Variable density proppant placement in CBM wells fractures.

The migration law in the cracks of variable density proppant particles had been researched, for effective support fracture length of CBM hydraulic fracturing was too short and seam sanding concentration distributed uneven. The mutual influence of the fracture proppant particles was considered using Pseudo Fluid model, and the corresponding calculation software was written with the Visual Studio 2012 design platform, then the accuracy of the calculations was checked through comparison with the value of field monitoring software. The effective law to seam sanding concentration and effective support slot length of the fracturing fluid viscosity, wall cracks, displacement and proppant density parameters were discussed, and the broken rate of the ultra-low density proppant was analyzed at different confining pressure and temperature conditions. The results show that broken rate of a nut shell proppant is less than 2% in the condition of confining pressure 69 MPa and the ambient temperature 90°C,which meet the site requirements; With the increase of fracturing fluid viscosity, the construction displacement and fracture bracing length, the seam sanding is more uniform; with the proppant particle diameter increases, the crack support length decreases; compared to single ceramic sand, using variable-density proppant makes effective support half-slot length increasing 19.5 m, and the sanding effect is more uniform. [ABSTRACT FROM AUTHOR]