准噶尔盆地西北缘中段石炭系火山岩油藏储层特征及其控制因素

准噶尔盆地西北缘中段石炭系火山岩油藏的储层岩性为火山熔岩、火山碎屑岩及火山沉积岩。根据孔隙与裂缝系统的配置关系，可分为孔隙型、孔隙裂缝型、裂缝孔隙型及裂缝型4种储层类型。油藏控制因素研究表明，区域构造作用及火山活动奠定了储层形成与分布的基础，岩性、岩相决定了储集空间的发育程度与规模，成岩作用对储层改造作用明显。在爆发相火山角砾岩、凝灰岩及喷溢相块状安山岩、玄武岩和玄武质角砾熔岩中，气孔等原生孔隙发育；火山沉积相沉凝灰岩及砂砾岩以细小原生粒间孔隙为主。区域构造作用使石炭系内部发育4种裂缝类型，其中垂直高角度裂缝在喷溢相熔岩储层中发育，网状裂缝和层面裂缝系统则多发育于火山角砾岩、凝灰岩及沉凝灰岩互层中，砂砾岩中以发育程度低、有效性差的不规则裂缝为主。熔结、溶蚀等成岩作用对储层改造作用明显，火山碎屑沸石化和沸石溶蚀作用是油藏次生孔隙发育的主要途径，而碳酸盐、二氧化硅胶结作用及粘土矿物水化作用则降低了储层孔隙度和渗透性能。

Characteristics and controlling factors of Carboniferous volcanic reservoir in the middle section of the northwestern margin of Junggar Basin

The volcano lava, pyroclastic rock and volcanic sedimentary rock are the main lithology of the Carboniferous volcanic reservoir in the middle section of the northwestern margin of Junggar Basin. According to the juxtaposition relation of pores with fractures, the Carboniferous volcanic reservoir was divided into four styles of pores, pore fractures, fracture pores and fractures. The pore fracture and fracture pore reservoirs generated in the pyroclastic rocks are the high productive reservoirs. The controlling factors of the Carboniferous volcanic reservoir show that the regional tectonic and volcanic activities are the base of reservoir generation and distribution. The volcanic lithology and facies are the development conditions of pores and fractures. The reservoir property was reformed prominently by the diagenesis evolution. The primary pores such as gas pores were developed in the volcanic breccia, tuff of explosive facies and basalt, andesite, basalt breccia of effusive facies. The fine primary intergranular pores were mainly developed in the sedimentary tuff and sandstone of volcanic sedimentary facies. Four types of fracture were generated in the Carboniferous reservoirs under the regional tectonic action. The vertical and steep fractures appeared in the effusive facies reservoir. The net fractures and bedding fractures were developed in the volcanic breccia tuff sedimentary tuff interbed. The irregular fractures with the poor development degree were primary in sandstone, which caused the decrease of fracture effectiveness. The welding diagenesis and corrosion diagenesis controlled the characteristics of reservoir. It is important for generating secondary pores in volcanic breccia and tuff by the zeolitization of pyroclastic rocks and corrosion of zeolites. The capability of the porosity and permeability decreased rapidly with the silica cementation and the clay mineral hydration.