A common misunderstanding

Because GGI data provides a superior measurement of high frequencies and thus more detailed geological resolution in the shallow earth section, a common misunderstanding in our industry is that GGI cannot measure longer wavelength information and therefore, deeper geological information is not acquired. This conclusion is in fact incorrect.

It can be demonstrated that at lower frequencies gravity begins to outperform gravity gradiometry but there is a lot of conjecture as to where the cross over comes between the respective systems and this is a function of each systems sensitivity. It has been shown that this cross over occurs at circa 20km for an airborne system. This means that GGI measures all wavelengths better than conventional gravity up to and including 20km. In fact, GGI continues to measure the longer wavelength information beyond 20km sufficiently well to resolve deep geology. For example GGI data has been used to resolve the base salt in deep water Gulf of Mexico at target depth in excess of 7.5km. Likewise the system has also been used extensively in North America to image rotated fault blocks in rifted sections and piggy back anticlines in the Rocky Mountain fold and thrust belt and the Utah Hinge Line. All surveys imaged structures at target depths in excess of 5 km.

Whilst GGI is capable of measuring longer wavelengths, ARKeX has recently modified its FTG systems to incorporate a Gravity Measurement Assembly (GMA). The GMA is integrated with the FTG system to provide an independent measure of the longer wavelengths. Using proprietary workflows and software the GMA data is combined with the FTG measurements. The result is that our systems have an improved signal to noise response across an increased bandwidth when compared to other instruments.