Fracture development and hydrocarbon accumulation in tight sandstone reservoirs of the Paleogene Huagang Formation in the central reversal tectonic belt of the Xihu Sag, East China Sea

ZHOU Xinhuai,XU Guosheng,CUI Hengyuan,ZHANG Wu

Fig. 3. Microscopic characteristics of fractures in the Huagang Formation in zones A and B. (a) Well A-2, 3610.97 m, 2.5×10, single polarized light, penetrating fractures, filled with peat; (b) Well A-3, 4108.90 m, 5×10, single polarized light, penetrating fractures, filled with calcite; (c) Well A-4, 3911.40 m, 2.5×10, single polarized light, a penetrating fracture, about 1.5 mm wide; (d) Well B-2, 3797.50 m, 2.5×10, single polarized light, edge fractures.