辽河坳陷火山岩岩性特征及储层评价

辽河坳陷火山岩主要为玄武岩、粗面岩、响岩、安山岩、流纹岩和凝灰岩,以抗压强度较弱的少含暗色矿物的粗面岩和流纹岩为主.粗面岩主要分布在东部凹陷第三系,流纹岩主要分布在西部凹陷中生界.岩石化学分析表明,以浅色造岩矿物为主的火山岩抗压强度低,在应力作用下容易形成裂缝,而含暗色矿物较多的火山岩,抗压强度高,在相同应力下难以形成裂缝,并且暗色矿物蚀变后形成的绿泥石、方解石等,往往将早期形成的裂缝充填.运用岩石化学分析和测井响应特征,分别建立火山岩岩性和火山岩储层划分标准；同时,根据中子和电阻率测井响应特征,将火山岩划分为轻度蚀变、中度蚀变、重度蚀变和泥化火山岩4类.应用氧化物分析法,可将东部凹陷火山岩区分开；利用能谱测井,可将西部凹陷的火山岩划分出来:采用测井交会图法,可以划分辽河坳陷火山岩储层.

Volcanic Rock Characteristics and Evaluation of Volcanic Reservoir in Liaohe Depression

Basalt,trachyte,klingstein,andesite,rhyolite and volcanic tuff consist of the volcanic rocks in Liaohe depression.Trachyte and rhyolite with low dark mineral content and weak compressing strength are the main lithology.The trachyte is mainly distributed in Tertiary formations of eastern sag,and the rhyolite is mainly distributed in Mesozoic formations of western sag.Petrochemical analysis shows that the volcanic rocks with light rock-making mineral mainly have low compressing strength,and fractures are easy to form under stress.The volcanic rocks with dark mineral content have high compressing strength,and fractures are difficult to form under the same stress.Chlorite,calcite and other minerals formed after dark minerals altered usually fill the early fractures.Petrochemical analysis and log response features are applied to make classification criterion of lithology and reservoir of the volcanic rocks respectively.At the same time,the volcanic rocks are classified into four main types by neutron log response and resistivity log response: light alteration volcanic rocks,medium alteration volcanic rocks,severe alteration volcanic rocks and argillization volcanic rocks.The volcanic rocks in eastern depression may be classified by oxide analytic method;and those in western depression may be classified by in hole spectrometry.The volcanic reservoirs in Liaohe depression may be classified by log cross plot.