提高稠油底水油藏转注井注水效率研究

Improving water injection efficiency of transfer injection well in heavy oil bottom water reservoir

针对稠油底水油藏转注井注入水在正韵律作用下驱油效果差,大部分注入水无效循环等问题,对底水油藏转注井注入水驱油效果差的原因进行了分析,提出了对转注井渗透率锥体型变化带底部进行“置胶成坝”、扩大底水油藏转注井注水波及体积的方法,并利用数值模拟、流线模拟等方法对“置胶成坝”关键参数进行了评价。结果表明:稠油底水油藏转注井注入水驱油效果差的原因是定向井转注后注入水受正韵律及大液量冲刷的影响,在“渗透率锥体型变化带底水区生产井波及区”形成“U”形管式无效水循环;“置胶成坝”技术提高了稠油底水油藏转注井注入水的驱油效果。先导试验井组增油效果明显,增油量达 40 m^3/d,改变了底水油藏转注井注入水驱油效果差的现状,将底水油藏注水由“注够水”转变为“有效注水”。这种新的注水模式对稠油底水油藏提高转注井注水驱油效果具有重要指导意义。

In view of the problems of poor flooding effect and ineffective circulation of most injection water in heavy oil bottom water reservoir under positive rhythm,the causes of the poor flooding effect of injected water in bottom water reservoir were analyzed. A method was put forward to build a dam by placing glue at the bottom of cone-shaped changing zone of permeability,and to expand the sweep volume of water injection in a bottom water reservoir. The key parameters of the dam were evaluated by numerical simulation and streamline simula- tion. The results show that the poor effect of injection water flooding in heavy oil bottom water reservoir is due to the effect of positive rhythm and large amount of liquid scouring on injection water after directional well injec- tion,which forms a U-shaped tubular ineffective water cycle in the cone-shaped changing zone of permeability, bottom water zone and production well sweep zone. The technology of“gel dam”improves the flooding effect of injected water in heavy oil bottom water reservoir. The oil increasing effect of pilot test well group is obvious the daily oil increment is 40 m^3/d. This method changes the poor effect of water flooding in bottom water reservoir, and changes the water flooding in bottom water reservoir from“enough water injection”to“effective water injection”. This new water injection model is of great significance for improving the flooding effect of water injection in heavy oil bottom water reservoirs.