NEAR-SURFACE GEOCHEMICAL METHODS FOR PETROLEUM FIELDS' STRUCTURE ELABORATION

Near-surface geochemical exploration is a direct method of finding hydrocarbon deposits. It is low-cost and express-method determination. Developing of new approaches to data interpretation of subsurface geochemical exploration will allow to carry out exploration within the prospective sites more effectively. Also, these techniques can be used in combination with geological, geophysical, geochemical and production methods to improve the quality of the results. The method of this study is to identify the relationships between the deep geological settings of prospective areas and gas recording survey near the Earth's surface. As a result, new approaches to the interpretation of geochemical anomalies will be developed. Geological information was used for exploration of the Nedilna structure. The structure is located within the northern edge of the Dnieper-Donets depression. It is a narrow anticline that is complicated with longitudinal and transverse faults. Five wells were drilled; two of them were gas productive. The area was studied with traditional oil and gas methods, including geophysical well surveys. The results of structural-thermal-atmogeochemical method were used; the survey is a complex technology for oil and gas prospecting. The analysis of geological and geochemical data was conducted in order to identify areas with conductive and screening faults. Structural maps of the area coated with faults and data of hydrocarbon and non-hydrocarbon gases content near the Earth's surface were used. Faults were divided into screening or conductive ones using interpreted data. The surveys which were conducted using concentrations of various gases gave similar results. The data of faults conductivity were compared with the results of the methane survey in order to determine tectonically-shielded deposits. Scientific novelty of the research is that the preconditions of using surface geochemical indicators in conjunction with geological parameters for oil and gas fields' structure determination were developed. The research results can be used for oil and gas prospecting as a supplementary tool to determine the structural features of hydrocarbon deposits.