A Systematic Study for Refracturing Modeling Under Different Scenarios in Shale Reservoirs

Abstract

Abstract A key characteristic in unconventional reservoirs development is that they need massive hydraulic fracturing to create high permeability conduits to connect the reservoir to the wellbore and assure appropriate flow rates to make the development economical. In general, production performance for this type of reservoirs show an early high inflow followed by a steep decline. Refracture jobs have been a common practice to mitigate the flow rate decline and revitalize wells productivity. In this paper, a wide range of possible refrac configurations are evaluated using synthetic models. Parameters such as fracture spacing, matrix permeability, fracture conductivity, fracture orientation and refrac locations were varied to study their impact on the success of the refrac job. Results showed significant impact on both the overall productivity, recovery and the economic value. The results show the impact of refracturing in higher permeability cases (greater than micro Darcy) is not as economical as in the low permeability scenarios (less than micro Darcy). Results also show a possible threshold in fracture spacing (60 – 80 ft between clusters) below which refracturing may not an economical completion strategy. In scenarios where the initial fracture conductivity is severely degraded, refrac can be an alternative to improve the net present value (NPV) and estimated ultimate recovery (EUR). Under the conditions of this study, fracture re-orientation cases show improvement in recovery factor (RF) but does not have a significant impact on the overall NPV. The timing of refrac has a large impact on both the NPV and recovery for the wells. In all cases, NPV was used to define optimal condition for each scenario evaluated. All cases presented demonstrate potential impact of refracturing for a typical range of properties in shale reservoirs. The results shown in the paper could be used as a catalogue for better decision support to estimate the impact of refracturing in field cases under similar configurations to determine whether refrac will beneficial.