Well pump device

This invention relates to a well pump in particular for use in a well in connection with the recovery of hydrocarbons.

In recent years the development in the drilling technology for the recovery of petroleum has steadily moved in the direction of more deviation drilling, which means that from a drilling station wells can be drilled to petroleum deposits located at a considerable horizontal distance from the drilling station.

Such drilling involves that the pipe angle in the well strongly deviates from the vertical direction. In some cases the well may be approximately horizontal.

It is often necessary to place a pump in the well in order to increase the pressure or pump fluid up. Conventionally, the pumps have been positioned by being lowered into the well by means of gravity in order then to be pulled back up by means of a line or similar attached to the pump. The pump delivers the fluid through a connected pressure pipe or hose. In wells that have a large angular deviation relative to the vertical axis, the pump must be pushed forward to its predetermined position in the well. This may be accomplished by the use of a so-called drive plug. The drive plug is a device adapted for transporting equipment internally in pipes. It may be provided with seals that seal against the inner wall of the pipe, and is, in that case, pushed back and forth within the pipe by means of the pressure difference in the pipe. Another type of drive plug is provided with driven wheels or belts, which carry the plug in the desired direction through contact with the pipe wall.

Drive plugs based on propulsion by means of differential pressure normally have the greatest pull-thrust-force, and are therefore often used when relatively large loads are to be transported.

The use of such plugs, which must be pulled out of the well after the pump has been installed, represents a great risk of damage to the power and instrument cable of the well pump. To position an often long pressure pipe from the pump up to the surface is expensive and labour-intensive.

The object of the invention is to remedy the drawbacks of known techniques/devices that make use of a drive plug and a separate pressure pipe/hose.

The object is realized according to the invention through the features specified in the description below.

An electrically or hydraulically operated pump of a kind known in itself, comprising a motor, a suction screen/inlet, a pump housing, one or more pump stages, outlet and connected cables or pipes/hoses for the supply of energy and control, is provided with an external seal which seals against the internal wall of the pipe. The pump is provided with centralizing devices, which keep the pump centred in the pipe. The pump may further be provided with a valve/blocking device which may shut off the flow of fluid through the pump.

When the pump is to be used, it is inserted into the well pipe in the same way as a differential pressure drive plug. Because the passage through the pump is closed and the external seal is sealing against the wall of the well pipe, fluid cannot get past the pump.

The position of the pump in the well can be determined by, for example, previously mounted stops or a seat in the well pipe, or in that the pump is retained by a line or reinforced cable/hose attached to the pump.

After the passage has been opened and the pump started, the pump delivers fluid from one side of the pump to the other side, thus using the well pipe as a pressure pipe. The external seal against the wall of the well pipe prevents the fluid from returning past the pump.

A development of the pump may be to adapt it for use in tanks and other containers to which access is difficult, but where there are premounted access pipes or similar.

In the following a non-limiting example of a preferred embodiment is described, and it is visualized in the accompanying drawings, in which:

FIG. 1 shows, partly in section, the pump mounted in a well pipe;

FIG. 2 shows a section through the pump and the well pipe at the centralizing devices.

In FIG. 1 the reference numeral 1 identifies an electrically or hydraulically driven pump comprising a motor 2 , a suction screen/inlet 3 , a pump housing 4 , which may be provided with one or more pump stages not shown, an outlet 5 and an attachment bearing 6 for connected cables or pipes/hoses 7 for the supply of energy and control of the pump. The pump 1 is provided with an external seal 8 , which seals against the internal wall surface of a well pipe 10 , and a centralizing device 9 , which keeps the pump centred within the pipe. The centralizing device may comprise three or more resilient bows secured to the motor housing 2 and arranged to press resiliently against the internal wall of the pipe 10 . The pump 1 may further be provided with a valve 11 or a blocking device of a kind known in the art, which may shut off the flow of fluid through the pump 1 .

When the pump 1 is to be used, it is inserted into the well pipe 10 . The internal valve 11 is closed, thereby sealing against fluid passage through the pump housing 4 . The external seal 8 seals against the internal surface of the well pipe 10 . The pump 1 thus seals against the well pipe 10 in the same way as a drive plug and may be carried forward to the desired position in the well by means of differential pressure within the pipe.

The position of the pump 1 in the well pipe 10 may be predetermined, for example by a previously installed (not shown) stop in the well pipe 10 , or in that the pump 1 is retained by a line or reinforced cable/hose 7 attached to the pump 1 in the attachment bearing 6 .

Energy is supplied to the motor 2 through the cable/hose 7 . When the valve 11 , which may be a butterfly valve, and which may close to fluid flow through the pump, is opened, for example in that the current for the motor 2 is also connected to the valve 11 , and the motor 2 is started, fluid will enter through the annular gap 12 which is formed between the well pipe 10 and the motor 2 , through the suction screen/inlet 3 and further to not shown pump stages in the pump housing 4 . From the pump housing 4 the fluid exits through the outlet 5 into the well pipe 10 on the pressure side of the pump 1 and further through the well pipe 10 . The fluid on the pressure side of the pump 1 is prevented from returning between the pipe 10 and the pump 1 by the seal 8 .

A device according to the invention remedies the main drawbacks of conventional equipment in that it eliminates the need both for a separate drive plug to be used to position the pump, and for a separate pressure pipe to be used for the transport of the fluid out of the well pipe.