Optimization of Temporary Plugging Parameters Under Rough Fractures

Abstract

Temporary-plugging-and-diverting (TPD) fracturing technology is widely used in the development of the unconventional reservoir. The operational procedure of temporary plugging and the size and combination of diverters are very much concerned by field engineers. This study compares different pumping procedure of diverters and optimizes the combination and pumping rate of diverters under the different width of the fracture. The experimental method is based on a simulated fracture apparatus, which is manufactured by the 3D printing technology. The surface morphology of the fracture is obtained through a 3D scanning of a fracture. The experimental procedure is pumping the carrier liquid and diverter mixtures into the fracture while recording pumping pressure and the outlet volume of carrier fluid. The fracture plugging efficiency was evaluated through the recorded parameters. The diverter concentration and composition were optimized at a wide range of fracture width (1 mm to 4 mm). Low the diverter concentration could help to reduce the operational risk of the diversion. Under the low concentration of the diverters, the plugging mechanism is that the large particle diverters bridge in the fracture due to the fracture tortuosity and roughness; the smaller particle and fiber diverters then fill the voids of the large particles and form a strong and low permeable diverter pack. The results indicate that pumping the mixture particle and fiber diverters are more beneficial to plug the fracture than pumping them separately and sequentially. High particle concentration has a two-sided effect, which leads to the existence of an optimal fiber-to-particle ratio. The concentration of diverters could decrease when the size of diverters is increased. At a constant fracture width, higher pumping rates can help to temporarily plug the fracture more efficiently.