Localization of stock of abandoned wells and typification of territory of Astrakhan region by levels of environmental risk

Abstract

The article highlights the study of the part of a comprehensive geoecological survey related to the analysis of the potential ecological risk due to the abandoned deep wells on the territory of the Astrakhan region. The research methods are based on a comprehensive study of the basic parameters of the geological and technogenic environments that determine the potential ecological consequences of technogenic accidents. There are discussed the principles of the methodology of ranking the territory of the Astrakhan region, depending on the complex of geological and hydrogeological parameters determining the degree of protection of the geological environment from the technogenic pollution. A detailed description of the main lithofacies and hydrogeological features of the the section of the quaternary deposits of the studied area is presented. The most vulnerable deposits in terms of lithofacies and hydrogeology for technogenic pollution deposits are indicated. Data on the filtration characteristics of quaternary deposits presented in the section of the studied area is given. There is given information about the location of oil and gas from the abandoned deep wellheads as one of the technogenic factors that determine the pollution of the environment. There has been developed a comprehensive first aquifer protection scheme of south-western part of the Astrakhan region based on available hydrogeological, lithofacies features of the section structure. Four main categories of protection of the Pleistocene aquifer within the studied area from technogenic pollution have been identified. Their percentage ratio within the studied area was determined, in particular, the least protected aquifer (category 1) is predominant. The abandoned deep wells are localized in relation to the protection categories of the Pleistocene aquifer. The studied area has a complex of lithofacies and hydrogeological parameters that maximally contribute to the risk of developing technogenic pollution, which may arise as a result of the poor technical condition of the abandoned deep wells.