Морфометрические параметры рельефа и локализация месторождений углеводородов Волго-Уральской антеклизы

The paper describes a complicated relationship between the relief and the oil and gas occurrence within the Volga-Ural anteclise. Our geomorphologic studies have shown that the eastern part of the structure, with a large number of oil and gas fields, is marked by increased values of the following morphometric parameters: 1) the difference between the base surfaces of the first and second orders, constructed according to V.P. Filosofov’s method at the scale of 1:2 500 000; 2) the length of watercourses of the second order; 3) the density of watercourses of the first order; 4) the depth of the vertical dissection; 5) the steepness of slopes; 6) the maximum curvature of the relief surface; 7) the density of the elongation lines constructed in the A.A. Zlatopolsky’s LESSA program. It was found that the median values of these parameters within oil and gas fields exceed the corresponding values calculated for the entire territory of the Volga-Ural anteclise, and the confidence intervals of the medians do not overlap. Using the automated analysis of the digital terrain model, a general pattern of orientations of linearly elongated oil and gas fields and slopes is revealed. The predominance of two main directions – north-west and north-east could be explained by the activation of the diagonal system of planetary fracturing. In our opinion, the relationship between the relief and oil and gas fields is due to the features of the recent tectonic movements influencing the shape of relief and the migration of hydrocarbons. The significance of neotectonic movements as factors of relief formation is evidenced by the fact that the epicenters of modern earthquakes are confined to the areas of increased horizontal and vertical dissection of relief. The relative amplitudes of compressive stresses were calculated using computer geodynamic modeling in the Roxar’s RMS 2013 program. There is a numerical correlation between their values and the coefficient of total erosion dissection of the relief with the Spearman’s rank correlation coefficient being 0,48. It is achieved if the latitudinal horizontal compression is set as an external load. Probably, this type of stress state manifests itself in recent times and is associated with the influence of the Urals mountain structure.