Main Controlling Factors and Genetic Mechanism of High-Quality Volcanic Reservoirs in Huoshiling Formation of Longfengshan Area

Abstract

The genesis of volcanic reservoir of the Huoshiling Formation in the Longfengshan area of the Changling fault depression is complex. The study on the main controlling factors and genetic mechanism of high-quality reservoirs in this area can improve the effectiveness of oil and gas exploration. By means of core observation, thin section identification, porosity and permeability analysis and logging interpretation, starting from the study of reservoir characteristics, the main controlling factors and genetic mechanism of high-quality reservoirs development are analyzed. The results show that the main rock types of volcanic rocks in Huoshiling Formation are andesitic tuff and andesitic breccia of explosive facies and andesite of effusive facies. Volcanic rocks belong to medium porosity and medium permeability reservoir, and the reservoir space is dominated by intergranular dissolved pores, ingranular dissolved pores, matrix dissolved pores and microfractures. Lithology, lithofacies and apparatus-cycle control the formation and distribution of high-quality reservoirs, and weathering and leaching, acid fluid dissolution and tectonism determine whether volcanic rocks can become high-quality reservoirs. The genesis of high-quality reservoirs includes three types: primary reservoir, weathering crust reservoir, and fault-corrosion reservoir. High-quality reservoirs are distributed in the high part of the structure, the upper part of the lava flow and the boundary of the cycle periods near the faults and hydrocarbon generation depressions.