Study on the relationship between hydrocarbon generation and pore evolution in continental shale from the Ordos Basin, China

The relationship between hydrocarbon generation and the evolution of shale pore structure and its heterogeneity of continental shale from the Ordos Basin, China was quantitatively studied based on thermal simulation experiment, mercury injection capillary pressure (MICP), gas adsorption, vitrinite reflectance (R-o) analysis, and hydrocarbon generation test combined with Frenkel-Halsey-Hill (FHH) fractal model. The result shows that the pore volume (PV) and specific surface area (SSA) of pores with different pore sizes show a trend of decreasing first and then increasing as the maturity increases in general, R-o > 1.59% is initially defined as a favorable stage for pore development in continental shale. Hydrocarbon generation has different effects on pore heterogeneity of different scales. For the N-2 adsorption, the roughness of small pore surface (D-1) decreases in the oil window; the complexity of large pore structure (D-2) increases in the oil window but decreases in the gas window. For the MICP, the heterogeneity of small pore (D-1) increases in the oil window and increases first and then decreases in the gas window; D-2 remains basically constant during the whole stage and is close to 3, indicating that the heterogeneity of large pores is extremely strong and is not affected by hydrocarbon generation. (C) 2021 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.

Automated summary

The relationship between hydrocarbon generation and the evolution of shale pore structure and its heterogeneity of continental shale was quantitatively studied in this research. The results show that hydrocarbon generation has different effects on pore heterogeneity of different scales, indicating the complexity of the relationship.