Influence of folding intensity on the formation of technogenic hydrocarbon accumulations

Purpose. To analyse the intensity of folding as a factor in the formation of technogenic hydrocarbon accumulations. Methodology. Construction and integrated analysis of maps of hypsometry, first-order trend surfaces, local structures, intensity of local folding, and dip angles of reservoir tops, combined with the spatial distribution of technogenic reservoirs. Application of trend analysis and mathematical processing of hypsometric surfaces. Analysis and generalization of geological data from archival and published sources. A structural surface slope analysis method was used for morphometric characterization, detection of deformation zones, and evaluation of bed inclinations. Findings. The study integrates the analysis of geological prerequisites and technological factors to assess the formation of technogenic reservoirs in depleted gas fields. To evaluate folding intensity and identify zones of intense deformation and decompaction, a first-order derivative method was applied, enabling the identification of bed surface morphology, localization of deformation and fault zones, refinement of structural trap boundaries, and assessment of bed inclination intensity. A correlation was established between zones of intense fold-fault deformation and increased permeability and additional gas saturation of reservoirs, leading to gas inflow into previously depleted horizons. Using the Rudkivske field as a case study, it is shown that the primary factors influencing the formation of technogenic reservoirs and additional gas inflow are zones of intense folding and tectonic disturbance with enhanced natural and induced fracturing, creating conditions for the formation of secondary gas-saturated zones. Originality. A correlation has been established between zones of intense fold-fault deformation with increased reservoir permeability and additional gas saturation, resulting in additional gas inflow into previously depleted horizons and the formation of technogenic accumulations. Practical value. A new methodological approach has been developed to identify potential zones of gas increment by analysing structural deformations of beds (top surface gradients) and considering bed pressure dynamics during field development.