东沙隆起珠江组礁滩相储层主要成岩作用及演化模式

根据岩心观察和镜下薄片分析资料,对珠江口盆地东沙隆起珠江组礁滩相储层主要成岩作用及演化模式进行了研究,结果表明:该地区珠江组礁滩相储层成岩阶段可划分为同生—准同生期、早成岩期以及中—晚成岩期等3个阶段;主要成岩作用可划分为积极成岩作用(如溶解作用、包壳作用、藻类-生物相互穿插、生物钻孔等)和消极成岩作用(如胶结作用、泥晶化作用和压实-压溶作用等)两大类,其中溶解作用是礁滩相储层中次生孔隙形成的关键因素,而胶结作用是礁滩相储层中孔隙减少的主要原因。在此基础之上,建立了该地区珠江组礁滩相储层演化模式,认为只有那些经历过成岩阶段强烈溶解作用改造的礁滩才能形成良好储层,为珠江组礁滩有利目标的搜索与评价提供了重要指标。

Main diagenesis and evolution model of reef flat facies reservoir in Zhujiang Formation,Dongsha uplift

Based on core observation and microscopic thin section analysis data,the main diagenesis and evolution model of Zhujiang Formation reef flat facies reservoir in Dongsha uplift of Pearl River Mouth basin were studied.The results show that the diagenetic stages of Zhujiang Formation reef flat facies reservoir in this area can be divided into three stages:syndiagenetic—penecontemporaneous stage,early diagenetic stage and middle-late diagenetic stage;and the main diagenesis can be divided into positive diagenesis(such as dissolution,coating,algae-organism interfingering and boring pore)and negative diagenesis(such as cementation,micritization,compaction-pressolution),among which,dissolution is the key factor for the formation of secondary pores in reef flat facies reservoir,while cementation is the main reason for the decrease of pores in reef flat facies reservoir.On this basis,an evolution model of reef flat facies reservoir of Zhujiang Formation in this area is established.It is considered that only reef flats that have undergone strong dissolution in diagenetic stage can form good reservoirs,which provides an important index for searching and evaluating favorable targets of reef flat facies reservoir in Zhujiang Formation.