Mathematical Assessment of the Hydrogeochemical Evolution of Formation Waters and Salt Precipitation Risks in the Amirkhanli Area of the Siyazan Monocline

Abstract

This article presents a comprehensive study of the geological structure, hydrogeological characteristics, and chemical composition of formation waters in the Amirkhanli field, located within the Siyazan monocline. The primary objective of the research is to determine the relationship between the mineralization level of formation waters and geological factors—based on an analysis of the field's lithological-tectonic structure and groundwater chemistry—and to calculate quantitative indicators of salt precipitation processes using mathematical methods. In terms of regional structure, the Amirkhanli field is situated southeast of the Zaghli field and northwest of the Saadan field. The region is tectonically bounded by the Tengi-Beshbarmak anticlinorium to the south and the Talebi-Gaynarcha uplands to the north, while its eastern boundary is defined by the Gilgilchay River valley. The stratigraphic section of the field comprises Cretaceous deposits as well as Lower Paleogene sediments belonging to the Sumgayit, Govundagh, and Maykop series. During the research process, laboratory analyses were conducted on 58 water samples collected from 48 wells spanning 16 geological horizons of the Amirkhanli field. It was determined that the genetic types of formation waters are primarily represented by calcium-chloride (CaCl₂), magnesium-chloride (MgCl₂), and sodium-bicarbonate (NaHCO₃) groups. The mineralization level of the groundwater varies across a wide range, from 3240 mg/L to 48907 mg/L. Minimum values for this parameter were found in the Upper Cretaceous complex, while maximum values were localized in the Maikop-Oligocene deposits. This differentiation is directly linked to lithological factors: Upper Cretaceous sandstones, characterized by high filtration capacity, facilitate the formation of waters with low mineralization, whereas Maikop clay-marl rocks, characterized by low permeability, foster the formation of highly mineralized waters. Based on the chemical analysis results of the field's formation waters, the study examined the salt composition distribution (calculated using the Fresenius method), hydrogeochemical characteristics, and potential technological complications that might arise during field development. The calculations indicate that the formation waters of the studied wells generally exhibit high mineralization and are characterized by complex ion-salt compositions. The research results enable the development of engineering and technical measures to prevent risks such as salt accumulation in the near-wellbore zone, equipment corrosion, and emulsion formation.