[Significance]Breakthrough pressure and fracture pressure of rocks play a critical role in controlling hydrocarbon migration, accumulation, and entrapment, thereby determining the formation and spatial distribution of hydrocarbon reservoirs. [Analysis]This study investigates the testing methods for breakthrough and fracture pressures, the variations in these pressures among different lithologies, and their implications for hydrocarbon migration and accumulation mechanisms. [Conclusions]The main findings are as follows: (1) Significant differences exist in the breakthrough and fracture pressures across various rock types. In sandstones (conventional reservoirs), the breakthrough pressure is substantially lower than the fracture pressure; in siltstones (tight reservoirs), the relationship between the two pressures is more complex; in clay-rich mudstones and shales, the breakthrough pressure is often higher than the fracture pressure. (2) The relative magnitudes of residual pressure in source-reservoir, breakthrough pressure, and fracture pressure jointly control the efficiency and pathways of hydrocarbon migration. When residual pressure is lower than both breakthrough and fracture pressures, hydrocarbon migration is restricted; when it exceeds the breakthrough pressure but remains below the fracture pressure, stable percolation occurs through pore networks; when it surpasses the fracture pressure but remains below the breakthrough pressure, rapid migration may occur along fractures. (3) Hydrocarbon migration and accumulation in sedimentary basins can be classified into two regimes: steady-state and non-steady-state. The former involves continuous and stable flow through pores and fractures, while the latter is characterized by episodic migration and accumulation under overpressured conditions, often facilitated by hydraulic fracturing. These findings provide valuable insights into the mechanisms of hydrocarbon migration and entrapment in both conventional and unconventional petroleum systems.
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