In two disposal wells on the North Slope operating field of Nikaitchuq, diesel was deployed before each brief shut-in period in order to prevent the formation of ice in the tubing due to the presence of water-based fluids.
A temperature model was built to determine if the use of diesel as a freeze protection fluid could substituted with an available briny waste water stream. In particular, the model was used to determine how long the waste water fluid would provide freeze protection with respect to the operational requirements. The temperature model was also checked against the data acquired by distributed temperature sensing fiber optic technology deployed in similar wells of the same field.
The paper will review the model, the temperature data retrieved from an injection well in the same field using DTS technology and discuss the cost benefit deriving from the avoidance of the diesel batches formerly used for freeze prevention.