The Bakken shale oil boom in North Dakota resulted in a two-year period of significant equipment, personnel and materials shortage in 2010 and 2011, following which a period of more rational supply and demand has been seen in the stimulation industry. Throughout the four year period Liberty Resources was designing and pumping multi-stage fracture treatments averaging ~4 Million pounds of ceramic proppant per well. A total of 88 wells were stimulated with 2565 separate fracture stages, placing over 283 Million pounds of proppant. At its height of activity the company managed two 24-hour frac fleets.

Key to the well design was the use of a high conductivity ceramic proppant in order to preserve longer term productivity from the wells which have closure stress approaching 10,000 psi. Ceramic proppants were initially categorized into one of three groups based on manufacturer supplied conductivity test data:

  • Highest performing proppants; these materials were given a preferred status for supply.

  • Materials having conductivity that was close to Category A proppants; frac service companies were allowed to substitute these materials when no Category A proppant was available.

  • Ceramic proppant that had test data significantly below Category A proppants; and were never to be utilized even if it meant postponing the fracture stimulation of the well.

Samples of each proppant type supplied to the field on each well site were sent for post-treatment testing at an independent testing laboratory to verify if the actual product delivered replicated the manufacturer supplied data that had been used in the design and the initial categorization of the proppant. Standard sieve, crush testing and a 50-hour long-term conductivity test were run on all samples.

This paper presents the results of these test data over the past four years. Significant results include:

  1. As a standard across the industry it appears that while sieve data are in specification, manufacturer crush and conductivity technical data is only representative of the best materials being delivered to the well site.

  2. In a number of cases field proppant quality was significantly below that of the manufacturer's technical literature. After further investigation this resulted in some products being re-categorized lower than their initial Category A or B designations.

  3. Proppant pumped with severely reduced conductivity resulted in a measureable decrease in well productivity.

  4. As material supply options improved the company used the field testing data to select a preferred proppant with test data that consistently met the highest level of performance.

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