川西拗陷须家河组致密砂岩成岩作用特征及其对储层的影响  

Impact of diagenesis on reservoir-quality evolution in the Upper Triassic Xujiahe tight sandstones,West Sichuan,China

作　　者：李嵘[1] 吕正祥[2] 叶素娟[2] 

机构地区：[1]成都地质矿产研究所,成都610081 [2]中国石化西南油气分公司勘探开发研究院,成都610081

出　　处：《成都理工大学学报（自然科学版）》2011年第2期147-155,共9页Journal of Chengdu University of Technology: Science & Technology Edition

摘　　要：通过对川西拗陷须家河组储层的岩石学、矿物学、物性等特征研究,明确了砂岩成岩作用特征及其对储层质量演化的影响。受沉积相和成岩作用的影响,川西拗陷须家河组砂岩储层致密-超致密并具极强非均质性。影响储层质量的成岩事件包括机械压实作用、石英颗粒压溶作用、自生矿物胶结作用、溶蚀作用以及绿泥石衬边的形成。压实作用是造成砂岩孔隙度降低的最主要因素。晚期碳酸盐胶结作用在须四段钙屑砂岩和须二段细粒砂岩中较为普遍,较高含量碳酸盐胶结物对储层具有明显的破坏作用。自生石英主要来自碎屑石英的压溶,在须二段砂岩中含量较高。具一定厚度、连续性较好的绿泥石衬边可以抑制石英胶结物的形成以及压溶作用进行,对须家河组,特别是须二段砂岩储层孔隙保存具有双倍积极作用。须家河组相对优质砂岩储层主要孔隙类型为剩余粒间孔和粒间溶蚀扩大孔,原生孔隙的保存对次生孔隙形成以及储层质量至关重要。破裂作用可以提高砂岩的储渗能力,同时也有利于砂岩中溶蚀孔隙的形成。The diagenetic characteristics and the impact of diagenesis on reservoir quality in the Xujiahe sandstones of West Sichuan are described based on petrologic,mineralogy,and petrophysical analysis.Depositional facies and various types of diagenetic alterations have caused considerable deterioration and heterogeneity in the Xujiahe sandstones.The diagenetic events that influence the reservoir quality mainly include mechanical compaction,pressure dissolution of detrital quartz,cementation by authigenic minerals,dissolution of detrital silicates,and the formation of grain-rimming chlorite.The mechanical compaction is the main cause of porosity loss.The mesogenetic carbonate cementation pervasively occurrs in calcarenaceous sandstones in T3x4 and fine-grained sandstones in T3x2 and the reservoir quality is significantly deteriorated by the extensive carbonate cementation.The authigenic quartz forms mainly by the pressure solution of detrital quartz and is more abundant in T3x2 than in T3x4.Thick and continuous chlorite pore-lining helps to preserve porosity by inhibiting quartz cementation and pressure dissolution and thus can be doubly beneficial to the Xujiahe sandstones,especially to T3x2.The main pore types of high-quality reservoirs include the surplus intergranular pores and solution enlarged pores and the preservation of primary pores is critical to the formation of secondary pores and the reservoir quality.Fracturing has resulted in an increase in sandstone porosity and permeability and enhanced the development of secondary pores.

关 键 词：须家河组 致密储层 成岩作用 储层质量 绿泥石衬边 川西拗陷 

分 类 号：TE122[石油与天然气工程—油气勘探]