Far-Field Diverters Protect Parent-Well Production in Unconventional Wells

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 217813, “Protecting Parent-Well Production Using Far-Field Diverters in Unconventional Wells,” by Foluke O. Ajisafe, SPE, Liberty Energy, and Hank Porter, SPE, and Sunny Kothare, Lime Rock Resources, et al. The paper has not been peer reviewed. The effect of fracture-driven interaction (FDI) is an increasing concern in mature developed unconventional plays in the US. In this study, parent-well production performance after infill-well stimulation is evaluated to understand the effectiveness of a far-field diverter in mitigating FDIs. Studies to determine whether FDIs result in a negative or positive effect have concluded that the effect varies from basin to basin. In this project, the purpose of pumping the far-field diverter is to mitigate wellbore sanding and production loss in existing parent wells. The operator in this study is active in the Bakken and Three Forks formation in the Williston Basin and had experienced the negative effect of FDIs. These can occur because of close well spacing and large fluid and proppant volumes and can be exacerbated by reservoir pressure depletion caused by production. In the project described in the complete paper, pressure depletion is the main driver for fracture hits to the parent wells. Most of the parent wells have been in production for years before infill-well drilling and completion. The main goal is to maximize production of parent and infill wells and avoid sanding the parent well by decreasing the frequency and severity of fracture hits to parent wells. To combat this issue, operators have tried several solutions, such as optimized well spacing and treatment designs, repressurization, and even refracturing, with mixed results. A cost-effective solution with simpler operational logistics, the use of a far-field diverter was considered to create more complexity and reduce the occurrence of extended fracture geometry toward the depleted zone or region. The far-field diverter pill is a mixture of materials transported to the tip of the fracture, where they bridge and create a low-permeability plug for fracture geometry control to mitigate FDIs. The complete paper provides a history of the operator’s experience with the use of far-field diverters. Since 2019, multiple infill (child) wells have been completed, and far-field diverters implemented, to mitigate fracture hits to offset parent wells. Extensive work was completed in eight different well pads (Pad A through Pad H) across three different counties, Dunn, Mountrail, and McKenzie. The far-field diverter pill was pumped in 25 horizontal wells landed in both the Middle Bakken and Three Forks formations. The main objective of this study was to investigate the production effect on parent wells after the use of far-field diverter on the infill wells.