Abstract:

Chang-3 layer in Weibei oilfield belongs to the middle-shallow reservoir, with the buried depth of 200 ~ 1 000 m. The fractures formed diring the fracturing have complex shape with horizontal joints, vertical joints and oblique crack, which impact the evaluation of the fracturing and fracturing effects. Taking Chang-3 reservoir in Weibei oilfield as the research object, combined with the reservoir rock mechanics and crustal stress experiment, and through the analysis of logging data and fracturing construction curves, we calculated the relative values of the vertical stress and horizontal stress and reveal the formation law of fracture forms, so that to summarize the fracture formation identify and prediction technology of Chang-3 reservoir in Weibei oilfiled. When the reservoir depth was less than 450 meters, the horizontal joints formed; when the depth was more than 550 meters, the vertical joints formed; when the depth was between 450 and 550 meters, the complex fractures formed. It was recommended to conduct the mini frac testing to determine the fracture forms.

Key words: Weibei oilfield, Chang-3 reservoir, fracturing construction curve, crustal stress, fracture form