构造应力场与油气运移关系的研究

Ground stress field modeling and relation to hydrocarbon migration.

构造应力对油气运移聚集的影响是油气运移聚集机理研究中的重要课题。大民屯凹陷是个勘探程度高的“小而肥”的凹陷。依据其翔实的勘探开发资料研究该凹陷构造应力场与油气运移聚集的规律性关系，对其它小型盆地或坳陷的勘探有指导意义。应用ＳＡＰ５软件模拟大民屯凹陷油气主要运移期的古构造应力场，并在此基础上计算孔隙流体压力和石油势的分布，预测石油运移的主要方向和聚集部位，其结果与油田实际情况基本吻合。研究表明，石油总是由高势区向低势区运移，油势低势区是石油富集的区域。地应力变化影响孔隙压力和油势，因而对石油运移和聚集有重要影响。在平行最大主应力（垂直最小主应力）的方向上储集层连通性最好，为油气运移的主要方向；与最大主应力小角度相交的先期主要断裂的方向也可能成为油气运移的主要方向。图３表１参１１（王孝陵摘）

The influence of ground stress field on migration accumulation of oil and gas is an important issue in mechanism study of the migration accumulation. Damintun sag is a well explored hydrocarbon rich but small sag. Based on the full and accurate E&P data of the sag, to study the regular relation of its ground stress field to hydrocarbon migration accumulation has guiding significance for the exploration in other small basin or depression. The palaeostructural stress field in principal period of hydrocarbon migration in the sag is modeled, the distributions of pore fluid pressure and oil potential are computed on the basis of the simulated ground stress field, and main migration direction and accumulation place of oil are predicted. The study results essentially coincide with the actual situation of the oil field. It can be concluded from the study that: oil always migrates from high potential area to low potential area, and the low potential area of oil is accumulation place of oil. Change of ground stress influences pore pressure and oil potential, thus has a great influence upon oil migration accumulation. In the direction parallel to maximum principal stress (perpendicular to minimum principal stress) the communication of reservoir is the best, and the direction is the major direction of oil migration. While direction of previous main faults that intersect the maximum principal stress by minor angle also probably becomes the major migration direction of oil and gas. Subject