To emulate a fractured well in ExcSim, follow these simple steps:
The skin value given in point 5. corresponds to an infinite conductivity fracture. Use a slightly higher skin (less negative) to account for any finite conductivity. Note, however, that very small increases in the skin factor may have significant impacts. A typical skin adjustment, to account for finite conductivity, would be in the +0.01 to +0.1 range.
A 2012 study, evaluating several GOM reservoirs, comparing various methods for modeling fractured wells (including use of skin factor, local grid refinement (LGR), and ExcSim's method), concluded that:
"Following [ExcSim's] method for infinite conductive fractures, we simulated the fractured vertical well for hydraulic fracture lengths of 75 ft and 200 ft and compared the results with the LGR method as shown in Figure 18 and Figure 19 respectively. They confirm that this up-scaling method provides an accurate estimate when the hydraulic fracture conductivity was 20000 md-ft. In Figure 20 it is shown how a realistic conductive fracture can be modeled by [ExcSim's] method by introducing a small skin factor."
It should be noted that to use this method on other simulators (other than ExcSim), the transmissibility multipliers given above must be multiplied by 1.47467 and the pressure equivalent radius, ro, must be set to 0.346 DX (where DX is the sides of the square grid blocks). See our blog on Peaceman for further details.