Identification of Uncertain Parameters in a Tidal Model of the North Sea by SPSA

2010 ◽  
Author(s):  
M. U. Altaf ◽  
A. W. Heemink ◽  
M. Verlaan ◽  
Theodore E. Simos ◽  
George Psihoyios ◽  
...  
Keyword(s):  
North Sea ◽  
Uncertain Parameters ◽  
Tidal Model ◽  
The North ◽  
The North Sea

Long-term seafloor tidal gravity and pressure observations in the North Sea: Testing and validation of a theoretical tidal model

Geophysics ◽  
2008 ◽  
Vol 73 (6) ◽  
pp. WA143-WA148 ◽  
Author(s):  
Glenn Sasagawa ◽  
Mark Zumberge ◽  
Ola Eiken
Keyword(s):  
North Sea ◽  
Pressure Gauge ◽  
Earth Tide ◽  
Time Lapse ◽  
Pressure Measurements ◽  
Tidal Model ◽  
Tidal Gravity ◽  
The North ◽  
Ocean Loading ◽  
The North Sea

Seafloor gravity and pressure measurements for 4D reservoir monitoring require precise models of the time-varying tidal signals. Current seafloor instrumentation can resolve [Formula: see text] in time-lapse gravity differences and [Formula: see text] [Formula: see text] in pressure. To verify model accuracy, a seafloor gravimeter and pressure gauge were operated continuously for [Formula: see text] next to the Troll A gas platform in the North Sea (60.64227° north, 3.72417° east) at a depth of [Formula: see text]. The seafloor gravity and pressure time series were filtered and corrected with estimates from the tidal model, which predicts the solid earth tide, ocean loading, and direct gravitational attraction of the varying water level. The rms difference between the observed tidal gravity signal and the prediction is about [Formula: see text] during periods when there are no surface storms. A slight difference is observed for the direct attraction of the water overhead as computed from the tidal prediction versus that computed from direct seafloor pressure measurements when the entire [Formula: see text] record is analyzed; it shows an rms difference of [Formula: see text], equivalent to [Formula: see text] of water-height variation, yielding a gravity effect of [Formula: see text]. We conclude that existing theoretical tide models in combination with in situ pressure records are sufficiently precise for correcting time-lapse gravity observations.

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