不同流动单元微观渗流特征研究--以华池油田长3油藏华152块为例

A STUDY ON THE MICROFLOW CHARACTERISTICS OF DIFFERENT FLOW UNITS——Taking Hua-152 Block of Chang 3 Reservoir in the Huachi Oilfield as an Example

利用不同流动单元的真实砂岩微观孔隙模型,进行了不同流动单元微观渗流特征的试验研究,为提高油层开采效果提供科学依据。鄂尔多斯盆地华池油田华152块长3储层流动单元可分为A,B,C 3类,存储性能和渗透性能由好到差依次为A,B,C类。研究结果表明,不同流动单元的微观渗流特征有着明显的不同,体现在流体进入次序、流体驱替方式和剩余油类型上的不同。流体总是优先进入A类流动单元,其次进入B类流动单元,C类流动单元流体进入困难,在水驱油时,注入水无法进入C类流动单元;流体驱替方式不同,A类流动单元油驱水为非活塞式,而B类和C类流动单元油驱水均为活塞式;水驱油之后剩余油类型不同,A类流动单元主要为小绕流形成的小簇状油块和厚膜状残余油,而B类流动单元主要为大绕流形成的大簇状油块和珠状、滴状残余油。不同流动单元孔隙结构和润湿性的差别是造成各流动单元不同特征的主要原因。实验研究还表明,研究区C类和B类流动单元是剩余油的主要富集区,应加大挖潜力度。

A physical simulation experimental study on the micro-flow characteristics of different flow units has been conducted by using the natural sandstone micromodels with the aim to provide a scientific basis for improving exploitation effect. The flow units in Hua-152 block of Chang 3 reservoir in the Huachi oilfield, the Ordos Basin can be classified into 3 types, e. g type A, type B and type C, with the reservoir properties and the permeability properties changing from superior to inferior. The study shows that the microflow characteristics of different flow units are significantly different in the aspects of the entry order of the fluid, the displacement pattern of the fluid, and the type of the residual oil. The fluid always enters into type A flow unit preferentially, then type B flow unit, and is always difficult to enter into type C flow unit. The injection water during oil displacement cannot enter into type C flow unit. As for the difference in the displacement pattern of the fluid, the pattern of oil displacing water is non-piston displacement in type A flow unit, while in type B and type C flow units, the pattern of oil displacing water is piston-like displacement. The types of the residual oils in different flow units are also differentafter being displaced by water. The residual oils in type A flow unit are mainly small clustered oil block and thick film-like oils caused by the injection water going around small pore spaces, whereas the residual oils in type B flow unit are mainly larger clustered oil block and spherical or drop like oils caused by the injection water going around larger pore spaces. The difference in the pore structure and the wettability between different flow units is the main reason leading to the above differences in the microflow characteristics. The experimental study also indicates that type C and type B flow units is the main areas for the residual oil to accumulate, where more exploration efforts should be made.