Sustainable economic development of many of the world's oil and gas reserves will require application of novel technologies such as underbalanced drilling (UBD) for improved drilling efficiency and high pressure air injection (HPAI) based processes for improved oil recovery (IOR). High pressure air injection is an IOR technique in which compressed air is injected into a light oil, high pressure/high temperature reservoir. The aim of this process is to react the oxygen in the injected air with a fraction of the reservoir oil at an elevated temperature to produce carbon dioxide. This flue gas, which consists mainly of the nitrogen from the injected air and the produced carbon dioxide, mobilizes the oil downstream of the reaction region, sweeping it towards the production wells. Knowledge of the oil's oxidation behaviour is key to the successful implementation of this process. Underbalanced drilling is a technique used to minimize formation damage in hydrocarbon reservoirs. In UBD operations, de-oxygenated air is often injected along with an oil-based drilling fluid. This de-oxygenated air may contain up to 5% oxygen which can react with oil and/or an oil-based drilling fluid during the drilling process to form potentially hazardous oxidized hydrocarbons, leading to the presence of potentially flammable or explosive mixtures in the surface piping, wellbore and drill string. For successful and safe operation of UBD and HPAI processes, knowledge of the oxidation processes involved is a must. Discussion of the oxidation behaviour of light oils and oil-based drilling fluids in the literature is limited, particularly regarding the effects of long term exposure to oxygen. (Abstract shortened by UMI.)
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