STRESS MEASUREMENTS AT DEPTH IN NORTH CHINA BY HYDRAULIC FRACTURING

In measuring stress at depth, the method of hydraulic fracturing is now receiving more attention. In China, this method is for the first time employed in oil wells in conjunction with the injection of water to increase oil production. On the North China Plain, 62 oil wells of depths of 1000-4000 meters have been tried to measure stress in-situ. They are in the oil fields, Dagang (大港), Hejian (河间), Fengnan (丰南), Huanghua (黄骅), Beizhen (北镇), Qingyang(庆阳), Qianjiang (潜江) etc.This paper gives some of the field results and related calculations. The stress thus measured appears to vary linearly with depths, differing slightly with the areas. The processes of fracturing and directions of fracturing as well as the pecularities of stress variations with depths are also discussed.