Synthetic simulation dataset that was created from a simulation campaign consisting of 36 GEOSX-based simulations. Latin Hypercube sampling method was employed by varying three GEOSX simulation input parameters (i.e., Aquifer Permeability, Leaky well Permeability, Porosity). The simulated problem is based on the first benchmark case presented in Class et al. (2009), which is also provided as one of the example problems in GEOSX distribution under Advanced Examples - Validation and Verification Studies. Two quantities of interest were retrieved and used in constructing a surrogate model in PSUAE UQ toolkit to be used in lieu of actual GEOSX simulations for global sensitivity analysis. The results of the preliminary Sobol' Indices based sensitivity analysis is also presented. Files provided: (1) Summary.pdf: contains the destailed description of the workflow employed for sensitivity analysis. (2) C1_LH_n36_i3_o2.csv: Tabulated input and output data is provided in CSV file format, which is compiled from the results of the simulations and provided as input to PSUADE for constructing the surrogate models and carrying out sensitivity analysis. (3) R*.tar.gz: Input files and raw output files generated from GEOSX simulation from each sampling simulation (work directories R1 to R36)