Instruments and Systems: Monitoring, Control, and Diagnostics Annotation << Back Frequency-phase Method for Monitoring Oil Product Leaks Into the Geological Environment Adjacent to fuel and Energy Complex Facilities D.I. SURZHIK, A.O. KOVALENKO, O.R. KUZICHKIN, G.S. VASILYEV This article proposes a method for phase-metric monitoring of the geological environment near fuel and energy complex (FEC) facilities exposed to the risk of oil leaks, implemented using frequency detection and possessing increased accuracy and sensitivity of recording small geodynamic events. To study weak signals caused by leaks, an approach to spectral-temporal analysis (STA) of data with optimization of the choice of window functions and fast Fourier transform (FFT) parameters was developed. An experimental testing of the method was carried out, which confirmed its effectiveness in identifying precursors of emergency situations. Keywords: fuel and energy complex (FEC), oil product leaks, phase-metric monitoring, spectral-temporal analysis (STA), window functions, fast Fourier transform (FFT). DOI: 10.25791/pribor.9.2025.1611 Pp. 10-16.