摘要:
A centrifugal pump has impellers for pumping low flow, high viscous materials. The impellers have high exit angles greater than 30 degrees and preferably greater than 50 degrees. The impellers and diffusers have specific geometry that varies with viscosity. The pump has zones of impellers and diffusers with the exit angles and geometry in the zones differing from the other zones. The exit angles decrease and geometry varies in a downstream direction to account for a lower viscosity occurring due to heat being generated in the pump. One design employs small diameter impellers and high rotational speeds.
摘要:
A centrifugal pump has impellers for pumping low flow, high viscous materials. The impellers have high exit angles greater than 30 degrees and preferably greater than 50 degrees. The impellers and diffusers have specific geometry that varies with viscosity. The pump has zones of impellers and diffusers with the exit angles and geometry in the zones differing from the other zones. The exit angles decrease and geometry varies in a downstream direction to account for a lower viscosity occurring due to heat being generated in the pump. One design employs small diameter impellers and high rotational speeds.
摘要:
A low volume submersible pump assembly has features to stabilize the operation. The pump assembly includes a centrifugal pump driven by a submerged electrical motor. The centrifugal pump has an impeller configuration that is designed for high specific head, but potentially unstable operation. At the design speed, the pump potentially could deliver an indeterminate flow rate for a given head. Also, at the design speed, the design flow rate will yield a design head that is very close to the maximum head at zero flow. The pump has the characteristic of requiring a significant increase in torque to produce higher flow rates. To stabilize the potentially unstable pump, a variable speed drive varies the speed of the motor to maintain constant torque. Maintaining a constant torque allows a considerable variance in head with only a small variance in flow rate resulting.
摘要:
Cathodic protection of a deep well submersible pumping assembly against the corrosive effect of electrolysis is achieved by providing a DC voltage source at the downhole pumping assembly, the negative terminal of the source being electrically connected to the metal surfaces which are in contact with the well fluid while the source's positive terminal is electrically connected to a sacrificial anode submerged in the well fluid. Current flows from the anode to the metal surfaces to reverse the process of electron flow caused by the electrolytic corrosion, thereby inhibiting the corrosion process on the metal surfaces. In effect, the corrosion is transferred to the sacrificial anode.
摘要:
A centrifugal pump is lowered into a well and retrieved from the well by means of its power cable. The power cable has a single conductor. The pump has a downhole electrical motor which is three-phase. Single-phase AC power will be supplied from the surface down the conductor, with the return being the casing. A phase converter converts the single-phase AC power to three-phase AC power downhole for driving the pump motor.
摘要:
An electric submersible pump system has a pressure monitoring device for monitoring the pressure down the hole. The pressure monitoring device has a pressure transducer whose resistance varies with the pressure. The pressure transducer is connected to ground and is supplied with a DC current that is superimposed on the AC power cable. A temperature switch is connected between the pressure transducer and the motor winding. The temperature switch is normally open, and closes when it reaches a selected temperature. The temperature is selected to be above the ambient temperature in the well and below the temperature that occurs when the motor is operating and fully warmed up. The temperature switch isolates the windings from ground when the motor is shut off and cooled down. This enables the motor winding and power cable to be checked for insulation resistance.
摘要:
Low voltage starting of a three-phase submersible pump motor in a shallow well is achieved by employing a high-impedance transformer for supplying the three-phase power to the motor. Upon starting, the normally heavy current drawn by the motor results in a voltage drop through the high-impedance transformer sufficient to substantially lower the voltage across the motor and hence the starting current. In the absence of limiting the starting current, abnormally high starting torques will be produced on the motor shaft resulting in mechanical fatigue and eventually shaft breakage.
摘要:
A method for producing gas from a well with low pressure involves running a bottom hole pressure test to graph a P-Q curve. The operator computes a frictional pressure drop due to friction of the gas flowing through the production tubing to the surface. A packer is set above perforations in the well. A screw pump is selected that has a capacity equal to the sum of the frictional pressure drop plus a desired wellhead pressure. The screw pump has a flow rate capacity determined from the P-Q curve. The operator may vary the frequency of a downhole motor to achieve the desired wellhead pressure.
摘要:
A method and system for downhole treatment and pumping of well fluids enhances the pumping of viscous fluids to the surface. The first step is to separate the oil and water from the well fluid and then channel the oil to a chamber that encloses the motor. The heat from the motor will increase the heat of the crude oil flowing past the motor, thereby lowering the viscosity of the crude oil. The water flows separately past the motor in another passageway, and remixes with the oil. After the oil and water recombine, the treated well fluid has a lower viscosity, and the fluid is then pumped to the surface more efficiently than without treating the oil.
摘要:
A well pump assembly has a tube extending into the well for delivering water to a point below the pump to reduce the viscosity of the oil being pumped. The downhole motor that drives the pump is surrounded by a jacket. The tube that delivers the water extends to a point below the jacket to a cross-over member mounted to the lower end of the jacket, which directs the water upward and inward. The cross-over member also has passages that directs the production fluid upward and outward.