Analysis of Tool Joint Effects for Accurate Friction Pressure Loss Calculations

摘要

The prediction of friction pressure losses is very important in many oil-field operations, including drilling, completion, fracturing, acidizing, workover and production. Many theoretical and experimental studies have dealt with the flow of fluids through pipes and annuli for friction pressure loss calculations. Most of these studies have concentrated upon the fluids rheological models, pipe roughness, and geometrical parameters. However, the important effect of tool-joint in conjunction with the drillpipe in estimating the friction pressure loss in annulus has yet not been investigated. The tool joint is a necessary part to extend the drillpipe. The space between the tool joint and casing is narrower than the space between drillpipe and casing because of the larger diameter of the tool joint than the drillpipe. Therefore, there will be an additional pressure loss due to effect on the fluid flowing in the annulus expansion and contraction. This paper presents the experimental data of the tests performed with three different fluids and discusses the results in light of the effect of tool joints on the annular friction pressure loss. It is found that the effect of the presence of tool joints on the annular friction pressure is significant and an accurate prediction method for annular pressure loss is proposed.