Factors controlling the development of tight sandstone reservoirs in the Huagang Formation of the central inverted structural belt in Xihu sag, East China Sea Basin

XU Fanghao,XU Guosheng,LIU Yong,ZHANG Wu,CUI Hengyuan,WANG Yiran

Table 4 Electronic probe analysis results of quartz secondary overgrowth in central inversion structural belt of the Xihu sag.

Well	Layer	Depth/m	Composition/%
Well	Layer	Depth/m	Na₂O	MgO	Al₂O₃	SiO₂	K₂O	CaO	TiO₂	Cr₂O₃	MnO	FeO	NiO
E-3	H3	3 850.4	0.001	0	0.018	99.831	0.041	0.041	0	0	0.015	0.052	0
E-3	H3	3 857.9	0	0.001	0.116	99.809	0.011	0	0.002	0.01	0.005	0.047	0
E-3	H3	3 857.9	0.008	0.006	0.026	99.898	0.003	0	0.019	0.004	0	0.004	0.029
E-3	H3	3 726.6	0.028	0.008	0.006	99.795	0.07	0.028	0	0	0.041	0.024	0
E-3	H3	3 795.5	0	0	0.007	99.919	0.005	0.008	0.01	0.005	0.008	0.03	0.007
E-3	H3	3 795.5	0	0	0	99.793	0.02	0	0.024	0	0.025	0.137	0
E-3	H4	4 023.1	0.024	0	0.095	99.853	0.026	0.002	0	0	0	0	0