为了厘清四川盆地自贡地区中二叠统茅口组储层的差异发育机制与分布规律,基于丰富的测井、录井、取心和测试资料,对储层类型及主控因素进行了综合分析.研究结果表明:区内主要存在石灰岩类、白云岩类两种储集岩类.白云岩类储层主要发育于茅二段和茅四段,一般单层厚十几至几十厘米,多发育于向上变浅序列顶部,平面上茅二段白云岩储层主要分布于威远—自贡—富顺一线,而茅四段白云岩储层则主要分布于观音场—青杠坪一带;石灰岩类储层厚度变化大、非均质性强,纵向上可发育于茅二段—茅四段,平面上主要分布于沉积期地貌或风化壳岩溶地貌的高地或斜坡.进一步分析表明,白云岩储层形成与高频海平面下降驱动的蒸发浓缩—回流渗透白云石化和短期暴露岩溶相关,其中沉积期地貌相对坡折和滩体叠置迁移加剧了研究区局限蒸发的海水环境:石灰岩储层主要有滩控早成岩期岩溶、风化壳岩溶和断溶优化3种成因类型,分别受沉积期地貌坡折、岩溶地貌高地和斜坡以及断裂控制.综合分析认为,区内茅口组强非均质性、多成因类型储层具有受沉积期古地貌、古环境、风化壳岩溶古地貌、古断裂等"四古"复合控储特征.有利储层具有"沿高环坡"的分布规律,下一步勘探方向应重视东北部自贡一富顺区带的多层系、多成因类型储层的立体勘探和西南部观音场—青杠坪一带规模性白云岩储层的勘探.

在盆地地质背景基础上,根据火山机构的宏观和微观特征,综合运用地质-地球物理等手段,在松辽盆地南部地区建立营城组火山机构地质模式,讨论不同类型火山机构的储层特征.火山机构识别综合利用3类方法:包含地质界面特征、岩性岩相特征、化学成分、喷发方式和单元叠置关系的地质识别,包含自然伽马测井、电阻率测井的测井识别以及包含地震相特征、地震反射特征、地震属性的地震识别.依据以上方法将德惠断陷营城组火山机构分成3类6种,包括流纹质熔岩机构、英安质熔岩机构、安山质熔岩机构、流纹质碎屑岩机构,安山质碎屑岩机构和复合火山机构.针对长岭断陷流纹质不同类型火山机构储层的孔隙度及储集空间类型进行统计,结果表明:复合火山机构的储层物性较好,碎屑岩火山机构的储层物性次之,熔岩火山机构的储层物性较差;酸性火山熔岩机构顶部物性最好,中部物性次之,底部物性最差;火山碎屑熔岩机构在横向上分布较为广泛,在纵向上由多个堆积单元组成.

Volcanic lava is widely distributed in Yingcheng Formation of Yingtai fault depression in southern Songliao Basin.It is one of the most important hydrocarbon reservoirs of volcanic reservoirs.The reservoir is characterized by large thickness,excellent reservoir properties and high productivity,and has favorable prospect.Volcanic lava has complicated lithologies,variable seismic reflection characteristics and strong heterogeneity,so it is difficult to define the volcanic lava boundary and identify volcanic apparatus.Besides,deep reservoir burial,low quality of seismic data,low-angle of gathers and superposed wave impedance enhance the difficulty of the reservoir prediction.This paper applied several techniques to identify the boundary and inner of volcanic lava of Yingcheng Formation,and defined its distribution.According to the log response and gas reservoir characteristics,we used pre-stack simultaneous inversion technology based on log reconstruction,which improves the inversion accuracy and reliability of prediction of volcanic lava reservoir.This method provides newthought and method for the identification and prediction of this kind of complicated reservoirs.