Petroleum migration

Abstract

The transport of petroleum from the source rock to the reservoir rocks is called migration which occurs along permeable carrier beds. It is important to understand this process so that the direction of migration and trapping of petroleum can be predicted. Many different theories have been proposed in the past but it is now clear that petroleum is mainly transported as a separated phase and that the process is mainly driven by the buoyancy of petroleum relative to water. The pore water is normally not moving much in relation to the rocks. The upwards flow of the pore water is constrained by the rate of compaction and it is moved downwards by the basin subsidence during sedimentation. The solubility of oil in water is very low for most compounds. The solubility of gas, particularly methane, is much higher both in oil and water and increases with depth (pressure). There is, however, also very limited flow in sedimentary basins to transport petroleum.