Effectiveness of Fiber Optic Distributed Acoustic Sensing (DAS) in Vertical Seismic Profiling (VSP) Field Survey

Abstract

The evolution of fiber optic technology in the past few decades has led to significant advancements in various fields, including high-speed and long-distance communication, big data transport, optical imaging, and sensing. However, relatively few studies have examined the use of fiber optic sensors (FOSs) as point and distributed sensors in geophysics. Distributed Acoustic Sensing (DAS) is a widely used method for subsurface imaging and monitoring in wells, specifically in Vertical Seismic Profiling (VSP) surveys. This method allows for detailed analysis of subsurface structures and properties of reservoirs. Four different strategies for deploying FOS cables in DAS VSP are evaluated and compared: cementing behind casing, cable behind inflatable liner, strapping to production tubing, and wireline deployment. Cementing the fiber behind casing is considered the most effective method for coupling with the formation. However, the other methods also have their own advantages and limitations. The fiber cable behind inflatable liner, for example, allows for accessibility to the fiber without affecting the acoustic signal, while strapping the fiber to production tubing can still record DAS signals; tubing noise and signal attenuation from the annular fluid, however, can make it difficult to differentiate from the seismic signal. Nonetheless, this method has the benefit of being simpler to deploy and replace in case of failure. Wireline deployment can pick up some acoustic signals in regions where the cable touches the well wall, but in vertical sections where the cable is not in contact with the wall, the signal is attenuated. Results from pilot tests in a field in Canada are discussed and evaluated, and suggestions for improving the VSP signal are provided.

Application of Distributed Acoustic Sensing in Geophysics Exploration: Comparative Review of Single-Mode and Multi-Mode Fiber Optic Cables

“…The authors of [55] carried out a DAS VSP field survey to evaluate the effectiveness of fiber optic DAS by comparing four cable deployment approaches, namely with cables behind the well casing, behind an inflatable liner, clamped to production tubing, and deployed with wireline logging. The SMF cable was lowered along the well with a different approach and connected to a DAS interrogator.…”

Invisible track bed defect classification method based on distributed optical fiber sensing system and FFT Attention Transformer model

“…In recent years, with the rapid development of optical fiber sensing technology, distributed optical fiber sensing technology has been widely used in the safety and health detection of various structures because of its advantages of high precision, high reliability, anti-interference, long distance transmission, and long detection distance. [9][10][11][12][13][14][15][16][17] The distributed sensing detection system of a multiplexing ultra-weak fiber Bragg grating (UWFBG) has attracted the attention of researchers and has been applied to the actual safety inspection of metro corporation due to its advantages of high sensitivity, fast response, and dynamic measurement. 18,19 At present, the application of a sensor system in subway safety detection is mainly in tracking the speed and positioning the subway trains, 20 detecting personnel intrusions, 21 detecting external construction disturbances, and 22 classifying abnormal events.…”

A Concise Review of the Progress in Photonic Sensing Devices

“…For example, a photonic sensor can detect variations in the refractive index (RI), absorption, or fluorescence of a substance under observation, which can be correlated with the concentration of a target molecule or the presence of a specific substance [7,8]. They have a wide assortment of applications in different fields, containing: (I) medical applications, such as monitoring blood glucose levels, measuring oxygen saturation in blood, and detecting cancer cells [9]; (II) environmental surveillance, where these sensors can be used to monitor environmental parameters such as air and water quality, temperature, and humidity; (III) aerospace and defense: such as aircraft control systems, missile guidance, and remote sensing; (IV) structural health surveillance: photonic sensors can be employed to monitor the structural health of buildings, bridges, and other infrastructure [10][11][12]; (V) industrial process control: such as monitoring the temperature and pressure in chemical reactors and detecting gas leaks; (VI) communication networks: photonic sensors are used in communication networks for monitoring the performance of optical fibers and detecting fiber breaks; (VII) energy sector: photonic sensors can be used for surveillance of the condition of wind turbine blades, detecting pipeline leaks [13], and monitoring the temperature and pressure of oil and gas wells [14][15][16].…”