三塘湖盆地牛东地区石炭系火山岩相储层特征及其成因机理

根据岩石学特征及层序特征，分析了牛东地区石炭系火山岩相类型及其测井响应特征。牛东地区石炭系火山岩可以分为溢流相、爆发相、空落堆积相、火山沉积相，测井曲线中能较好地区分这4 种岩相的是自然伽马（GR）、密度（DEN）测井曲线，火山沉积相对电阻率测井（Rt）也有较好的反应。火山岩储集空间分为两大类：一类为孔洞类，主要有纳沸石未完全充填的气孔、杏仁体溶蚀孔、粘土矿物及葡萄石杏仁收缩孔、基质溶孔；另一类为裂缝类，主要为未被钠沸石及绿泥石完全充填的火山岩自碎缝、收缩缝、构造缝以及各类缝充填物溶蚀形成溶蚀缝。通过研究，岩浆的物质成分、喷溢相带以及后期改造作用是火山岩优质储层形成的主要控制因素。粘度大、流动性差、气体逸散较慢的中性岩浆形成的安山岩是最佳储层，而喷溢旋回末期是形成杏仁体、气孔及自碎缝的有利时期，喷溢旋回间歇期的风化淋滤为各类溶蚀孔形成提供了条件。火山岩储集空间的成因机理对寻找火山岩储层具有重要意义。

Volcanic reservoir characteristics and genetic mechanism of Carboniferous in Niudong area of Santanghu Basin

Based on the petrological characteristics and sequence features, the volcanic facies and logging response characteristics of Carboniferous in Niudong area are analyzed. There are four volcanic facies in the the study area： effusive facies, eruption facies, empty accumulative facies and volcanic sedimentary facies, which can be well distinguished by logging curve GR and DEN. And volcanic sedimentary facies can get better response by Rt. Thevolcanic reservoir spaces include primary and secondary accumulation spaces. The primary accumulation spaces mainly include air pores, intercrystal pores, shrinkage pores and fractures. The secondary accumulation spaces mainly include dissolved pores, structural fractures and weathered fractures. The main factors for forming high quality volcanic reservoirs are magma composition, effusive facies belt and later reformation. Andesite, formed by intermediate rock with high viscosity, slow fluidity and slow gas dispersion, is the optimum reservoir. The end period of eruptive cycle is the favorable period for forming amygdaloid body, gas hole and auto-fracture. The weathering and eluviation in the period of eruptive cycle provide forming conditions for various corrosion pores. The genetic mechanism of volcanic reservoir space is of significance for seeking volcanic reservoirs.