Application of the method of reflected electromagnetic waves to study cryohydrogeological conditions

The article presents a petrophysical justification for using the method of reflected electromagnetic waves (electromagnetic common depth point method (ECDP)) to differentiate geological sections by electrical properties, including the study of cryolithozones, as well as permafrost and sub-permafrost waters. An analysis of the results of the ECDP experimental work on the territory of an oil and gas field in the Republic of Sakha (Yakutia) in 2023 was carried out, including a study of the obtained distribution of the interval velocity of the electromagnetic signal with depth in a number of measurements. The result of data processing is presented in the form of a “virtual well” – a vertical distribution of specific electrical resistivity with a resolution of 2–5 m in depth. The reliability of the ECDP results is confirmed by their stable correspondence with all measured data and geological information from depths of at least 500 m, in particular, the nature of frozen rock occurrence and the position of watersaturated rocks. The advantages of the ECDP are shown, such as sensitivity of the parameter under study (the velocity of the electromagnetic signal) to changes in the physical properties of rocks, increased detail, and the non-requirement of a priori geological and geophysical information for quantitative interpretation of measurement data.