准噶尔盆地中拐地区佳二段沸石类矿物成岩作用及其对油气成藏的意义

通过岩心、铸体薄片、电子探针、包裹体等资料,对中拐地区二叠系佳木河组佳二段沸石类矿物成岩作用进行研究,并分析其对油气成藏的意义。结果表明:佳二段沸石类胶结是最主要的胶结类型,主要有浊沸石、片沸石和方沸石3种沸石类矿物;前期沸石的胶结保存了部分原始孔隙结构,为后期浊沸石和方沸石的溶蚀提供了物质基础。佳二段沸石类矿物主要分布在扇三角洲河道厚层的砂砾岩体中,其形成与火山物质密切相关;地层水化学性质、pH值以及离子的性质和比率、温度和压力等决定了沸石类型的转化:沸石从上到下的转化序列为方沸石-片沸石-浊沸石,除了沸石矿物的转化,斜长石的钠长石化也形成了部分浊沸石;浊沸石含量和溶蚀强度决定了储层质量,其次生孔隙发育带是寻找有利油气储层的目标区域。

Diagenesis of zeolite minerals and its significance for hydrocarbon accumulation in the second member of Jiamuhe formation of Zhongguai area, Junggar Basin

Diagenesis of zeolite minerals and its significance in hydrocarbon accumulation in the second member of Jiamuhe formation of Zhongguai area were studied using data from the core, casting thin section observation,electron probe and inclusions. The results show that there are three kinds of zeolites, which include laumontite,heulandite and analcite in the second member of Jiamuhe formation of Zhongguai area, Junggar Basin. Zeolite cementation is the main type of cementation. The cementation of early zeolite reserved some of the original pores, which formed a foundation for the dissolution of laumontite and analcite at the later stages. The zeolites whose formation is closely related to volcanic material are mainly distributed in the glutenite of fan delta river in the formation. The formation of zeolite types is determined by the chemical properties of surrounding water:the pH value, the properties of the ions and their ratios between each other, and the temperature and pressure. The transforming sequence of zeolite is from analcite, to heulandites, and then laumontite downwards. Additionally, albitization of plagioclase can also form some part of laumontite. Enriched reservoirs, in which the secondary pores are favorable for oil and gas accumulation, can be determined by the content of laumontite and the degree of dissolution.