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Australian Energy Producers Journal Australian Energy Producers Journal Society
Journal of Australian Energy Producers
RESEARCH ARTICLE (Non peer reviewed)

Marine seismic triple source case studies from the Asia–Pacific region

Ed Hager
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Polarcus, One Fullerton, Singapore, 049213. Email: ed.hager@polarcus.com

The APPEA Journal 58(2) 816-820 https://doi.org/10.1071/AJ17131
Accepted: 1 March 2018   Published: 28 May 2018

Abstract

There has been a rapid uptake on the idea of using multiple sources in marine seismic data acquisition because of the additional flexibility the technique offers in survey design based not only on geophysical quality, but also for health, safety and environment (HSE) and efficiency. This paper examines three case studies conducted in Australia and Indonesia covering aspects of the advantages.

An important consideration in survey design is efficiency, and multisource designs improve this by allowing wider spreads to be towed, so more data is acquired per vessel pass. In turn, HSE exposure is decreased by reducing survey times and by reducing the amount of in-sea equipment.

The Trepang Survey carried out for Ophir Energy offshore West Papua was designed for efficiency, but the HSE aspect came to the fore when large amounts of floating debris (several hundred tree trunks) were found in the path of the survey vessel. By reducing the acquisition time, the risk the timber posed was minimised.

The Cygnus survey in the Vulcan sub-basin is an example of where the multisource technique increased quality by improving the cross-line resolution and increasing fold without decreasing efficiency.

Bianchi and Hockey were two surveys in the same area and, because the surveys were small, they were inefficient to acquire because much of the time was spent on line changes. The operator Quadrant used the fact that a triple-source design would allow for symmetrical bins to be acquired and joined the two small surveys together: effectively two sets of line change times were turned into acquisition time.

Keywords: broadband, exploration, survey.

Ed Hager is a graduate of Southampton University, where he studied Geophysical Sciences. Ed has been working in the geophysical industry since 1991, starting with Western Geophysical as an on-board field geophysicist. Since then he has spent time in geophysical support, data processing and survey design departments for WesternGeco, becoming Solution Design and Modelling Regional Manager for the Middle East Area before leaving in 2014. Since 2014, Ed had been working for Polarcus as area geophysicist for the Asia–Pacific region, helping develop and commercialise the ‘deep-tow’ broadband concept and multisource technologies, especially Penta Source as its inventor. In addition, Ed technically advises clients, particularly on survey design.