银额盆地查干凹陷苏红图组火山岩储层特征

VOLCANIC RESERVOIR CHARACTERISTICS OF THE SUHONGTU FORMATION IN THE CHAGAN SAG,YIN-E BASIN

火山岩空间分布形态多变,物性变化复杂,加强储层描述是提高火山岩油气藏勘探成功率的关键。以岩芯分析资料为基础,研究表明查干凹陷苏红图组火山岩储层的岩石类型为玄武岩和安山岩,以玄武岩为主,多为灰黑色或灰绿色,具有斑状结构、玻晶交织结构。火山岩的储集空间类型包括原生孔隙、次生孔隙和原生裂缝三类。储层岩石类型、成岩作用、岩相带、裂缝及溶蚀作用、断裂作用等共同控制了有效火山岩储层的分布和发育程度。对查干凹陷苏红图组而言,断裂带背景下的自碎角砾熔岩微相、气孔—杏仁火山岩微相和底部扁平气孔—杏仁火山岩微相为火山岩储层发育的有利相带。在新建查干凹陷火山岩储层分类标准基础上,进一步研究认为,该区域火山岩体储层Ⅲ型为主,Ⅰ型和Ⅱ型较少。

The spatial distribution and physical properties of volcanic rocks are variable.To improve our understanding of volcanic reservoirs,it is important to have detailed description of volcanic reservoirs.Based on core analysis,this paper provides a systematic description of the Suhongtu volcanic reservoir in the Chagan Sag.Volcanic rocks of the Suhongtu Formation include basalts and andesites,with basalts being the dominant type.Suhongtu basalts are bedded eruptive rocks and they are mostly dark gray or graygreen,with porphyritic to glassy textures.These volcanic rocks have primary and secondary porosities,as well as cracks and fractures.The distribution and development of volcanic reservoirs are controlled by reservoir rock types,volcanic facies,fractures,dissolutions,and faults.The most favorable volcanic reservoir facies in the Suhongtu Formation include lava breccia facies and amygdaloidal lava facies.Based on a new classification scheme,type III volcanic reservoir is common and type I and type II volcanic reservoirs are rare in the Chagan Sag.The research results can effectively guide the exploration of the region and significantly reduce exploration risk in the Chagan Sag.Additionally,this research also has implications for the exploration of similar volcanic reservoirs in other areas.