Abstract:

In low permeability-tight reservoir,fluid filtration belongs to the non-Darcy flow. Only when the pressure gradient comes to the starting pressure gradient, can the filtration occur. Overpressure is a predominant dynamic force for hydrocarbon migration and accumulation in low permeability-tight reservoir, and “dynamic trap” is the most important action for hydrocarbons overpressure-charged into low permeability-tight reservoirs to form accumulations and also a three-dimensional space for hydrocarbons to be relented and accumulated. “Dynamic trap” is quite different from the conventional trap with mid-high permeability reservoir such as structural trap, stratigraphic trap and lithologic trap. The difference shows not only in charging dynamic force, filtration way, but also in oil-gas-water relation, trap shape and distribution. Advantages to form a “dynamic trap” are believed as sources and reservoirs are superimposed or interbedded in large scale, overpressures of hydrocarbon generation can act on reservoirs next to sources and hydrocarbons migrate in short distance in a pore-fracture network, which finally lead to the formation of large-scale continuous hydrocarbon-bearing interval. The “dynamic trap”, located in the superimposition part of the source “sweet point” and the reservoir “sweet point”，is the most easliy to form unconventional reservoirs. The presentation of the “dynamic trap” concept hopes to supply new thinking for enriching petroleum geology theory, deepening hydrocarbon accumulation’s classification and prospecting unconventional hydrocarbon accumulations.

Key words: dynamic trap, non-Darcy flow, starting pressure gradient, overpressure, sweet point, low permeability-tight reservoir

摘要：

流体在低渗透致密储层中的渗流属低速非达西流，且只有在达到所需启动压力梯度后渗流才能发生。超压是油气在低渗透致密储层中运聚的主要动力，而“动力圈闭”就是油气被超压充注到低渗透致密储层中最重要的一种成藏作用，也是在低渗透致密储层中能滞留油气聚集成藏的一个三维空间。“动力圈闭”与中、高渗透储层中的构造、地层、岩性等常规圈闭相比较，除充注动力、渗流方式不同外，在油气水关系、圈闭的形态和分布上也有很大的差异。源岩与储层大范围叠置或互层，生烃超压近源充注，以及在孔缝网络中的短距离运移是形成动力圈闭的有利条件，并最终可导致地层中大面积连续含烃。源岩与储层“甜点”叠合部位的动力圈闭最容易富集油气而形成非常规油气藏。动力圈闭概念的提出，希望能为丰富石油地质学的理论、深化油气藏的分类和非常规油气藏的勘探提供思路。

关键词: 动力圈闭, 非达西流, 启动压力梯度, 超压, 甜点, 低渗透致密储集层