| The main means of exploitation of hydraulic fracturing as low permeability,ultra-low permeability reservoirs. Traditional fracture mode is difficult to increase the yield of such reservoir, due to the limitation of variety of conditions such as reservoir conditions, injection and production wells network and fracturing technology. Fracturing techniques currently used cutting volume fracture for reservoirs stimulations in low permeability, ultra-low permeability reservoirs.While cutting volume fracturing technology will produce crack interaction phenomenon, it is difficult to get an ideal yield.Based on rock and soil mechanics, fluid mechanics theory and considering fluid-structure coupling effect, the establishment of the mechanical model of vertical multi-slit open simultaneously in horizontal wells.Using numerical simulation analysis,Simulating the distribution of situ stress and the law of crack initiation and propagation when 2-4 vertical crack open simultaneously in horizontal wells. The studies shows that:When two-slit fracturing simultaneously, the optional spacing of crack is 20 to 50 meters;When three-slit fracturing simultaneously, the optional spacing of crack is 20 to 60 meters;The optional amount of liquid is 8-13m3/min;The optional distance of interval is 20 to 60 meters. The research methods of vertical slit simultaneously initiation and propagation for cluster horizontal wells will be used in the actual calculation for the well on site.Verifying the rationality of the methods and according this to modify the model.Developing the optimization study of vertical multi-slit(cluster type fracture), different crack spacing and construction parameters in horizontal wells. It can effectively reduce the mutual interference between the cracks and improve the effect of crack propagation to improve the fracturing effect, and also providing theoretical basis for the field application of cluster type fracturing technology in horizontal wells. |
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