Well Integrity Monitoring Using Distributed Fiber Optic Sensing

Abstract

SUMMARYNew concepts are required to accelerate the global development of high-temperature geothermal resources in a cost effective and environmentally safe way. Keeping the geothermal system in operation for several decades is challenging -yet key to economic success. Real-time monitoring of temperature and strain along the well bore is a powerful tool to evaluate the performance and integrity of installed subsurface components.A fiber optic cable was installed behind the casing of a high temperature geothermal well in Iceland (IDDP2). A second cable was installed in a low temperature well in Germany. During cementation, distributed strain data (Rayleigh backscatter) as well as distributed temperature sensing data (Raman backscatter) was acquired. In a subsequent measurement campaign, data shall be acquired in these wells during load changes (production/injection).In combination with concurrent laboratory investigations and conventional borehole logging data, this study will identify processes influencing the long-term integrity of casing and cement in high-temperature geothermal environments.

Distributed viscosity and flow velocity measurements using a fiber-optic shear stress sensor

“…The FIMT borehole cable is an example of a rigid fiber optic cable designed for borehole applications containing five fibers, a stainless steel layer, bronze wires and a low-density polyethylene layer (d c = 5.5 mm, k = 597 kN). Detailed information of the example cable properties is published in literature [40]. Fig.…”