井底交变流场提速工具的研制及特性测试

现有脉冲射流发生工具存在脉冲强度沿程损耗大、提速效果不明显的问题。为此,研制了一种新型井底交变流场提速工具。该工具主要由叶轮式动力机构和盘阀式脉冲发生机构组成,通过将脉冲发生机构放入钻头内部的方法来减少脉冲强度沿程损耗。采用室内试验方法对其脉冲特性进行研究。研究结果表明:叶轮倾角的增大会提高叶轮转速;随排量的增加,叶轮转速先趋于线性增加,最终稳定在500~600 r/min,当盘阀孔数为2、3、4时,对应的脉冲频率分别稳定在20、30、40 Hz左右,当排量为23 L/s时,工具压耗最大为0.6 MPa,压力波动幅值最大1.6 MPa,且脉动幅值随盘阀孔数减少而增大。最后对井底交变流场提速工具结构参数进行了优选,即动力机构优选叶片倾角为30°的叶轮,脉冲发生机构优选2扇形孔盘阀。研究结果可为井底交变流场提速工具及相似工具的优化设计提供依据。

Development and Characteristic Test of Downhole Alternating Flow Field ROP Enhancing Tool

Existing pulse jet tools have the problems of large pulse intensity loss and inferior ROP enhancement performance.To address the problem,a new type of downhole alternating flow field ROP enhancing tool is developed.The tool is mainly composed of an impeller-type power mechanism and a disc valve-type pulse generating mechanism.By placing the pulse generating mechanism inside the drill bit,the pulse intensity loss is reduced.Laboratory tests are conducted to study its pulse characteristics.The results show that the increase of impeller angle will increase the impeller speed.With the increase of displacement,the impeller speed tends to increase linearly,and finally stabilizes at 500~600 r/min.When the number of disc valve holes is 2,3 and 4,the corresponding pulse frequency is stabilized at about 20 Hz,30 Hz,and 40 Hz,respectively.When the displacement is 23 L/s,the maximum pressure loss is 0.6 MPa,and the maximum pressure fluctuation amplitude is 1.6 MPa.The pressure fluctuation amplitude increases with the decrease of the number of disc valve holes.The structural parameters of the downhole alternating flow field ROP enhancing tool are selected.The power mechanism has an impeller with an optimal blade inclination angle of 30°,and the 2 fan-shaped hole disc valve is selected for the pulse generating mechanism.The study can provide a basis for the optimization design of the downhole alternating flow field ROP enhancing tool and similar tools.