摘要
特高含水期矿场开发实践证实,在水驱开发方式不变、平面和垂向波及系数极高的情况下,继续水驱仍可以较大幅度提高油藏采收率;而传统的理论采收率计算方法不能解释上述现象,也不能从理论上指导特高含水期进一步提高采收率的工作方向。从压汞、核磁共振检测和可视化微观驱油实验3个方面对岩石孔隙波及特征进行了分析,结果表明,驱替过程实际是孔隙波及程度不断增大的过程,在较小的驱替动力和注水倍数条件下无法波及的一些孔隙,随着驱替动力和注水倍数的增加,将进一步被波及进而参与渗流;随着驱替剂(水)的继续注入,已波及孔隙的波及范围不断增大。在此基础上提出孔隙波及系数的概念,即为波及区域内的被驱替剂(水)占据的体积与波及区域内的可动油体积之比,建立了引入孔隙波及系数的水驱理论采收率计算方法;其采收率为平面波及系数、垂向波及系数、孔隙波及系数和驱油效率的乘积,增大孔隙波及系数是特高含水期提高水驱采收率的主要方向。
The field development practices at extra high water-cut stage demonstrated that the oil recovery can still be enhanced a lot by the following water-flooding even if the water-flood mode is not changed and the areal and vertical sweep efficiency are very high. This phenomenon can not be interpreted by the conventional theory recovery definition in which the theory recovery is defined as the product of displacement efficiency, areal sweep efficiency and vertical sweep efficiency. Moreover, it is difficult to theoretically give advice for further improving oil recovery at extra high water-cut stage based on the conventional comprehension and the definition of the recovery. The laboratory experiments proved that the sweep degree of microscopic pores, which are in the areal and vertical sweep scope, increased continuously besides the increment of the macroscopic areal and vertical sweep efficiency during the water-flood process. On one hand, the number of the swept pores increased continuously, on the other hand, the swept volume(swept scope) of the swept pores became greater too. The conventional definition of theory recovery can only characterize the relevance of areal and vertical sweep efficiency to recovery, and not sufficient to represent the sweep features of the rock pores. Therefore, the definition of pore sweep extent is presented, and then, it is used to deduce a new evaluation expression of the water-flooding recovery. It indicates that the increment of the pore sweep extent is the main factor for improving oil recovery at extra high water-cut stage.
出处
《油气地质与采收率》
CAS
CSCD
北大核心
2013年第5期1-3,111,共3页
Petroleum Geology and Recovery Efficiency
基金
国家科技重大专项"整装油田特高含水期提高水驱采收率技术"(2011ZX05011-002)
关键词
水驱采收率
平面波及系数垂向波及系数孔隙波及系数
体积波及系数驱油效率
water-flooding recovery
areal sweep efficiency
vertical sweep efficiency
pore sweep extent
volumetric sweep efficiency
oil displacement efficiency
