安塞油田坪桥区、王窑区长6油层储层特征及驱油效率分析

Analysis of Oil Displacement Efficiency of Chang6 Reservoir in Wangyao and Pingqiao Areas of Ansai Oilfield

分别在坪桥、王窑二区块取芯后制作了真实砂岩微观孔隙模型 ,并利用该模型在室内进行了油水两相渗流试验。结果表明王窑区长 6油层的驱油效率 (40 34 % )高于坪桥区 (30 48% )。分析认为二区块孔隙结构的差异 。

Reservoir's recovery percentage of oil is equal to the injected water's sweeping efficiency in macro and the oil displacement efficiency of the injected water in micro. So the final reservoir's recovery percentage of oil can be affected by the oil displacement effecency. Ansai oilfield is a typical low permeability oilfield. It's reservoir is Yanchang formation of Triassic system,and the oil is mainly reserved in Chang6 reservoir of Yanchang ormation.Pingqiao and Wangyao are located in the north and the south of Ansai oilfield.The study about the oil displacement efficiency of Chang6 reservoir in the two areas has practical significances. According to the study it can be seen that the differenct petrologic feature leads to the difference in pore structure and petrophysical property between the two areas under the later diageneses. The results are that the heterogeneity of pore structure in Pingqiao is more serious than in Wangyao,and the petrophysical property in Wangyao is better than in Pingqiao. The natural sandstone micromodels are made with sampled cores.Using the micromodels,the displacement experiments of oil and water have been done. Experimental results indicate that oil displacement efficiency of the Chang6 reservoir in Wangyao (40.34%) is higher than in Pingqiao (30.48%). The difference of pore structure, especially the difference of heterogeneity of pore structure is the reason that leads to the great difference of oil displacement efficiency between Wangyao and Pingqiao.