鄂尔多斯盆地东部下奥陶统碳酸盐岩埋藏成岩事件研究

鄂尔多斯盆地东部下奥陶统碳酸盐岩埋藏成岩事件主要有埋藏白云岩化、埋藏溶解作用、埋藏胶结作用、埋藏去白云岩化、有机质成岩作用和粘土矿物转化作用等.不同类型的埋藏成岩事件的产物和岩石学及地球化学特征各异,对油气藏的最终形成起着不同的作用.有机质成岩作用和埋藏溶解作用产生的埋藏溶蚀孔洞缝构成区内主要的油气储集场所;埋藏胶结作用及成岩自生粘土矿物的形成作用是区内成岩圈闭和复合圈闭形成的必要条件;埋藏白云岩化和埋藏去白云岩化可提供部分油气储集空间.上述诸埋藏成岩事件的相互叠加对油气的形成、运移、聚集、圈闭和保存具有重要意义.

BURIAL DIAGENETIC EVENTS OF CARBONATE ROCKS OF LOWER ORDOVIAN IN THE EASTERN ORDOS BASIN

Carbonate rock reservoirs of Lower Ordovician in the eastern Ordos Basin have undergone all sorts of burial diagentic events of which burial dolomitization, burial dissolution, burial dedolomiti-zation, burial cementation, organic matter diagenesis and clay mineral transformation are major. Each of these plays distinctive role on the formation of oil/gas deposit. The products, petrology and geochemistry of various burial diagenetic events are distinctively different. The burial dissollution porosities derived from organic matter diagenesis and burial dissollution constitute the mainly significant oil/gas reservoir spaces. Burial cementation and diagenetic authigenic clay minerals forming are of most important roles on the formation of oil/gas diagenetic traps or oil/gas composite traps. Burial dolomitization and dedolomitization not only contribute significant parts of oil/gas reservoir spaces, but provide direct evidence for exploration of new kinds oil/gas deposit. The combination of all these burial diagenetic events are of most importance on oil/gas formation, migration, accumulation, trapping and preservation.