恒速压汞在储层微观孔隙结构研究中的应用——以鄂尔多斯盆地吴起油田下组合长9油藏为例

Application of Constant Pressure Mercury in the Study of Micro-pore Structure of Reservoir——A Case Study of Chang 9 Reservoir in Wuqi Oilfield,Ordos Basin

吴仓堡长9油藏岩性致密、物性差,属于典型的致密油藏。为了充分认识长9致密油藏孔隙结构特征及其对渗透率的影响,采用恒速压汞测试技术对区内7块岩心样品进行了测试。数据结果显示:不同渗透率的岩心样品孔隙半径分布范围基本相同,主要分布在60~250μm之间,平均孔隙半径在120μm左右;喉道半径主要分布在3μm以内,但平均喉道半径相差较大,从0.2μm到1.9μm大小不等。分析发现,孔隙半径大小只和孔隙度相关,平均喉道半径与渗透率呈正相关关系,是影响致密油储层渗流能力的主要因素。

Chang 9 reservoir in Wucangbu area is a typical dense reservoir with lithology dense, poor physical properties. In order to fully understand the pore structure characteristics of Chang 9 dense reservoir and its effect on the permeability, seven samples of core samples were tested by constant-rate mercury injection test. The data was displayed： the distribution of pore radius of different core samples was basically the same,mainly distributed in the range of 60- 250μm, the average pore radius was about 120μm; throat radius distributes within 3μm, hut the average roar radius had larger difference ranging from 0.2μm to 1.9μm size. It was found that the pore radius was only related to the porosity, and the radius of the roar was positively correlated with the permeability, which was the main factor affecting the seepage capacity of the dense oil reservoir.