重质油藏氮气辅助蒸汽驱注采参数敏感性分析及优化

为明确氮气辅助蒸汽驱中各注采参数对开发效果的影响,并优选最佳注采方案。以JY油田J2区块的11-12井组为例,采用CMG数值模拟软件的STAR热采模块,通过模拟各种氮气辅助蒸汽驱方案,分别评价了注气量、采注比、蒸汽干度、注汽(气)速度及油藏特征参数对最终采收率的影响,并结合正交试验方法对注采参数进行了优化研究,获得了最佳注采方案。结果表明:氮气辅助蒸汽驱过程中氮气注入段塞的体积应小于0.6HCPV,采注比以1.4左右为宜,氮气段塞注入前,蒸汽干度越高越好,而氮气段塞注入后,蒸汽干度控制在50%以上,提高注汽(气)速度以提高采油速度。最优注采参数组合为氮气注入体积0.2HCPV,注入速度为140 m³/d,采注比为1.6。试验井组开展氮气辅助蒸汽驱后单井平均产油量从1.8 m³/d提高至5.9 m³/d,单井平均含水率由97.2%下降至67.8,降水增油效果显著。研究成果为重质油藏开展氮气辅助蒸汽驱提供了参考依据。

SENSITIVITY ANALYSIS AND OPTIMIZATION OF INJECTION PRODUCTION PARAMETERS FOR NITROGEN ASSISTED STEAM FLOODING IN HEAVY OIL RESERVOIRS

In order to clarify the influence of injection production parameters on development effect in nitrogen assisted steam flooding and optimize the best injection production scheme.Taking well group 11-12 in block J2 of JY oilfield as an example,the star thermal recovery module of CMG numerical simulation software is used to simulate various nitrogen assisted steam flooding schemes.The effects of gas injection rate,production injection ratio,steam dryness,steam(gas)injection rate and res?ervoir characteristic parameters on the final recovery are evaluated respectively.The injection production parameters are opti?mized by combining with orthogonal test method,and the optimal injection rate is obtained.The results show that:in the pro?cess of nitrogen assisted steam flooding,the volume of nitrogen injection slug should not be more than 0.6 HCPV,and the pro?duction injection ratio should be about 1.4.Before nitrogen slug injection,the higher the steam dryness,the better.After nitro?gen slug injection,the steam dryness should be controlled above 50%,and the steam(gas)injection rate should be increased to improve the oil recovery rate.The optimal injection production parameters are nitrogen injection volume of 0.2HCPV,injection rate of 140 m3/d and production injection ratio of 1.6.After nitrogen assisted steam flooding,the average oil production of single well increased from 1.8 m³/d to 5.9 m³/d,and the average water cut of single well decreased from 97.2%to 67.8%.The research results provide a basis and reference for nitrogen assisted steam flooding in heavy oil reservoirs.