松辽盆地北部深层天然气储层特征

松辽盆地北部深层天然气藏的储层主要为火山岩、浊沸石化砂岩和高碱碎屑砾岩等。研究表明，深层砂岩的储集空间主要为经溶解、交代作用所产生的各类次生孔隙，矿物学上以浊沸石化和伊利石绢云母化和钾长石的钠长石化为显著特征，储层受成岩作用和沉积作用共同控制；砾岩有利储层主要集中在营城组4段，主要孔隙类型为压实后砾间砂质部分保留的粒间孔和砾内、砾边裂缝，原始含砂量和砂内填隙物数量是储层物性主控因素；而火山岩的有利储集体主要为酸性熔岩、酸性熔结凝灰岩等，原生气孔和经脱玻化等作用所形成的微孔隙及长石斑晶溶蚀孔具重要储集意义，火山岩相和碱交代及风化淋滤作用是主要控制因素。酸性流体的溶解营力和深层烃碱流体的双重作用是深层次生孔隙形成的主要原因，碱交代作用是主导和控制次生孔隙形成和分布的地球化学因素。

CHARACTERISTICS OF DEEP GAS RESERVOIRS IN THE NORTHERN SONGLIAO BASIN

Volcanic rock, adelforsitized sandstone and high alkalinity angular conglomerate are the main reservoir rocks of the deep gas pools in the northern Songliao Basin. The reservoir spaces of the deep sandstone are mainly composed of various secondary pores resulted from dissolution and metasomasis, and are characterized mineralogically by adelforsitization, sericitization of illite and albitization of K-feldspar. The sandstone reservoirs are jointly controlled by diagenesis and sedimentation. The favorable conglomerate reservoirs are mainly distributed in the 4th member of Yingcheng Formation and the main pore types include intergranular pores preserved in the inter-gravel sandy part after compaction, intra-gravel and gravel edge fractures. Initial sand content and matrix volume are the main factors that control poroperm characteristics of reservoir. While the favorable volcanic rock reservoirs are mainly composed of acidic lava and acidic welded tuff, with initial bubbles and micropores resulted from devitrification and dissolution pores of feldspar phenocryst as the main reservoir spaces. Volcanic facies and alkali metasomatism, as well as weathering and leaching are the main control factors. Dissolution of acidic fluid and double action of the deep hydrocarbon and alkaline fluids are the main factors that led to the formation of the secondary pores in deep reservoirs, while alkali metasomatism is the main geochemical factor controlling the formation and distribution of secondary pores.