Turbine for generating power in a fluid stream

Abstract

 A turbine for generating power in a fluid stream comprises a tubular housing (1) in which a tubular turbine blade carrier body (2) is supported by a bearing assembly (3). One or more turbine blades (4A-D) protrude from an inner surface of the tubular carrier body. The turbine blades (4A-D) have free tips that surround a central opening (5), which provides a passage for equipment and inhibits accumulation of debris and fouling between the turbine blades (4A-D). The turbine is suitable for generating electrical power in wells or pipelines.

Description

BACKGROUND OF THE INVENTION

[0001] The invention relates to a turbine for generating power in a fluid stream.

[0002] It is generally known to use turbines in jet engines or electrical power generating plants.

[0003] The known turbines comprise turbine blades that are mounted on a central shaft which is rotatably supported in a tubular turbine housing, such that blades rotate the shaft when fluid flows through the housing.

[0004] International patent application WO 93/04288 discloses a contra-rotating turbine, wherein turbine blades are mounted in an annular space between a pair of contra-rotating sleeves, such that swirling of the fluid stream is inhibited. The sleeves are mounted on contra rotating shafts that protrude from opposite sides of the turbine housing and that are supported by bearing assemblies which permit rotation of the shafts relative to the housing.

[0005] US patent 5,839,508 discloses a turbine for generating electrical power downhole in an oil and/or gas production well. The known turbine and associated electrical generator assembly do not allow passage of equipment, like logging tools or well robots or wireline operated well inspection, maintenance of fishing tools. Therefore, the known assembly is mounted in a side pocket of the production tubing, so that equipment can be lowered into the well below the assembly via the remaining part of the production tubing. Installation of the assembly in a side pocket requires a complex installation and retrieval procedure and restricts the available width of the assembly, such that the turbine has only a small diameter housing and a relatively small power output. The small diameter of the housing and small gaps between the turbine blades also make the turbine vulnerable to fouling and reduces the period during which the turbine and associated electrical generator can be deployed before requiring inspection or replacement.

[0006] It is an object of the present invention to provide a turbine for generating power in a fluid stream, which permits passage of equipment through the interior of the turbine.

[0007] It is a further object of the present invention to provide a turbine for generating power in a fluid stream, which is less vulnerable to fouling than the known turbines.

SUMMARY OF THE INVENTION

[0008] The turbine according to the invention comprises one or more turbine blades that are mounted on a carrier body which is supported by a bearing assembly such that the carrier body is rotatable within a turbine housing, wherein the carrier body has a tubular shape, the bearing is arranged within an annular space between the tubular carrier body and the turbine housing, the turbine blades protrude from an inner surface of the tubular carrier body and the turbine blades have free tips, which surround a central opening, which is substantially co-axial to a central axis of the tubular carrier body.

[0009] This central opening may provide a passage for movable equipment, such as a well or pipeline robot or wireline retrievable tool, such as a logging sonde, or a well or pipeline cleaning or inspection tool.

[0010] The turbine may be connected to an electrical power generator and provide a downhole power generating assembly for use within an oil and/or gas production well.

[0011] In such case the turbine and electrical power generating assembly may be provided with latch means for retrievably mounting the assembly within a production tubing of an oil and/or gas production well and with electrical contacts that are configured for connecting the assembly to electrical monitoring and/or control equipment, such as a downhole valve and/or a flow, pressure, fluid composition or other sensors.

[0012] These and other features, advantages and embodiments of the turbine according to the invention will be apparent from the accompanying claims, abstract and detailed description with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

[0013] 

Fig.1 depicts a schematic cross-sectional view of a turbine according to the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0014] Fig.1 shows a turbine according to the invention, which comprises a tubular turbine housing 1 in which a tubular blade carrier body 2 is supported by a ball bearing assembly 3. A set of four turbine blades 4A-4D is mounted on the inner surface of the tubular carrier body 2. The turbine blades 4A-4D have a helical shape and free tips which are arranged around a central opening 5, which is substantially co-axial to a central axis 6 of the turbine. The central axis 6 also forms the axis of rotation of the carrier body 2 and turbine blades 4A-4D.

[0015] The central opening 5 provides a passage through which equipment, such as a well robot or a wireline conveyed tool, such as a logging tool or well inspection or fishing tool can be lowered and raised. The central opening 5 also provides a passage for debris and inhibits coarse debris or fouling to be trapped in the flow passages formed between the turbine blades 4A-4D. A cleaning tool such as a cleaning pig or chimney-sweep like bristle assembly may be moved up and down through the central opening 5 to clean the turbine blades 4A-4D and inner surface of the tubular carrier body 2 so that wax, pariffinic and scale deposition can be easily removed therefrom without retrieving the turbine to surface.

[0016] A series of magnetic strips (not shown) may be embedded in the outer surface of the carrier body 2 and a toroidally coiled copper wire assembly may be embedded in a recess in the inner surface of the tubular housing 1, such that rotation of the carrier body 2 generates electrical power in the coiled copper wire assembly. The thus generated electrical power may be used as a downhole electrical power source for providing electrical power to downhole equipment, such as a downhole valve, downhole flow, pressure, temperature or fluid composition sensors and/or other downhole electrical equipment.

[0017] The outer surface of the turbine housing 1 may be provided with expanding locking pins or rings (not shown) for retrievably securing the turbine housing 1 within a production tubing of an oil and/or gas production well. Since well equipment can be lowered through the central opening 5, the turbine according to the invention can be installed within the production tubing itself by a wireline tool or well robot and there is no requirement to install the turbine in a small diameter side pocket, so that the turbine can be installated and retrieved easily, without complex downhole manipulation.

Claims

1. A turbine for generating power in a fluid stream, the turbine comprising one or more turbine blades that are mounted on a carrier body which is supported by a bearing assembly such that the carrier body is rotatable within a turbine housing, wherein the carrier body has a tubular shape, the bearing is arranged within an annular space between the tubular carrier body and the turbine housing, the turbine blades protrude from an inner surface of the tubular carrier body and the turbine blades have free tips which surround a central opening which is substantially co-axial to a central axis of the tubular carrier body.

2. The turbine of claim 1, wherein the central opening provides a passage for movable equipment, such as a well or pipeline robot, or a wireline retrievable tool, such as a logging sonde or a well or pipeline cleaning or inspection tool.

3. The turbine of claim 1, wherein the turbine is connected to an electrical power generator.

4. The turbine of claim 3, wherein the turbine and electrical power generator are configured for use as a downhole power generating assembly for use within an oil and/or gas production well.

5. The turbine of claim 4, wherein the turbine and electrical power generating assembly are provided with latch means for retrievably mounting the assembly within a production tubing of an oil and/or gas production well and with electrical contacts that are configured for connecting the assembly to electrical monitoring and/or control equipment.

6. The turbine of claim 5, wherein the downhole electrical monitoring and/or control equipment comprises a downhole valve and/or a flow, pressure, fluid composition or other sensor.

7. The turbine of claim 5, wherein the central opening provides a passage for movable well equipment, such as a well robot or wireline retrievable tool, such as a logging sonde or a well cleaning or fishing tool.

8. The turbine of any preceding claim, wherein the turbine blades have an elongate helical shape.

Drawing