松辽盆地徐家围子地区火山岩储层主要次生矿物研究  

Study on major secondary minerals in volcanic reservoir in Xujiaweizi area, Songliao Basin

作　　者：李欣[1] 杜德道[1] 蔡郁文[2] 王珊[1] 

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《岩性油气藏》2014年第6期98-105,共8页Lithologic Reservoirs

基　　金：国家重点基础研究发展计划(973)项目"火山岩油气藏的形成机制与分布规律"(编号:2009CB219301)资助

摘　　要：以松辽盆地北部徐家围子地区深层火山岩储层为研究对象,通过对徐深气田50多口井深层火山岩岩心观察得出,该区岩石类型从基性、中性到酸性岩均有分布,以酸性岩为主。火山熔岩有玄武岩、安山岩、粗面岩和流纹岩等;火山碎屑岩包括凝灰岩、流纹质熔结凝灰岩、火山角砾岩和集块岩。通过岩石薄片显微镜下鉴定发现,各种火山岩均见不同程度的交代作用,如绿泥石化、碳酸岩化、高岭土化及硅化等。交代作用形成的次生矿物如石英、长石、绿泥石、浊沸石、碳酸盐矿物及黏土矿物,多充填在气孔和裂缝中。对以上几种次生矿物特征作了详细描述,并根据热力学第三定律对石英、绿泥石和浊沸石的形成进行了热力学模拟。根据石英、绿泥石和浊沸石3种矿物形成的反应方程式,并结合地层水资料中K+,Ca+,Na+,H+,(Fe,Mg)2+和(Fe,Al)3+等离子的浓度,分别计算出它们各自形成的平衡常数K,再根据热力学公式ΔG(T)=-R·T·ln K计算出它们各自在不同温压条件下的吉布斯自由能变量ΔG(P,T)。通过比较ΔG(P,T)的大小判断出3种矿物沉淀的先后顺序为绿泥石→石英→浊沸石,与镜下观察到的成岩顺序一致,为研究火山岩储层次生矿物的成岩演化提供了热力学依据。Based on the volcanic rock core observation of more than 50 wells in Xushen Gas Field, this paper studied the deep volcanic reservoir in Xujiaweizi area in northern Songliao Basin. The result shows that the rock types of deep volcanic reservoir include basic rock, neutral rock and acidic rock, with the acidic rock being dominated. Volcanic lava includes basalt, andesite, trachyte and rhyolite, while volcaniclastic rock includes tufts, rhyolitic ignimbrites, volcanic breccia and agglomerate. Through thin section observation by microscope, it is discovered that the volcanic rocks are in a variety of different degrees of metasomatism which formed many secondary minerals such as laumontite, chlorite, quartz, feldspar, siderite, calcite and clay mineral filling in pores and cracks. The characteristics of these secondary minerals were detailedly described and their forming thermodynamics conditions were simulated accordingto the third law of thermodynamics. According to the chemical equation of laumontite, chlorite and quartz, combined with the ionic concentration of K＋, Ca＋, Na＋, H＋, （Fe, Mg）2＋ and （Fe, Al）3＋ in formation water, we can work out the equilibrium constant K, and then calculate the △G（P.T） values under different temperature and pressure according to the equation △G0（T）= -R· T2 in K. By comparing the △G（P.T） values of laumontite, chlorite and quartz, the formation time order was determined. The chlorite is formed firstly then the quartz, and the last one is laumontite. The thermodynamic simulation result can be proofed by microscope observation, which provides thermodynamics proof for the study on diagenetic evolution of secondary minerals in volcanic reservoir.

关 键 词：火山岩储层 次生矿物 热力学 松辽盆地 

分 类 号：P57[天文地球—矿物学]