Many operators have been working on optimizing stage spacing or clusters per stage to maximize production and reduce completion capital investment in unconventional wells. The operator has successfully proved that eXtreme Limited Entry (XLE) design works well in the Bakken. This paper uses a continuous improvement concept to improve on the paper presented in 2020 URTeC: 2796. The objective of this study is to push the boundary of perforation design that has been used as a standard design since 2020 to evaluate the optimum Shots Per Cluster (SPC), the minimum Rate Per Cluster (RPC), and the maximum Clusters Per Stage (CPS) that can still further maximize well production and provide optimum fracture cluster efficiency and Uniformity Index (UI). This paper will also address the comparison between XLE design and other diversion techniques.
Through the 3-year journey of understanding and optimizing XLE design, the operator had a total of 4 pads planned as a part of this study. The first 2 pads used to prove the XLE design concept utilized Radio Active (RA) tracer, deployable fiber optic, step down tests, downhole camera, perforation acoustic imaging tool, and production data. The other 2 pads are the observation lateral project [Cipolla et al. 2022] and a permanent fiber project; both projects include lateral bottom hole gauges, offset well fiber optic strain, and permanent fiber along the lateral. This paper uses part of the data from these projects to help validate fracture morphology, rate per cluster, and maximum clusters per stage. The operator uses the Lean continuous improvement and plan-do-check-adjust process to work from the planning to the standardization of the design.
RA tracer, step-down test, and deployable fiber optic results show that XLE with 1 Shot Per Foot (SPF) yields high production cluster efficiency of more than 90%, high uniformity index, and comparable production data to the non-XLE design while lowering the completions cost. From the permanent fiber optic data, the results show that the minimum rate per cluster to yield a uniformity index of more than 80% in the Bakken is ~ 5 BPM for 4-1/2" liner and ~6 BPM for 5-1/2" liner.
Using a continuous improvement process, the operator adopted the XLE design with 1 SPF as the current completion design standard. This design is proven to yield high productivity and increase asset value by lowering the cost of completions by more than 12%. In the high oil price environment, the XLE design can also be used to maximize asset value by increasing entry points in the well. This leads to an increase in short-term production. Throughout the data gathering and trial process, the operator also gathered novel pressure data allowing for direct measurement of perforation friction, and near-wellbore friction Limited Entry and Extreme Limited Entry Designs