Design of Surface Seismic Programs for CO2 Storage Monitoring. WesternGeco North America Geophysics Manager Houston

Transcription

1 Design of Surface Seismic Programs for CO2 Storage Monitoring Mark S. Egan WesternGeco North America Geophysics Manager Houston

2 Objectives Baseline seismic program Structure & stratigraphy of the storage tank & overburden Volume of the storage tank Is the storage tank is sealed? Barriers within the tank Repeat seismic programs Where is the CO2 going? Is it escaping? Objectives of the survey design Survey design required to meet the above objectives Permitting restrictions

3 Agenda Deliverables Image of the subsurface Rock properties (porosity, etc.) Geophysical issues Illumination Resolution Repeatability Signal-to-Noise ratio Survey design parameters 2D vs. 3D Shooting direction Narrow azimuth vs. wide azimuth Aperture Source-receiver distances Sampling

4 Imaging Seismic 35 Hz Ultrasound 3,500,000 Hz

5 The Seismic Method Arrival times Amplitudes seismic source geophone groups ρ, I p, I s ρ, I p, I s ρ, I p, I s

6 The Seismic Method 2 km 7 km km 6 km

7 The Seismic Method

8 The Seismic Method

9 The Seismic Method

10 The Seismic Method

11 The Seismic Method 2D survey

12 The Seismic Method

13 The Seismic Method

14 The Seismic Method

15 The Seismic Method

16 The Seismic Method

17 The Seismic Method

18 The Seismic Method 3D survey

19 Illumination

20 Illumination

21 Imaging analogy

22 Illumination problems from complex overburdens

23 Imaging analogy

24 Imaging analogy Shooting direction All azimuths needed? d

25 Illumination problems from complex overburdens Narrow azimuth 3D survey

26 Illumination problems from complex overburdens Wide azimuth 3D survey

27 Illumination problems from complex overburdens Wide azimuth 3D survey

28 Survey Design Ray tracing (Requires an earth model)

29 Survey Design Ray tracing (Requires an earth model)

30 Survey Design Ray tracing (Requires an earth model) Low Hit Count High

31 Illumination maps from a survey design study Dip Shooting Strike Shooting 45 Shooting (A top-salt boundary) Low Hit Count High In some surveys, a single shooting direction is not sufficient.

32 Illumination maps from another study (A base-salt boundary) Low 1-azimuth Hit Count All azimuths High

33 Illumination Data courtesy of BHP Billiton, Hess Corporation and Repsol YPF Narrow-azimuth 3D Wide-azimuth 3D

34 Illumination So we see that illumination requirements impact the width of the geophone spread and/or the number of source points seismic survey? what about the size of the survey? Aperture

35 Illumination seismic survey Aperture

36 Aperture 15,000-ft aperture 34,000-ft aperture

37 So we see that aperture decisions impact the size of the seismic survey what about the influence of aperture on resolution?

38 Lateral resolution

39 Lateral resolution

40 Lateral resolution 300 m 400 m 20 m

41 Lateral resolution 300 m 400 m 20 m

42 Lateral Resolution in Imaged Section Imaging aperture 300 m 20 m gap Imaging aperture 1000 m

43 Faults and Fracture Networks Acoustic Impedance Poisson s Ratio

44 Faults and Fracture Networks Acoustic impedance Poisson s Ratio

45 An example of monitoring from the North Sea Started production in 1997 Gas and water injection Seismic surveys in 1992, 2001, 2003, The 1992 survey used conventional technology Subsequent surveys used better repeatable technology

46 Comparison of the 2001 & 2003 seismic programs

47 Comparison of the 2001 & 2003 seismic programs Water injection OWC movement 2003 velocity pull-down 2003 Difference

48 Comparison of monitoring differences full DP difference final DP difference 4 years production 2 years production

49 An additional way to improve resolution - denser sampling

50 The Seismic Method seismic source geophone groups ρ, I p, I s ρ, I p, I s ρ, I p, I s

51 The Seismic Method with denser sampling seismic source geophone groups ρ, I p, I s ρ, I p, I s ρ, I p, I s

52 Example from Texas 0 Feet Q-Land single-sensor data (Decimated) ~3000 Horizontal slice ~1300 ft depth

53 Example from Kuwait Producer Injector Conventional data interpretation shows the fluids should flow freely Producer Injector Q-Land single-sensor data interpretation shows baffles impeding flow

54 The Seismic Method Arrival times Amplitudes seismic source geophone groups ρ, I p, I s ρ, I p, I s ρ, I p, I s

55 The Seismic Method Arrival times Amplitudes seismic source geophone groups ρ, I p, I s ρ, I p, I s ρ, I p, I s

56 The Seismic Method Arrival times Amplitudes seismic source geophone groups ρ, I p, I s Reservoir Properties Lithology Porosity Fluids Saturation ρ, I p, I s ρ, I p, I s

57 Reflection Amp Log Data Φ Porosity R = I p1 I p2 ΔI p 2 I pavg I P di I P P = ln ( I ) P

58 Reflection Amp Single-sensor survey Log Data Porosity Φ porosity I P 0% 32%

59 Summary Survey design parameters 2D vs. 3D Shooting direction Narrow azimuth vs. wide azimuth Aperture Source-receiver distances Sampling

60 Summary Survey design parameters 2D vs. 3D Shooting direction Narrow azimuth vs. wide azimuth Aperture Source-receiver distances Sampling

61 Summary Survey design parameters 2D vs. 3D Shooting direction Narrow azimuth vs. wide azimuth Aperture Source-receiver distances Sampling

62 Summary Survey design parameters 2D vs. 3D Shooting direction Narrow azimuth vs. wide azimuth Aperture Source-receiver distances Sampling

63 Summary Survey design parameters 2D vs. 3D Shooting direction Narrow azimuth vs. wide azimuth Aperture Source-receiver distances Sampling

64 Summary Survey design parameters 2D vs. 3D Shooting direction Narrow azimuth vs. wide azimuth Aperture Source-receiver distances Sampling

65 Summary Survey design parameters 2D vs. 3D Shooting direction Narrow azimuth vs. wide azimuth Aperture Source-receiver distances Sampling

66 Summary Survey design parameters 2D vs. 3D Shooting direction Narrow azimuth vs. wide azimuth Aperture Source-receiver distances Sampling

67 Summary Noise!!! Survey design parameters 2D vs. 3D Shooting direction Narrow azimuth vs. wide azimuth Aperture Source-receiver distances Sampling Modeled shot record