Controlling Factor Analysis and Modeling of Fractures in Volcanic Rocks on The Basis Of Outcrop Database

Abstract

Summary Research results show the following: first, Structures of rock fragment belt, en echelon fold, fracture corridor and pinnate cleavage are likely present near faulting belt, and there was a conspicuous negative exponential correlation between fracture frequency and distance to main fault set. Second, this paper modified the weathering crust model of fractured volcanic rock, further subdividing it into 4 sections of soil layer, water-resolved, fracture and bedrock downward, which could be used to better explain the vertical distribution pattern of subsurface fractures in volcanic rocks. Third, the volcanic explosion breccia is the most preferable lithology for fracture, followed by overflow lavas, and the least one is tuff. Fracture favors acidic volcanics more than neutral and basic volcanics. Simulation runs revealed that, the producer connected directly by fracture with injector was flooded soon after injection, while the producer connected by fracture and matrix combination with injector presented a displacement feature resembling matrix flow. It is therefore inferred that, although with fracture present, the impact of matrix permeability of fractured volcanic reservoirs on water-flooding development cannot be ignored.