Abstract: Various implementations include electric centrifugal pump assemblies for producing oil from wells. A submersible electric motor includes a housing, a shaft inside said housing that transmits rotational power from the electric motor section to the pump section, a mechanical seal surrounding the shaft to keep a dielectric fluid inside the electric motor, and a unit for compensating the volume of the dielectric fluid. Said unit maintains a constant positive pressure and includes a spring mounted inside a metal bellows. The spring is arranged in a tensioned state inside a cavity containing dielectric fluid. The spring is rigidly fastened facing the electric motor and to the bottom of the bellows such as to be capable of axial movement. The volume compensation unit is provided with a sensor for sensing the position of the spring/bellows. The cavity is filled with a barrier fluid preventing scale build-up.

Abstract: Various implementations include electric centrifugal pump assemblies for producing oil from wells. A submersible electric motor includes a housing, a shaft inside said housing that transmits rotational power from the electric motor section to the pump section, a mechanical seal surrounding the shaft to keep a dielectric fluid inside the electric motor, and a unit for compensating the volume of the dielectric fluid. Said unit maintains a constant positive pressure and includes a spring mounted inside a metal bellows. The spring is arranged in a tensioned state inside a cavity containing dielectric fluid. The spring is rigidly fastened facing the electric motor and to the bottom of the bellows such as to be capable of axial movement. The volume compensation unit is provided with a sensor for sensing the position of the spring/bellows. The cavity is filled with a barrier fluid preventing scale build up.

Abstract: Various implementations include a safety valve for mounting in a landing nipple in a wellbore. The safety valve includes a composite housing having a central passage, a shutoff element and a control mechanism. The shutoff element includes a collet and a movable mandrel having stops located in the upper part. When the shutoff element moves axially, the stops extend through the composite housing to interact with a landing nipple stop surface. The control mechanism includes a spring-loaded tubular plunger having a ring piston on its upper outer surface and longitudinal openings in its lower part, the openings being configured to align with openings in the composite housing. The movable mandrel is connected to the safety valve head at the mandrel top and rests against the plunger at the mandrel bottom. The movable mandrel has grooves and shoulders on its outer surface, which allow for taking one of the fixed positions.

Abstract: A small-sized submersible pump unit having a submersible motor, discharge module, pump housings which are connected by flangeless coupling is disclosed. The flangeless coupling is made using embedded ring segments. The coupled housings each have the covering and the covered parts, and the covered part of one of the housings contains a blind rectangle groove, and the covering part of another housing has a through rectangle groove, and the grooves form a cavity having an embedded ring segment.

Abstract: The invention relates to oil production equipment, more particularly, small-sized submersible pump units that are run in holes on a carrying cable within an additional pipe. The technical result is improvement of reliability of small-sized submersible pump unit in operation, elimination of submersible motor overheating, and simplification of the pump unit mounting. This result is achieved by a small-sized submersible pump unit having a submersible motor, foldable module, pump housings of which are connected by flangeless coupling wherein the flangeless coupling is made using embedded ring segments. The coupled housings each have the covering and the covered parts, and the covered part of one of the housings contains a blind rectangle groove, and the covering part of another housing has a through rectangle groove, and the grooves form a cavity having an embedded ring segment.