Study of the Critical Collapse Cave Span for Fracture-cavity Oil Storage Karst Caves

As the major field in petroleum reserve growth, fractured-vuggy reservoir is the key research in the future. However, in the development of fracture-cavity reservoir, collapse may occur in karst cave which greatly affects the oil well output. In order to forecast the cave collapse before drilling, this work adopts the method of span dichotomy reduction to determine the critical karst collapse of the fracture-cavity reservoir cave on the background of Tahe Oilfield’s fractured-vuggy reservoir. Different factors which influence on the tunnel span of karst collapse and the failure modes of collapsed cave are obtained by great amounts of numerical calculation and analysis on working conditions. Research results in this work provide significant theoretical evidence to the oil exploration in Tahe Oilfield’s fracture-cavity reservoir.