The use of high density brines has been a major factor in reducing formation damage during completion operations. However, recent studies have suggested that high-density brines can be potentially damaging. More specifically, CaBr2/CaCl2 brines (≥14.2 lbm/gal. [1702 kg/m3]) were found to reduce core permeability from 25 to 29 percent at relatively low temperatures (150°F/51°C). The literature does not address the effects of high-density brines at the elevated temperatures where they are typically in use.

A laboratory study was conducted to determine potential formation damage from high-density brines at temperatures of 250-400°F (94-204°C). Core flow experiments confirm that calcium containing brines produced the most damage at higher temperatures. In addition, at a threshold temperature of approximately 350°F (177°C) all brines have the potential to produce damage.

Numerous operational guidelines have been provided to predict damage potential and identify cost effective preventive measures when high reservoir temperatures are anticipated.

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