Bob Hardage's gas hydrates talk.

1. Bureau of Economic Geology Centennial Lecture Program DEEP-WATER HYDRATES: ENERGY POTENTIAL AND TECHNICAL CHALLENGES Dr. Bob A. Hardage

4. Bureau Facilities in Austin, Texas

5. What is hydrate?

6. Definitions Clathratus : Latin word meaning “enclosed by bars.” Clathrate: Any compound formed by the inclusion of one kind of molecule within cavities in the crystal lattice of another kind of molecule. (No chemical bonds constrain the trapped molecule.) Hydrate: A subgroup of clathrates involving gas molecules trapped inside structured water molecules.

7. Clathrate Hydrate of Natural Gases Structure I

8. The Energy Potential

9. Size Comparisons One “very fine” mineral grain One unit volume of hydrate Diameter ~ 60μm Diameter ~ 6nm 10 12 unit volumes required to fill the grain QAd6959F

10. Size Comparison of Hydrate Unit Volume and Typical Pores QAd6609 Micrograph courtesy Robert G. Loucks, BEG 0.1 mm Structure I Unit Volume Frio Sandstone (  = 30%) Pore diameter ~6x10 -5 m ~10 13 unit volumes of hydrate in one pore space 3x10 -9 m

11. Hydrates as an Energy Source QAd6959 Energy density of LNG Energy density of hydrate = 0.42

12. Exposed Structure II Gas Hydrate Block GC 185 QAd5851

13. Deep-Water Oil Seeps and Hydrate Gulf of Mexico QAd5901

14. The Carrot Dangled by the Government

15. Energy Policy Act of 2005

16. Technical Challenge: How do you find deep-water hydrate?

17. Characteristics of Deep-Water Hydrate Systems Deep water Hydrate stability zone Free-gas zone Gas/water contact BSR (Bottom-simulating reflector) Sea floor Bright reflectivity Expulsion crater QAd6937D

18. BSR Event: Gulf of Mexico, Line A 1.5 2.0 Time (s) QAd5890(a)

19. BSR Event: Gulf of Mexico, Line A QAd5890 1.5 2.0 Time (s)

20. Characteristics of Deep-Water Hydrate Systems Deep water Hydrate stability zone Free-gas zone Gas/water contact BSR (Bottom-simulating reflector) Sea floor Bright reflectivity Expulsion crater QAd6937D

21. Study Site 2: Genesis Field Area Block GC 205 QAd6510

22. Technical Challenge: How do you evaluate the resource?

23. The Expensive Option: Drill a well.

24. Hydrate Log Data: Blake Ridge (ODP 995) QAd5173 G R ( A P I ) 3 0 8 0 1 . 1 0 . 7 1 . 6 1 . 9 1 . 5 1 . 9 B u l k - d e n s i t y V e l o c i t y R e s i s t i v i t y g / c m 3 k m / s e c o h m - m Hydrate ~0.2  -m 400 600 500 300 200 Depth below seafloor (m) Paull and others (1996)

25. A More Attractive Option: Develop a remote, large-area evaluation technology (seismic imaging?).

26. VSP AND DEEP-WATER OBC/OBS DATA ACQUISITION: SIMILAR ELEVATION DIFFERENCES BETWEEN SOURCES AND RECEIVERS QAd4647 VSP OBC/OBS Vibrator Well Air gun Deep water Similar geometry Seafloor Sea level Multicomponent sensor Multicomponent sensor Source station Source station

27. 4-C OBC COMMON-RECEIVER GATHER, CDP 13949, LINE 549, BLOCK 204 (50-m SHOT SPACING) QAd4171

28. COMMON-RECEIVER GATHERS IN REDUCED-TIME FORMAT WITH SPHERICAL DIVERGENCE CORRECTION QAd4172

29. BASIC RESPONSES OF OBC SENSORS QAd4170

30. SEPARATING DOWNGOING AND UPGOING WAVEFIELDS QAd4175

31. Hydrophone/15 (P) Vertical geophone (Z) 2.0 1.5 1.0 0.5 -2000 0 2000 Time (s) Time (s) 2.0 1.5 1.0 0.5 -2000 0 2000 Source offset (m) Source offset (m) QAd4612x GAS HYDRATE OBC VSP EXAMPLE 1

32. Down wave Up wave 2.0 1.5 1.0 0.5 -2000 0 2000 Time (s) Time (s) 2.0 1.5 1.0 0.5 -2000 0 2000 Source offset (m) Source offset (m) SEPARATION OF DOWN AND UP WAVEFIELDS: COMMON-RECEIVER GATHER, WATER DEPTH = 871 M SEPARATION OF DOWN AND UP WAVEFIELDS: COMMON-RECEIVER GATHER, WATER DEPTH = 871 M P + Z / cos(  ) P - Z / cos(  ) QAd4613x

33. Seafloor 0.5 0.3 0.1 0 -2000 0 Time (s) Source offset (m) 0.4 0.2 2000 P-P REFLECTIVITY: SEAFLOOR DATUM (1) Reflectivity (f) = Up wave (f) Down wave (f) + (2) Damping + (3) Inverse Fourier transform + (4) Time derivative QAd4614x

34. HORIZON-ORIENTED STATIC CORRECTIONS: IDEAL FOR ANGLE-DEPENDENT REFLECTIVITY AND VELOCITY ANALYSIS Pre-NMO 3.5 2.5 1.0 0 -2000 0 2000 Time below seafloor (s) Source offset (m) 0.5 1.5 2.0 3.0 d dt (PP) Static corrected -2000 0 2000 Source offset (m) 0.24 0.20 0.16 0.08 Time below seafloor (s) 0.12 QAd4620x Target event

35. COMPARISON OF DYNAMIC CORRECTIONS AND HORIZON- ORIENTED STATIC CORRECTIONS, WATER DEPTH = 871 M QAd4619x Static corrections Dynamic corrections 0.24 0.20 0.16 0.08 -2000 0 2000 Time below seafloor (s) -2000 0 2000 Source offset (m) Source offset (m) 0.12 0.24 0.20 0.16 0.08 Time below seafloor (s) 0.12

36. NMO-CORRECTED COMMON-RECEIVER GATHER WITH DEPTH-POINT-OFFSET OVERLAY, WATER DEPTH 871 M QAd4618x 0.35 0.25 0.15 0.10 -2000 0 Time below seafloor (s) 0.30 0.20 2000 1000 -1000 0.05 0 Source offset (m) Depth point offset 10 m 85 m 160 m

37. CONSTRUCTING P-P IMAGE WITH VSP MINI-IMAGES

38. BASIC RESPONSES OF OBC SENSORS QAd4170

39. ISOLATING THE P-SV MODE HL = Hemipelagic layer QAd4177

40. QAd4179 Before After EMPHASIZING P-SV EVENTS, LINE 549, BLOCK GC204

41. QAd4181 ESTIMATION OF P-SV REFLECTIVITY

42. QAd4771 PS DATA, DYNAMIC TIME CORRECTIONS

43. CONSTRUCTING P-SV IMAGE WITH VSP MINI-IMAGES QAd5877

44. Comparison of PP Images QAd4760 R e c e i v e r n u m b e r 5 0 1 0 0 1 5 0 P P i m a g e ( 5 - m s p a c i n g ) 3 5 0 0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 R e c e i v e r n u m b e r 5 0 1 0 0 1 5 0 P r o d u c t i o n P P ( 1 2 . 5 - m C D P ) 3 5 0 0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 S e a f l o o r E x p u l s i o n c h i m n e y E x p u l s i o n c h i m n e y 4 k m 4 k m Reduced time (ms) PP time (ms)

45. Chirp Sonar Data, Line 549 Time (ms) QAd4234(a)

46. Comparison of P-SV Image with AUV P-P Image QAd4767 PS time (ms) Vp/Vs = 34 PP time (ms) R e c e i v e r n u m b e r C h i r p - s o n a r ( 2 5 - m s p a c i n g ) 0 5 1 0 R e c e i v e r n u m b e r N e w P S p r o c e s s i n g 3 5 0 0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 4 0 0 4 5 0 2 0 2 5 2 0 1 0 0 1 6 0 4 0 6 0 8 0 1 2 0 1 4 0 2 0 1 0 0 1 6 0 4 0 6 0 8 0 1 2 0 1 4 0 1 5 V p / V s - 5 0 - 5 0 5 8 S e a f l o o r 3 4 2 7 U n c o n f o r m i t y R 0 1 4 4 k m 4 k m s u r f a c e

47. Hydrate Log Data: Blake Ridge (ODP 995) QAd5173 G R ( A P I ) 3 0 8 0 1 . 1 0 . 7 1 . 6 1 . 9 1 . 5 1 . 9 B u l k - d e n s i t y V e l o c i t y R e s i s t i v i t y g / c m 3 k m / s e c o h m - m Hydrate ~0.2  -m 400 600 500 300 200 Depth below seafloor (m) Paull and others (1996)

48. ACCURACY OF INTERVAL VP (< 1%?)

49. Technical Challenge: You have to know the morphology if velocity is used to estimate hydrate concentration

50. Hydrate/Sediment Grain-to-Grain Morphology Models Model C: Layered, Solid Phase Model D: Layered, Disseminated Phase Model A: Disseminated, Load-bearing Model B: Disseminated, Non-Load-Bearing Sediment Hydrate QAd4571

51. Model-Based Vp, Host Sediment = Sand, Porosity = 0.37 0 0.1 0.2 0.3 0.4 1500 2000 2500 3000 3500 4000 Vp [m/s] Model C: Layered, Solid Phase 0 0.1 0.2 0.3 0.4 1500 2000 2500 3000 3500 4000 Vp [m/s] C gh = volume fraction of gas hydrate Model D: Layered, Disseminated Phase 0 0.1 0.2 0.3 0.4 1500 2000 2500 3000 3500 4000 Vp [m/s] Model A: Disseminated, Load-bearing 0 0.1 0.2 0.3 0.4 1500 2000 2500 3000 3500 4000 Vp [m/s] Model B: Disseminated, Non-Load-Bearing Fast Slow Fast Slow c gh c gh QAd4572

52. Hydrate Cores: Offshore Korea QAd6545

53. The Biggest Technical Challenge: How do you produce the hydrate?

54. Stability Domains: Hydrate, Ice, Methane Depth (m) Pressure (atm) QAd4240 Modified from Kvenvolden (1998)

55. So, how do we summarize the technical challenges?

56. “ Reports that say that something hasn’t happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are things we know we don’t know. But there are also unknown unknowns — the ones we don’t know we don’t know.” Donald Rumsfeld Department of Defense News Briefing February 12, 2002

57. ACKNOWLEDGEMENT ● U.S. Department of Energy Contract DE-FC26-05NT42667 ● Minerals Management Service Contract 1435-01-05-CT-39388 Hydrate research funded by: