Experimental study on horizontal wellbore cleanout by rotating jets

• Published in: Journal of petroleum science & engineering Vol. 75; no. 1-2; pp. 71 - 76
• Main Authors: Song, X.Z., Li, G.S., Huang, Z.W., Wang, H.Z., Tian, S.C., Shi, H.Z.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01-12-2010; Elsevier
• Subjects: Annular; Applied sciences; Cleaning; Crude oil, natural gas and petroleum products; Energy; Exact sciences and technology; Flow rate; Fuels; Helical flow; Horizontal; horizontal wellbore; nozzle assembly; Nozzles; rotating jet; Sand; sand cleanout; Wipers; rotating jet; helical flow; nozzle assembly; horizontal wellbore; sand cleanout; Tubing; Hydraulics; Cleaning; Performance; Strength
• ISSN: 0920-4105; 1873-4715
• DOI: 10.1016/j.petrol.2010.10.015

Horizontal wellbore cleanout by rotating jets has been developed rapidly in the past decades. To improve the sand cleanout efficiency, the strength of helical flow as one of the most important factors is necessary to be investigated and optimized. The flow rate, nozzle size, nozzle orientation and annular size have the major influence on the arising, performing and attenuating of annular helical flow. This paper presents the experimental results of a horizontal wellbore cleanout with varying nozzle assemblies in orifice size and orientation, tubing size, solid size, and flow rate. The tests of stationary circulation and wiper trip were carried out respectively. In the stationary circulation stage, there exists a critical length between sand bed and cleaning tool which results the two kinds of mechanisms to transport the sand. When the distance is shorter than the critical length, the primary mechanism of sand suspend is annular helical flow. As the distance is longer than it, the mechanism turns into straight annular flow which results in lower cleanout efficiency. In this study, the critical length increases rapidly with the increase of flow rate, tubing size and sand size. The sand bed moving velocity changing with the distance was also investigated and it is beneficial to optimize the wiper trip speed of cleaning tool. For the wiper trip stage, there exists the maximum wiper speed which can fulfill the requirement of completely sand cleanout when the tool is pulled out of the hole(POOTH), and it increases with the increase of flow rate and tubing size, and the decrease of sand size. The nozzle assembly is one of the most important factors to affect the helical flow profile and sand cleanout efficiency. The optimum lateral nozzle size and nozzle orientation were also obtained to get a best performance in annular helical flow and wiper trip speed. This study can contribute to the optimum design of nozzle assemblies, operation procedures and hydraulic parameters so that the highest efficiency of horizontal wellbore cleanout can be achieved.