隔离液流性指数对水平段顶替界面影响规律研究

Displacement Interface Characteristics with Different Spacer Fluid Indices in Horizontal Wells

水平段的固井顶替效率是水平井固井质量的关键,隔离液流变性是影响水平段固井顶替效率的重要参数。为此,基于国家超级计算中心天河一号计算平台,采用FLUENT软件进行1 000s的长水平段偏心环空固井顶替数值模拟,研究隔离液流变性对固井顶替界面的影响规律。研究结果表明:低居中度时,减小隔离液流性指数,可以大幅减少环空宽边与窄边隔离液滞留,减小顶替界面长度,提高顶替效率;中等居中度时,减小隔离液流性指数,可以大幅减少环空宽边隔离液滞留,有效减小顶替界面长度,提高顶替效率;高居中度时,减小隔离液流性指数,有利于减少环空宽边隔离液滞留,减小顶替界面长度,提高顶替效果;理想居中度条件下,隔离液流性指数一定不能大,否则出现严重的水泥浆窜流。研究表明,固井设计施工时需考虑隔离液流变性与套管居中度,以降低环空高边窜流的概率,提高固井质量。

Displacement efficiency in the cementation of the horizontal interval is the key for high-quality cementation operations in horizontal wells and rheological properties of spacer fluids are the important parameters affecting displacement efficiency. Large-scale cluster computing platforms in the National Super Computing Center and Fluent software were used to conduct a numerical simulation for displacement in 1,000 seconds during cementation of eccentric annulus in horizontal interval to determine the impact of rheological properties of spacer fluids on displacement interfaces in cementation. Results show that the re- tention of spacer fluids can be reduced dramatically on both sides of the annulus at low eccentric degrees by reducing flow index of these spacer fluids and displacement efficiencies can be enhanced significantly as displacement interface length reduction, while it can be reduced dramatically or obviously on the wider side of the annulus at medium and high eccentric degrees, respectively, by reducing flow index of these spacer fluids, and displacement efficiencies can be enhanced significantly as displacement interface length reduction. At ideal eccentric central degrees, it is necessary to maintain low flow indexes, otherwise severe channeling of cement slurries might be expected. In conclusion, the rheological properties of spacer fluids and eccentric degrees of casing shall be considered during design and implementation of cementation operations to minimize possibility of channeling on wider side of the casing so as to enhance quality of cementation operations.