West Franklin - How Geophysical Tenacity Led a Modest Franklin Satellite to a Full-Blown Field Development

摘要

The West Franklin HP/HT Field discovered in 2003 by the well 29/5b-F7z was drilled on a simple structure defined using the 1996 Elgin/Franklin 3D seismic - vintage data which has since been superseded by state-of-the-art seismic processing techniques. The original PSTM displayed relatively continuous seismic reflectivity with large uncertainty on imaging and interpretation. The highly productive porous sandstone interval within the Upper Jurassic Fulmar Formation was identified as a high amplitude reflector due to a strong decrease in impedance. Anisotropic PSDM processing followed by an acoustic inversion study highlighted the probable extension of this ‘Porous Zone’ to the west and underlined the high potential for a second appraisal/development well. Positive results from the second well 29/5b-F9y in 2007 showed dramatic thickening and improvement in reservoir quality to the west and initiated additional PSDM processing of the original 1996 data. Following developments in tomography and migration algorithms, strong imaging improvements were observed from the integrated anisotropic velocity model updates and by reducing the amount of destructive interference from multiples. The resulting interpretation allowed for a better understanding of the salt tectonics and in predicting Fulmar reservoir thickness to the west. A 7km Long Offset 3D survey acquired by CGGV in 2009 with subsequent PSDM processing is bringing further imaging improvements over areas of amplitude degradation leading to potential upsides. A first 4D monitor acquisition over Elgin/Franklin in 2005 (before production had started on West Franklin in 2007) is being followed-up by a second 4D monitor in 2011, aimed at providing additional information on the depletion pattern around the field. Such strategy in ongoing investment in seismic data will further unlock the resource potential over and around West Franklin in the coming years, ensuring a mature area remains in the spotlight.