Fracture Plug Completions: Evolution, Technological Advancements, and Reservoir Simulation Guided Implications
Authors: Shukla Priyavrat , Malpani Raj , Dardis Michael , Norrid Mark 
Published: September 2022

Hydraulic fracturing operations are increasingly becoming larger through a reduction in cluster spacing, wellbore proximity, and fast-paced "zipper" operations to maximize efficiency. Low-cost operation is the primary motive behind this. Some issues hindering optimal performance include fracturing plug failure, under/over stimulation and adverse well performance as stated in published literature. This paper addresses plug effectiveness and impacts on production, fracture geometry and well spacing using a historical review of fracturing plugs and a simulation-based approach. Using numerical simulation, the study also shows that if a fracture plug failure happens, it results in under or overstimulation which leads to inefficient reservoir drainage.

This paper will elaborate on the technological growth for fracturing plugs (material choices and plug architecture). A simulation-based approach will then be used to understand the effect of fracturing plug failures on well interference and the production impact on a three-well pad containing one parent and two child wells in an unconventional reservoir. A parent well will be produced for 1.5 years before two child wells are drilled and completed. Knowing the performance from the three-well case, a comparative simulation study is performed for frac plug failure at 25%, 50%, and 75% of the job pumped on the child wells.

Quantifying the potential losses from plug failure can help to understand potential effects on well recovery. Such an event can be recognized through a surface pressure signature or using DAS/DTS or microseismic measurements or even using sealed wellbore pressure monitoring (SWPM) on parent wells. A comparative analysis using numerical simulation of hydraulic fractures and their calibration and production modeling is presented in this paper. Three cases for 25%, 50% and 75% understimulation is considered in failed stages. One-third of the well portion of the well is considered understimulated, one third is overstimulated and one third is treated as per design. Impact of well spacing (330 ft and 660 ft) as well as parent well depletion is considered to create a realistic scenario of plug failures to quantify the impact.

Applying advanced materials and using the bottom set, mandrel-less concept has resulted in the shortest, strongest, best milling and most reliable plugs currently available. At lesser well spacing, this is even more drastic when parent wells get fracture hits due to prior depletion and also because stages larger than planned are pumped at the neighboring child wells due to fracture plug failure. This paper will enable the reader to make better decisions about the best plug technology depending on the application. It also provides a quantifiable understanding on the adverse effects of frac plug failure on production. So far, this understanding has been limited to field observations alone. This paper combines the understanding from field evidence, literature and modeling-based approach.