塔里木盆地志留系柯坪塔格组砂岩储层成岩作用

DIAGENESIS OF KEPINGTAGE FORMATION SANDSTONE RESERVOIRS IN SILURIAN SYSTEM OF TARIM BASIN

综合利用岩心与露头样品的铸体薄片、电子探针、扫描电镜、x衍射及物性分析等资料，对塔里木盆地志留系柯坪塔格组砂岩储层岩石学、成岩作用及成岩相进行了研究。柯坪塔格组储层岩性主要为岩屑石英砂岩、长石岩屑石英砂岩、岩屑砂岩、长石岩屑砂岩等。成岩作用主要有压实作用、胶结作用、交代作用及溶解作用，其中溶解作用以早期碳酸盐胶结物溶解为主，产生的次生孔隙明显改善储层物性，而压实作用与晚期碳酸盐胶结作用则导致原生孔隙与次生孔隙消失。识别出早期碳酸盐胶结物强溶解一晚期弱、中等充填、晚期碳酸盐强烈胶结、较强石英次生加大一较强压实和强烈压实等4种主要成岩相。其中早期碳酸盐胶结物强溶解一晚期弱、中等充填相有利于次生孔隙的形成与保留，为最有利的储层成岩相；强烈压实可导致原生孔隙减少或消失，且不利于次生孔隙形成，为储集性能较差的成岩相。

By comprehensive use of the chemical testing data of cast thin section, electronic probe, scanning elec- tron microscope, X-ray diffraction, physical properties analyses and s on for the cores and outcrop samples, the studies on the petrology, diagenesis and diagenetic facies are conducted for Silurian Kepingtage Formation sandstone reservoirs in Tarim Basin. The reservoirs are mainly composed of lithie quartzose sandstone, arkose quartzose sand- stone, litharenite, feldspathic litharenite ; the diageneses mainly include compaction, cementation, replacement and dissolution. Among them, the later takes the dissolution of early-period carbonate cements as main form, the generated secondary pores and fissures can obviously improve the physical properties of the reservoirs, but the com- paction and later-period carbonate cementation result in the losses of primary and secondary pores and fissures. Four kinds of main diagenetic facieses are recognized, including strong dissolution of early-period carbonate ce- ments-later-period weak-medium packing, strong dissolution of later-period carbonate, compaction with rather strong induced quartz swelling and strong compaction. The former is beneficial to the generation and maintenance of the secondary pores and becomes most favorable diagenetic facies for the reservoirs; the later can result in the re- duction and loss of the primary pores and furthermore is not good for the formation of secondary pores, so turns to be the diagenetic facies with rather poor reservoir properties.