Mechanism And Performance Of Diverting Agents In Hydraulic Multi-fractures

In recent years,great achievements have been made in the exploration and development of unconventional energy sources.Multistage hydraulic fracturing of horizontal well is the key technology to realize the effective development of unconventional oil and gas.Fracture diverting using temporary plugging agents(diverting agent)is an important technical means to increase the complexity of the hydraulic fracture network.Diverting agent can increase the resistance of fracture propagation,increase the net pressure in the fracture,realize the fracture diverting by the fracture tip bridge blocking.Diverting agents increases the stimulated volume and the fracture network complexity by creating new sub-fractures.It has been effectively used in oil and gas reservoir stimulation.So far,the plugging mechanism and rules under the condition of multistage hydraulic fracturing and multi-fracture need to be further studied.This paper carried out diverting agent blocking experiments,proppant migration,crack turning tests under true triaxial conditions,and carried out related theoretical analysis to obtain composite temporary plugging agents that can improve blocking performance.“Fibre,rigid agent and expandable agent” constitutes a composite temporary plugging agent,and the optimal ratio of the three components of the composite temporary plugging agent is specified.The true triaxial simulation experiment obtained the single crack temporary blocking diverting law.Analysis of influencing factors of the initiation position and the fracture morphology after blocking was carried out through numerical simulation.It was found that silt has the function of adaptive plugging in multi-fracture volume fracturing.The proppant migration test shows that the silt can remain suspended in the slippery water fracturing fluid for a long time,thereby ensuring that the silt can be transported to the fracture tip and form plugging due to the hydraulic fluid filtration desanding.The movement of silt is controlled by the flow rate,and preferentially reaches the leading edge of the large fracture to achieve the blocking of the dominant fracture,thus having the function of adaptive plugging.This explains to a certain extent the mechanism of a large increase in the amount and proportion of silt in multistage hydraulic fracturing construction.