1. Seismic expression relay ramps in the Taranaki Basin, New Zealand
AASPI
Seismic expression relay ramps in the Taranaki Basin, New Zealand
Pierre Karam, Shankar Mitra, Kurt Marfurt
1. Introduction:
3. Data Quality: A
Relay ramps are structures between fault segments that undergoes deformation as a result of faults displacements. The characteristics of the ramp is defined by the lithology, deformation conditions and strain amount (Peacock, 2001). To better understand its evolution we examine the history of the Parihaka fault by the mean of seismic attributes. Coherence, curvature and other attributes can help explain the degree of deformation of those ramps and the timing of structural events.
Some acquisition footprint are mainly observed on the southern part of the survey particularly in the shallow zone. However, those footprints do not affect the quality of the data. In general, the data is good where faulting and other geological features can be well be observed, mapped and modeled. A’
Fig(1). Time slice at 500ms showing seismic acquisition footprints
2. Geology Background:
4. Interpretation: A A’
The Taranaki Basin is an extensional basin offshore New Zealand with oil and gas potential. The Structural history of the basin is characterized by mainly 2 episodes of extensional deformations: (1) Late Cretaceous to Paleocene and (2) Late Miocene until recent (Giba et al. 2012). NW SE
Late Pliocene
Early Pliocene
The Parihaka fault defining the basin is a NE-SW set of three echelon faults connected by relay ramps. Displacement along those faults vary by location and age.
Miocene
Fault 1
Fault 2
Fig(2). Location of the Taranaki Basin and the Parihaka fault offshore New Zealand (after Giba et al, 2012)
Fig(3). NW-SE Cross-section showing interpreted horizons and faults on seismic amplitude.

2. (a) (b) (c) (d) (a) (b) (c) Fault 2 Fault 1 500ms 1200ms 1500ms 800ms
Opacity K1 K2
Opacity K1 K2
Opacity K1 K2
Opacity K1 K2
500ms
5km
5km
1200ms
5km
1500ms
5km
800ms
Fig(4). Most positive and negative curvatures co-rendered with coherence at time (a) 500ms with isolated non-connected faults, (b) 800ms with some faults breaching, (c)1200ms with faulted relay ramp, and (d) 1500ms with connected normal faults.
(a)
(b)
(c)
5km
5km
5km
Fig(6). Dip magnitude for different horizons (a) Late Pliocene, (b) Early Pliocene, and (c) Miocene examining structural deformation and horizons displacement using seismic attributes. Note breaching of the relay ramps in (b) and (c)
Fig( 5). Block Diagram of the geometry of relay ramps with different level showing different stages of relay ramp evolution corresponding to different displacements (after Peacock, 2001).
6. Conclusion:
7. References:
Giba, M., Walsh, J.J., Nicol, A., 2012 Segmentation and Growth of an Obliquely Reactivated Normal Fault. Journal of Structural Geology. Vol. 39:
Knox,G.J.,1982,Taranaki Basin, Structural Style and Tectonic Setting. New Zealand Journal of Geology and Geophysics. Vol.25:
Peacock, D.C.P., 2001, Propagation, Interaction and Linkage in Normal Fault Systems. Earth-Science Reviews. Vol. 58: 1-2.
Seismic attributes can help map and characterize relay ramps associated with normal faulting. The degree of faulting indicate the stage of the ramp evolution and insight on the timing of events.