4.18.24 Movement Legacies, Reflection, and Review.pptx
ÖNCEL AKADEMİ: INTRODUCTION TO SEISMOLOGY
1. Department of Earth Sciences KFUPM Introduction to Seismology Reservoir Induced Seismicity ( Reading Assignment: pp.384-386 ) Introduction to Seismology-KFUPM Ali Oncel [email_address]
8. Filling curves & Seismicity Rate Introduction to Seismology-KFUPM
9. Filling curves & large earthquakes Introduction to Seismology-KFUPM
10. • Earthquakes are associated with change in water level: with large scale filling of the dam, possibly with emptying • Seismicity often tapers off within ten years of water level stabilization • Variable time delays may occur between dam filling and earthquakes General characteristics of reservoir triggered seismicity Introduction to Seismology-KFUPM
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12. • Gas extraction greatly decreases pore pressure • Subsidence/earthquakes occur • Many small earthquakes in the Lacq Gas Field, France • Gazli gas field, Uzbekistan. Gas withdrawal started 1966; max production 1968-71. 2. M 7earthquakes in 1976, one in 1984. Were they induced?? • Some people have wondered about 1983 M 6.5 Coalinga earthquake, M 5.8 Does oil and gas extraction cause earthquakes? Introduction to Seismology-KFUPM
14. The seismic event was induced owing to stress changes caused by water injection (Ottemo¨ ller, et al., 2005, JGR, Vol.110). . Conclusion for 2001 EQ(M=4.4) Introduction to Seismology-KFUPM
15. Induced Event: M max : 4.3-1984 Introduction to Seismology-KFUPM
17. M max =4.3 Introduction to Seismology-KFUPM Injection rate Seismicity
18. Location of the Valhall and Ekofisk oil fields are shown in a map of the southern Norwegian North Sea (a). A profile along line AA' illustrates the dome structure of the Valhall oil field (b). Introduction to Seismology-KFUPM A B
23. Two event sub-clusters each delineating the intersection of two planes. Looking along line of intersection (top) and face-on views (bottom). Linear trends can be seen along fracture faces (bottom). The event sequences indicate early fluid invasion along linear trends.
24. Event rate changes correlate with production rate changes. Seismic response lags production by 2–3 weeks. Introduction to Seismology-KFUPM
25. Fracture planes are delineated by production-induced events occuring over a 6-month monitor period. Composite fault plane solutions indicate thrust displacement along the mapped, low-angle fractures. Induced stress changes are very small (<0.1 MPa). Introduction to Seismology-KFUPM
26. Small magnitude events were detected above the reservoir by placing a downhole receiver array within the upper 800 feet of an abandoned well. Event occurrence terminates near the base of the serpentine unit. WELL-BORE DEFORMATION The Geysers, California Introduction to Seismology-KFUPM
27. Both the above reservoir and the deeper reservoir seismicity show correlations with reservoir injection activity in the study area. WELL-BORE DEFORMATION The Geysers, California Introduction to Seismology-KFUPM