Method of Pumping a Well with Dual Alternate Submersible Pumps

Abstract

A tubing wet mate sub is secured to a string of tubing within the well, the wet mate sub having a tubing electrical wet mate connection secured to a lower motor power cable extending from the tubing electrical wet mate connection alongside the tubing to a wellhead. An electrical submersible pump assembly has at least one pump, an upper motor and a lower motor, the lower motor having a lower motor electrical wet mate connection in electrical engagement with the tubing electrical wet mate connection to supply power to the lower motor. An upper motor power cable is connected to the upper motor and extends through the tubing to the wellhead to supply power to the upper motor.

1 . A method of producing a well, comprising the following steps:
 (a) providing an electrical submersible pump assembly (ESP) having at least one pump, an upper motor and a lower motor, the lower motor having a lower motor electrical wet mate connection;   (b) installing a string of tubing in a well with a tubing electrical wet mate connection at a selected depth and a lower motor power cable extending from the tubing wet mate connection alongside the tubing to a wellhead;   (c) connecting an upper motor power cable to the upper motor and running the ESP assembly into the tubing, then engaging the lower motor wet mate connection with the tubing wet mate connection;   (d) selectively supplying power through the lower motor power cable and the wet mate connections to the lower motor while not supplying power through the upper motor power cable; and   (e) selectively supplying power through the upper motor power cable to the upper motor while not supplying power through the lower motor power cable.   
     
     
         2 . The method according to  claim 1 , wherein:
 said at least one pump comprises an upper pump operatively connected to the upper motor and a lower pump operatively connected to the lower motor.   
     
     
         3 . The method according to  claim 1 , wherein:
 said at least one pump comprises an upper pump operatively connected to a lower end of the upper motor and a lower pump operatively connected to an upper end of the lower motor.   
     
     
         4 . The method according to  claim 1 , wherein:
 the ESP assembly comprises:   an upper pump connected below the upper motor,   a lower pump connected above the lower motor;   a valve connected between the upper pump and the lower pump; and   an annular packoff that seals the valve to the tubing, defining an upper annulus separate from a lower annulus;   step (d) comprises, with the lower pump discharging well fluid through the valve into the upper annulus, which flows around the upper pump and the upper motor; and   step (e) comprises, with the upper pump drawing well fluid from the lower annulus through the valve into an intake of the upper pump and discharging well fluid from the upper pump into the upper annulus.   
     
     
         5 . The method according to  claim 1 , wherein:
 the upper motor is operatively connected to an upper end of the pump;   the lower motor is operatively connected to a lower end of the pump;   step (d) comprises driving the pump with the lower motor; and   step (e) comprises driving the pump with the upper motor.   
     
     
         6 . The method according to  claim 1 , wherein:
 the at least one pump of the ESP assembly is located between the upper motor and the lower motor;   step (e) comprises disengaging a shaft of the upper motor from the pump and driving the pump with the lower motor; and   step (f) comprises disengaging a shaft of the lower motor from the pump and driving the pump with the upper motor.   
     
     
         7 . A method of producing a well, comprising the following steps:
 (a) providing a lower electrical submersible pump assembly (ESP) having a pump and a motor with a motor electrical wet mate connection;   (b) providing an upper ESP having a pump and a motor with an upper ESP power cable connected to the motor of the upper ESP;   (c) installing a string of tubing in a well with a tubing electrical wet mate connection at a selected depth and a lower ESP power cable extending from the tubing wet mate connection alongside the tubing to a wellhead;   (d) coupling the lower ESP to the upper ESP, defining a dual ESP assembly having a longitudinal axis, and running the dual ESP assembly into the tubing while feeding the upper ESP power cable into the tubing from the wellhead, then engaging the motor wet mate connection with the tubing wet mate connection;   (e) selectively supplying power through the lower ESP power cable and the wet mate connections to the motor of the lower ESP and pumping well fluid up the tubing with the pump of the lower ESP while not supplying power through the upper ESP power cable; and   (f) selectively supplying power through the upper ESP power cable to the motor of the upper ESP and pumping well fluid up the tubing with the pump of the upper ESP while not supplying power through the lower ESP power cable.   
     
     
         8 . The method according to  claim 7 , further comprising;
 in step (e), isolating a discharge of the pump of the lower ESP from an intake of the pump of the upper ESP; and   in step (f), isolating a discharge of the pump of the upper ESP from an intake of the pump of the lower ESP.   
     
     
         9 . The method according to  claim 7 , wherein:
 step (d) comprises, with a packoff sealing between the dual ESP assembly and the tubing, defining an upper annulus surrounding the upper ESP and a lower annulus surrounding the lower ESP;   step (e) comprises drawing well fluid from the lower annulus into an intake of the pump of the lower ESP and flowing a discharge of the pump of the lower ESP through the packoff into the upper annulus; and   step (f) comprises flowing well fluid in the lower annulus through the packoff into an intake of the pump of the upper ESP.   
     
     
         10 . The method according to  claim 7 , wherein:
 step (d) comprises, with a packoff sealing between the dual ESP assembly and the tubing, defining an upper annulus surrounding the upper ESP and a lower annulus surrounding the lower ESP;   the pump of the lower ESP has an intake in fluid communication with the lower annulus and a discharge in fluid communication with the upper annulus, and the pump of the upper ESP has an intake in fluid communication with the lower annulus and a discharge in fluid communication with the upper annulus;   step (e) comprises drawing well fluid from the lower annulus into the intake of the pump of the lower ESP and flowing a discharge of the pump of the lower ESP through the packoff into the upper annulus;   step (f) comprises flowing well fluid in the lower annulus through the packoff into the intake of the pump of the upper ESP and flowing a discharge of the pump of the upper ESP into the upper annulus;   during step (e), the upper pump is not operating; and   during step (f), the lower pump is not operating.   
     
     
         11 . The method according to  claim 7 , further comprising:
 mounting a valve between the upper end of the lower ESP and the lower end of the upper ESP, the valve having a lower pump inlet port, a lower annulus inlet port, an upper pump outlet port and an upper annulus outlet port; wherein   step (d) comprises sealing between the valve and the tubing, defining an upper annulus above me valve and a lower annulus below the valve;   step (e) comprises flowing a discharge of the pump of the lower ESP through the lower pump inlet port and out the upper annulus outlet port to the upper annulus; and   step (f) comprises flowing well fluid in the lower annulus through the lower annulus inlet port and out the upper pump outlet port to an intake of the pump of the upper ESP.   
     
     
         12 . The method according to  claim 7 , further comprising:
 mounting a valve between the upper end of the lower ESP and the lower end of the upper ESP, the valve having a lower pump inlet port, a lower annulus inlet port, an upper pump outlet port and an upper annulus outlet port, the valve having a first position communicating the lower pump inlet port with the upper annulus outlet port, the valve having a second position communicating the lower annulus inlet port with the upper pump outlet port; wherein   step (d) comprises sealing between the valve and the tubing, defining an upper annulus above the valve and a lower annulus below the valve;   step (e) comprises placing the valve in the first position; and   step (f) comprises placing the valve in the second position.   
     
     
         13 . The method according to  claim 7 , further comprising:
 in step (d), sealing to the tubing an intermediate area of the dual ESP assembly between the upper ESP and the lower ESP, defining an upper annulus separated from a lower annulus;   mounting a valve in the intermediate area of the dual ESP assembly, the valve having a lower pump inlet port in fluid communication with a discharge of the pump of the lower ESP, a lower annulus inlet port in fluid communication with the lower annulus, an upper pump outlet port in fluid communication with an intake of the pump of the upper ESP, and an upper annulus outlet post in fluid communication with the upper annulus;   providing the valve with a first position communicating the lower pump inlet port with the upper annulus outlet port, and a second position communicating the lower annulus inlet port with the upper pump outlet port, and biasing the valve to the second position with a spring; wherein   pressure caused by the discharge of the pump of the lower ESP in step (e) overcomes the spring and places the valve in the first position; and   cessation of operation of the pump of the lower ESP in step (f) causes the spring to move the valve in the second position.   
     
     
         14 . An apparatus for pumping well fluid front a well, comprising:
 a tubing wet mate sub adapted to be secured to a string of tubing within the well, the wet mate sub having a tubing electrical wet mate connection adapted to be secured to a lower motor power cable extending from the tubing electrical wet mate connection alongside the tubing to a wellhead;   an electrical submersible pump assembly (ESP) having at least one pump, an upper motor and a lower motor, the lower motor having a lower motor electrical wet mate connection in electrical engagement with the tubing electrical wet mate connection to supply power to the lower motor; and   an upper motor power cable connected to the upper motor and adapted to extend through the tubing to the wellhead to supply power to the upper motor.   
     
     
         15 . The apparatus according to  claim 14 , wherein:
 said at least one pump comprises an upper pump operatively connected to the upper motor and a lower pump operatively connected to the lower motor.   
     
     
         16 . The apparatus according to  claim 14 , wherein:
 said at least one pump comprises an upper pump operatively connected to a lower end of the upper motor and a lower pump operatively connected to an upper end of the lower motor.   
     
     
         17 . The apparatus according to  claim 14 , wherein the ESP assembly comprises:
 an upper pump connected below the upper motor;   a lower pump connected above the lower motor;   a valve connected between the upper pump and the lower pump;   an annular packoff for sealing the valve to the tubing to define an upper annulus separate from a lower annulus; wherein,   the valve has a first position defining a flow path for the lower pump to discharge well fluid from the lower annulus through the valve into the upper annulus, which flows around the upper pump and the upper motor; and   the valve has a second position defining a flow path for the upper pump to draw well fluid from the lower annulus through the valve into an intake of the upper pump and discharge well fluid from the upper pump into the upper annulus.   
     
     
         18 . The apparatus according to  claim 14 , wherein the ESP assembly comprises:
 an upper pump connected below the upper motor;   a lower pump connected above the lower motor;   a valve connected between the upper pump and the lower pump;   an annular packoff for sealing the valve to the tubing to define an upper annulus separate from a lower annulus; wherein,   the valve has a first position defining a flow path for the lower pump to discharge well fluid from the lower annulus through the valve into the upper annulus, which flows around the upper pump and the upper motor;   the valve has a second position defining a flow path for the upper pump to draw well fluid from the lower annulus through the valve into an intake of the upper pump and discharge well fluid from the upper pump into the upper annulus;   the valve is biased by a spring into the second position; and   pressure caused by the discharge of the lower pump overcomes the spring and moves the valve to the first position.   
     
     
         19 . The apparatus according to  claim 14 , wherein:
 the upper motor is operatively connected to an upper end of the pomp;   the lower motor is operatively connected to a lower end of the pump;   
     
     
         20 . The apparatus according to  claim 14 , wherein:
 the at least one pump of the ESP assembly is located between the upper motor and the lower motor and is driven selectively by the lower motor and by the upper motor; wherein the apparatus further comprises:   means for disengaging a shaft of the upper motor from the pump and driving the pump with the lower motor; and   means for disengaging a shaft of the lower motor from the pump and driving the pump with the upper motor.