德惠断陷沙一段凝灰岩储层特征及测井识别

Tuff Reservoir Properties and Logging Identification in the Sha1 Member of Dehui Fault Depression

为明确德惠断陷沙一段凝灰岩储层特征,以薄片、X衍射分析、物性等资料为基础,开展了凝灰岩储层微观特征研究。结合测井曲线,利用GR-DEN、AC-DEN和Rt-AC曲线交会图版将凝灰岩储层从围岩中区分开来。研究结果表明:沙一段储集空间的岩石类型为晶屑凝灰岩、玻屑晶屑凝灰岩和凝灰质砂岩;凝灰岩中的主要矿物为石英和长石,储集空间类型为以长石溶蚀孔为主的次生孔隙;凝灰岩储层具有中低孔、超低渗微细喉道的特征,微小的孔喉和以伊蒙混层为主的强水敏黏土矿物导致渗透率极低。由测井曲线交会图版可知,凝灰岩储层具有低的DEN,相对高的GR与AC和较低的Rt特征。该研究对德惠断陷沙一段凝灰岩油气藏的勘探具有指导意义。

In order to clarify the tuff reservoir properties in the Sha1 Member of Dehui fault depression,thin-section,s-ray diffraction analysis,physical properties and other data are used to study the microscopic properties of tuff reservoir.Combining with logging data,the intersection chart between GR-DEN,AC-DEN and Rt-AC curves are used to identify the tuff reservoir from the surrounding rock.Research indicates that the reservoir rock of Sha1 Member mainly consists of crystal tuff,vitreous-crystal tuff and tuff sandstone.The dominant minerals in tuff are quartz and feldspar.The corresponding reservoir space is secondary porosity dominated by feldspar dissolved pore.Tuff reservoir is characterized by medium-low porosity and small pore-throat with ultra-low permeability.The tiny pore-throat and strong water-sensitive clay minerals dominated by illite-smectite results in ultra-low permeability.According to the intersection plot of logging curves,tuff reservoir is featured by low DEN,relatively high GR and AC and lower Rt.This research could provide certain guidance for the further exploration of tuff reservoirs in this area.