Arthroscopic characteristics

distribution and occurrence of kaolinite are analyzed through quantity thin section analysis

core observation

scanning electron microscope and X-ray powder diffraction.The results show that the kaolinite of sandstone reservoirs in Dongying Sag has two genetic types including authigenic kaolinite and terrigenous kaolinite.The authigenic kaolinites are common in the reservoirs.Microscopically

they show complete crystal form

and fill intergranular pores and dissolution pores of feldspar in typical sheet or vermicular shapes.The "spotted" filling feature of the authitgenic kaolinite aggregates are clear on cast thin sections.The terrigenous kaolinites are rare and often occur in shallow layers.They are formed in association with the non-clay minerals like clastic particles in deposition process.Based on the study mentioned above

the genetic mechanism of authigenic kaolinite is discussed.It is supposed that feldspar dissolution is the main material source for the formation of authigenic kaolinite.Sandstones with large grain size and well sorting have high content of kaolinite

indicating that

in addition to acid fluid environment and sufficient material supply

strong fluid dynamic is also an important controlling factor of authigenic kaolinite formation.