There has been a rapid increase in tight oil production from Bakken Formation in recent years due to the combination of horizontal drilling and multi-stage hydraulic fracturing. However, there are high uncertainties in characterization of fracture properties such as fracture spacing, fracture half-length and fracture conductivity. Additionally, there is a high cost of drilling and fracturing treatments. Therefore, quantifying these fracture properties based on field production data in the Bakken Formation and optimization of fracture design for single well and multiple wells through economic analysis is clearly critical.
In this work, we performed history matching with field production data in the Bakken Formation, where the wells were pumped with three different proppant types such as sand only, sand/ceramic, and ceramic only. Geomechanics effect, i.e., stress-dependent fracture conductivity, is taken into account. Based on the history matching results, fracture half-length and fracture conductivity were quantified with and without the geomechanics effect. For reservoir modeling including multiple fractures, we compared bi-wing fracture and fracture network models. Each cluster in single perforation stage is assumed to generate an effective hydraulic fracture. Subsequently, we performed optimization of fracture design for single horizontal well with purpose of maximizing the objective function of net present value. Furthermore, based on the optimal fracture design for the single well, we performed optimization of multiple horizontal wells placement in a spacing unit of 1280 acres (1 mile × 2 miles) of the Bakken Formation. Finally, the optimal number of wells was determined. This work is valuable for guiding fracture treatments design and multiple wells placement in the Bakken tight oil reservoirs.
