The Effect of Cluster Uniformity Index on Production: A Look at 200 Wells in the Williston Basin

Abstract Over 200 Bakken and Three Forks wells in ten areas of the Williston Basin were evaluated using innovative acoustic-sensing technology to determine stage-level cluster uniformity index. A study was performed to understand how uniformity impacts production of wells in similar geologies. A critical consideration of the study was the influence of localization in the basin on both the Uniformity Index (UI) achieved during completion and ultimate well performance. Acoustic friction analysis (AFA) was used to directly measure pipe and perforation friction during each stage of the program. The number of perforations open were determined using these friction components and combined with information about slurry volume pumped to deliver a stage-level volumetric Uniformity Index in real time. Completion design is often driven by optimal cluster uniformity which is understood to be tied to well performance (Cipolla et al. 2024b). Previous methods of measuring UI accurately were too costly and operationally invasive to be used at volume until the acoustic tool was introduced which allowed for learnings at a program-level instead of well- or pad-level. In this project, UI trended positively with production in both Bakken and Three Forks wells when broken down into specific operating areas. The relationship became even clearer when directly comparing similar and adjacent pads with differing UI. Normalizing for every variable to directly compare well performance is a significant challenge. This large dataset enabled engineers to see the bigger picture with production trends. A completion design was also fine-tuned to enable optimal UI in each part of the basin. Measuring cluster distribution is critical in quantifying completion success, and geology and depletion impact will also play a key role in well performance. Prior to acoustic friction analysis, technologies did not exist that could deliver this information easily for every well. Understanding each variable at a large scale instead of an individual well level and designing for what can be optimized, in this case Uniformity Index, can ultimately drive program success.