A geometrical method for migrating 3D or 2.5D seismic reflection data

Classical processing of 2.5D land seismic surveys has shown to yield unsatisfactory images, even though shot gathers show clear reflections and a good signal to noise ratio. If some major interfaces are easily identified within the stack volume, their 3D geometry remains difficult to appreciate because of a lack of continuity in the cross-receiver line direction. The theoretical aspects of an alternate method allowing a construction of these 3D structures an presented here. This method geometrically migrates picked reflection traveltimes on good quality shot gathers without amplitude or frequency considerations. It is tested on a synthetic dataset from a 3D smoothly deformed reflector that is well recovered by the technique and applied to major reflections of a 2.5D seismic survey, allowing a successful reconstruction of the reflectors.