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

Table 1 A reference table for classification of fracture occurrence[19].

Fracture type Fracture angle/(°) Vertical fracture Larger than 85 High-angle oblique fractures 45-85 Low-angle oblique fractures 5-45 Horizontal fractures Less than 5