Abstract: The connotation, optimization design and implementation of the volume Fracturing technique are discussed. The connotation includes five aspects as follows: (1) break up reservoirs to form complex fracture network, and "create" the artificial permeability; (2) fracture initiation is not single open-fracture but shear failure and slip; (3) "breakthrough" the traditional fracturing seepage theory model, greatly shorten the effective fluid seepage distance; (4) more suitable for high brittleness formations; (5) multi-stage and multi-cluster perforation mode. Research shows that: the time required to seep through matrix (0.000 001 x 10^-3 μm²) to fracture for 100 m distance is about more than 100 x l04 years, and only volume fracturing can realize "the most short-distance" seepage. Cluster spacing optimization, non-uniform stage (cluster) interval and proppant transportation are the key to achieve volume fracturing. Small cluster interval technology, multiple stop injection mode and tip screen-out fracturing technology are the key techniques to realize volume fracturing in low brittleness formations. Volume fracturing technique has a good application prospect in tight oil (gas), volcanic and carbonate, and the further developed "integrated" volume fracturing (based on multi-layer and multi-branch well technology) is the future development direction of unconventional reservoir development.

Key words: unconventional reservoirs; volume fracturing technology; connotation; optimization design; multi-stage and multi-cluster; "integrated" volume fracturing; development direction