

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20. Bureau of Economic Geology 3-D DELINEATION OF RESERVOIR POROSITY

21. 600 ms 700 ms 800 ms Grayburg Bureau of Economic Geology SEISMIC RESOLUTION OF RESERVOIR POROSITY Amplitude Queen San Andres Main Pay Zone

22. GR DT 700 ms - 5ms Grayburg -10ms -15ms -20ms 800 ms 1 mile Bureau of Economic Geology HORIZON SLICING OF RESERVOIR INTERVAL W E Queen 16-3A San Andres

23. OWC strong weak 2 mile Bureau of Economic Geology MAP OF SEISMIC AMPLITUDE Maximum Negative Amplitude20 ms window

24. 800 ms 700 ms + _ Bureau of Economic Geology NEGATIVE AMPLITUDE ARCHITECTURE NW SE GR DT GR DT Queen Grayburg San Andres

25. Permeability OWC OWC strong weak kh < 100 kh 100 - 500 kh 500 - 1000 2 mile kh > 1000 Bureau of Economic Geology COMPARISON OF SEISMIC AMPLITUDE AND CALCULATED PERMEABILITY Negative Amplitude (20 ms) PILLARS

26. Cumulative Production OWC OWC strong weak < 100 Mbbl 100-500 Mbbl 2 mile 500-1000 Mbbl > 1000 Mbbl Bureau of Economic Geology COMPARISON OF SEISMIC AMPLITUDE AND CUMULATIVE OIL PRODUCTION Negative Amplitude (20 ms)

27. Bureau of Economic Geology CONCLUSIONS • 3-D seismic data are a valuable compliment to wireline data in defining the structural setting and distribution of reservoir properties in the South Cowden Grayburg field. • 3-D data illustrate that the field owes its development to the deposition of a lowstand progradational wedge during the middle San Andres. • Regional data suggest that such progradational wedges may be common along the margin of the Central Basin platform where they provide the structural underpinnings for reservoir development. • Simple amplitude extraction provides an excellent image of phih and kh distribution which can be used to guide future field exploitation.