提高固井过程中环空摩阻计算精度的方法

Method to Increase the Accuracy of Annular Friction Calculation while Cementing

分析了固井过程中理论计算方法计算环空摩阻值误差较大的原因;在理论计算的基础之上,采用现场环空摩阻拟合、计算反演及最小二乘法,建立了排量和环空附加摩阻值的对应关系,以此估算出注水泥过程中精度更高的环空摩阻值;并且进行了现场应用的计算。结果表明,该方法拟合出的环空摩阻比理论计算值精度更高,以此推算的泵压与实际的泵压值相比最大误差仅为4.86%。该方法计算简便、准确,对固井设计和固井安全具有一定的实际意义。

The causes of errors in using theoretical method to calculate annular friction while cementing was an- alyzed. And then, a numerical relational expression between the delivery rate and additional friction has been built to calculate the annular friction in this article. The expression is established on the basis of the theoretical calcula- tion ; furthermore, least square method and annular friction fitting technology in cementing scene have been adopted in it. The method was applied in cementing practice too. The result shows that the fitted annular friction losses based on this expression have a higher accuracy than the theoretical ones. The maximum error is no more than 4. 86% between the fitted solution pump pressure and actual value. The procedure which is accurate and handy has practical meanings for cementing documentation and safety.