Full Spectrum Gravity: a Case Study from the South Sumatra Basin

Abstract

During November 2016, in the South Sumatra Basin, CGG acquired two airborne Full Spectrum Gravity surveys, over 11,300km2. Full Spectrum Gravity combines the high resolution Falcon Airborne Gravity Gradiometry (AGG), and the sGrav airborne gravity systems. The sGrav is a proprietary strap-down gravimeter that recovers long wavelength gravity information that full tensor gradiometers cannot provide, and is a product a recent CGG R&D project. The South Sumatra basin is a mature area in terms of hydrocarbon exploration, with many known and producing oil and gas fields. One of the key reservoir units in this basin are the uplifted areas of Mesozoic and Eocene fractured and weathered basement consisting of granites and quartzites. These uplifted basement blocks provide a positive density contrast. The Full Spectrum Gravity data has provided detailed structural information, while preserving the regional context in terms of gravity signal. It shows an impressive correlation between the gravity highs and the known oil and gas fields, and has provided new leads in this mature area. This paper demonstrates how Full Spectrum Gravity data can drastically improve the information and interpretation achievable from 2D seismic, and even provide clarity where imaging on 3D seismic is poor. We show how the data allows better decisions to be made throughout the exploration process; from seismic positioning, through integrated interpretation projects, and ultimately drilling decisions, providing tangible cost savings to any exploration project.