Abstract:

The mechanism and genesis of ore deposit can be basically concluded as the dynamics of mineralization. Temperature will play an important role in hydrocarbon migration under subsurface environment, i.e. migration in reservoir rocks deeply buried in sedimentary basins with high temperature, high pressure and low permeability. Temperature can not only change the physical property of petroleum (e.g. specific gravity and viscosity) during migration,but can also act as the major dynamic force of fluid migration,especially in deep geological condition.An experimental equipment has been installed to simulate the petroleum migration with temperature difference to be the thermodynamic force under normal temperature and pressure environment. The installation is composed of two thermoregulators and a glass tube filled with sands of different sizes. The main objective is to explore the mechanism of heat as the direct diving force during the petroleum migration, by means of the physical simulation of petroleum migration under different thermodynamic systems. The result will provide some helpful information to the study of the mechanism of hydrocarbon accumulation, especially hydrocarbon charging and accumulating in deeper part of the basin. The modeling results include:(1)Oil can migrate under the action of temperature difference, and it migrates from the site with high temperature to the site with lower temperature, indicating that temperature can act as the dynamic force for fluid flow. Under the experimental condition, the temperature difference and time control, the migration velocity and distance. Given in the same time interval,the higher the temperature difference is, the higher velocity and larger distance the migration would be. However, the velocity of oil migration is much slower in water-saturated sands.(2)As to a certain temperature difference, the distance of oil migration is constant no matter how long the experiment would be continued, which indicates that the temperature difference is the most important force to oil migration under the experiment condition.(3) Since the pressure within the tube decreases when the confined glass tube is opened, the velocity and amount of oil migration in the open system would be larger than that in confined system, and they also depend on the temperature difference. (4)The migration distances of oil are almost the same in sands with different grain sizes. The result indicates that the poroperm characteristics of reservoir do not affect the migration distance, but the temperature difference does. (5)No matter how long the experiment would be continued under a certain temperature difference, more oil supple would not increase the distance of oil migration. This also shows that the migration distance has no relation to the amount of oil supply, it just depends on the temperature difference.

Key words: temperature difference, dynamic force of migration, simulating experiment