Real-Time and In-Situ Detection of Calcium Carbonate Scale in a West Texas Oil Field

Abstract

Summary A novel technique has been developed to detect the onset and increase of calcium carbonate scale deposition from oilfield production fluids. This method uses an attenuated total reflectance (ATR) probe, called the scale sensor, to detect scale formation in situ. Because this method is based on existing technology and requires little supporting equipment, a simple, cost-effective monitoring device could be placed in many locations within a production system. This method could provide a system-wide, in-situ, real-time response to calcium carbonate scale formation at its earliest stages. As a first step toward evaluating the effectiveness of this new technology, the scale sensor was field tested at a west Texas oil field. The scale sensor was observed to detect the deposition of calcium carbonate under static and flowing conditions in actual produced fluids. In the static tests, crude oil, suspended solids, and other endogenous materials did not affect the scale sensor's response. Under flowing conditions, like those found in the production flowlines at this west Texas oil field, scale sensor response was observed to correlate to the chemical injection rate of both the scale inhibitor and the dispersant. On the basis of the results from the scale sensor, the scale inhibitor's injection point will soon be moved to the wellhead.