油田构造应力场驱动油气运移的理论和方法研究

依据连续介质力学的理论,采用有限元数值模拟方法,通过平均应力将固体应力场与流体压力场有机结合,并以辽河油田现今构造应力场为例,探讨了构造应力与构造热应力对多孔介质中油液不同的驱移作用.研究表明:具挤压特征的构造应力场对盆地油气宏观分布有重要意义,油液有从高应力区向盆地内以主干断裂和软弱带为代表的低应力区迁移的趋势.温差引起的局部应力相当于孔隙压力的作用,能较好地模拟低洼带的油气向周围高点迁移的特点,也是重要的驱动因素.二者联合作用驱动的流体运移速度场能更好地解释现今油田的分布特征,并对预测油气聚集的优势区有指导意义.

THEORY AND METHOD OF STUDYING HYDROCARBON MIGRATION DRIVEN BY TECTONIC STRESS FIELD

Continuous media mechanic theory and Finite Element Method are introduced to solve the problems concerning hydrocarbon migration driven by tectonic stress field through an example of Liaohe Oilfield.Both in order to gain the flow velocity of pore fluid,the fluid pressure and the solid tectonic stress were studied.Three cases of tectonic forces imposed on the basin:1.only under the action of tectonic boundary force;2.only being loaded by temperature differences;3.under the actions of tectonic forces and temperature loads.The numerical calculation showed that the tectonic pressing stress played a dominant role in driving pore fluid from the high stress area to the low one.Hydrocarbons tend to be driven into the basin where the main structural belts are located.The effects of thermal stress caused by difference of temperature are equivalent to pore pressure in the basin.Thermal stresses have regional effects on oil gas migration.The phenomena that the generated hydrocarbons in depth of basin always migrated upward to the relative higher points of the basin could be simulated.So the temperature differenceis is also an important factor for oil migration.The distribution patterns of oil resources of the basin may be better recognized by knowing the driving effects on oil from both the tectonic stress and thermal stress,which is of importance in predicting favorable areas for oil accumulation.