沉积盆地深凹部位非常规圈闭油气藏的探讨

PROBE INTO A KIND OF HYDROCARBON POOLS UNCONVENTIONALLY TRAPPED IN DEEP DEPRESSION OF SEDIMENTARY BASIN

高建民

Gao Jianmin

海洋石油勘探开发研究中心 河北新城

Research Centre of Offshore Petroleum Exploration and Development

本文认为在含油气盆地的深凹处,存在一种非常规圈闭的油气藏。其圈闭的形成完全不需要任何常规的圈闭构造。一般说来,在沉积盆地的深凹处发育有良好的生油岩,储集岩则主要是各种砂体的前缘。由于储集岩的孔隙度、渗透率都很低,所以其本身就有较高的排替压力。当沉积盆地的深凹部位到达生油门限后、生成的大量油气经初次运移进入储集岩,就会将储层孔隙中原有的水向上推挤,直至形成油气藏。由于这种油气藏下部无水,或即使有水也不与油气藏上部的水连通。因而,油气藏不受浮力的作用。这时封闭油气藏的压力主要为地层水静压力和储层本身孔隙毛纲管徘替压力之和,其封闭效果可与常规油气藏盖层的封闭效果相媲美。

The author thinks that there exists a kind of hydrocarbon pools unconventionally trapped in the deep depression of a sedimentary basin different from any conventional structural traps. Generally, good source rocks are developed in the deep depression of a sedimentary basin, while reservoirs are concentrated in the front of various sand bodies. Because of their low porosity and poor permeability, the sand bodies have quite high expulsive pressure. Large quantity of hydrocarbons entered reservoirs after primary migration when the deeply depressed part in the sedimentary basin had reached the mature threshold, which would expel the original pore water in the reservoirs upward until hydrocarbon pools formed. Because there is no water in the lower part of the pools, or if there is, it would not connect with that on the top, the pools will not be affected by buoyant force. At this time, the sum of static pressure of formation water and expulsive pressure of porosity cappillary in the reservoir itself is the major confining pressure, the trapping results are comparable with those from conventional capping traps.

https://doi.org/10.11781/sysydz199101033