Submersible electrical well pump having nonconcentric housings

1. A pump section with a centre line in the axial longitudinal direction, wherein the pump section comprises:

at least two pump steps, the pump steps having a centre line and each pump step comprising a motor and one or more pump stages,

wherein the pump section comprises an outer casing enclosing one or more inner casings, the outer casing forming a confined and sealed enclosure round the pump section and having a larger diameter than the inner casings, the inner casings forming a confined and sealed enclosure round the at least two pump steps,

wherein the centre line of the pump section is displaced relative to the centre line of the pump steps, thereby forming an annulus between the outer casing and the inner casing,

wherein the annulus is sealed to prevent fluids from penetrating into the annulus, and

wherein the inner casings comprise at least one distance piece, on a radial outside surface of the inner casings, that displaces the centre line of the pump steps relative to the centre line of the pump section.

2. A pump comprising:

at least one pump section, wherein the pump section has a centre line and comprises at least two pump steps,

the pump steps having a centre line and each pump step comprising a motor and one or more pump stages,

wherein the pump section comprises an outer casing enclosing one or more inner casings, the outer casing forming a confined and sealed enclosure round the pump section and having a larger diameter than the inner casings, and the inner casings forming a confined and sealed enclosure round the two pump steps,

wherein the centre line of the pump section is displaced relative to the centre line of the pump steps, thereby forming an annulus between the outer casing and the inner casing,

wherein the annulus is sealed to prevent fluids from penetrating into the annulus, and

wherein the inner casings comprise at least one distance piece, on a radial outside surface of the inner casings, that displaces the centre line of the pump steps relative to the centre line of the pump section.

3. The pump according to claim 2 , wherein the annulus is fluid-filled and in pressure communication with a surrounding fluid.

4. The pump according to claim 2 , wherein each pump stage comprises an impeller and a diffuser.

5. The pump according to claim 2 , wherein the pump is configured to permit installation of the pump by cables or pipes.

6. The pump according to claim 2 , wherein the distance pieces comprise lead-through holes for cables, wires, or lines.

7. The pump according to claim 2 , wherein the pump steps are driven by either ring motors or axial motors.

8. The pump according to claim 7 , wherein the motors are permanent magnet motors or electric induction motors.

9. The pump according to claim 2 , wherein the pump stages in each pump step are connected to a common shaft.

10. The pump according to claim 2 , wherein the pump sections are electrically connected by wet connectors.

11. The pump according to claim 2 , wherein the motors in the pump steps are electrically connected, thereby enabling them to be operated independently of one another, with the same or a different number of revolutions per minute, and with the same or a different direction of rotation.

12. The pump according to claim 2 , wherein axial bearings and radial bearings are employed to absorb the forces generated by rotation of the motors.

13. The pump according to claim 12 , wherein the bearings are active magnetic bearings, passive magnetic bearings and/or mechanical bearings.

14. The pump according to claim 2 , wherein fluid-tight couplings are provided between each pump step in the pump sections so that the inner casings are fluid-tight.