This paper describes results of laboratory and field testing of a solid, controlled-release scale inhibitor for use in fracturing treatments. Laboratory testing with a continuous flow apparatus has yielded inhibitor release rates under dynamic conditions. The inhibitor was tested to determine the minimum inhibitor concentration required to inhibit the formation of CaCO3, CaSO4, and BaSO4 scales in a brine. A model to predict the long-term release rate of the inhibitor was developed from data collected on the continuous flow apparatus. Data from treated wells will be compared with predictions of the model.

Inhibitor release-rate testing in a continuous-flow apparatus shows that a solid, calcium-magnesium polyphosphate inhibitor has a sustained release profile. Release-rate testing shows that the inhibitor can be used up to 175°F. The inhibitor is compatible with both borate and zirconium crosslinked fracturing fluids and foamed fluids.

The effective lifetime of the scale treatment can be predicted based on a model developed from laboratory data. The input variables required for the prediction include

  • temperature

  • water production

  • amount of inhibitor

  • minimum effective concentration of inhibitor for the specific brine

The model can be used to aid in the design of the scale inhibitor treatment.

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