Characteristics and Influencing Factors of Tight Carboniferous Tuff Reservoir in Malang Sag

Based on the investigation of the predecessors’ literature, this paper takes the Carboniferous tuff reservoirs in the Malang sag as the research object, and clarifies the characteristics of dense reservoirs, which provides a basis for the geological evaluation of tight tuff. Technologies such as casting thin sheets and high-pressure mercury injection are mainly used. Analyze the data obtained, and study the pore structure and physical properties of tuff reservoirs. The results show that the Carboniferous tuff in the Malang sag is mainly developed as swarf tuff. The porosity is less than 10% and the permeability is less than 0.5 mD. In general, the Carboniferous tuff reservoirs in the Malang sag are highly heterogeneous, but the fluid mobility is poor, probably due to a large amount of carbonate cementation and blockage of pores during reservoir formation. This results in smaller pores and poor porosity. However, such small pores or micro-cracks can play a certain role in percolation, and can also contribute to the storage of oil and gas.