枯竭油气藏改建为储气库的过程中，识别并封堵复杂老井是至关重要的步骤。对于含有铁磁性管柱的老井，通常采用磁探测技术进行定位；而对于无铁磁性信标的裸眼老井，地下定位则依赖于欠精确的井史资料，易产生较大误差。声波远探测技术通过分析声波反射特征，可实现对井旁异常地质体的探测与识别，理论上具备对裸眼老井精确定位的能力。采用空间四阶时间二阶的时域交错网格有限差分法（FDTD）求解弹性波动方程，从声场特征、裸眼井反射成像特征、声波远探测数据处理与定位3个方面系统地分析了该技术在裸眼井探测和地下定位中的可行性。首先，采用空间四阶时间二阶的时域交错网格有限差分法求解弹性波动方程，模拟不同地质条件下声波在井旁传播的行为；随后，基于实际工况下的声波反射特征，结合数值模拟结果，分析了裸眼井反射成像特征；最后，通过对实测数据进行处理，验证了声波远探测技术在实际应用中的探测范围和精度。实验结果表明，声波远探测技术不受外界因素影响，能准确定位地下3 000 m深度的裸眼老井在地层中的空间位置，探测范围可达4~16 m，定位误差小于0.5 m，适用于复杂地质条件下的废弃井定位。研究表明，声波远探测技术不仅突破了传统定位方法的局限性，还显著提升了裸眼老井的定位精度，为枯竭油气藏改建天然气储库提供了关键技术支撑。该技术的应用不仅提高了废弃井安全封堵的效率，还降低了地下定位误差引发的风险。后续研究将进一步优化算法，拓展探测范围，提升地下定位精度，以满足更广泛的工程需求。

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.