Development and Testing of a New Fiber Optic System for Monitoring CO2 Solubility in Aqueous High-Pressure Geological Systems

Abstract

A new distributed intrinsic fibre optic sensor has been developed by Intelligent Optical Systems (IOS) for in situ measurement of dissolved CO 2 in brines at conditions relevant for applications in groundwater analysis, Carbon Capture and Storage reservoir surveillance, environmental monitoring of sweet/sea water systems and general water remediation applications. Our tests have shown that the sensor can withstand exposure to increased total pressures (up to 350 psi) and provide a stable signal response proportional to dissolved CO 2 concentrations in an aqueous solution. This is the first implementation of a distributed optical sensor, which is sensitive to dissolved CO 2 concentration or partial pressure of CO 2 and also exhibits feasibility to commercially produce lengths relevant for actual reservoir monitoring. In addition, first promising results from high-pressure experiments suggest that the sensor has potential for eventually being used in long-term installations for measuring dissolved CO 2 concentrations at different reservoir depths. With regard to carbon sequestration, these first high-pressure experiments represent a first step in the development of a new fibre optic sensor system that can eventually be employed to continuously monitor the reservoir and overlying rock layers for CO 2 leaks, quantify the extend of the potential leak and help to take informed decisions regarding remediation and further leak-containment measures.

Review of Structural Health Monitoring Techniques in Pipeline and Wind Turbine Industries

“…Since its emergence in the 1990s, a special class of fiber structure for OFS with tremendous capability for DCS has been provided by micro-structured optical fibers [108][109][110], which features the air holes extending along the whole length of the fiber parallel to the longitudinal axis known as photonic crystal fibers (PCF) [108][109][110][111], unless the air holes are regularly organized within the cladding matrix. Figure 11 shows the internal and external look of an evanescent field-based semiconductor [112]. While microstructured fibers provide highly sensitive and versatile fiber structures, large production and marketing are still limited, demanding the cost-effective long-distance production of such fibers.…”

Corrosion Sensors for Structural Health Monitoring of Oil and Natural Gas Infrastructure: A Review

“…Optical fiber-based chemical sensors are enabled by functional chemical sensing coatings mostly on the fiber core or cladding, such as metallic films [53,102], oxides [103,104,105,106,107,108,109], polymers [49,110,111,112], nanomaterials [113,114,115], and metal-organic frameworks (MOFs) [116,117]. Figure 15 illustrates one example of the evanescent field-based chemical sensor [118]. The optical fibers can be etched, tapered, spliced, or side-polished to allow the light interactions with chemical sensing layers on the core or cladding and with the surrounding media [47,50,119].…”

“…Schematic of evanescent field-based chemical sensor with a colorimetric indicator contained in the cladding of optical fiber [118]. …”

Hollow-core photonics crystal fiber for CO2 leakage monitoring

“…Direct chemical sensing (DCS) on fiber is the viable alternative but is relatively immature. Leading DCS approaches integrate functional sensor layers with optical fibers [6] but inherent technical challenges to field deployment have emerged including insufficient selectivity to analytes, instability of sensing layer functionalized optical fibers, and difficulties with scaling.…”