Oil Oxidation and Adiabatic Compression as Ignition Sources in Oilfield Operations
Abstract
Well interventions or work-overs are generally a safe operation, however there are areas where an explosion might occur in surface equipment during the process, causing Health, Safety, and Environmental (HSE) hazards and damages to surrounding equipment and the environment. The source of these explosions often remains a mystery as they are initiated inside the process piping under conditions where there is no obvious source of oxygen and often no obvious ignition mechanism. The In-situ Combustion Research Group (ISCRG) believes that trapped pockets of air in contact with immobile hydrocarbons, accumulated in surface equipment, could be the source of ignition.
These accumulations under the right temperature conditions such as during a hot summer day could raise the temperature of the trapped pocket of air and immobile hydrocarbon high enough to exceed the Self-ignition Temperature (SIT) of the immobile hydrocarbon and initiate the generation of flammable liquid and vapor phase components through spontaneous liquid phase oxidation (LTO) reactions.
Therefore, the objective of this dissertation was to analyze the ignition and self-heating characteristics of oxidized oils in order to better understand LTO-initiated explosions. Three (3) different oil samples (Athabasca bitumen, a paraffinic light oil, and diesel as a refined product) were chosen. Twelve (12) High Pressure Isothermal Oxidation (HPIO) tests were performed to oxidize the oil samples in the batch reactors at temperatures of 25°C, 50°C, 75°C, and 100°C, by keeping them in contact with normal air (21% O2 and 79% N2) at a nominal pressure of 7 MPa for the period of seven days.
Seven (7) Accelerating Rate Calorimeter (ARC) tests were conducted on original (un-oxidized) and selected oxidized oil samples to determine the ignition and self-heating characteristics.
The major finding of the study was that two of the oil types (Oil B – light paraffinic crude oil and Oil C - diesel) exhibited oxidation characteristics that could lead to explosive events. Both of these hydrocarbons exhibited increased maximum reaction rates when they were pre-oxidized. The third sample, Oil A or Athabasca bitumen exhibited easily observable oxygen uptake rate at 75°C, but it is unlikely that the bitumen would support an explosive event during a well work-over operation.
Description
Keywords
Engineering--Petroleum
Citation
Panjeshahi, E. (2016). Oil Oxidation and Adiabatic Compression as Ignition Sources in Oilfield Operations (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/27168