Abstract:

The directions of maximum horizontal stresses of the present tectonic stress field and palaeostress field are of great significance to mineralization analysis, especially to the exploration and development of oil and gas. Fractures induced by drilling are controlled by present stress field, while the highconductive and highresistant fractures caused by tectonic genesis are closely related to palaeostress and can be the indications of the directions of palaeostress fields. After the statistics analyses of fractures identified from FMI images in groups, it is drawn to the conclusion that the current direction of the maximum horizontal major stress of the Lower Cretaceous Yingcheng Formation in Xujiaweizi Rift, Daqing Oilfield is identified to be nearly eastwest, and has changed frequently in the geological history, with obvious three directions of NS, NE and WE.

Key words: FMI, fracture, tectonic stress field, Xujiaweizi Rift