Abstract:

Vertical micro-seepage of hydrocarbon can be not directly observed but measured by the instruments,which is usually referred to as a circle-liked halo distributed on the top of oil and gas reservoirs.The study shows that the equilibrium time of vertical micro-seepage system has a linear relation with strata thickness,and the equilibrium time of this system is exponentially decreased with porosity increase.When annual adsorption rate of soil changes from average 1% to near 0, the equilibrium time of this system is exponentially increased.As the consumption rate of hydrocarbon derived from microorganism is increased, the equilibrium time of this system is exponentially decreased.Through the comprehensive analysis of the influence of soil adsorption rate of and microorganism-derived hydrocarbon consumption rate on the system equilibrium time, respectively,it is shown that the influence of the former would be less than the latter's.For the overlying and underlying formations,the influences of either soil adsorption rate and rock porosity on the equilibrium time of micro-seepage system are nearly equivalent.When the microorganism-derived hydrocarbon consumption rate both in overlying and underlying formations is about 2% per year,their influence on equilibrium time are nearly equivalent,i.e. the influence of microorganism's consumption rate in overlying and underlying formations on the equilibrium time of micro-seepage system are nearly equivalent.When the microorganism-derived hydrocarbon consumption rate both in overlying and underlying formations is less than 2% per year,the microorganism's effect in underlying formation would be more than that in overlying formation;while the microorganism-derived hydrocarbon consumption rate both in overlying and underlying formations is more than 2% per year, microorganism's effect in underlying formation would be less than that in overlying formation.

Key words: hydrocarbon, microorganism, equilibrium time, consumption rate, adsorption rate