A DTS-based method for estimating the radial distance of permanently installed optical fiber from the casing centerline

Abstract The advancement of distributed optical fiber sensing technology has led to its growing adoption in oil and gas wells for monitoring downhole hydraulic fracturing and production profiles. However, when optical fibers are permanently installed, uncertainties in their downhole positioning complicate the interpretation of acquired data. To address this issue, this paper proposes a method for inverting the radial position of the fiber using Distributed Temperature Sensing (DTS) data. This approach estimates the fiber's distance from the casing by analyzing depth-specific temperature responses during heating events. The inversion results were validated using Distributed Acoustic Sensing (DAS) data recorded during hydraulic fracturing through the same fiber. The derived radial distances were further applied to correct production DTS data influenced by fiber positioning variations. This method enables the estimation of radial distances in permanently installed fibers, facilitating the evaluation of fiber coupling conditions along different sections and the correction of biased responses caused by inconsistent coupling.