Abstract:

Zhuhai Formation is the major reservoir in , Wenchang 9 area between the No.6 Fault and the South Fault of Wenchang A depression,which deeply buried over 3 km. It is the rontal subfacies of fan delta. The reservoir properties are low permeability mainly. In order to expanding the prospecting for oil and gas reserves and later the reasonable and effective development,diagenetic facies and the distribution of reservoir thickness and physical properties are recognized by normal physical characteristics,logging interpretatio,analysis of rock thin and two dimensional nuclear magnetic resonance. The reasons of low permeability formation and factors of reservoir thickness and physics quality are analysed finly from sedimentary facies and diagenesis. It is determined that compaction is the main reseron to low permeability. The most favorable Sedimentary facies are underwater distributary channel,tidal channel,sand flat, the second is the mixed flat. All of them can form “sweet spots” reservoir. Less compaction, coarse grain size, the dissolution stronger intensity or chlorite grain-coatings are the areas of “sweet spots” reservoir. The area between the fault zone 6 to the South fault zone of weaker compaction is “sweet spots” reservoir zone. The zones near the fault are more favorable to sweet spots than the zones further away from the sixth fault with similar depth.

Key words: “sweet spots”, low permeability reservoir, sedimengtary facies, diagenesis facies, reservoir quality, Zhuhai Formation, Pearl River mouth basin