Calibrated seismic measurements for improved reservoir definition: a UKCS case study
| Autor: | Stephen Pickering, A. Furber, S. McHugo, J. Bacon |
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| Rok vydání: | 2005 |
| Předmět: | |
| Zdroj: | First Break. 23 |
| ISSN: | 1365-2397 0263-5046 |
| DOI: | 10.3997/1365-2397.23.1090.26767 |
| Popis: | Steve McHugo, John Bacon, Andrew Furber, and Steve Pickering of WesternGeco present a UK North Sea case study to show the benefits of recent advances in marine seismic imaging. In 2003, WesternGeco acquired a new high-resolution seismic survey for Chevron over the Captain field, UK North Sea. The seismic data were acquired using pointreceiver technology and processed using deterministic data-processing techniques. The objective of the new survey was to provide improved seismic imaging of the field, improve confidence in the detailed mapping of known reservoir zones, and identify new targets. The new survey took advantage of significant technological advances made in seismic exploration. These advances included calibrated point-receiver acquisition, streamer steering, high-accuracy acoustic positioning, and recording of near-field source signatures allowing for much more reliable and detailed images of the subsurface. This article focuses on the impact that sampling and near-field source measurements have on the quality of the final dataset. Background Rose (1999) describes some aspects of the reservoir characterization of the Captain oilfield and refers to issues associated with the seismic data used during appraisal and development. The field, in UKCS Block 13/22 (Figure 1) in the Western Moray Firth, produces heavy oil (19 to 21o API) from two Lower Cretaceous deepwater turbidite reservoirs and an Upper Jurassic shallow marine reservoir. The field was discovered in 1977 and was brought into production in 1997 using closely spaced long-reach horizontal wells. Field appraisal was performed using more than 25 vertical delineation wells; these, combined with existing 1990 vintage seismic data, yielded a top reservoir structure map that has been used to land many long-reach high net-togross horizontal development wells. The 1990 seismic survey, however, provided poor overall imaging and depth estimates of the reservoir zones because of weak signal-to-noise ratio and limited resolution at the key target reflectors. This was primarily caused by known geophysical problems associated with the relatively weak seismic reflectivity of the target sands and the complex geology of the overburden. The new seismic survey was charged with overcoming these geophysical problems. |
| Databáze: | OpenAIRE |
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