Comparative assessment of porosity and permeability properties of different reservoir types using express core analysis: a case study of the Tas-Yuryakh field

Abstract

The purpose of the article is to present the results of comprehensive express petrophysical core studies conducted at one of the wells of the Tas-Yuryakh oil and gas condensate field. The research covers three productive horizons: Є₁blᵒ⁻ˡˡ (Osinsky), Vbk₁ᵇᵗ (Botuobinsky), and Vcrᵗˡ (Talakhsky). The study obtains and analyzes a dataset including the measurements of effective porosity, absolute permeability, residual water and hydrocarbon saturation and carbonate content. As a result, fundamental differences in the reservoir properties of the studied horizons have been established, determined by their lithology and type of void space. The Botuobinsky horizon is characterized as a high-quality terrigenous reservoir with record permeability values of up to 837.1 mD and porosity of up to 27.5%. For the Osinsky horizon composed of carbonate rocks a diagnostic paradox has been revealed between the extremely low matrix permeability (0.42 mD) and clear signs of hydrocarbon saturation that indicates a fractured reservoir type. The Talakhsky horizon, despite the signs of residual bituminization, features isolated void space and low reservoir properties (permeability is around 3.5 mD), which excludes its commercial value in the studied area. The study focuses on the detailed analysis of the porosity-permeability relationship, which becomes a key tool for differentiating reservoirs by the genetic type of void space and their potential assessment. The research results are of significant practical importance for building a reliable geological model of the field and designing an effective development system.