This paper proposes and validates a robust methodology to estimate fracture properties (half-length and conductivity), formation permeability, and, where possible, drainage area of individual layers in hydraulically fractured vertical gas wells producing commingled from multiple layers. Estimation of these fracture and individual layer properties is required to evaluate fracture treatment effectiveness and forecast future production for these wells.
To achieve our objectives, we applied an analytical elliptical flow solution to analyze production data from hydraulically fractured vertical tight gas wells producing from multilayer reservoirs. We were able to estimate the fracture half-length, formation permeability, and minimum drainage area of each layer. This study considered variations in completion details, initial reservoir pressures, reservoir temperatures, and other reservoir parameters in layers producing simultaneously.
The technology we developed includes the following components used in our analysis: flow rate allocation using available production logging test data, deconvolution to convert variable-rate pressure data into constant-rate pressure responses, identification of the elliptical flow regime, and analysis of elliptical flow data. We developed and present a new technique to identify the elliptical flow regime. We validated our method with synthetic data generated with a reservoir simulator.