Well jet device and the operation method thereof

Abstract

Well jet enables forming, via jet pump, range of different depressions in well tail area at specified differential pressure value. Logging instrument enables recording well and pumped out medium physical parameters. Well operating modes are adjusted by spring-loaded stepped piston positioned in seal unit body so as to open and close holes. Return valves in pumped out and active media supply channels, combined with stepped through channel, of diameter equal to or greater than diameter of the axial through hole of a packer and which is made in the pump body below a mounting seat, enable supplying chemical reagents along a pipe string to a production formation without additional units and prevent media pumped to the production formation, from annular above-packer space penetration. Said invention enables increasing reliability and performance by preventing active medium backflow and by maintaining the depression produced on the formation when the jet pump is stopped.

1 . A well jet device comprising: a jet pump and a packer with an axial passage opening that are installed on a pipe string, an active nozzle and a mixing chamber with a diffuser being arranged in alignment in the jet pump body, and the said body also has a stepped through channel with a mounting seat between steps, a channel for supplying a medium pumped out of a well, which communicates below the mounting seat through lateral holes made in the jet pump body to the stepped through channel, and a channel for supplying an active operating fluid, which communicates to the active nozzle on its outlet end and to the pipe string annular space on its inlet end, the channel for supplying a pumped out medium communicating to the pipe string below the stepped through channel via a check valve, and the stepped through channel providing the possibility of installing a sealing unit which is made as a hollow stepped cylindrical housing which upper part comprises a sealing element and below, in the cavity, a stepped piston is arranged, which abuts against a shoulder made in the sealing unit housing and is spring-loaded against the sealing element; holes are made in the wall of the sealing unit housing opposite to the lateral holes made in the jet pump body, and the stepped piston in its lower position closes the holes in the wall of the sealing unit housing, and in the stepped piston upper position the channel for supplying a medium pumped out of a well is communicated to the pipe string below the jet pump body via the lateral holes in the jet pump body and the holes made in the wall of the sealing unit housing; axial channels, which are in alignment, are made in the stepped piston and the sealing element for the purpose of passing a logging cable therethrough which serves for suspending a logging instrument with the use of a cable head and below the jet pump body; a check valve is installed in the channel for supplying an active operating fluid; and the diameter of the stepped through channel below the mounting seat is not less than the diameter of the axial through opening of the packer. 
     
     
         2 . A method of operating the well jet device, including: assembling a pipe string by arranging a jet pump and a packer on the pipe string, lowering the whole assembly into a well, releasing the packer, supplying a pressurized hydrofracturing fluid or an acid solution via the pipe string into a producing formation, lowering a sealing unit with the use of a logging cable, together with a logging instrument attached to a logging cable head, installing the sealing unit onto the mounting seat in the stepped through channel of the jet pump, arranging the logging instrument in the producing formation area, registering background values of physical fields, in particular thermal fields, in rocks along the well hole during the said lowering operation, creating differential pressure drawdown onto the producing formation by supplying an active operating fluid to the active nozzle with the use of the jet pump, pumping the hydrofracturing fluid or products of chemical treatment out of the producing formation, and registering, while the jet pump is operated, current values of physical fields in rocks and those of formation fluid coming into the well; then during the said registration the logging cable is moved along the well hole, including the producing formation, with the use of the logging cable, then the jet pump is stopped, and the inner cavity of the pipe string above the jet pump together with the annular space above the packer is separated from the inner cavity of the pipe string under the jet pump together with the under-packer space with the use of the check valve installed in the channel for supplying a pumped out medium, thus maintaining a reduced bottomhole pressure and registering a formation pressure-restoration curve with the use of the logging instrument; then, the logging instrument is lifted up with the use of the logging cable, and the stepped piston is pressed by the cable head from below for moving it up and communicating the well under-packer space to the pipe string inner cavity above the jet pump and the well annular space above the packer via the holes made in the sealing unit housing and the lateral holes made in the jet pump body, thus equalizing pressures above and under the packer, and then the logging instrument together with the sealing unit is moved out of the well.