A Fully Coupled Geomechanics and Fluid Flow Model for Well Performance Modeling in Stress-dependent Gas Reservoirs

Predicting the performance of wells in stress-dependent gas reservoirs can be quite challenging to most conventional reservoir engineering tools. In this paper, a fully coupled geomechanics and fluid flow analytical model was developed for modeling well performance in stress-dependent gas reservoirs. For tight and unconsolidated gas reservoirs that exhibits variable formation compressibility, reservoir compaction, and stress-dependent properties deterioration such as permeability and porosity, the geomechanics effect may not be ignored. All these physical contributes play an important role on well performance. The coupled model considered all these contributes and evaluate their impact on well productivity. The model also accounts for the effect of the transient flow period and variable producing conditions in addition to the effect of non darcy flow in gas wells. An optimization algorithm was used with the coupled model to estimate original gas in place and performance characteristics for each layer in case of multilayered gas reservoirs. Different simulation cases and selected examples from gas wells producing from stress dependent gas reservoirs are used to illustrate the coupled model application. The results from this study indicates that a fully coupled geomechanics and fluid-flow modeling approach is necessary for analyzing highly stress-sensitive gas reservoirs