Tahe Oilfield was one of the important oilfields in western China. The monitoring and development of remaining oil reserves were paid significant attention to and were regarded as one of the current challenges in oil and gas exploration and development. Well-to-surface time-frequency electromagnetic detection technology, due to its sensitivity to oil-gas-water interfaces, was increasingly applied in oilfield development. However, as time-frequency electromagnetic detection technology was introduced relatively late in oil and gas detection, the related detection mechanisms and high-resolution signal extraction and interpretation were still under research. Through the analysis of well-to-surface time-frequency electromagnetic exploration principles, a technical sequence for differential apparent resistivity, differential phase processing, and imaging analysis of well-to-surface time-frequency electromagnetic data was established, starting from the definition of regional apparent resistivity. The differential processing results of time-frequency electromagnetic data collected from the actual production well TX1 in Tahe Oilfield demonstrated that the high-density sampling provided by multi-pole transmission and multi-frequency reception of well-to-surface time-frequency electromagnetic detection technology offered high-resolution reservoir detection datasets. The new differential data processing technology could greatly enhance the effective identification capability of deep oil-gas-water interfaces. The successful trial of this method provided a promising technical means for oil-gas-water detection in oilfield development. Additionally, through comparative analysis with seismic exploration results, it was found that well-to-surface electromagnetic exploration had unique advantages in identifying complex underground structures and could provide complementary information to seismic exploration.