Gas from shale reservoirs is difficult to produce, unless they are effectively stimulated. Production from wells completed in these quad-porosity reservoirs is dependent on the placement of hydraulic fractures and their degree of connectivity to the existing natural fractures. These propped fractures and their effectiveness is a direct function of the in situ stress in the formation. Furthermore, geochemical diagenesis in the created fractures significantly impacts fracture conductivity. This paper utilizes a fracture-completed horizontal well in different configurations of quad-porosity shale gas reservoir models to assess the effect of gas flow and storage in these systems on production parameters. Furthermore, sensitivity analysis is carried out on critical parameters to observe its impact on well performance. This work will help to provide a better understanding of hydraulic fracturing treatments and its effect on the forecast of a stimulated well with reasonable certainty.

Purpose This paper aims to review the quad-porosity shale system from a production standpoint. Understanding the complex but coupled flow mechanisms in such reservoirs is essential to design appropriate completions and further, optimally produce them. Dual-porosity and dual permeability models are most commonly used to describe a typical shale gas reservoir. Design/methodology/approach Characterization of such reservoirs with extremely low permeability does not aptly capture the physics and complexities of gas storage and flow through their existing nanopores. This paper reviews the methods and experimental studies used to describe the flow mechanisms of gas through such systems, and critically recommends the direction in which this work could be extended. A quad-porosity shale system is defined not just as porosity in the matrix and fracture, but as a combination of multiple porosity values. Findings It has been observed from studies conducted that shale gas production modeled with conventional simulator/model is seen to be much lower than actually observed in field data. This paper reviews the various flow mechanisms in shale nanopores by capturing the physics behind the actual process. The contribution of Knudson diffusion and gas slippage, gas desorption and gas diffusion from Kerogen to total production is studied in detail. Originality/value The results observed from experimental studies and simulation runs indicate that the above effects should be considered while modeling and making production forecast for such reservoirs.