Modeling Horseshoe Wells Performance in Unconventional Plays

The development of unconventional plays often presents unique challenges, such as drilling through overpressured zones with narrow mud windows. A prime example is the Inyan Kara formation in the Bakken, where operators have had to add additional casing to drill safely, incurring extra costs of approximately half a million dollars per well. In the Permian Basin, a different challenge arises due to lease constraints, which limit drilling to a square mile, resulting in horizontal wells with short laterals of 5,000 ft. To mitigate these issues, novel drilling techniques have been adopted, such as the U-shape well design first implemented by Shell in 2019. This design, featuring one vertical section and two laterals connected by a U-turn, has been increasingly utilized to reduce risks associated with drilling in shallow formations while allowing for extended lateral lengths of up to 12,000 ft. However, a comprehensive evaluation of the performance of these wells has been lacking in the literature. This study presents a numerical modeling analysis of U-shape wells, using a well-calibrated model of the Bakken formation. The model, built on a fully coupled physics-based simulator, incorporates reservoir, fractures, and wellbore data, enabling a nuanced understanding of multiphase flow and pressure losses. The study compares the performance of U-shape wells with conventional wells in unconventional plays over a 30-year period, considering total oil production. The results indicate that U-shape wells, on average, have longer fracture lengths towards unstimulated regions compared to two horizontal wells, due to the dissipation of stress shadow when moving from heel to toe. This effect enhances the performance of U-shape wells. Furthermore, when comparing two U-shape wells with four conventional wells, the performance was found to be similar. This study provides valuable insights into the potential of U-shape wells as a viable solution for drilling in unconventional plays.