准噶尔盆地东部流体势场演化对油气运聚的控制

The control or palaeo-fluid-potential over migration of oil and gas in the east of Junggar Basin

流体势是控制地下孔隙流体流动的基本动力，影响流体最终的富集程度和富集部位。古流体势分析的关键在于孔隙度的演化、地层古厚度的恢复以及剥蚀厚度的计算。由模型建立了准噶尔盆地东部地区受埋藏深度和埋藏时间双重因素控制的吉孔隙度函数，并由此求出地层古厚度和古埋深。用“改进的Ｐｈｉｌｉｐｐｏｎｅ公式”进行古地层压力的计算，并用今实测压力对计算的古地层压力进行校正，能获得比较合理的古流体势场。通过综合分析准噶尔盆地东部地区二叠系油藏和侏罗系油气藏流体势场演化过程，发现流体势场演化及分布特征对油气运移聚集的控制作用在不同地区、不同层位有明显差异。总体上讲，油气有向相对低势区聚集的趋势，但不同类型的油气藏与流体势场的关系又不完全相同。

This paper presents the porosity evolution models in the east of the Junggar basin firstly, which accounts for the depth and age of layers. The palaeodepth and palaeothickness can be calculated by using these models. While the palaeopressure can be obtained through the improved Phillippone formula, and then should be rectified in accordance with the measured data. After the palaeodepth and palaeopressure are determined, the palaeo-fluid-potential can be obtained by using the formulas calculating the fluid potential. As the evolution of the fluid potential of oil-bearing sets in different time is studied synthetically, we could make the conclusion that the distribution of the fluid potential has a close relation with migration and accumulation of hydrocarbon in this area. But there is some difference in different strata and different belt. In a word, there is tendency of the migration in oil and gas from higher potential zone to lower potential zone and different types of pool have different relations with the potential field.