Application of Combination of Plugging and Chemical Oil Displacement Agents to Steam-flooding Heavy Off EOR

摘要

The auxiliary EOR technique by adding chemical oil displacement agents to steam-flooding has been applied to the heavy oil recovery recently. However, the noticeable reservoir heterogeneity in xinjiang heavy oil reservoir has resulted in steam channeling, which may allow the injected chemicals directly to move to the producing well through the steam channeling, leaving the pay-zone with high oil saturation untouched, and therefore leading to a poor utilization efficiency and sweep efficiency of the chemicals. On account of this fact, this paper puts forward a new technique combining the plugging and the chemicals to challenge the problem. To be specific, it is suggested to inject the plugging agents, to a certain extent, to block the steam channeling before injecting the chemicals. This helps to expand the sweep range of chemicals to the untouched area, thus producing an improved utilization efficiency and sweep efficiency of the chemicals. The plugging agent required by the technique is of high temperature resistance and washout resistance to the steam, and the chemicals proves workable at 250°C, with a surface tension of 34mN/m and an interfacial tension of 1.5 × 10<'3> mN/m with the viscous crude. The laboratory experiments show that an increase of over 30% EOR can be obtained by adopting this technique. The plugging and chemicals can be used as simply as direct injected in the field, therefore reducing the operation cost to a certain degree. The technology has been applied to the 44 well groups Reign nine of Xinjiang Oilfield, and the results show that 164 out of 256 wells were observed obtaining an increased oil production and a reduced water cut, and that increase was over 3.4×10<'4> tons from the on-site operation with a total number of injection of 220lm<'3> chemicals.