A centrifugal pump assembly (2) includes an impeller, an electric drive motor (4), driving the impeller (12), and a back-flow channel (24), forming a flow connection from a delivery side (18) to a suction side (16). A valve (26), in a pressure-dependent manner, closes the flow connection. A control device (28) adjusts/sets the speed (n) of the drive motor (4), and is configured with a venting function for venting the centrifugal pump assembly (2) on operation. According to the venting function, after the detection of an air accumulation, the speed (n) of the drive motor (4) is automatically reduced, and subsequently the speed (n) is rapidly increased again. A method is also provided for removing an air accumulation from a centrifugal pump assembly during operation, which method includes reducing the speed (n) of the centrifugal pump assembly and subsequently rapidly increasing the speed (n) of the centrifugal pump again.

The invention relates in a first aspect to method of venting air out of a closed fluid system comprising a number of inter connected pipes configured for flow of a fluid, a variable speed pump configured for controlling the volume flow of fluid in said fluid system and an air venting device configured to let air out from the fluid system, the method comprising operating said pump in at least three phases.

Various downhole tools are discussed, including intake and gas separators for a downhole rotary pump. Multiple intakes configured in parallel and series are discussed, along with compact axial length gas separators, and gas separators that remove gas in novel ways. Related apparatuses and methods are discussed.

There is provided a centrifugal pump comprising a pumping chamber (106). The pumping chamber (106) has an inner surface (108) defining a pump cavity (110); a pump inlet (112) defined in a first side of the pumping chamber (106); a shaft opening (116) defined substantially centrally in a second side of the pumping chamber (106), the second side substantially opposing the first side and arranged to be above the first side, in use; and a pump outlet (114). The centrifugal pump further comprises an impeller (120) retained within the pump cavity (110); and a shaft member (140) mechanically connected to the impeller (120) through the shaft opening (116), whereby rotation of the shaft member (140) causes rotation of the impeller (120) about a shaft axis (157) passing through the shaft opening (116) and movement of a pumping liquid from the pump inlet (112) towards the pump outlet (114). The centrifugal pump further comprises a flow modifier (150) provided adjacent to an outer surface (107) of the pumping chamber (106) at the shaft opening (116) to substantially prevent ingress of air into the pump cavity (110) through the shaft opening (116) during operation of the pump even when a water level in a liquid tank (104) surrounding the pumping chamber (106) drops below a level of the shaft opening (116). The flow modifier (150) comprises an annular portion (152) having defined therein a further shaft opening (156) spaced from the shaft opening (116) and having the shaft member (140) passing therethrough. The centrifugal pump comprises a spacing member (154) spacing the annular portion (152) from the outer surface (107). The flow modifier (150) defines a liquid overflow outlet (164) for liquid flow from the shaft opening (116) in a direction substantially transverse to the shaft axis (157). In one example, the liquid overflow outlet (164) is sized to substantially prevent the ingress of air into the pump cavity (110) through the shaft opening (116) during operation of the pump, even when the water level in the liquid tank (104) surrounding the pumping chamber (106) drops below the level of the shaft opening (116). In the same or an alternative example, the annular portion (152) comprises a first portion (158) having defined therein the further shaft opening (156) and a second portion (160) extending towards the outer

A pumping device for pumping liquids includes a centrifugal pump with a radially pumping pump wheel having a hollow center, and is configured to remove accumulations of gas from the interior of the pump. The pumping device includes a detecting device for detecting a first operating parameter, a sensor for measuring a second operating parameter, and a control unit for controlling the pump. The control unit is configured to control the operation of the pump so as to remove accumulations of gas from the hollow center of the pump during liquid pumping operation.

Various downhole tools are discussed, including intake and gas separators for a downhole rotary pump. Multiple intakes configured in parallel and series are discussed, along with compact axial length gas separators, and gas separators that remove gas in novel ways. Related apparatuses and methods are discussed.

A metering pump is typically used to move a specified volume of liquid in a specified amount of time. Because it may be desirable to maintain fluid in the pumping system such that the metering pump is maintained in a primed condition, an automatic prime detection function is provided by monitoring the current to a solenoid assembly of the pump. A loss of prime condition can then be detected by comparing the measured current to a characterized selected current value such that operation of the metering pump can be changed based on load.

Gas lock resolution during operation of an electric submersible pump is provided. An example method, module, or computing hardware with software product, detects a gas lock during current operation of an electric submersible pump (ESP) and intervenes to relieve the gas lock without stopping the ESP. After sensing a gas lock condition, an example module calculates a pump speed for attempting gas lock resolution. The example module may decrease the speed of the ESP to flush the gas lock, and then reaccelerate the ESP to check that the gas lock has been eliminated. The example module may apply one or more stored motor speed patterns that iteratively seek a pump speed that succeeds in clearing the gas lock, without stopping the ESP. The example module has built-in protections to protect the ESP from thermal overload and other damage.

Systems and apparatuses for regulating a multi-phase fluid stream flowing from a subterranean geological formation, and related methods are described herein. The system and apparatus generally include a conduit defining a flow path for the fluid stream, the conduit further defining a first restriction having a throat portion, and the conduit further defining a first return path including an inlet positioned downstream of the first restriction and an outlet positioned upstream of the inlet of the first return path. Related methods include placing the apparatus or system within a wellbore conduit defined by a wellbore.

A fluid moving system and apparatus for an electric submersible pump (ESP) is described. A fluid moving system includes a gas separator between an electric submersible pump and an ESP motor, the gas separator including a separation chamber including an impeller and a diffuser, the impeller including a plurality of regressively pitched main vanes interspersed between a plurality of mixer vanes, each of the plurality of main and mixer vanes extending along the hub with a positive slope and a concave top face, and a diffuser, the diffuser including blades extending along a diffuser body in a sloped direction substantially opposite the slope of the impeller main vanes, the blades having a concave top face and a regressive pitch that mirrors the pitch of the impeller main vanes, wherein the impeller vanes and diffuser blades serve to homogenize the well fluid while facilitating downstream movement.