低渗浅薄层稠油油藏水平井注氮技术研究

A Study on Nitrogen-injection Technology by Horizontal Well in Low-permeability Shallow-thin Heavy Oil Reservoir

为了研究低渗浅薄层稠油油藏水平井注氮技术,以某区块为例,探讨了氮气辅助蒸汽吞吐的机理,并利用数值模拟方法优化设计了注氮参数。结果表明:氮气辅助蒸汽吞吐的作用机理主要包括隔热作用、增能作用、助排作用和解堵作用;随注氮量的增加,累积产油量逐渐增加,但是相对增油量、相对换油率和折算油汽比逐渐减小,最佳的混注比为60∶1左右;太早或太晚注氮效果不佳,宜从第4周期开始每间隔一个周期注氮气;采用大段塞且先注氮气后注蒸汽的注氮方式效果最好。

In order to study nitrogen-injection technology by horizontal well in low-permeability shallow-thin heavy oil reservoir, a block as an example is takem, the mechanisms of nitrogen-assisted steam stimulation and op- timized the injection-parameters with numerical simulation were studied. The results showed that the mechanisms mainly conclude heat insulation, pressure supplement, cleanup and plugging effect. With the amount of nitrogen injection increases, even though cumulative oil production gradually grows, the relative increased oil, the relative gas to oil exchange ratio and the converted oil-steam ratio decrease gradually, the optimum volume ratio of nitrogen to steam is 60：1 or so. Nitrogen should be injected from No. 4 cycle and the interval is one period, either early or late is not good, also, using large plug and injecting nitrogen before steam is the best.