Pressure transient and Blasingame production decline analysis of hydraulic fractured well with induced fractures in composite shale gas reservoirs

Vertical wells large scale fracturing and stimulated reservoir volume (SRV) treatments is an important method to enhance productivity of shale gas wells. Since the existence of micro-fractures in shale reservoirs, micro-fractures are opened and connect with hydraulic fracture after vertical wells large scale fracturing. Of course, some microfractures do not connect with hydraulic fracture, which leads that average permeability around wellbore is higher than reservoirs permeability. A radial composite model is used to describe the physical phenomenon with SRV region. Therefore, a semi-analytical model of hydraulic fractured well with induced fractures in composite shale gas reservoirs is established and solved by the Laplace transform, pressure drop superposition, vertex rate balance. Wellbore pressure solution of real domain is obtained by the Stehfest numerical inversion. The simplified model is verified by numerical solution and comparison result gets a good match. According to the difference between pressure and pressure derivative curve, wellbore pressure approximate solution of this model during pseudo-steady flowing regime is obtained. According to the wellbore pressure derivative curve and Blasingame production decline integral derivative curve, the seven flow regimes can be distinguished and curve characteristic of every flow regime is analyzed. The influence of hydraulic fracture conductivity, induced fracture number, Langmuir volume, SRV region radius, permeability ration et al. on wellbore pressure response, Blasingame production decline curve is discussed in detail. This work provides a method to calculate single well controlled reserves with short production time by pressure transient and Blasingame production decline analysis for hydraulic fractured wells with induced fracture.

Automated summary

This study establishes a semi-analytical model for hydraulic fractured wells with induced fractures in composite shale gas reservoirs, which is validated through numerical methods. Various factors influencing wellbore pressure response and production decline curve are discussed in detail.