Formation conditions and exploration direction of large natural gas reservoirs in the oil-prone Bohai Bay Basin, East China
XUE Yong’an,WANG Deying
Table 1 Caprock characteristics of large and medium gas fields in the Bohai Bay Basin (After reference [13]).
No. Natural
gas field		 Caprock Structure Reserves
Type Thickness/
m		 Pressure
coefficient		 Natural
gas/108 m3		 Condensate/
104 m3
1 BZ19-6 Mudstone of Dongying Formation
and Shahejie Formation		 200-1 200 1.20-1.60 Complex fault block with
anticline shape		 1 578 14 862
2 Xinglongtai Mudstone of Dongying Formation and the first member of Shahejie Formation 500-1 000 1.20-1.40 Complex fault block with
anticline shape		 171
3 JZ20-2 Mudstone of Dongying Formation 324-530 1.48 Drape structure over low
buried hill		 144 399
4 Banqiao Mudstone of the first member of
Shahejie Formation		 320-400 1.40 Semi-anticline, locally
horst and nose structure		 242
5 Baimiao Mudstone of Shahejie Formation 300-700 1.20-1.60 Semi-anticline and
reverse-drag fold		 126
6 CFD18-2 Mudstone of Dongying Formation 450-760 1.35 Drape structure
over buried hill		 54 347
7 BZ28-1 Mudstone of the first member
of Dongying Formation		 270-420 1.20 Fault block in buried hill 87 294
8 BZ13-1 Mudstone of the third member
of Dongying Formation		 300-600 1.30-1.54 Drape structure over
buried hill		 50 522
9 Qianmiqiao Mudstone and tuff of Mesozoic 310-400 Normal pressure Buried hill with
anticline shape		 242
10 Suqiao—
Wenan		 Bauxite of Carboniferous-Permian
and mudstone of Mesozoic		 300-400 Normal pressure Monocline fault block 109
11 Wen23 Gypsum with mudstone interbeds of the third and fourth member of Shahejie Formation Large thickness and stable Normal pressure Salt uplifting anticline 154