马朗凹陷哈尔加乌组火山岩储集层特征

摘要

Based on the data of core,thin section,scanning electron microscopy and the petrophysical property,this paper presents the characteristics of Harjiawu volcanic reservoir of the Carboniferous in Malang sag,and obtains the following understandings.①The lithology is dominated by basalt,andesite and transitional lithology;②The main lithofacies is overflow facies,explosion and volcano-sedimentary facies are secondary;③The volcanic reservoir are of medium-low porosity and low-super low permeability;④Primary porosity is not developed because of its underwater eruption,however,the pores,vugs and fractures often superimposed on the original storage space after the transformation of the post-magmatic diagenesis and woven together form the effective storage spaces;⑤The phenomena such as albitization,arfvedsonitization and Sideritization prove existence of hydrocarbon alkali fluid in the Carboniferous volcanic rocks and the extensive development of alkali metasomatism;⑥Devitrification,weathering,tectonism,metasomatism and dissolution have significant effects on the volcanic reservoir modification,which are the main diageneses for forming secondary pores and the key factors for forming effective reservoirs of the Harjiawu formation.%利用岩心、薄片、扫描电镜及物性资料,通过对三塘湖盆地马朗凹陷石炭系哈尔加乌组火山岩储集层特征的研究,得到以下认识：以玄武岩、安山岩及其过渡岩性为主;以溢流相为主,爆发相和火山沉积相次之;为中低孔、低渗透-特低渗透火山岩储集层;主要为水下喷发,原生孔隙不发育,通过岩浆期后成岩作用的改造,形成叠加在原生储集空间之上的交织在一起的孔、洞、缝构成本区的有效储集空间;由钠长石化、钠铁闪石化和菱铁矿化等现象证明了火山岩中碱性流体的存在以及碱交代作用的广泛发育;脱玻化作用、风化作用、构造作用、交代作用和溶解作用等对火山岩储集层的改造产生了至关重要的影响,是形成次生孔隙带的主要成岩作用,更是哈尔加乌组形成有效储集层的关键因素。