Effect of Pressure on Crude-Oil Kinetics During In Situ Combustion

摘要

We study the effects of pressure on crude-oil oxidation kinetics using ramped temperature oxidation for a large range of pressures and heating rates (1.5, 2.0, 5.0, 7.5, 8.0, 10.0, 15.0, 20.0, and 30.0 degrees C/min). Results are relevant to the combustion of crude oil within reservoirs to produce heat and pressure that enhance oil recovery. Our study results suggest that the activation energy of global reactions is sensibly independent of changes in both partial pressure and total pressure (100-2000 psig) with values ranging between 50 and 60 kJ/mol for the low-temperature oxidation regime (roughly 250 degrees C) and 90-100 kJ/mol for the high-temperature oxidation regime (roughly 350-450 degrees C). Three different crude oils were tested. For one of the crude oils, we observe an increasing trend in oxygen consumption as the total pressure is increased up to a particular pressure (similar to 500 psig), after which it remains constant. This trend is, apparently, associated with the evaporation of relatively lighter components at low pressures, decreasing the amount of oil available for fuel generation. Total oxygen consumption starts to decrease again at very large pressures (1500 psig), and we associate this trend with water phase behavior at these conditions.