This study documents an ongoing analysis of frac plug integrity and inter-cluster treatment distribution using multiple datasets. It includes post-treatment acoustic imaging data from three Montney pads, in which the dimensions of 3538 perforations and casing wear patterns at 150 frac plug setting locations were determined. The analysis process features an iterative approach to improving execution performance during field appraisal – execute the design, measure performance, identify failures, and then implement an improved design. This approach identified execution performance issues that would have otherwise been undetected and provided insights that were used to inform manufacturers of necessary design improvements.
The fiber optic and acoustic imaging programs for Pad 1 indicated loss of frac plug isolation in 70% of stages. Acoustic imaging data gathered from Pad 2 indicated loss of frac plug isolation in 57.5% of stages. Additionally, the measured diameters of eroded perforations were smaller than the expected unstimulated diameter in 48% of measurements. This finding revealed a discrepancy in the perforation-charge manufacturer's published performance information which led to unintended treatment behavior.
Building on Pad 2 results, multiple vendors were engaged to provide engineered solutions to the issues identified through acoustic imaging campaigns for potential implementation on future wells. The findings from this exercise confirmed the underperformance of dissolvable frac plug technology and the importance of verifying perforation performance by conducting surface tests that are representative of field conditions. The outcome led to modified perforation charges and dissolvable frac plugs for trial on Pad 3.
Outputs from the analysis performed on Pad 3 revealed improved performance, with confinement issues identified in only 28% of the total stages. Initial unstimulated perforation diameters were within 3.59% of the pre-job surface validation tests. Improvements contributed to better treatment conformance relative to Pad 1 and Pad 2.