The Use of Pressure Drop Measurements to Monitor Scale Build-Up in Pipelines and Wells

Abstract

Pressure profiles in the reinjection pipelines at the Dixie Valley geothermal power plant revealed that pressure drops were substantially higher than design. Measurement indicated a fairly uniform pressure gradient throughout the lines, and the excessive pressure drop was attributed to a buildup of silica scale. Analysis of the pressure drops indicated that the pipeline roughness was far greater than had been expected. To cure this, one of the lines has been partially cleaned by pigging; pressure profiles before and after each pigging run have been analyzed and show a substantial reduction in the Darcy friction factors. Reinjection well capacities increased slightly with pipeline cleaning, and it has been possible to estimate the likely benefit of further pigging operations. Similar analysis has been applied to reinjection wellbores, and evidence of scaling has been similarly found. Wellbore pressure profiles will, in the future, be used to monitor the increase in scale buildup, and to determine when a wellbore cleanout may be required.