Abstract
The production. of oil and gas from deeper seas and deeper wells means that crude oil is now to befound at higher temperatures than previously experienced. It is expected that oil from wells with bottom hole temperatures of up to 300°C will be produced in thefuture. To model the effect of elevated external skin temperature on the effectiveness of the cathodic protection of an uncoated steel riser, three sea water cells were used, each of which consisted of a fabrication comprised of a simulated riser housing a cartridge heater, a sacrificial anode, and measuring instrumentation. After a preliminary aging period under cathodic protection at low temperature to allow a calcareous deposit to form on the substrate, the heaters were switched on and the specimens were subjected to temperatures in the range 40–90°C, and the applied current density to achieve a suitable level of cathodic protection was recorded. The results, which are discussed in the context of previous studies, show that there is no simple and reliable relationship between the operating temperature of a surface and the required current density for cathodic protection in sea water. Further work needs to be undertaken to produce a more reliable model for the determination of necessary cathodic protection densities.
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