自生绿泥石对砂岩储层孔隙的保护机理  

Protection Mechanism of Authigenic Chlorite on Sandstone Reservoir Pores

作　　者：田建锋[1] 陈振林[2] 杨友运[1] 

机构地区：[1]西安石油大学油气资源学院,西安710065 [2]中国地质大学资源学院,武汉430074

出　　处：《地质科技情报》2008年第4期49-54,共6页Geological Science and Technology Information

基　　金：陕西省教育厅专项科研基金项目(07JK364)

摘　　要：自生绿泥石可以抑制石英的胶结作用,但其抑制机制目前尚无定论。根据自生绿泥石的产状、性质及其与伴生成岩矿物的关系,综合分析了自生绿泥石的形成条件及其对后期成岩环境的影响,系统研究了自生绿泥石在整个成岩演化过程中对储层孔隙发育的作用。认为对储层有建设意义的是早期形成的孔隙衬里绿泥石,它通过占据石英的结晶基底并保持孔隙流体和颗粒表面的碱性条件来抑制石英颗粒的自生加大,但不能抑制自生石英雏晶的生长,只有与高孔渗的开放环境相配合,流体运移频繁,硅质能被及时带出,自生石英雏晶的生长才能得到有效抑制。孔隙衬里绿泥石常与浊沸石伴生并不表明绿泥石的生成是产生浊沸石的条件,而是说明孔隙衬里绿泥石和浊沸石具有相似的形成条件,适量孔隙衬里绿泥石的存在具有指示并维持高孔渗的碱性成岩环境的意义,并预示浊沸石可能出现,而浊沸石的形成对压实作用的抑制和次生溶蚀孔隙的发育具有重要意义。Numerous published studies have shown that the authigenic chlorite grain coatings can inhibit the quartz cementation, but the mechanism is still unclear. The chlorite formation conditions and the effects of authigenic chlorite on subsequent diagenesis environment were comprehensively studied from the occurrence and character of chlorite, and the relationships between the chlorite and other diagenetic minerals. Then, the effects of authigenic chlorite on sandstone reservoir pores were concluded as follows in the whole diagenesis evolution. The actual contributor to the sandstone reservoir is pore-filling chlorite which predates quartz overgrowth and laumontite cementation in eogenesis. Although the pore-filling chlorite hinders quartz overgrowth by blocking potential nucleation sites for quartz and maintaining pore fluid and grains surface in alkaline condition, it can not retard the growth of secondary quartz crystals effectively, unless it occurs in the sandstone with high porosity and permeability in an open system. If the pore liquid can not migrate continually, the silica can not be taken out timely and will concentrate in the pore fluid, leading the secondary quartz crystals to precipitate on the spot. The pore-lining chlorite associating with laumontite does not mean that the formation of pore-lining chlorite is the premise of laumontite cementation, but this presents that the precipitation of chlorite and laumontite is similar. Laumontite frequently precipitates in higher pH value subsequent to the formation of pore-lining chlorite. The existence of moderate pore-lining chlorite indicates an alkaline diagenesis environment, and at the same time, signifies the subsequent development of laumontite cementation. The upgrowth of laumontite has profound significance in inhibition of mechanical compaction and development of secondary solution pore.

关 键 词：自生绿泥石 浊沸石 石英加大 孔隙衬里 碳酸盐胶结 成岩作用 

分 类 号：P278.962[天文地球—测绘科学与技术]