Development of a supra-bit jet pump for opening a productive formation

Abstract

The article proposes a jet pump for the bottom hole assembly. The developed supra-bit jet pump provides an additional circulation loop of the drilling fluid above the bottom of the well, which creates a local depression of the formation. In addition, the jet pump grinds the sludge injected from the annular space in the mixing chamber and feeds it to the bridging machine, which is included in the assembly, for temporary isolation of the productive formation. Isolation of the productive formation is necessary to prevent the flow of formation fluids into the wellbore when underbalanced. Grinding of the sludge in the jet pump is ensured by the cross flows of the working and injected liquid, which occur during the angular and eccentric displacement of the working nozzle of the jet pump relative to the mixing chamber. The angular and eccentric displacements of the working nozzle, the roughness of the flowing part of the mixing chamber and the diffuser, at which the pressure losses in the jet pump are insignificant, have been determined. Recommendations are proposed for increasing the efficiency of the jet pump in case of non-stationary operation at the bottom of the well, which occurs as a result of ground vibrations of a roller cone bit and uneven supply of working fluid by mud pumps.