盆地模拟技术新进展(二)──油气运聚平面分层模拟方法

NEW ADVANCEMENT IN BASIN MODELLING TECHNOLOGY (Ⅱ)-SEPARATE FORMATION 2D PLATE MODELS FOR SIMULATION OF OIL AND GAS MIGRATION-ACCUMULATION HISTORY

运聚史模拟是盆地模拟最重要也是最薄弱的环节。针对已有运聚史模型的不足，提出分层的平面二维运聚模型，即现今流体势分层模拟和油气运聚历史分层模拟的模型。分层流体势模拟需要井点的地表海拔、潜水面位置和分层的流体流动压力梯度这3项已知参数，提出水势、油势和气势计算公式，求得各井点的分层流体势，即可绘出分层的现今势平面等值图，为晚近地质时期油气再次运、聚的分析提供依据。分层油气运聚史模拟为拟三维二相模型，基于浮力驱动原理及达西定律，烃源层的排烃量分配可由地质家拟定，计算结果给出探区各烃源层和运载层在不同地质时代的烃柱高度及聚集量的平面等值图。

The simulation of oil and gas migration-accumulation history is the most important part in basin modeling system. In view of the deficiency of the current migration -accumulation history models, the separate formation 2D plate models are presented here, i. e., (1) the model of fluids potential simulation at present for each formation and (2) the model of migrationaccumulation history simulation of oil/gas for the related formations. The first model requires three parameters at wells as follows: sea level elevation of the earth surface, height of phreatic water above the earth surface, fluid now pressure gradient in each formation; involves formulas for potentials of water, oil and gas; calculates these potentials at each well of each formation; then draws out the contours of the potentials at present for each formation, to provide the witness for the analysis of secondary oil/gas migration at the recent geological period. The second model, pseudo 3D and 2-phase model, is based on the principles of the driving buoyance, the Darcy law, and the distribution of expelled oil/gas from source rocks by geologists. The simulating results can be drawn to the contours of oil/gas column and migration-accumulation in carrier beds and source rocks at various geological times.