Temporary Coating for Dissolving Frac-Balls Used in Multi-Stage Fracturing Systems
- Deepak Kumar (Baker Hughes a GE Company) | Erwin D. Hernaez (Baker Hughes a GE Company) | James S. Sanchez (Baker Hughes a GE Company) | Zhiyue Xu (Baker Hughes a GE Company)
- Document ID
- Offshore Technology Conference
- Offshore Technology Conference, 30 April - 3 May, Houston, Texas, USA
- Publication Date
- Document Type
- Conference Paper
- 2018. Offshore Technology Conference
- 2 Well completion, 4.2.3 Materials and Corrosion, 3 Production and Well Operations, 2.5.2 Fracturing Materials (Fluids, Proppant), 2.4 Hydraulic Fracturing
- self-disintegrating, systems, multi-fracturing, Temporary coating
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One challenge with dissolving frac-balls used in remote multi-stage fracturing systems is their premature disintegration in the ball-launcher used for the deployment of balls downhole. As a solution, a "temporary" coating was developed which prevents disintegration of frac-balls until they land on the desired ball-seat downhole. The current paper discusses laboratory tests conducted to qualify the coating.
Two types of corrosion resistant coatings were studied: phenolic based and aliphatic based epoxy. Laboratory tests were conducted to verify that the coatings satisfied service requirements: coating remained intact in the ball launcher filled with frac-fluid for a few days, ball maintained its pressure rating even after extended exposure in the frac-fluid, and the ball disintegrated to the outer diameter, which enabled the ball to fall through its associated seat within a week. In-situ tests comparing disintegration rates of coated and uncoated balls were conducted to determine if coating interferes with the eventual disintegration of the frac-balls downhole.
Results showed that the phenolic coating provided better protection to the frac-balls than the aliphatic coating. Further, a thick coating must be applied to prevent any disintegration of the frac-balls in the launcher, because thin coating failed locally along the microscopic defects. Pressure test results demonstrated that the coated balls formed a tight seal with the seat up to its pressure rating. After landing on the ball seat the coating failed, allowing the frac-ball to disintegrate per the service requirement, and fall through the seat in a timely manner. Thus, it is concluded that phenolic based epoxy coating can be used to protect the dissolving frack-balls in hydraulic fracturing tools.
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