In-Well Distributed Fiber Optic Solutions for Reservoir Surveillance

Abstract

Abstract Recently two new distributed fiber-optic sensing technologies, Distributed Acoustic Sensing (DAS) and Distributed Strain Sensing (DSS), have become available for use in oil and gas applications in addition to the more traditional temperature profiling with Distributed Temperature Sensing (DTS). These technologies offer a wide range of applications which include well integrity monitoring, gas lift optimization, flow profiling, and borehole seismic for geophysical reservoir monitoring. Fiber optic sensing can be very cost-effective in deepwater environments, where wells are exceedingly expensive and non-intrusive operations are a must to avoid very costly rig time. With a permanent fiber optic installation one may monitor, on demand, in-well pressures, temperatures, flow, and casing or completion deformation, as well away from the well using time-lapse vertical seismic profiles (VSP). The combined interpretation of DAS, DTS, and/or DSS data allows for a more robust interpretation of flow. DAS is expected to be particularly cost-effective for geophysical surveillance in deepwater as it eliminates the need for well intervention, which often precludes down-hole monitoring altogether. Typical geophysical applications include surveillance of water injectors and propagation of waterfronts near injectors or producers. In this paper recent field trials are discussed to demonstrate the value of these novel in-well fiber optic applications. These trials highlight the benefit of integrated data interpretation and the versatility of applications that are possible using fiber optic installations in wells. The applications shown are the use of the DSS for inflow profiling in a water injector in a deepwater asset, gas flow monitoring by combined interpretation of DAS and DTS data, and the first offshore applications of DAS for borehole seismic in Shell.