Diagenesis and its influencing factors of the Chang 6 interval of Upper Triassic Yanchang Formation in Ordos Basin
Wang Lan1, Li Wenhou2, Lin Tong1,3, Wang Ruogu2
1 Research Institute of Petroleum Exploration and Development，PetroChina，Beijing 100083 2 Department of Geology， Northwest University，Xi′an 710069，Shaanxi 3 Research Institute of Petroleum Exploration and Development-Langfang，PetroChina，Langfang 065007，Hebei
Abstract：The reservoir of the Chang 6 interval of Upper Triassic Yanchang Formation in the Ordos Basin，controlled by deposition and diagenesis，is characterized by low porosity and extraordinary low permeability.Its rock types mainly include feldspathic sandstone，lithic arkose and feldspathic litharenite.The sandbodies are rich in feldspar and low in quartz in the southern basin，but low in feldspar and rich in quartz and argillaceous matrix in the southwestern basin.The reservoir spaces are mainly residual intergranular pore and dissolution pore.The diagenetic types controlling the reservoir include compaction，cementation and dissolution，in which the chlorite cementation，feldspar dissolution and laumontite dissolution are favorable to form high quality reservoirs，while the compaction and carbonate cementation are the main contributors to decreasing the intergranular pore and reservoir compaction.There are two kinds of diagenetic facies models which are the Ansai and Huachi.The controlling factors on diagenesis are provenance，sedimentary environment，tectonic activity，hydrocarbon generation，meteoric water etc.，and the sedimentary environment controlled the sandbody development firstly，then influence the type of diagenesis and physical property of the reservoir.
Wang Lan,Li Wenhou,Lin Tong et al. Diagenesis and its influencing factors of the Chang 6 interval of Upper Triassic Yanchang Formation in Ordos Basin[J]. JOPC, 2012, 14(3): 311-320.
