海上油田聚合物注入质量浓度优化新方法

A new method of optimal polymer injection concentration in offshore oilfield

王立垒 李彦来 瞿朝朝 杨锁 刘玉娟

中海石油（中国）有限公司天津分公司渤海石油研究院，天津 300459

Bohai Oilfield Research Institute, Tianjin Branch of CNOOC Ltd., Tianjin 300459, China

海上油田早期注聚设计方案中，同一油田所有注聚井的注聚浓度为同一值。随着海上油田的高速开采，不同井组之间的非均质性以及注采强度等的差异，导致不同井组的含水率和采出程度差异很大，同一注聚浓度已不符合油田实际。文中从聚合物溶液调整水油流度比的基本原理出发，综合考虑聚合物质量浓度与黏度、阻力系数的关系，同时结合油田的相渗曲线和分流量方程，首次绘制出了不同含水率下聚合物最优注入质量浓度的理论关系图版，创新性地提出了一种海上油田单井聚合物质量浓度优化的新方法。该方法简便易行，已应用于渤海全部3个化学驱油田，首次实现化学驱注入质量浓度调整，见到了降水增油效果，同时节约了聚合物用量。其中，L油田实施4个井组，受效井含水率下降4%，平均日增油33.0 m3，累计增油达1.2×104 m3。

According to the early design of polymer flooding scheme in Bohai oilfield, the polymer concentrations of all the wells are the same in one oilfield. With the high speed of offshore oilfield development, the heterogeneity and the injection-production intensity vary from different well groups. The result is that the water cut and recovery of different well groups are quite different. The same concentration is not in line with the practical oilfield. This paper starts from the basic mechanism that the polymer solution controls the water-oil flow ratio. The relationship between polymer concentration and the viscosity and the resistance factor is considered. At the same time the relative permeability curve and fractional flow equation of the oilfield are combined. The theoretical plate of the relationship between water cut and optimal polymer injection concentration is firstly drawn. A new method of optimal polymer injection concentration of single well in offshore oilfield is innovatively proposed. This method is simple and convenient. It has been applied to three chemical flooding oilfields in Bohai. Under the guidance of the method, the polymer concentration adjustment of Bohai chemical flooding was first realized. The water cut was reduced and the oil production was increased after adjustment. At the same time the dosage of polymer was saved. For example, four well groups were implemented in L Oilfield. The water cut decreases 4%, while the oil production increases 33.0 m3 per day. The cumulative increasing oil is 1.2×104 m3.

10.6056/dkyqt201806019