地应力对排烃的影响方式及作用模型

本文在对不同排烃阶段排烃机理分析的基础上,结合盆地构造力学,研究分析了地应力对排烃的影响方式,建立了地应力作用下的微裂缝排烃的理论模型,指出地应力对排烃的作用主要表现为两个方面:形成排烃的通道(微裂缝)和作为油气初次运移的动力(改变烃源岩的孔隙流体压力)。研究结果表明,地应力分量中对排烃起决定作用的是最大差应力;在应力作用下,排烃方向为微裂缝的延伸方向,即平行于最大主压应力方向;不同类型盆地中地应力对排烃的影响方式和影响程度是不一致的,其中挤压盆地影响较大,伸展盆地影响相对最小;盆地构造活动期最有利于排烃。 

THE WAY AND MODEL OF STRESS EFFECT ON HYDROCARBON EXPULSION

Based on analysis of hydrocarbon expulsion mechanism in different stages, the way of stress effect on hydrocarbon expulsion is discussed, and theoretical model of hydrocarbon expulsion with stress effect is developed. By these models, the stress effect on hydrocarbon expulsion is defined on two aspects: pathway formation of hydrocarbon expulsion (microfracture) and as a power of primary oil migration (causing the change of fluid pressure of source rock). The result shows that the stress component which has main effect on hydrocarbon expulsion is maximum differential stress, and the direction of hydrocarbon expulsion is parallel to microfracture, which is parallel to maximum main stress. It is also shown that, in different kind of basins, the way and result of stress effect on hydrocarbon expulsion is different, in which compressive basin has relative bigger effect, and extensional basin has smaller one, and it is the most propitious to hydrocarbon expulsion in active tectonic stage.