Formation of volcanic reservoir and its controlling on accumulation in Changling Fault Depression

In the Changling Fault Depression,volcanic rock formation is very thick.There are various types and facies of rock.Reservoirs are well-developed.The storage capacity of volcanic reservoir is not restricted by burial depth.It is favorable for reservoir in deep fault depression,characterized by high porosity and low permeability or low porosity and high permeability.Reservoir space is mainly composed of bubble pore,solution pore,fissure and their combination.Fissures improve the seepage ability of reservoir."Double porosities and double permeabilities" is the main reservoir type.Some reservoirs have homogeneous porosity and permeability.The formation of good volcanic reservoir is controlled by multiple factors.Favorable facies belt is the foundation.Tectonic movement is the key.Weathering leaching and dissolving also play important roles.The volcanic reservoirs near to the high position of tectonic fault are favorable for accumulation.