Fiber-Optic Motion Sensing: Distributed Acoustic Sensing, Fiber Bragg-Gratings, and their Land and Marine Seismic Applications

Fiber-optic motion sensing (FOMS) is a topic that has attracted the interest of many over the past decade. Geophysical interests have primarily been in borehole seismic imaging (BSI) via distributed acoustic sensing (DAS), with a recent interest in utilizing the technology for surface seismic imaging (SSI). The technology has potential for many applications. This dissertation investigates some applications while comparing the fiber-optic sensors to conventional sensors that have been used by industry. In an attempt to address some of the limitations of DAS, Fiber-Bragg Gratings (FBGs), which are single-point fiber-optic sensors, are investigated as well. The motivation and objective of this dissertation are presented in Chapter 1, along with a brief introduction to fiber-optic sensing focused on DAS and FBG theory. FOMS applications in BSI are presented in Chapter 2. Demonstrating the application of DAS VSP first, investigating the influence of seismic sources and optical parameters on DAS measurements in comparison to geophone measurements. Next, testing the application of FBGs in comparison to hydrophones in a VSP field trial. Chapter 3 explores applications of FOMS to SSI. Starting with a novel application of Multichannel Analysis of Surface Waves (MASW) on surface trenched DAS fiber, then demonstrating an application of DAS in urban infrastructure monitoring using existing telecommunication fiber-optic networks. Also, some field trials are presented, investigating the use of FBGs for surface seismic imaging. Then, FOMS applications in a simulated marine environment are explored in Chapter 4, demonstrating applications of DAS and FBGs in pipeline flow assessment and integrity, marine seismic source characterization, and underwater communications. Multicomponent FOMS considerations are made in Chapter 5, where I developed a multicomponent FBG sensor and test it against multicomponent geophones. A summary of the findings and contributions of this dissertation are finally presented in Chapter 6, followed by a discussion of future work and conclusion in Chapter 7. In conclusion, various applications of FOMS have been demonstrated in comparison to conventional seismic sensors, finding that FOMS demonstrates advantages to conventional sensing systems along with challenges in processing and handling large amounts of data.Earth and Atmospheric Sciences, Department o