Miskimins, Jennifer L.Kebert, Brent Austin2023-04-272023-04-272022https://hdl.handle.net/11124/176616Includes bibliographical references.2022 Fall.Multistage hydraulic fracturing in horizontal wells has allowed the oil and gas industry to economically pursue unconventional plays, particularly in North America. A leading methodology in unconventional well completions is limited entry (LE) which aims to maintain a high bottom hole treating pressure (BHTP). LE completions, in theory, are utilized to establish an even distribution of the hydraulic fracturing slurry by maintaining a high pressure differential between the internal wellbore pressure and external fractures. The perforation friction, or the pressure drop across the perforation, is the primary design criteria to achieve a high BHTP. The slurry that is pumped during hydraulic fracturing treatments includes proppant, commonly sand, which is needed to hold open the initiated fractures post treatment. The proppant inherently travels through the perforations at high velocities resulting in the perforations eroding. The erosion leads to less of a pressure drop across the perforations, and because it is the primary metric by which treatment pressures are designed, it can negatively impact the success of the well completion. Oil and natural gas wells rely on successful completions to achieve economic production rates. In this work, perforation erosion is investigated for a single completion cluster in a LE horizontal well using computational fluid dynamics (CFD) as the numerical solver. CFD has been applied to the industry for proppant transport research and is capable of capturing material erosion. By the novel approach of implementing pseudo-transient simulations with a deforming mesh, the correct perforation erosion rates and pattern were established through the generated CFD model. The CFD model was established and validated using pressure responses throughout the erosion process and post-treatment downhole perforation images, both from field data. Using this model, sensitivity simulations were completed to test the impact of different completion parameter’s roll in perforation erosion. The sensitivities included varying proppant sizes, proppant concentrations, proppant sphericity, fracturing fluid viscosity, perforation sizes, and proppant ramping schedules. The results of this work identify that perforation erosion should be separated into two phases, the perforation rounding phase and the stable growth phase, with respect to the driving factors in erosion severity. The perforation rounding phase erosion rate is primarily driven by the number of particles passing through the perforation. When normalizing the erosional impact to the total mass of proppant pumped, the most predominate factor in the perforation rounding phase is the number of individual proppant particles that pass through the perforation. During the stable growth phase, the primary driver of erosion is how efficiently the proppant can exit the perforation. The efficiency of proppant exiting the perforation can be improve by way of decreasing the proppant’s particle inertia or increasing the pressure drop across the perforation. Improving the efficiency of proppant exiting the system allows for the proppant to turn the corner and exit the wellbore while minimizing the erosional impact on the perforation. This work focused on the last perforation of a completion stage; under these and the model conditions the proppant sphericity made a negligible impact on perforation erosion. This work allows the industry to gain a better understanding of the factors that impact perforation erosion severity. With a better understanding, practices for post-treatment perforation evaluation can be improved and perforation erosion can be better mitigated.born digitaldoctoral dissertationsengCopyright of the original work is retained by the author.computational fluid dynamicshydraulic fracturingperforation erosionproppant transportText2023-04-22