Application of 3D Optical Fibre Reflection Seismic in Challenging Surface Conditions

Abstract

Distributed Acoustic Sensing (DAS), which uses strain-induced optical distortion effects to use optical fibres as multi-channel seismic arrays, enable efficient and inexpensive high-resolution seismic surveying in the challenging surface conditions, such as salt lakes. In this study, we present a first published 3D seismic survey completed with a fibre optic network. Since DAS cables freely deployed on surface can be sensitive to ambient noise such as strong wind, which is common in many field conditions, we developed an efficient methodology for cable burring by fast ploughing it in both soft and hard ground conditions. Even a standard telecommunication fibre optic cable deployed beneath the surface by this ploughing method delivers reflection seismic recording performance comparable to conventional geophone systems, offering substantial cost savings in practice. Combined with light and mobile seismic sources such as Betsy gun, DAS technology deployed in 3D surface reflection configuration across a hyper-saline salt-lake environment delivered a performance akin to modern nodal seismic systems. We show that the introduction of DAS technology into seismic surveying practice in the mineral sector could deliver an order of magnitude saving, while substantially increasing the data density and hence allowing optimum performance of modern seismic imaging algorithms.