The reservoir development model of different lithology basement rocks in Erlian Basin，Northeast China.

In sedimentary basins, the basement typically exhibits non-conformable contact with the overlying sedimentary strata. The basement surface undergoes a complex history of uplift, weathering, erosion, and sediment burial, all of which contribute to its reservoir structural composition. This study integrates microscopic observations, macroscopic well logging data, and seismic data to analyze the physical and weathering effects on the basement reservoirs with different lithologies and distinct structural features within the Erlian Basin. The basement rock types in the study area mainly include tuff, limestone, granite, cataclastic rock, and the basement has been affected by weathering, denudation, dissolution and structural transformation during the evolution of the basin. The basement has been subjected to long-term tectonic modification, forming network cracks on the macro scale and micro-fractures on the micro scale. Weathering and underground fluids along the fractures dissolve the matrix of tuff rock, feldspar in granite and limestone, thus forming dissolution fractures and dissolution pore in the basement rocks. These fractures and dissolution pores make the porosity and permeability of the basement rocks surface show obvious heterogeneity. According to the microstructure and physical property changes, the structure of different lithology basement surface is analyzed. Among them, the surface of the tuff basement rock has undergone multi-stage volcanic eruptions and weathering leaching, with a structure of multi-stage ancient weathering crust reservoir superposition, and the porosity and permeability of the gentle slope at the structural high part is large. The surface of granite and cataclastic rock basement is controlled by tectonic activity, weathering leaching, and formation fluid action. The double-layer structure comprises the top paleo-wind crust reservoir and the middle and lower fracture dissolution reservoirs, exhibiting high porosity and permeability in the elevated structural positions and the region proximate to the fault zone. Controlled by karstification, tectonic activity, and ancient landform, the limestone basement rock surface displays longitudinal variations in reservoir storage space types, featuring a structure with multiple sets of vertically arranged reservoirs, particularly characterized by high porosity and permeability in elevated structural positions and near fault zones. The concept and results of this work can be used for future studies on unconventional basement reservoirs in other regions.