The impact of fine-scale sedimentary heterogeneities on hydrocarbon recovery has been explored within channelized reservoirs. However, scant attention has been given to the influence of facies heterogeneities on flow and heat transport for geothermal energy extraction. These fine-scale heterogeneities are frequently overlooked due to data limitations and geological uncertainty, resulting in the omission of internal variations in channel deposits. To address this gap, we introduce a geothermal synthetic case study that examines the ramifications of shale drapes within turbidite channels on reservoir performance. Utilizing parametric surfaces and conformal stratigraphic grids, we represent channel volumes and shale drapes, conducting unconditional Sequential Gaussian Simulation to model petrophysical properties. Two geological scenarios are analyzed: i) a heterogeneous channel, and ii) a heterogeneous channel with shale drapes. Our findings underscore variations in energy production due to shale drapes, while the time for thermal breakthrough remains consistent across both scenarios. This study prompts the need for enhanced model realism understanding flow and heat transport for geothermal energy extraction, emphasizing the importance of accounting for fine-scale heterogeneities.