Abstract
This paper will discuss a simplified quantitative method for calculating the human health impacts of failures during high-pressure fluid operations. The methodology ties catastrophic high-pressure failure energies to specific human impacts. The methods are then applied to specific hazard situations found in the oil and gas-operating environment through examples. Simplified graphical methods for standard field piping "iron" at common design pressures are presented. These methods should assist engineers and operators in performing rapid quantitative assessment of the high-pressure hazards to their operations.
Since there has already been rigorous study of TNT explosions, we implement a TNT equivalent model relating it to an equivalent potential explosion energy of a pipeline based on the volume of the gas it contains. With an equivalent TNT energy, we can implement scaled distances for respective thresholds of injury based on biological studies that have created pressure-duration curves related to survivability. Using these survivability curves based on the overpressure and impulse respectively, we have created safe standoff distances for pipelines with a specific diameter and length.
Since survivability of an explosion depends on both overpressure and impulse respectively, a literature review was executed to account for these differences between a high explosive such as TNT and a pipeline explosion. We conclude that the differing explosion factors (overpressure and impulse) in a pipeline explosion counteract each other so that in terms of potential injury, a TNT explosion would produce relatively similar results.
Another difference between the two respective types of explosions is that the geometry of a pipeline explosion is highly directional and must be considered since it is not perfectly spherical as the TNT equivalent model assumes. Nevertheless, the calculations of the graphs are conservative relative to a TNT explosion in terms of both potential energy since the energy equation used represents an upper boundary. Additionally, the same applies in terms of the energy available for the explosion of a pipeline since not all gas will be readily available for detonation. In effect, we are describing a very complex problem that could potentially have many different outcomes. Thus, the conservative assumptions will allow the application of engineering judgement in assessing the risk of potential injury in specific drilling scenarios.
