Gravity and Magnetics

doi:10.1017/9781108913256.004

4 - Gravity and Magnetics

Published online by Cambridge University Press: 25 November 2021

Edited by

Keith Nunn and

Hamish Wilson: Affiliation:
BluEnergy Ltd
Keith Nunn: Affiliation:
Nunngeo Consulting Ltd
Matt Luheshi: Affiliation:
Leptis E&P Ltd

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Summary

The gravity and magnetic survey methods have been in use since the early days of geophysical prospecting for petroleum. They find most application in frontier exploration. In that context, regional and global datasets are often available to assist with early evaluations.

The design and execution of modern, targeted surveys has been transformed as a result of advances in instruments and the advent of satellite navigation. Imaging and interpretive techniques have been transformed by modern computer-based approaches. The potential field methods are extremely cost-effective at delineation of basins and determining structural controls on those basins, especially delineating normal faulting within rift basins. Magnetic surveys yield depth to basement and delineate any igneous rocks present. Such surveys therefore enable early decisions about cost-effective placement of seismic surveys and other intensive follow-ups.

In more mature exploration, gravity and gravity gradient data combine well with seismic data in distinguishing between alternate interpretations, thereby removing ambiguities. High-resolution magnetic data offer an effective means of fault connection in conjunction with regional seismic coverage, if shales or mudstones are present.

In a production environment, gravity logging is the most sensitive density log available, and 4D-gravity finds application in gas production and also water-flood monitoring.

Keywords

basement basement depth deconvolution density faults geoid gravity magnetic magnetite potential field regional geology structure susceptibility

Type: Chapter
Information: Integration of Geophysical Technologies in the Petroleum Industry , pp. 71 - 123

DOI: https://doi.org/10.1017/9781108913256.004 [Opens in a new window]

Publisher: Cambridge University Press

Print publication year: 2021

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4 - Gravity and Magnetics

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