Features of localization of remaining oil in terrigenous reservoirs and potential for their recovery at the final stage of field development

Abstract

The paper considers one of the unique fields in terms of geological reserves. The paper also analyzes the development of the D3ps formation sections of the Devonian terrigenous layer of the studied field. A detailed geological and hydrodynamic model was constructed based on the consolidation of all available information. An integrated analysis of actual well performance data, field geophysical tests, geological and technical measures, results of infill drilling, as well as geological and hydrodynamic modeling confirmed the localization of reserves primarily in the upper bed of D3ps.1. The analysis of all performed studies revealed higher values of current oil saturation in the upper bed – up to 0.8 unit fractions and lower values in the lower bed – up to 0.68 unit fractions. Similar results were obtained from 87 sidetracks. Drilling of wells and sidetracks is proposed in areas with no well stock. Despite the final stage and high degree of field development, the proposed strategy will support oil production levels, increase remaining recoverable reserves, increase the efficiency of reserve recovery and improve the economic performance of field development. The introduction of modern development technologies, approaches to the analysis and monitoring of development will increase the target value of the final recovery factor from 0.608 to 0.613 unit fractions, which, with a significant amount of in-place reserves, made it possible to increase the remaining recoverable reserves by 35%. The strategy will make it possible to achieve higher oil recovery rates. The approaches used to solve the tasks set in the study can be applied to the fields of the Volga region.