珠江口盆地陆丰凹陷珠江组沉积相带与储层特征

Sedimentary facies and reservoir quality of the Zhujiang Formation in the Lufeng depression,Zhujiangkou Basin

陆丰凹陷珠江组发育的多套砂岩储层是珠江口盆地东部重要的产油层,但对这些储层沉积特征的研究程度不足制约了下一步的勘探部署。在岩心观察的基础上,结合测井资料、岩石学特征、矿物成分、沉积构造等对珠江组砂体储层沉积相类型和物性特征进行了分析。结果表明,研究区主要发育辫状河三角洲和滨岸两大沉积体系,并可进一步细分为分流河道、河口坝、远沙坝等10种沉积微相。不同的沉积相带控制不同砂体储集物性,按储层物性好坏,划分出3类沉积相带砂体储层。滩砂、滩砂水道、沿岸坝等砂体储层物性最好,上临滨、分流河道、河口沙坝次之,下临滨砂体最差。综合研究认为,寻找优质油气储层,应优先考虑最有利的形成优质储层的沉积相带。

Several successions of sandstone reservoirs in the Zhujiang Formation, Lufeng depression occur as key pay horizons in the eastern part of the Zhujiangkou Basin. The present paper deals with sedimentary facies types and reservoir quality of the sandstone reservoirs in the Zhujiang Formation on the basis of well logs, mineral compositions, sedimentary structures and physical properties of the sandstone reservoirs. Four sedimentary facies types are discriminated, including the braided delta facies, littoral facies, carbonate platform facies and shallow sea shelf facies. The braided delta facies may be subdivided into the distributary channel, interdistributary bay, channel-mouth bar, distal bar and sheet sand microfacies, whereas the littoral facies is made up of the beach sand, beach channel, coastal bar, upper shoreface and lower shoreface microfacies. The sandstone reservoirs in the beach sand, beach channel and coastal bar micrafacies have the best reservoir quality, followed by those in the upper shoreface, distributary channel and channel-mouth bar microfacies. The reservoir quality is too worst for the lower shoreface sandstones.