Changes

====Early diagenesis====

====Early diagenesis====

Early diagenesis was controlled by the depositional facies and detrital composition. Early diagenesis mainly includes mechanical compaction, early diagenetic carbonate cementation, dissolution of the detrital fragments, and the mechanical infiltration of grain coating smectitic clay, and precipitation of kaolinite. Mechanical compaction reduced porosity and permeability through increased grain packing and the bending and rupturing of mica and plastic deformation of ductile rock fragments and mud intraclasts. Interaction of meteoric water with sandstones resulted in the dissolution of detrital fragments (mainly feldspars) and the precipitation of kaolinite and smectite.  

Early diagenesis was controlled by the depositional facies and detrital composition. Early diagenesis mainly includes mechanical compaction, early diagenetic carbonate cementation, dissolution of the detrital fragments, and the mechanical infiltration of grain coating smectitic clay, and precipitation of kaolinite. Mechanical compaction reduced porosity and permeability through increased grain packing and the bending and rupturing of mica and plastic [[deformation]] of ductile rock fragments and mud intraclasts. Interaction of meteoric water with sandstones resulted in the dissolution of detrital fragments (mainly feldspars) and the precipitation of kaolinite and smectite.  

====Late diagenesis====

====Late diagenesis====

====Effect of compaction on reservoir quality====

====Effect of compaction on reservoir quality====

Mechanical compaction during the early diagenetic phase reduced porosity and permeability through increased grain packing, displacement and rearrangement of the detrital fragments, plastic deformation of the ductile mud intraclasts to pseudo matrix as well as bending and squeezing of Biotite between rigid grains. The overall small amounts of early diagenetic cements rendered compaction to be more important than cementation in reducing porosity and permeability (figure 11).

Mechanical compaction during the early diagenetic phase reduced porosity and permeability through increased grain packing, displacement and rearrangement of the detrital fragments, plastic [[deformation]] of the ductile mud intraclasts to pseudo matrix as well as bending and squeezing of Biotite between rigid grains. The overall small amounts of early diagenetic cements rendered compaction to be more important than cementation in reducing porosity and permeability (figure 11).

[[File:Sandstone-Fig-11.png|thumb|300px|Figure 11: Plot of intergranular volume (%) versus cement (%) for the Jurassic-Triassic fluvio- deltaic sandstones with a depositional intergranular volume of 40% (after Li Renwei et al<ref>Li Renwei, Lu Jiacan, Zhang Shukun et al., 1999, Organic carbon isotopic composition in black shales of Sinian and early Cambrian. (6th edition), vol.42, Science in China, pp. 595-603.</ref>).]]

[[File:Sandstone-Fig-11.png|thumb|300px|Figure 11: Plot of intergranular volume (%) versus cement (%) for the Jurassic-Triassic fluvio- deltaic sandstones with a depositional intergranular volume of 40% (after Li Renwei et al<ref>Li Renwei, Lu Jiacan, Zhang Shukun et al., 1999, Organic carbon isotopic composition in black shales of Sinian and early Cambrian. (6th edition), vol.42, Science in China, pp. 595-603.</ref>).]]