Fiber-optic sensing technology for in-well applications has traditionally focused on temperature profiling. This has limited the application of fiber-optic reservoir surveillance to recovery processes with a pronounced thermal signature. Currently, novel fiber-optic technologies entering the market promise a much wider range of subsurface measurements. This opens new avenues in well and reservoir management and highlights the opportunity for fiber-optics to become a pervasive oilfield technology. In this paper we discuss field trials that combine Distributed Temperature Sensing (DTS), Distributed Strain Sensing (DSS) and Distributed Acoustic Sensing (DAS). These trials demonstrate the potential of fiber-optic sensing technology for well integrity monitoring, gas lift optimization, in-flow profiling and downhole seismic acquisition.
Esential to realizing this potential is the development of cost-effective, easy-to-deploy fiber-optic cables optimized for these various fiber-optic measurements. We also highlight the business integration challenge of handling, storing, and interpreting data volumes that in some applications reaches levels of 1 TB/well/day. We conclude that while significant technology challenges remain, with a broad cross section of oilfield technology providers working on derisking fiber-optic sensing technologies, the industry is on the verge of a step change in well and reservoir monitoring capability.
Its passive nature and inherent long-term reliability, combined with the ability to string together numerous individual sensing elements in a single fiber, makes fiber-optic technology ideally suited for distributed sensing in harsh and remote environments. Despite this compelling proposition, for many years this technology was synonymous with temperature sensing and thereby limited to the monitoring of well operations and recovery processes with a pronounced thermal signature. In recent years, this situation has started to change rapidly. A variety of fiber-optic sensors developed in the aerospace and defense industries are finding their way into the oil and gas industry. As multiple fibers, each providing a specific distributed measurement, can be bundled in a single downhole-deployable cable, the industry is facing a unique opportunity for robust well and reservoir surveillance based on an abundance of measurements continuous in time during the well's productive life and continuous along its well path.