Diagenesis of the Member 4 of the Shahejie Formation in the south slope of the Dongying depression, China
SONG Ming-shuiDepartment of Exploration Administration of Shengli Oilfield, Dongying 257001, China
The sandbodies of the Member 4 of the Shahejie Formation (Es4) in the south slope of the Dongying depression are mainly conglomeratic sandstone, sandstone, and minor siltstone. The sandstones are mostly lithic arkose. The main diagenetic minerals of the sandstones include authigenetic clay minerals, quartz and feldspar overgrowth, late carbonate cement and sideropyrite. The authigenetic clay minerals include kaolinite, illite, chlorite and illite-montmorillonite. There are four diagenetic facies in the south slope of the Dongying depression. Obviously, the reservoir quality is controlled by diagenetic facies. In this area, braided-channel sandbodies are important locations for oil and gas storage. The reservoir diagenetic stages can be divided into A_1-substage of late diagenesis. The petroleum fillings of this reservoir occurred from about 7.5 Ma to 25 Ma.