烃类组分垂向微运移的模拟研究

SIMULATION TEST OF VERTICAL MICRO-SEEPAGE OF HYDROCARBON COMPOSITION

烃类垂向微渗漏是一种不能被直接观察但可为仪器所检测的油气微渗漏 ,通常在油气藏的上方形成环形晕或顶部异常。研究表明 ,地层的厚度与烃类垂向微渗漏系统平衡时间呈线性相关性 ;随着孔隙度的增加 ,系统的平衡时间呈指数降低的趋势 ;当土壤的吸附率从每年 1%到接近 0时 ,系统的平衡时间呈指数增加 ;随着微生物对烃类组分的消耗率的增加 ,系统的平衡时间呈指数降低的趋势。土壤的吸附率和微生物对烃类组分的消耗率与系统的平衡时间联合影响研究发现 ,微生物对系统平衡时间的影响比土壤吸附率要小。对于两层地层而言 ,上、下地层的孔隙度和土壤的吸附对系统的平衡时间影响是对称的 ;上、下两层地层的微生物消耗率为每年 2 %时几乎是对称的 ,即此时上、下地层微生物的消耗率对系统的平衡时间影响是等价的。当上、下两层地层的微生物消耗率小于每年 2 %时 ,下伏地层的微生物影响要大于上覆地层的影响 ,当上、下两层地层的微生物消耗率大于每年 2 %时 。

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.