辽河东部凹陷火山岩相测井响应特征及储集意义

在郯庐断裂多期构造活动作用下,辽河坳陷东部凹陷发生了多期火山活动,致使中基性火山岩广泛发育,以玄武岩和粗面岩为主,可分为5相14亚相。以常规测井曲线特征为基础,结合电成像的分析,识别出了爆发相(火山碎屑流和热基浪亚相)、溢流相(玻质碎屑岩、板状熔岩流和复合熔岩流亚相)、侵出相(内带、中带和外带亚相)和火山沉积相(含外碎屑和再搬运火山碎屑沉积亚相)10种岩相/亚相:火山碎屑流亚相具"焊接"特征,热基浪亚相具层理特征;玻质碎屑岩亚相具高CNL的特征,板状熔岩流亚相DEN、CNL和AC测井曲线显示微齿平滑的特征,而复合熔岩流亚相测井曲线呈指状叠加的特征;侵出相内带→中带→外带电阻率逐渐减小;含外碎屑和再搬运火山碎屑沉积亚相GR值范围不同,并且再搬运火山碎屑沉积亚相具水平层理特征。火山岩相控制原生储集空间的类型,并作用于后期的次生改造,从而影响储层的物性、储集性和有效性。复合熔岩流亚相储层孔隙发育,物性好,但由于内部纵向上结构不一致,非均质性强,因而储层含油性差。火山碎屑流亚相内部在纵向上岩性及结构相对一致,因而储层物性相对均一、分布集中,为有利的火山岩储层,可以作为东部凹陷进一步勘探开发的有利相带。

Logging Response Characteristics and Reservoir Significance of Volcanic Rocks in the Eastern Sag of Liaohe Depression

Because of the Tanlu fault,many tectonic movements occurred in the eastern sag of Liaohe depression,all of which were accompanied by volcanic activities with different intensity.So volcanic rocks are widely developed.The volcanic rocks are dominated by basalt and trachyte,which are divided into 5 lithofacies and 14 sub-facies.Furthermore,based on the analysis of conventional logging curve and electrical image logging,10 lithofacies / sub-facies are recognized such as explosive facies (pyroclastic flow,surge sub-facies),effusive lava flow facies (hyaloclastite,tabular flow,compound flow subfacies),extrusive dome facies (inner zone,intermediate zone,and outer zone sub-facies),volcaniclastic facies (resedimented volcaniclastics,epiclast-bearing volcanogenic deposits sub-facies).The pyroclastic flow sub-facies ischaracterized by welding,and pyroclastic surge sub-facies is characterized by various beddings;the hyaloclastite sub-facies has high CNL,the tabular flow sub-facies is with smoothed logging curves of DEN,CNL and AC,and the compound flow sub-facies is with finger-shape logging curves;from inner zone to outer zone,the resistivity decreases;the ranges of GR values of the subfacies of resedimented volcaniclastics and epiclast-bearing volcanogenic deposits sub-facies are different,and the resedimented volcaniclastic deposits is with horizontal beddings.The volcanic facies control the type of primary reservoir space,and affect the secondary transformation,the physical properties,the storage,and the effectiveness of the reservoir.The reservoir of hyaloclastite sub-facies with pore development has good physical properties;however,because the internal vertical structure is inconsistent and strong heterogeneous,the oil content of the reservoir is poor.The lithology and structure of the pyroclastic flow sub-facies is consistent vertically,the reservoir physical properties are relatively uniformly distributed,which is a favorable facies belt for further exploration and development.