|dc.description.abstract||Hydraulic fracturing (HF) is widely used to stimulate and produce hydrocarbons from both conventional and unconventional reservoirs. Hydraulic fracturing creates thin but long fractures that frequently connect to pre-existing natural fractures or newly created micro-fractures resulting from the HF process in the formation; thus, creating a complex fracture network. The transport, placement, and distribution of the proppant in these complex fractures is dependent on the proppant type, size, density, the fluid viscosity and the slurry injection rate. The fracturing fluid and the proppants affect the productivity and conductivity of the complex fracture network created by the HF process. A 2015 study by Alotaibi at the Colorado School of Mines used inter-connected orthogonal fractures sets with water as the transport fluid. In this thesis, Alotaibi’s results are extended to a complex fracture network consisting of non-orthogonal fractures of unequal width with ‘slickwater’ used as the transport fluid. A complex fracture network made of Plexiglas® slots was constructed to simulate a prototype of an en echelon natural fracture system; thus, the fractures were not exactly parallel. The ultimate purpose of this research is to improve our understanding of proppant transport in complex fracture network using slickwater at various concentration of friction reducer, different proppant types (size and density), and different injection rates. The following was completed during this thesis: 1) a new laboratory apparatus was built to conduct proppant transport studies in a complex fracture system consisting of a main fracture, three sub-fractures branches or groups, and two open perforations; 2) using this apparatus, the minimum slurry velocity in the entrance of each branch of the fracture network at seven locations was determined; 3) computational fluid dynamics (CFD) software from ANSYS simulated the proppant placement, distribution and trajectory inside the complex fracture networks for three slickwater compositions, two proppant types, three proppant sizes, nine hybrid proppants, and two injection rates; and 4) experiments were also performed by alternately closing the top and bottom main entry points. Proppant dune development measurements were obtained in regard to dune height, dune area, and proppant distribution. Evaluations were made to the effects of proppant size, proppant density, fluid properties and injection rates on slickwater transport in the main as well as the sub-fracture groups, plus evaluations of transport using hybrid proppants mixtures. The results are reported for the transport mechanisms as a function of perforation location height. This research found that higher viscosity fluids resulted in proppant transportability increasing from 20% to 36% into the sub-fracture groups. Higher flow rates, going from 1 gal/min to 2 gal/min yielded higher velocities that transported proppants of all sizes further in the fracture network and yielded longer propped areas. The increased flow rates improved transport from 3% to 13%. The diameter of the proppants did hinder the transport of proppants when the median diameter was doubled as the change in dune height was decreased by 9.4%. The sieve analysis showed that 100 mesh had 35% more segregation than the 40/70 mesh while hybrid proppants of different sizes provided a 40% better coverage of the fractures of different widths. In vertically propped areas, hybrid proppants with different densities provided a 70% better propped area in each fracture. Comparisons were made between lab experiments and simulated results from ANSYS Fluent computer modeling and found to be very close. The results showed that higher concentrations of friction reducer combined with higher slurry velocity have a great impact on the distribution of the proppant into the sub-fracture groups including the quaternary fracture. The results from the numerical modeling indicated that the fracture width and fluid viscosity had the most significant impact on proppant placement, while the sand size and density had a lesser impact on the distribution of the proppant in fractures. The fracture network geometry, such as bends and angles, had the least impact on the proppant transport and settling.