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

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.