Correcting for water-column variations

Lacombe, C.; Butt, Suhail; Mackenzie, Graeme; Schons, M.; Bornard, R.

doi:10.1190/1.3086058

Cited by 19 publications

(17 citation statements)

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“…As Lacombe et al (2009) describe, such variations fall into two categories. During that time -and certainly between baseline and monitor surveys -the properties of the water column can change significantly.…”

Section: Water-column Staticsmentioning

confidence: 99%

“…First, tides, weather, and currents affect the elevation of the sea surface. To correct for water-column velocity changes (often called "cold-water statics"), Lacombe et al (2009) use a method based on direct measurements of the rms water velocity and the waterbottom zerooffset arrival time derived from the seismic data. This second category is particularly important in deepwater fields, as illustrated in Figure 11.…”

Section: Water-column Staticsmentioning

confidence: 99%

“…inversion of individual baseline and monitor data sets to impedance models, which are then differenced to obtain impedance changes • inversion of baseline data to obtain a baseline impedance model, which is subsequently used as the initial model in the inversion of monitor data; the impedance models are then differenced to obtain a time-lapse impedance model (see also Lafet et al [2005]) • inversion of seismic differences (see also Buland and El Ouair [2006])…”

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Practical Applications of Time-lapse Seismic Data

Johnston

2013

121

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Section: Water-column Staticsmentioning

confidence: 99%

Section: Water-column Staticsmentioning

confidence: 99%

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confidence: 99%

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Practical Applications of Time-lapse Seismic Data

Johnston

2013

121

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“…Water layer variability also complicates the suppression of multiples from water layer reverberations (Jakubowicz 2006;Hatchell et al 2008;Hardy & Jones 2009). Four-dimensional seismic surveying compounds these problems (Bertrand & Macbeth 2003;Lacombe et al 2009). Other risks related to oceanic variability affect prospect evaluation and production (Vogel & Symonds 2002).…”

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confidence: 98%

“…Variation in sound speed within ocean water can cause problems in sub-seabed seismic reflection imaging (Wombell 1997;Barley 1999;Bertrand & Macbeth 2003;Mackay et al 2003;Xu & Pham 2003;Lacombe et al 2006Lacombe et al , 2009. Water layer sound speed variations arise from natural variations in temperature and salinity associated with oceanic currents.…”

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confidence: 99%

Seismic imaging of variable water layer sound speed in Rockall Trough, NE Atlantic and implications for seismic surveying in deep water

Jones

Sutton

Hardy

et al. 2010

PGC

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Natural variation in sound speed within ocean water can degrade sub-seabed images from 2D, 3D and 4D seismic reflection datasets. Degrading effects include vertical offset of reflections between adjacent or intersecting sail lines and difficulties in suppressing multiples from water layer reverberations. Here we investigate water layer variability in Rockall Trough, offshore Ireland, in water depths ranging from 200 m to 3.5 km. A compilation of vertical sound speed profiles, calculated from temperature and salinity profiles obtained by probes lowered from ships, shows that the mean sound speed in the water layer mostly varies between 1490 and 1500 m s 21 . Vertical offsets of up to about 15 ms two-way travel time are predicted at seismic line intersections. A significant amount of the total observed sound speed variability can occur along a single seismic sail line. These effects result mainly from spatial and temporal fluctuations in the thicknesses of, and vertical sound speed gradients within, an upper layer of North Atlantic Central Water and a mid-depth layer of Mediterranean Outflow Water. Seismic sections across Rockall Trough commonly show lateral variability in reflectivity within these same two water layers. Some reflective packages contain lens-shaped structures consisting of reflective rims and transparent cores and with diameters between 10 and 50 km. Other reflective packages have abrupt, almost vertical boundaries and no distinct transparent core. We infer that the lateral boundaries of the reflective packages are likely to be associated with significant variations in average water layer sound speed. When processing 2D, 3D and 4D seismic surveys of regions of high oceanic variability, such as Rockall Trough, it is necessary to employ techniques that can solve for and then remove the effect of significant fluctuations in water layer sound speed over time periods as short as a few hours and distances as short as a kilometre.

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A simple method of correction for profile-length water-column height variations in high-resolution, shallow-water seismic data

Kim

Lee

et al. 2017

Ocean Sci. J.

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Correcting for water-column variations

Cited by 19 publications

References 0 publications

Practical Applications of Time-lapse Seismic Data

Practical Applications of Time-lapse Seismic Data

Seismic imaging of variable water layer sound speed in Rockall Trough, NE Atlantic and implications for seismic surveying in deep water

A simple method of correction for profile-length water-column height variations in high-resolution, shallow-water seismic data

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