Formation of X-shaped Hydraulic Fractures in Deep Thick Glutenite Reservoirs: A Case Study in Bohai Bay Basin, East China

Tight glutenite reservoirs are widely developed in Bohai Bay Basin, East China. They are mostly huge thick and rely on hydraulic fracturing treatment for commercial exploitation. To investigate the propagation behavior of hydraulic fractures in these glutenite reservoirs, the geological feature of reservoirs in Bohai Bay Basin is studied firstly, including the reservoir vertical distribution feature and the heterogeneous lithology. Then, hydraulic fracturing treatments in block Yan 222 are carried out and the fracturing processes are monitored by the microseismic system. Results show the hydraulic fractures generated in the reservoirs are mostly in X shape. The cause of X-shaped hydraulic fractures in this study is mainly ascribed to (I) the reservoir heterogeneity and (II) the stress shadow effect of two close hydraulic fractures propagating in the same orientation, which is confirmed by the following numerical simulation and related research in detail. This study can provide a reference for the research on the fracturing behavior of the deep thick glutenite reservoirs.