1887
Volume 24 Number 2
  • ISSN: 0263-5046
  • E-ISSN: 1365-2397

Abstract

Boff Anderson, Peter van Baaren, Mark Daly, Will Grace, John Quigley, and Denis Sweeney of WesternGeco explain how the ‘interleaving’ of seismic surveys provides benefits in terms of time saved between exploration and development as well as reduced investment in seismic data acquisition over the asset life cycle. The traditional cycle of land seismic exploration first employs a broad regional 2D seismic exploration survey with widely spaced seismic lines. After initial interpretation, a further 2D grid of intersecting lines is acquired over large areas of interest. This grid would normally have lines intersecting every few kilometers or closer. Following up on these programmes there is often a need for 3D surveys to image discovered structures of interest in greater detail to provide information for well planning. 3D surveys may subsequently be repeated several times through the life of the field to successively improve the subsurface image and, hence, help guide the reservoir management process. This article demonstrates a solution for two of the main drawbacks to this traditional cycle of acquiring land seismic data: the time taken to move through the seismic exploration cycle, and the inefficient use of seismic surveys through the life cycle of an asset. Shortening the asset development cycle time The time between starting a 2D exploration programme and receiving high-quality images from 3D surveys suitable to make business decisions, such as planning drilling locations or placing surface facilities, can be significant. Initial 2D seismic data must be recorded, tapes shipped to a processing centre (often out of country), then processed and interpreted. The cycle is then repeated with 3D seismic surveys acquired one or more times to generate images of sufficient quality over the right areas to enable the business decisions to be made. This cycle can take one or more years to complete. The ideal exploration seismic survey scenario would allow immediate pursuit of exploration leads to appraise structures of interest as they are identified. A crew’s acquisition plan could be adjusted to record infill seismic data over the identified lead. This idea can be compared to recording infill lines in a marine seismic survey. Rather than the marine case of infilling to improve fold that was ‘missed’ on the first pass, in land acquisition, infilling can be used to improve the resolution of an image through increasing the trace density over structures as they are identified. On land, rather than referring to infill, the term ‘interleaving’ is more descriptive. Two step changes in acquisition and processing methodology are required to make this possible: first, the initial data must be acquired in a sparse 3D mode rather than a closely spaced 2D programme, and second, the data must be processed through to an interpretable image within the time frame of the acquisition.

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/content/journals/0.3997/1365-2397.24.1092.26845
2006-02-01
2024-03-29
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  • Article Type: Research Article
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