Analysis of reservoir characteristics and main controlling factors of Chang 7 member in Hujianshan block of Yishan slope
This rock type of tight sandstone reservoir in Chang 7 member of the Hujianshan block of the Yishan slope in Ordos Basin is very complex.Clarifying the reservoir rock types,microscopic pore structure characteristics,and main controlling factors of physical properties of the reservoir is conducive to the evaluation of sweet spots in tight sandstone and the optimization of favorable areas.Using the Chang 7 member tight sandstone in the Hujianshan block as the research sample,the microscopic pore structure of the tight sandstone reservoir was studied u-sing experimental methods such as whole rock XRD diffraction,scanning electron microscopy,high-pressure mercury intrusion,and logging da-ta.The main controlling factors of the physical heterogeneity of the tight sandstone reservoir were discussed.The results show that the tight sandstone of Hujianshan block of Yishan slope in Ordos Basin,Chang 7 members,mainly consists of rock-forming minerals and fillers,the rock-forming minerals are mainly quartz,feldspar and clasts,and the fillers are mainly mica,clay minerals and calcite,etc.,with almost no sid-erite and pyrite;the work area mainly develops Class Ⅲa,Ⅲb,and Ⅳ reservoirs,which are relatively dense.Among them,there are four types of pores in tight sandstone:intergranular pores,intergranular pores,mixed matrix dissolution pores,and microcracks;diagenesis has a signifi-cant impact on reservoir properties,dissolution has a significant improvement effect on reservoir properties,and cementation,compaction,and other factors have a significant destructive effect on reservoirs.Research suggests that sedimentary rhythm has a controlling effect on the physi-cal properties of tight sandstone reservoirs.The positive sedimentary rhythm type is characterized by high porosity and high permeability sec-tions distributed at the bottom of the sand body,with upward porosity gradually decreasing,while the reverse rhythm type is characterized by porosity gradually increasing upwards,with high porosity and high permeability sections distributed at the top of the sand body.
reservoir characteristicsheterogeneityphysical controlling factorstight sandstoneOrdos BasinChang 7 member
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