我国海上低渗油田分类标准研究

A classification of low-permeability oilfields offshore China

在分析低渗油田国家分类标准的基础上,基于低渗油田启动压力梯度和岩心应力敏感性实验,形成了我国海上低渗油田分类标准:渗透率在10～50mD的油田为一般低渗透油田,此类油田储层可忽略启动压力梯度和压敏效应;渗透率在5～10mD的油田为特低渗透油田,此类油田储层存在启动压力梯度,但压敏效应可忽略;渗透率低于5mD的油田为超低渗透油田,此类油田储层同时存在启动压力梯度和压敏效应。根据这一分类标准,可以较好地梳理中国近海低渗油田的油气资源,筛选出在目前技术和经济条件下适合开采的低渗油田。

According to an analysis of the national classification for low-permeability oilfields and some experiments of threshold pressure gradient and core stress sensitivity in low-permeability oilfields, a new classification was developed for the low-permeability oilfields offshore China. In this new classification, the oilfields with permeability between 10~50 mD are considered as GENERAL low-permeability oilfields, in whose reservoirs the effects of threshold pressure gradient and stress sensitivity can be ignored~ the oilfields with per- meability between 5 ~ 10 mD are referred to SPE- CIAL low-permeability oilfields, in whose reser- voirs the stress sensitivity effect can be ignored, but the effect of threshold pressure gradient ex- ists~ and the oilfields with permeability below 5 mD are referred to ULTRA low-permeability oil- fields, in whose reservoirs both the effects of threshold pressure gradient and stress sensitivity exist. This new classification can be used to classi- fy reasonably the low-permeability hydrocarbon re- sources offshore China and select the low-permea- bility oilfields that can be developed effectively un- der the present technology and economy.