淀粉接枝共聚物凝胶的稳油控水效果及工艺参数优化

Oil Stabilizing Effect and Process Parameters Optimization of Starch Graft Copolymer Gel

绝大多数的陆上油田经过长时间注水及注聚合物开发,储层大孔道或高渗透条带发育,注入水无效低效循环日益严重。针对常规调剖堵水剂封堵效果较差的技术难题,以西部B油田储层及流体特征为研究对象,研究了淀粉接枝共聚物凝胶的基本性能、注入性、封堵性能,评价了不同影响因素下淀粉接枝共聚物凝胶的稳油控水效果。研究表明,淀粉接枝共聚物凝胶的初始黏度较低,注入性较好,但其受成胶空间环境影响较严重,成胶空间越大,成胶强度越高,对高渗透岩心的封堵能力强于对低渗透岩心的,对中低渗透储层中伤害较小,一定程度上具有选择性封堵的效果。此外,淀粉接枝共聚物凝胶的注入量为0.1 PV时采收率增幅最高,继续增大凝胶的注入量,对中低渗透岩心的伤害随之增大,反而不利于液流转向的发生。随着顶替段塞注入体积的增加,采收率逐渐增大,“产出/投入”比逐渐降低。淀粉接枝共聚物凝胶的注入时机对增油降水效果同样存在影响,注入时机越早,非均质性程度越弱,封堵效果越好,最终采收率增幅越高。

The vast majority of onshore oil fields have been developed by water injection and polymer injection for a long time,which leads to the development of large pore channels or high permeability bands,and the ineffective and inefficient circulation of injected water becomes more and more serious.Aiming at the technical problems of poor plugging effect of conventional profile control and water plugging agent,taking the reservoir and fluid characteristics of Western B oilfield as the research object,the basic performance,injection,plugging of starch graft copolymer gel(SGCG)was evaluated,and the stabilizing oil production and controlling water cut effect of SGCG under different factors was investigated.The results showed that the initial viscosity of SGCG was low,and the injection was good.However,the gel environment would affect seriously gelation.The larger the gelatin space,the higher the gelation strength.The sealing ability of SGCG to the high permeability core was stronger than that to the low permeability core,indicating that SGCG had less damage to the medium low permeability reservoir and had a selective sealing effect to a certain extent.In addition,it was found that the SGCG was not injected with PV,the more the better,there was a reasonable range.The highest recovery rate was obtained when injecting 0.1 PV SGCG.With the increase of gel dosage,the damage to the medium and low permeability increased,as a result,it was not conducive to the occurrence of fluid diversion.With the increase of displacement slug,the oil recovery increased gradually,however,the output-input ratio decreased gradually.The injection timing of SGCG also had an effect on increasing oil and decreasing water cut.The earlier the injection time was,the weaker the degree of heterogeneity was,the better the plugging effect was,and the higher the final recovery rate was.