断陷盆地油气运聚成藏的动力学模型与方程——以北部湾盆地迈陈凹陷为例

Dynamic models and equations of hydrocarbon migration and accumulation in graben basins:A case study of the Maichen Sag,Beibuwan Basin

随着油气勘探的逐渐深入和勘探条件的日益复杂,油气运聚成藏动力学定量化的研究已经成为石油地质研究的趋势和重要方向。该文以商业规模的油气体为研究对象,选择宏观层面的油气成藏动力和阻力参数,建立了一种新的定量计算油气运聚成藏动力和阻力的方法。该方法主要针对断陷盆地幕式成藏的特点,按照油气生排烃、运移、聚集成藏的不同过程,从油气运聚动力和阻力的角度,分析动力与阻力在幕式成藏关键时期的相互关系,建立4种动力学模型:超压驱动动力学模型、持续运移动力学模型、侧向封闭动力学模型和浮力驱动动力学模型,给出了相应的动力学方程,并以北部湾盆地迈陈凹陷为例,通过计算关键时期成藏动力与阻力,绘制平面等值线图,定量判断油气运聚的方向和距离,最终指出油气聚集有利圈闭。

The quantitative research of hydrocarbon migration and accumulation dynamics has become a trend and important direction of petroleum geological research with the gradual development of oil and gas exploration and increasingly complex exploration conditions. This paper concentrates on the commercial quantity of hydrocarbon to establish a new method,which can calculate the dynamics and resistance of hydrocarbon migration and accumulation quantitatively,by selecting several dynamic and resistance parameters in macro level. Considering the episodic accu-mulation features in graben basins and the different processes of hydrocarbon generation,migration and accumulation, the paper utilizes this method to analyze the relationship between accumulation dynamics and resistance during the critical episodic accumulation stage and to establish four dynamic models including the overpressure drive dynamic model,the continuous migration dynamic model,the lateral seal dynamic model and the buoyancy driven dynamic model accompanied with their equations. An example from the Maichen Sag of Beibuwan Basin has been given in this paper to illustrate the features of accumulation dynamics and resistance distribution by compiling their isogram maps through calculating these parameters and to judge the direction and distance of hydrocarbon migration and accumula-tion quantitatively. And then,the best prospective traps have been given at last.