Abstract: It was the first time to carry out the systematical statistical analysis on the joint occurrence, scale, width, density and distribution regularities to elaborate the reservoir significance. According to the analysis of joint position, the inter-cutting relationship and the regional tectonic settings, the formation epochs of joints in the target area were divided into three epochs, namely, Yingcheng epoch, the last stage of Yingcheng epoch and the late stage of K₂.By using conjugate joint occurrence and joint nature, basing on the statistics and calculation, Yingcheng epoch had nearly EW direction tectonic stress field with stretch and compression alternatively， NE-SW direction tectonic stress field was formed in the last stage of Yingcheng epoch， NW-SE direction compressional tectonic stress field was formed in the last stage of K₂.It was considered that the joint formation and distribution of Yingcheng Formation were mainly related with the first two compressional tectonic stress fields. The joint distribution regularities of Yingcheng Formation in Xujiaweizi region were predicted, which provides the visual correlation for the study on the distribution regularities of natural gas reservoir.

Key words: Eastern Songliao Basin, Yingcheng Formation, joint, joint prediction