密度差对水平段固井顶替界面影响规律研究

摘要

水平封固段的固井顶替效果是影响水平井固井质量的关键问题,居中度和密度差是影响水平段固井顶替效果的重要参数.本文基于国家超级计算中心天河一号大规模集群计算平台,采用Fluent软件对300 m长水平段偏心环空进行1000s的隔离液顶替界面的数值模拟实验,研究居中度和密度差对隔离液与钻井液顶替界面的影响规律.研究结果表明,在扶正器扶正条件和密度差设计许可时,尽量提高水平段套管居中度与密度差,可以达到理想顶替效果与固井质量.当井眼条件差、扶正器下入困难时,采用大密度差的浆体设计,可以大幅改善偏心环空窄边钻井液滞留,提高隔离液顶替效率与固井质量.当钻井条件限制无法采用合理的密度差设计时,提高水平段扶正器的扶正效果,可以大幅改善偏心环空窄边钻井液滞留,提高隔离液顶替效率与固井质量.本文研究结论对固井顶替施工具有重要理论与实践指导意义.%The displacement effect of horizontal cementing interval is the key issue of horizontal cementing quality.The casing center degree and the density difference are the key parameters of cementing displacement effect.The objective of this paper is the influence of casing center degree and density difference on the displacement interface of drilling fluid and spacer fluid by simulating the interface of drilling fluid and spacer fluid in 300 m horizontal eccentric annulus for 1 000 s using software Fluent on the calculating platform of national supercomputing center TIANHE-1A cluster Computing.The results show that:when the centralizer and the density difference design permit,the casing center degree in the horizontal section and density difference can be improved as far as possible,so the ideal replacement efficiency and cementing quality can be achieved.When the wellbore condition is poor and the centralizer is difficult to enter,the fluid with large density difference can greatly reduce the eccentric annulus drilling fluid retention,improve the displacement efficiency and cementing quality.When the drilling conditions cannot adopt reasonable density difference design,improving the level of a centralizer righting effect can significantly reduce the eccentric annular narrow side drilling fluid retention,improve displacement efficiency and cementing quality.The conclusion of this paper is of great value towards the vital theory and operation guidance.