Abstract:

Years of waterflooding researches show that Yangdachengzi reservoir possessing the same permeability level with Fuyu reservoir, has some severely problems, such as more rapid increasing of water cut, higher water injection pressure and poorer development effect. In order to study the influence factors for these problems, micro pore structure of Yangdachengzi reservoir was investigated. Firstly, the micro pore structure of 18 natural cores in Yangdachengzi and Fuyu reservoirs with different permeability levels, including throat radius, pore radius, pore throat ratio and coordination number were compared using CT scanning and constant velocity mercury injection technology respectively, in order to find out the distribution frequency and variation rules of micro pore structure. Then, the most controlling micro pore structure parameter affecting reservoir permeability was investigated using multi parameter linear regression analysis method. Finally, the pore structure parameters were compared with those of Fuyu oil layer with the same permeability level to explain the reasons for poor physical properties and difficult development of Yangdachengzi oil layer. The results show that the average pore radius difference is less than 1% between the Yangdachengzi and Fuyu reservoir with the same reservoir permeability, while the throat radius, pore throat ratio, coordination number and other microscopic pore structure parameters exhibit significant differences of 17.4%, 8.9% and 5.2% respectively, which are the key factors determining the reservoir seepage capacity.

Key words: Yangdachengzi reservoir, Micro pore structure, Constant rate mercury injection, Main control factor, Fuyu reservoir

摘要：

多年水驱开发，与扶余油层相比相同渗透率级别杨大城子油层表现出含水率上升快、注水压力高、开发效果差等问题。为了找出问题的原因，对杨大城子油层微观孔隙结构特征进行研究。首先分别应用CT扫描和恒速压汞技术测量不同渗透率级别杨大城子油层和扶余油层共18块天然岩心的微观孔隙结构，研究喉道半径、孔隙半径、孔喉比、配位数等微观孔隙结构分布频率及变化规律，然后进行多参数线性回归分析，明确影响储层渗透率大小的主控微观孔隙结构参数，最后与相同渗透率级别的扶余油层岩心相对比。结果表明，对于储层渗透率相同的杨大城子油层与扶余油层，平均孔隙半径相差不到1%，而喉道半径、孔喉比、配位数等微观孔隙结构特征具有明显差异，分别相差17.4%、8.9%、5.2%，是决定储层渗流能力大小的关键因素。

关键词: 杨大城子油层, 微观孔隙结构, 恒速压汞, 主控因素, 扶余油层