Sand-controlling model of source–slope-break coupling in Pinghu Slope Belt, Xihu Sag

Pinghu Slope Belt has become one of the important fields of lithologic reservoir exploration in the Xihu Sag. Exploration and production have confirmed that the distribution of sand bodies in the Pinghu Formation is complex, and sand body characterization guided by sand-controlling model has become the key to the breakthrough of lithologic reservoir exploration. Based on the studies on the source system and slope-break zone, the distribution characteristics of sand body under the control of source and slope-break coupling in the target area were summarized in this paper. The characteristics of ravines and heavy minerals indicate that there are three source systems in the target area: the western source and southwestern source of Haijiao Uplift, and the dynamic source of Baoyunting paleo-uplift, which controlled the source of sand material in the target area. Under the control of paleo-uplift, differential activities of faults and sedimentation, three types of slope-breaks developed in the target area, namely faulted slope-breaks, flexural slope-breaks, and depositional slope-breaks, controlled jointly the topographic features of the target area. Source system and slope-break coupling controlled the dynamic process of sediment from source to sink. Under the joint control of the southwestern source and the dynamic source of Baoyunting Uplift, the development of mixed-source sand body accretion is dominant in the lower member of Pinghu Formation. Under the main control of the source of the western Haijiao Uplift, the single-source-reformation sand-controlling mode restricted by flexural slope-break is dominant in the middle member of Pinghu Formation. Under the main control of the depositional slope break, the transitional sand-controlling mode of gentle slope was developed in the upper member of Pinghu Formation.