Mechanism analysis and process optimization of sand and plug removal with rotating jet in horizontal well

In the view of the problems existing in horizontal well, such as sand depositing and cleaning difficulty of borehole, a technology with rotating jet suitable to resolution of the problems was presented. Based on liquid-solid two-phase flow theory, the analyses on the sand movement law and the swirling field influential factors were conducted. Results show that: 1) With the increasing of displacement in horizontal section annulus, swirling field strength increases, and when the displacement is constant, the closer from the nozzle, the stronger the swirling field strength is; 2) Head rotating speed and liquid viscosity have little influence on the swirling field strength, but the sand-carrying rate of fluid can increase by increasing liquid viscosity in a certain range; 3) Rotating the string and reducing its eccentricity in annulus are conducive for sand migration in the annulus; 4) The sand can be suspended and accelerated again and the swirling field strength is enhanced by the helix agitator. Hence, the research results provide the theoretical basis for the design and application of rotating jet tool.