COUPLED RELATIONSHIP BETWEEN CREATED AND NATURAL FRACTURES AND ITS IMPLICATION TO DEVELOPMENT

According to outcrops, formation microscanner logging (FMI), paleomagnetism oriented cores and stress variation difference experiment, a close study has been made on the natural fractures of super-lower permeability reservoirs in the Yanchang Formation of the Ordos basin, and in combination with microseismic monitoring technique, an analysis carried out on the relationships between created fractures and earth stress and natural fractures. The results show a good coupling between created fractures and natural fractures. In northern Shaanxi, the well-developed natural fractures and heterogeneity of rocks lead the created fractures to stretch mainly along the natural fractures. In eastern Gansu, however, the natural fractures are poorly developed and the crushed fractures are controlled by present stress field. Therefore, in well pattern arrangement of super-low permeability reservoirs, our attention should be paid not only to the growth degree of the natural fractures but also to the orientation of natural fractures and their relation with the present stress field.