Application of magnetic and geochemical characteristics of soils for hydrocarbons prospecting. A case study “Nedilna field” Kharkiv region, Ukraine

Abstract

The search for hydrocarbon reserves often requires innovative and cost-effective exploration methods. This study investigates the application of magnetic and atmogeochemical techniques to identify hydrocarbon sites by analyzing the impact of hydrocarbon microseepage on soil magnetic properties. The study focused on analyzing 49 samples of soil and soil air collected near the wells Nedilyna-1, −3 (productive), and Nedilyna-2, −5 (non-productive). Hydrocarbons that migrate through the soil cover alter its magnetic characteristics, including magnetic susceptibility (MS, χ), and variations in the magnetic field. This alteration is attributed to processes such as oxidation and reduction of ferromagnetic minerals within the soil. The results show a significant heterogeneity of soil magnetic characteristics in the study area. The soil is characterized by an increase in soil MS in places of increased density and gravity (interpreted by Pixler and Wetness Ratio) of hydrocarbon gases in the soil in tableland areas. The explanation is the fact that hydrocarbons characterized by higher density and gravity, typically with more fused aromatic rings, exhibit greater biological activity due to their increased persistence in the environment and reduced solubility in water. The results provide evidences for the formation of highly magnetic minerals in close association with hydrocarbon seepage. Recognition of such seepage-induced magnetic anomalies can be used to facilitate the exploration for oil and gas. This approach provides a practical tool for early-stage hydrocarbon exploration, potentially reducing the cost and time associated with more conventional techniques. At the same time, the area with erosion processes requires a more detailed study, and the need to create a mechanism for adjusting the MS values for heavily eroded and washed soil.