Basic principles of the whole petroleum system

Abstract

This paper expounds the basic principles and structures of the whole petroleum system to reveal the pattern of conventional oil/gas – tight oil/gas – shale oil/gas sequential accumulation and the hydrocarbon accumulation models and mechanisms of the whole petroleum system. It delineates the geological model, flow model, and production mechanism of shale and tight reservoirs, and proposes future research orientations. The main structure of the whole petroleum system includes three fluid dynamic fields, three types of oil and gas reservoirs/resources, and two types of reservoir-forming processes. Conventional oil/gas, tight oil/gas, and shale oil/gas are orderly in generation time and spatial distribution, and sequentially rational in genetic mechanism, showing the pattern of sequential accumulation. The whole petroleum system involves two categories of hydrocarbon accumulation models: hydrocarbon accumulation in the detrital basin and hydrocarbon accumulation in the carbonate basin/formation. The accumulation of unconventional oil/gas is self-containment, which is microscopically driven by the intermolecular force (van der Waals force). The unconventional oil/gas production has proved that the geological model, flow model, and production mechanism of shale and tight reservoirs represent a new and complex field that needs further study. Shale oil/gas must be the most important resource replacement for oil and gas resources of China. Future research efforts include: (1) the characteristics of the whole petroleum system in carbonate basins and the source-reservoir coupling patterns in the evolution of composite basins; (2) flow mechanisms in migration, accumulation, and production of shale oil/gas and tight oil/gas; (3) geological characteristics and enrichment of deep and ultra-deep shale oil/gas, tight oil/gas and coalbed methane; (4) resource evaluation and new generation of basin simulation technology of the whole petroleum system; (5) research on earth system – earth organic rock and fossil fuel system – whole petroleum system.