A novel technique has been developed to detect the onset and increase of calcium carbonate scale deposition from oilfield production fluids. This method utilizes 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 towards evaluating the effectiveness of this new technology, the scale sensor was field tested at a west Texas oilfield. 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 response. Under flowing conditions, like those found in the production flow lines at the west Texas oilfield, scale sensor response was observed to correlate to the chemical injection rate of both the scale inhibitor and dispersant. Based on the results from the scale sensor, the scale inhibitor injection point will be moved to the wellhead shortly.