Impacts of Near and Far-Field Diverters on Proppant Transport in Complex Fracture Systems
Authors: Bahri A. , Miskimins J. L. , Hill A. D. , Zhu D. 
Published: January 2025

During hydraulic fracturing, temporarily plugging existing fractures and diverting the injected slurry further into newly created fractures is beneficial for maximizing reservoir contact and productivity. Typically, the injected slurry flows into the path of least resistance, which may not always align with the targeted stimulation zones. Consequently, this can result in leaving many created fractures inadequately propped, as much of the injected proppants settle near the wellbore or are lost in the overtreated fractures. To understand maximizing the fracture-propped area and the transport of the injected fluid and proppant into both nearby and distant fractures, various diverters were tested in this experimental work. The aim was to investigate the plugging behavior of near-wellbore and far-field diverters and determine the associated proppant transport within a complex slot system.

A laboratory-scale slot apparatus was used to investigate the plugging behavior of injected diverters within both smooth- and rough-wall surfaces. The apparatus consisted of a 4-ft.-long primary fracture and 1-ft. secondary fracture located 2 ft. from the injection point. The roughness of the wall surface was achieved using 3D-printing technology to mimic an actual fractured core sample. Both smooth- and rough-wall surface apparatuses were set at fracture widths of 0.2 in. for the main slot and 0.1 in. for the side slot. Fresh water and 100-mesh sand (2.65 SG) were tested with one near-wellbore diverter and two different far-field diverters. The near-wellbore diverters consisted of cylindrical pellets, while the far-field diverters were in powder form. The diverters were tested at room temperature by mixing both near- and far-field diverters without sand and pumping them into the slot system, followed by pumping the sand separately.

Lab results show the injected near-wellbore diverter effectively plugged most of the main fracture and caused different dune shapes to form associated with the fracture-wall roughness. The near-wellbore diverter also accumulated and blocked the majority of the secondary fracture inlet. No near-wellbore diverters entered or were transported into the secondary fracture due to the pellet's size compared to the width of the secondary fracture.

In the case of the rough-wall fractures, the far-field diverters contributed to plugging most parts of both the main and side fractures, as these materials expanded with an increase in the mixing time. The injected diverters helped divert the injected sand, resulting in most of the sand being transported further, and outside, of the slots. Only a small amount of the injected sand settled inside the fracture slots, as most of the cross-sectional flow area was plugged by the diverters. Sand turned into the secondary slot only through a small opening, without forming a clear sand dune as was observed without diverters. Overall, both near- and far-field diverters provided more effective plugging in the rough-wall fractures compared to the smooth-wall fractures.