A Comparison of Proppant Erosion during Slurry Injection

Abstract

Abstract During frac-pack treatments, proppant erosion is often a limiting factor for the allowable flow rate and total volume of proppant pumped during the job. Each completion assembly has a rating based on limited amounts of full scale erosion testing which is typically provided for one or two types of proppant. Previous testing results have shown that different types of proppant, such as lightweight ceramic (LWC), intermediate strength proppant (ISP), and high-strength proppant (HSP) have different erosion rates. A jet impingement test facility was used to compare different sources of proppant for each of the commonly used proppant types. The test facility was designed to replicate the downhole conditions, while providing the capability to control the test parameters. A nozzle diameter was selected to represent the typical flow-structure size within the completion equipment and a linear gel with proppant loadings between 2 and 10 PPA was selected for the test slurry. The test coupons were low-alloy steel with a representative heat treatment of the material used for downhole equipment. The results were analyzed by measuring mass removal and the 3D erosion profile to compare the overall erosion rate in each test, as well as the erosion profile produced by the various proppants. Furthermore, the proppant was inspected using a laser confocal microscope to provide comparisons between proppant types and sources. The test results, presented in this paper, show that different sources of proppant within a single type of proppant can lead to significantly different erosion rates. Comparison between two sources of HSP showed that there can be a variation in erosion rate of over 60% and that the variation in erosion rate can double when comparing two sources of ISP. These results have verified that proposed changes, such as changing the proppant from what was tested originally for the frac-job operation, can affect the erosion within the completion equipment. Therefore, it is of critical importance to evaluate the possible effects of any change to ensure that the rating of the tool will not be exceeded.