Study On Micro-heterogeneity Of Cenozoic Basaltic Reservoirs In Liaohe Depression

Basalt is widely distributed in the Liaohe Pass,and industrial oil flow has been obtained from several exploratory drills.However,the level of exploration for basalt is low,the microscopic formation mechanism of basalt reservoirs,reservoir inhomogeneity and other problems have not been effectively solved,affecting the further exploration of basalt oil and gas reservoirs.In this paper,based on the characterization of lithology,the microscopic components of basalt are analyzed by casts,scanning electron microscopy and energy spectroscopy,and different types of pore units are inductively summarized.By analogy with the classification scheme of microscopic non-homogeneity of fragmented rock reservoirs by Qiu Yinan et al.,the microscopic non-homogeneity of basalt is divided into four aspects: pore non-homogeneity,fissure non-homogeneity,porphyry non-homogeneity and matrix non-homogeneity.The results show that the basaltic rocks in the study area are mainly divided into volcanic lava and volcanic fragmented rocks,including stomatal almond basalt,dense basalt and conglomerate basalt.The volcanic fragmentation class includes basaltic volcanic conglomerates and basaltic aggregates.Primary pores in basalt include primary stomata and shrinkage seams,secondary pores include intra-matrix lysis pores,intracrystalline lysis pores,amygdaloid lysis pores,lysis seams,weathering seams and tectonic seams,and effective pores are mainly composed of amygdaloid lysis pores and lysis seams.The microscopic inhomogeneity of basalt reservoir is analyzed from three aspects: stomata,porphyry and matrix;stomata inhomogeneity mainly studies the primary stomata and amygdaloid bodies that develop in basalt reservoir,and explores the size,morphology,filling and erosion ratio and connectivity of stomata;porphyry inhomogeneity mainly analyzes the differences in porphyry type,erosion ratio and content;matrix inhomogeneity includes the differences in matrix erosion ratio and content.Statistics on the proportions of the components identify stomatal inhomogeneity as the main aspect contributing to microscopic inhomogeneity of the basalt reservoir.The physical properties of the reservoir,such as surface porosity,porosity and permeability,are synthesized,and the intersection of stomata,porphyry,matrix and porosity is plotted to determine that the physical development of the basalt is mainly related to the stomata content and not related to the porphyry content and matrix content.The high quality reservoir of the Liaohe Pass Basalt is mainly distributed in the pore development zone near the top interface of the flow unit.