Detection of scale deposition using distributed temperature sensing

The rapid deployment of distributed temperature sensor (DTS) systems in the oil and gas E&P industry provided the engineers with large amount of real-time, downhole data. Although the basic principles for DTS operations are simple, the interpretation of the downhole data presents a challenge for the production engineer. Inflow profiling has been promoted as the prime reason for the installation of DTS systems, though DTS data are currently used in all aspects of production engineering. The differences between the thermal properties of oil, gas and water allow the detection of unwanted fluids using DTS. Monitoring of the produced fluid temperature allow the engineer to prevent the formation of wax and hydrates, ensuring effective flow assurance. This paper examines a novel DTS application by analyzing the effect of scale deposition on the temperature profile of a conventional producing well. The low thermal conductivity of scale deposits increases the temperature of the producing fluid in the scaled region. A sensitivity study has examined the expected range of temperature increase caused by scale deposition to determine the conditions under which the flowing fluid temperature increase is a maximum. Low to moderate production rate environments with low water production yield the greatest increase in flowing fluid temperature when scale is present. The thermal insulation provided by the scale causes a unique temperature profile. Quantitative analysis allows the scale thickness to be determined. Copyright 2008, Society of Petroleum Engineers.