Quantifying Rise in Gas Water Contact from Time-Lapse Seismic on the Sleipner Øst Field

Alsos, T.; Tøndel, Richard; Aanvik, F.; Solheim, Odd Arve

doi:10.3997/2214-4609-pdb.6.a08

Cited by 4 publications

(3 citation statements)

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“…For our purposes, it is assumed that the reservoir is produced naturally through a strong basal aquifer drive. Although applicable only to an oil-water system, this analysis is equally appropriate for the gas-water case such as that of Alsos et al (2003). Further issues relating to other reservoir connectivity scenarios and stacking patterns in turbidite sands are discussed in a separate study (Al-Maskeri and MacBeth 2003).…”

Section: Rocksmentioning

confidence: 99%

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The 4D seismic signature of oil–water contact movement due to natural production in a stacked turbidite reservoir

MacBeth

Stephen

McInally

2005

Geophysical Prospecting

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A B S T R A C TCombined time-lapse reservoir simulation and seismic modelling has been performed on both 1D and 3D models of a channelized turbidite reservoir. The models have been built using core, log, laboratory and seismic data from the Nelson Field (central North Sea) as a template. Oil and water movement in the main channels, channel margins and interchannel regions is investigated, with a particular focus being the effect of poor net-to-gross. The analysis confirms that saturation effects dominate the response whilst stress-sensitivity effects play a minor role. The trough-peak signature in the seismic difference volumes formed by the sweep of the water can be continued and mapped slightly further than the channel margins. This characteristic 4D signature remains roughly intact, despite the complicated depositional architecture, and accurately delineates the area of moved fluid, but it needs additional calibration to combat the detrimental influence of the low net-to-gross. Signal strength is largely dependent on reservoir quality, but is also compromised by the net-to-gross, fluid distribution and, more critically, by the exact timing of the seismic survey. For example, a region of bypassed oil zone remains undetected as it forms early during the production. This work demonstrates that to understand fully the 4D signature at a quantitative level requires adequate knowledge of the fluid properties, but also, more critically, the geology.

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Section: Rocksmentioning

confidence: 99%

“…For our purposes, it is assumed that the reservoir is produced naturally through a strong basal aquifer drive. Although applicable only to an oil–water system, this analysis is equally appropriate for the gas–water case such as that of Alsos et al . (2003).…”

Section: Introductionmentioning

confidence: 99%

The 4D seismic signature of oil–water contact movement due to natural production in a stacked turbidite reservoir

MacBeth

Stephen

McInally

2005

Geophysical Prospecting

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“…4D seismic data has been mostly used to track the displacement of a single hydrocarbon phase by water (e.g. Koster et al 2000;Alsos et al 2003;Kloosterman et al 2003), sometimes used to monitor pressure changes (e.g. Landrø 2001;Hatchell et al 2003;Staples et al 2004, paper presented at joint SPE/EAGE workshop, http://www.spe.org/specma/binary/ files/2483651eage sess2 staples.pdf), and occasionally used to measure compaction (e.g.…”

Section: Introductionmentioning

confidence: 99%

4D Seismic for Oil Rim Monitoring

Staples¹,

Hague²,

Weisenborn³

et al. 2003

65th EAGE Conference &Amp; Exhibition

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4D seismic for oil‐rim monitoring

Staples

Hague

Weisenborn

et al. 2005

Geophysical Prospecting

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In the central North Sea ‘Gannet‐A’ field, a 50 ft oil rim is overlain by a gas cap of variable thickness. Oil is produced from horizontal wells which initially produced dry oil, but as the field became more mature, a significant water cut was seen in several wells. A dedicated 4D seismic monitor survey was acquired in order to assess the remaining distribution of oil reserves. By forward modelling the synthetic seismic response to parameters such as contact movement and residual saturations (using 2D and 3D wedge models), and comparing the results with real seismic data, we are able to decipher the contact movements across the field. It is shown that, in one part of the field, the increased water cut is caused primarily by the vertical displacement of the entire oil rim into the initial gas cap. This oil‐rim displacement produces a very different 4D seismic response from the case of a static gas–oil contact and rising oil–water contact (normal production). As a result of these observations, we are able to optimize field production by both re‐perforation of existing wells and by drilling sidetracks into the displaced rim: a brown‐field development opportunity that might otherwise be missed.

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Quantifying Rise in Gas Water Contact from Time-Lapse Seismic on the Sleipner Øst Field

Cited by 4 publications

References 0 publications

The 4D seismic signature of oil–water contact movement due to natural production in a stacked turbidite reservoir

The 4D seismic signature of oil–water contact movement due to natural production in a stacked turbidite reservoir

4D Seismic for Oil Rim Monitoring

4D seismic for oil‐rim monitoring

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