In the process of converting depleted oil and gas reservoirs into gas storage facilities, identifying and sealing complex old wells is a crucial step. For old wells with ferromagnetic casings, magnetic detection technology is typically employed for localization. However, for open-hole old wells without ferromagnetic beacons, underground positioning relies on inaccurate historical well data, often leading to significant errors. Acoustic remote detection technology, which analyzes acoustic reflection characteristics, theoretically enables the precise positioning of open-hole old wells by detecting and identifying anomalous geological bodies near the borehole. This study systematically investigated the feasibility of this technology for detecting open-hole old wells and their underground positioning from three aspects: acoustic field characteristics, reflection imaging features of an open-hole old well, and data processing and localization for acoustic remote detection. First, a staggered-grid finite-difference time-domain (FDTD) scheme with fourth-order spatial and second-order temporal accuracy was employed to solve the elastic wave equation, simulating acoustic wave propagation around the borehole under various geological conditions. Subsequently, based on acoustic reflection characteristics under actual working conditions and combined with numerical simulation results, the reflection imaging features of the open-hole old well were analyzed. Finally, by processing field data, the detection range and accuracy of the acoustic remote detection technology in practical applications were validated. Experimental results indicated that the acoustic remote detection technology was unaffected by external factors and could effectively determine the spatial position of open-hole old wells at depths up to 3 000 m. The detection range was 4 to 16 m, with a positioning error of less than 0.5 m, indicating its suitability for locating abandoned wells under complex geological conditions. This study demonstrates that acoustic remote detection technology not only overcomes the limitations of traditional positioning methods but also significantly improves the positioning accuracy of open-hole old wells, providing key technical support for the conversion of depleted oil and gas reservoirs into natural gas storage facilities. The application of this technology enhances the safety and efficiency of abandoned well sealing and reduces risks associated with positioning errors. Future research will focus on further optimizing the algorithm, expanding the detection range, and improving positioning accuracy to meet broader engineering requirements.