
TY  - JOUR
A1  - Beresford, Greg 
T1  - Elastic modelling of reflectivity and AVO at the Elang Formation, Laminaria East
JF  - ASEG Extended Abstracts
JO  - ASEG Extended Abstracts
Y1  - 2001
VL  - 2001
IS  - 1
SP  - 1
EP  - 4
KW  - 
UR  - https://doi.org/10.1071/ASEG2001AB006 
N2  - The Elang formation produces a weak event which is virtually impossible to pick on conventionally processed seismic sections. Its top is difficult to define on wireline logs. A rigorous approach to modelling its reflectivity is as a superposition of reflections from a sequence of layers at = 2m thickness. This formation response verifies that AVO can be derived for interfaces near the top of the Elang if Vp, Vs and ? are averaged over at least 10m above and 10m below this interface. Using a depth of 3264m for Top Elang this method predicts a polarity reversal at ray parameter, p=0.105 s/km (about mid-streamer). However, at near-to-mid streamer offsets (p < 0.105 s/km) the reflectivity is too sensitive to depth to derive an AVO representative of the Elang. At Laminaria East, the full depth model predicts a peak/trough wavelet at the TWT near top Elang (3215ms) which is grossly influenced by the sidelobes of boundaries beneath the reservoir. At far offsets (p > 0.105 s/km) a consistent trough develops in the t-p formation response which extends out to an equivalent 8km source/receiver offset. This trough is clear on the full model seismogram when multiples and guided waves are suppressed. It may provide the basis for defining a more interpretable signature for the Elang by weighting far offsets traces and perhaps acquiring data out to very long offsets. 
ER  -

