徐家围子断陷火山机构类型及其地质指示意义

庆深气田的勘探开发实践表明,火山岩气藏呈现出以孤立火山机构控藏的特征.火山机构的横向分布规律及其预测成为火山岩勘探开发的难点.在徐家围子断陷营城组开展了精细的火山岩地层结构对比研究,发现火山喷发受深大断裂控制,具有横向迁移和纵向多旋回叠置的特征.根据火山机构的地球物理响应特征及其地质指示意义,将火山机构分为层状火山、平状火山、歪斜火山、熔岩穹窿、破火山五大类.层状火山和歪斜火山指示了火山沿构造断裂带大规模的爆发与喷溢,形成了大面积广泛发育的火山熔岩和火山碎屑岩互层的地层,构成营城组火山岩地层的主体.火山机构错叠连片,火山岩储层发育.平状火山指示了火山强烈的风化剥蚀作用,风化壳储层发育,可形成高产的火山岩气藏.破火山口和熔岩穹窿指示了火山活动的局部性,破火山是局部火山能量瞬间快速的释放,形成大量的火山碎屑堆积,以致密储层发育为特征；熔岩穹窿是火山作用后期的产物,储层发育,但规模较小.

Volcanic edifice types of Xujiaweizi fault and their geological implications

Qingshen gas field exploration and development shows that isolated volcanic edifice control volcanic gas reservoir.Horizontal distribution of volcanic bodies and their projections become difficulties of volcanic exploration and development.Fine comparative study of volcanic formation of Yingcheng group of XJWZ fault is carried out,find that volcanic eruption control by the deep fault and have the feature of horizontal migration and vertical polycyclic superimposed.Volcanic edifice into the layer-shaped volcano,flat-shaped volcano,skew volcano,lava dome,caldera volcano five categories based on the geophysical response characteristics and their implications.Layer-shaped volcano and skew volcano shows that large-scale volcanic eruption along the tectonic fault zone and the eruption and extensive development of large areas of volcanic lava and pyroclastic rocks interbedded strata,these formation constitute main volcanic body of Yingcheng group.Volcanic edifice misfolding contiguous and volcanic reservoir developed.Flat-shaped volcano shows the strong weathering and erosion,weathering crust reservoir development and can form high volcanic gas reservoirs.Caldera and lava dome indicate the locality of volcanic activity.Caldera volcano is fast instant release of energy and formed large pyroclastic deposits,and mainly developed in tight reservoir.Volcanic lava dome is a product of late,relatively good reservoir,but small.