The S2 Parameter of Shale Formations: Unrealized Hydrocarbon Potential Under the Thermodynamic Regulation of Formation Pressure
Year: 2026
Type: article
Abstract: A cyclic development scheme for shale formations with a (36 months + 3 weeks) ·N period is proposed, providing a 2–5-fold increase in cumulative production per well at capital expenditures limited to the cost of re-fracturing, with an internal rate of return above 50%. The physical basis of the scheme is a revision of classical petroleum geochemistry as applied to shale formations. First, the Rock-Eval S2 parameter is proposed to be interpreted not as a “residual” generation potential, inert on development timescales, but as the not-yet-realized hydrocarbon potential of the formation — an operational category of replenishable reserves. Second, formation pressure is treated as a thermodynamic regulator of generation (a baric brake): in a closed, self-regulating system with nanodarcy permeability, pressure buildup during generation is capped by abnormally high formation pressure (AHFP) and arrests the reaction; pressure relief by production resumes it. Third, it is shown that transport of newly generated hydrocarbons within the nanopermeable matrix is not diffusive: kerogen realization is accompanied by a 10–20% volume increase, which drives generation-induced microfracturing — the hydrocarbons create their own migration pathways; a single act of such fracturing — hydraulic fracturing via a cavitation bubble collapsing with a hydraulic shock — is documented on core from the Maykop clay shales of the Ciscaucasus. Post-refrac rate recovery is decomposed into two contributions with different characteristic timescales: a fast one — redistribution and desorption of pre-existing fluids from the SRV volume, and a slow, cumulative one (2–3 years, over N cycles) — realization of S2 under relieved pressure, manifesting as anomalous well longevity. A field experiment for direct ΔS2 measurement is proposed.
Source: CyberLeninK (CyberLeninka)
Authors: Bochkarev V., Bochkarev A., Bochkarev Ar.
Language: English
Subfield: Geology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7204255248