Patent Description:
Systems and assemblies for inspecting internal spaces such as interior walls of pipelines or similar are known. When these systems are used downhole, for example in offshore environments, an inspection assembly comprising a source of illumination and a camera are lowered through the pipeline or conduit and the camera is configured to capture images of the internal surfaces of the pipeline. In this way the inspection system may be used to visualise the condition of the pipeline to determine if remedial action is required.

In some of these inspection systems the camera is located in a nose region of the assembly and is forward facing. In this way, the camera is able to capture images of the interior of the pipeline ahead of the inspection assembly as it is lowered or moved through the pipeline.

In order to provide even illumination of the field of view of the camera, the light sources are often located behind the camera lens and are angled in a direction towards the internal wall of the pipeline ahead of the inspection assembly. In this way the walls of the pipeline are illuminated at a distance from the front of the inspection assembly.

In some systems it is desirable to use a wide angle lens, such as a fish-eye lens.

When existing systems are retrofitted with such a wide angle lens, however, the configuration of the light sources is such that there is inadequate illumination of the entire field of view. In particular the periphery of the image tends to be under exposed and the central portion of the image tends to be over exposed.

It is, therefore, an object of the present invention to provide an improved illumination system that may be used, in particular, with camera systems incorporating a wide angle lens.

Conventional systems are known in <CIT>, <CIT>, <CIT>, <CIT>, or <CIT>.

According to a first aspect of the present invention there is provided an inspection assembly as defined in independent claim <NUM>.

The location of the reflection surface, therefore, causes a part of the light beam from the light source to be deflected such that an angle between the direction of travel of the deflected light beam and the longitudinal axis is greater than the angle between the direction of travel of the non-deflected light beam and the longitudinal axis.

When the inspection assembly is located in a pipeline or conduit, the fraction of the emitted light that is deflected or reflected, therefore, illuminates a region of the interior walls of the pipeline closer to the inspection assembly. This creates a more even illumination of the field of view when a wide angle lens is used in the inspection assembly.

In preferred embodiments the angle between the reflection surface and the longitudinal axis of the main body is between <NUM>° and <NUM>°.

In order to still provide adequate illumination of the central region of the field of view, however, it is preferable if the first fraction is less than <NUM>% of the emitted light.

In preferred embodiments of the inspection assembly a plurality of light sources is arranged around the main body and positioned radially outward of the lens. Furthermore, in particularly preferred embodiments an annular reflection surface extends around the main body. In this way, even illumination may be provided around the complete periphery of the field of view.

The inspection assembly of the present invention has particular advantages when the lens is a wide angle lens. In some embodiments the lens may be a fish-eye lens. In these embodiments the reflected light illuminates the periphery of the field of view while the emitted light that is not reflected illuminates central regions of the field of view.

To protect the lens from the environment of the pipeline a transparent window or cap is positioned to extend over the lens. The window is dome-shaped. In these assemblies, the reflection surface is located such that the first fraction of the emitted light is reflected in a direction substantially away from the window. As such, the likelihood of light directly entering the window and being internally reflected or refracted is significantly reduced.

The reflection surface is preferably an unpolished surface of the collar.

The reflection surface is preferably configured to cause diffuse reflection of the emitted light striking the reflection surface. This creates more even illumination of the field of view of the lens and allows the reflected light to illuminate a greater area. The inspection assembly preferably further comprises an image sensor arranged to capture an image of a field of view through the lens. The inspection assembly may additionally include a memory for storing the captured image data or a transmitter for transmitting the image data to a remote receiver in real time.

According to a second aspect of the present invention there is provided a method of inspecting a wellbore as defined in independent claim <NUM>.

The invention will now be further described by way of example only and with reference to the accompanying drawings, in which:.

Inspection assemblies or camera systems used to inspect passageways such as pipelines and wellbores typically include a camera and one or more light sources arranged to light the field of view of the camera. Typically these are housed in a first, distal end region of an elongate cylindrical housing which is lowered down the wellbore by cables or a shaft attached at a second end. In most cases, the camera systems will also include a viewport or window at or near the distal end of the camera housing that serves to protect the camera.

In use, when an inspection assembly is deployed along a passageway, the distal end of the assembly will be a front end with respect to a direction of travel of the assembly. Accordingly, in the following description the terms front end, forward facing or similar will be used to describe or refer to elements that are located at or near the first, distal end of the assembly or that face in a direction towards the distal end. Similarly, the terms rear end, rearward facing or similar denote elements that are located at or near the second, proximal end of the assembly or that face in a direction towards the second end.

A preferred embodiment of an inspection assembly <NUM> according to the present invention is illustrated in <FIG>. The inspection assembly <NUM> includes an elongate main body <NUM> having a first, distal end <NUM> and a second, proximal end <NUM>. The first and second ends <NUM>, <NUM> define a longitudinal axis <NUM> of the inspection assembly <NUM>.

An end region <NUM> of the main body <NUM> at the distal end <NUM> comprises a light emitting portion <NUM>, a light guide portion <NUM> and a nose portion <NUM>. The nose portion <NUM> includes a distal end face <NUM> of the main body <NUM>. The end region <NUM> is generally tapered such that an external diameter of the main body <NUM> at the light emitting portion <NUM> is greater than the external diameter of the nose portion <NUM>.

A decrease in diameter of the light emitting portion <NUM> creates a shoulder <NUM> having a generally forward facing surface <NUM>. A plurality of apertures <NUM> are formed in the shoulder <NUM>. The apertures <NUM> are sealed by transparent windows or viewports <NUM>. The apertures <NUM> are preferably in a substantially circular or annular arrangement around the shoulder <NUM>.

A bore <NUM> extends longitudinally through the end region <NUM> and terminates at an aperture <NUM> in the distal end face <NUM>. A lens <NUM> is mounted in the aperture <NUM>. The lens <NUM> is an ultra wide angle lens such as a fish-eye lens. The fish-eye lens will typically have an angle of view (α) of about <NUM>°, compared to a standard lens having an angle of view (β) of about <NUM>°, as illustrated in <FIG>. In this embodiment, including a fish-eye lens <NUM>, a part of the lens <NUM> projects forward of the distal end face <NUM> so that the angle of view or field of view is not obstructed by the end face <NUM> of the main body <NUM>.

The inspection assembly <NUM> further comprises a camera including an image sensor arranged to capture an image of the field of view through the lens <NUM>. Accordingly, the camera captures an image of a region substantially ahead or in front of the distal end <NUM> of the inspection assembly <NUM>. It will be appreciated that when an ultra wide angle lens <NUM> is used, having an angle of view of greater than <NUM>°, the periphery of the image may include a region located substantially parallel with or a small distance behind the distal end face <NUM> of the inspection assembly <NUM>.

To protect the lens <NUM>, the inspection assembly <NUM> includes a cap <NUM>, shown most clearly in <FIG>. The cap <NUM> comprises a hemi-spherical or dome-shaped window portion <NUM> and a tubular attachment portion <NUM>. At least the window portion <NUM> is optically transparent. Typically the cap <NUM> will be a unitary piece such that both the window portion and the attachment portion are made of the same transparent material. Preferably the cap <NUM> is made of a suitable acrylic material.

The attachment portion <NUM> includes a female securing feature in the form of a screw thread <NUM> on an internal surface <NUM> of the attachment portion <NUM>. A corresponding male securing feature in the form of a screw thread <NUM> is provided on an external surface <NUM> of the nose portion <NUM> of the main body <NUM>. The cap <NUM> is, therefore, secured to the main body <NUM> by engaging the complementary screw threads <NUM>, <NUM>. Once engaged, the attachment portion <NUM> of the cap <NUM> extends around the nose portion <NUM> of the main body <NUM>. Sealing elements such as o-rings <NUM> may be provided to form a seal between the external surface <NUM> of the nose portion <NUM> and the internal surface <NUM> of the cap <NUM>.

With the cap <NUM> secured to the main body <NUM> the window portion <NUM> extends beyond the distal end face <NUM> of the nose portion <NUM>. In particular the domed window portion <NUM> extends over the lens <NUM> such that there is a gap <NUM> between a front face <NUM> of the lens <NUM> and the internal surface <NUM> of the window portion <NUM> of the cap <NUM>.

The inspection assembly <NUM> further comprises a plurality of light sources <NUM> mounted in the light emitting portion <NUM> of the main body <NUM>. The light sources <NUM> are preferably light emitting diodes (LEDs). Each of the light sources <NUM> is arranged to emit a beam of light through a corresponding one of the apertures <NUM>. As such, the light sources <NUM> are substantially forward facing and the light emitted by the light sources <NUM> travels in a direction that illuminates an area ahead of or in front of the distal end <NUM> of the inspection assembly <NUM>.

The light guide portion <NUM> of the end region <NUM> comprises a plurality of radially extending webs or ribs <NUM>. Light guide channels are defined between neighbouring ribs <NUM>. Each channel is aligned with one of the apertures <NUM>.

As shown in <FIG>, each light source <NUM> emits a diverging beam of light <NUM>. A direction of the emitted light is defined by a centre line <NUM> of the light beam <NUM>. The beam divergence angle is preferably between <NUM>° and <NUM>°, and most preferably about <NUM>°.

A reflection collar <NUM> is located over and around the attachment portion <NUM> of the cap <NUM>. As shown in <FIG>, the collar <NUM> comprises a sleeve portion <NUM> and retaining means in the form of a retaining flange <NUM>. The sleeve portion <NUM> is substantially tubular and extends between first and second ends <NUM>, <NUM>. A bore <NUM> of the sleeve portion <NUM> extends along an axis <NUM> of the collar <NUM>. The retaining flange <NUM> projects radially inwardly from the second end <NUM> of the sleeve portion <NUM>.

In a preferred embodiment the collar <NUM> has a circular cross-sectional shape. An internal diameter of the sleeve portion <NUM> is constant along the length of the sleeve portion <NUM> and is sized to receive the attachment portion <NUM> of the cap <NUM>. An external surface <NUM> of the collar <NUM> at the first end <NUM> is tapered.

The external surface <NUM> of the collar <NUM> is also tapered at the second end <NUM>. This tapered portion of the surface <NUM> provides a reflection surface <NUM>. An angle between the reflection surface <NUM> and the axis <NUM> of the collar <NUM> is preferably greater than <NUM>° and less than <NUM>°. The angle between the reflection surface <NUM> and the axis <NUM> may be more than <NUM>° or more than <NUM>°. The angle between the reflection surface <NUM> and the axis <NUM> may be less than <NUM>°, less than <NUM>° or less than <NUM>°. Most preferably the angle is between <NUM>° and <NUM>° and will typically be about <NUM>°.

The collar <NUM> is made from a metallic material, and will typically be made from a suitable grade of stainless steel. The reflection surface <NUM> is preferably unpolished. This causes the light that is reflected from the surface <NUM> to be diffused, as illustrated in <FIG>.

To attach the reflection collar <NUM> to the main body <NUM> of the inspection assembly <NUM>, the collar <NUM> is fitted over the nose portion <NUM> of the main body <NUM> with the second end <NUM> of the collar <NUM> nearest the light sources <NUM>. The collar <NUM> is prevented from moving further along the end region <NUM> of the main body <NUM> by an abutment surface <NUM> of the main body <NUM>.

The reflection surface <NUM> of the collar <NUM> is, therefore, located between the light sources <NUM> and the lens <NUM> in a longitudinal direction. The reflection surface <NUM> is substantially rear facing so that a fraction of the light that is emitted by the light sources <NUM> is incident on the reflection surface <NUM>.

The cap <NUM> is screwed onto the nose portion <NUM> of the main body <NUM> such that the attachment portion <NUM> is located between the sleeve portion <NUM> of the collar <NUM> and the nose portion <NUM>. The cap <NUM> is screwed onto the nose portion <NUM> until an end <NUM> of the attachment portion <NUM> contacts the flange <NUM> of the collar <NUM> and the flange <NUM> of the collar <NUM> is in contact with the abutment surface <NUM>. In this way, with the collar <NUM> and cap <NUM> fully attached to the main body <NUM>, the flange <NUM> is clamped between the abutment surface <NUM> of the main body <NUM> and the end <NUM> of the cap <NUM>, thereby retaining the collar <NUM> on the main body <NUM>. Furthermore, in this position the flange <NUM> extends over and covers the end <NUM> of the cap <NUM>. In this way, the flange <NUM> blocks light emitted by the light sources <NUM> that would otherwise be incident on the end <NUM> of the cap <NUM>.

The length of the collar <NUM>, between the first and second ends <NUM>, <NUM>, is such that the first end <NUM> of the collar <NUM> does not extend beyond the front face <NUM> of the lens <NUM>. In this way the collar <NUM> does not block the field of view of the lens <NUM>. The collar <NUM> does, however, fully surround at least a part of the attachment portion <NUM> of the cap <NUM> thereby protecting this part of the cap <NUM> from damage.

The light sources <NUM> are arranged such that the centre lines <NUM> of the light beams <NUM> fall on a circle having a diameter greater than the external diameter of the collar <NUM>. In this way, at least <NUM>% of the light emitted by the light sources <NUM> passes around the collar <NUM> without being reflected or deflected by the reflection surface <NUM>.

A fraction of the light emitted by each of the light sources <NUM> is incident on the reflection surface <NUM>. The angle of the reflection surface <NUM> causes the light to be reflected in a direction away from the axis <NUM> of the inspection assembly <NUM>. In particular, a fraction of the light beam <NUM> located between the main body <NUM> of the inspection assembly <NUM> and the centre line <NUM> of the light beam <NUM> is reflected by the reflection surface <NUM>.

This is illustrated in <FIG> which shows the illumination pattern resulting from an annular arrangement of five light sources emitting divergent beams of light <NUM>. The centre line <NUM> of each of the beams of light <NUM> lies on a circle <NUM> having a diameter greater than the external diameter <NUM> of the collar. The central shaded region <NUM> in <FIG> denotes the part of each of the light beams <NUM> that is incident on a part of the inspection assembly <NUM> and does not reach the field of view of the lens <NUM>. The hatched region <NUM> denotes the fraction of each of the light beams <NUM> that strikes the reflection surface <NUM> and is reflected outwardly to a peripheral region of the field of view.

It can be seen that the result of reflecting a radially inner portion <NUM> of each of the light beams <NUM> is that the overall intensity of the light in a central region of the field of view is decreased while the overall intensity of the light in a peripheral region of the field of view is increased. In this way the field of view is more evenly illuminated decreasing the likelihood that regions of an image captured by the camera will be underexposed or overexposed.

In other embodiments the light sources may be arranged such that centre lines <NUM> of light beams <NUM> emitted by the light sources fall on a circle having a diameter smaller than the external diameter of the collar. This is illustrated in <FIG> which shows the illumination pattern resulting from an annular arrangement of five light sources emitting divergent beams of light <NUM>. The centre line <NUM> of each of the beams of light <NUM> lies on a circle <NUM> having a diameter smaller than the external diameter <NUM> of the collar. The central shaded region <NUM> in <FIG> denotes the part of each of the light beams <NUM> that is incident on a part of the inspection assembly <NUM> and does not reach the field of view of the lens <NUM>. The hatched region <NUM> denotes the fraction of each of the light beams <NUM> that strikes the reflection surface <NUM> and is reflected outwardly to a peripheral region of the field of view. In some of these embodiments at least <NUM>% of the light emitted by the light sources <NUM> passes around the collar <NUM> without being reflected or deflected by the reflection surface <NUM>. In one particular embodiment the diameter of the circle <NUM> on which the centre line <NUM> of each of the beams of light <NUM> lies is approximately <NUM> and the external diameter <NUM> of the collar is approximately <NUM>.

It will be appreciated that the reflection surface <NUM> has been described as being part of a reflection collar <NUM> that is separate from the main body <NUM> of the inspection assembly <NUM>.

Furthermore, in some embodiments, the collar <NUM> may be attached or secured directly to the main body <NUM> rather than being secured by means of the cap <NUM> as described above. Accordingly, in these embodiments the collar <NUM> may include means for securing the collar <NUM> to the main body <NUM>, for example by means of screw threads.

It will be appreciated that it is also possible to create a more even illumination of the field of view of a lens of an inspection assembly by providing a different arrangement of light sources or by changing the pattern of light emission from the inspection assembly, compared to known camera systems.

An inspection assembly may, for example, include a first, substantially forward-facing light source or set of light sources and a second, substantially outwardly facing light source or set of light sources. In these assemblies, the first set of light sources may be oriented such that the centre line of each of the beams of light, from the first set of light sources, is at an angle of between <NUM>° and <NUM>° to the longitudinal axis of the assembly. The second set of light sources may be oriented such that the centre line of each of the beams of light, from the second set of light sources, is at an angle of between <NUM>° and <NUM>° to the longitudinal axis of the assembly and is at a greater angle than the centre lines of the first set of light sources. In this way, the second set of light sources will illuminate a peripheral region of the field of view which is only weakly illuminated or not illuminated by the first set of light sources.

In other embodiments of the inspection assembly two light sources or two sets of light sources may be provided spaced apart longitudinally along the main body of the inspection assembly. In these embodiments the angle between the centre line of each of the beams of light, from all of the light sources, and the longitudinal axis of the main body of the inspection assembly may be the same. The light source or set of lights sources further from the distal end of the main body will, however, illuminate a peripheral region of the field of view which is more weakly illuminated by the light source or set of light sources nearer the distal end.

In other embodiments only one light source or one set of lights sources may be provided; however, the light source(s) may be arranged to emit light into an end of a suitable light guide or light pipe that conveys the light to one or more windows through which the light is emitted from the inspection assembly. The light guide may comprise two or more optical fibres, a first optical fibre being arranged to emit light predominantly in a first direction from the inspection assembly and a second optical fibre being arranged to emit light predominantly in a second direction from the inspection assembly. Alternatively the inspection assembly may comprise a light pipe including a first branch and a second branch. The first branch may be arranged to emit light from the inspection assembly predominantly in a first direction and the second branch may be arranged to emit light from the inspection assembly predominantly in a second direction. In these embodiments the predominant direction of the emitted light is defined by the direction of the centre line of the beam of emitted light.

Claim 1:
An inspection assembly comprising:
- a main body (<NUM>) having a longitudinal axis (<NUM>) and a distal end (<NUM>);
- an ultra wide angle lens (<NUM>) located at the distal end, said lens having an angle of view of greater than <NUM>°;
- a light source (<NUM>) positioned rearward of the lens (<NUM>) to illuminate an area to be viewed beyond the distal end (<NUM>) of the main body (<NUM>); and
- a metal collar (<NUM>) including a reflection surface (<NUM>) and a flange (<NUM>), the reflection surface (<NUM>) being located at a distance along the longitudinal axis (<NUM>) between the lens (<NUM>) and the light source (<NUM>), an angle between the reflection surface (<NUM>) and the longitudinal axis (<NUM>) of the main body (<NUM>) being between <NUM>° and <NUM>°,
wherein the metal collar (<NUM>) is a separate collar attached to the main body (<NUM>) of the assembly, and the reflection surface (<NUM>) is positioned such that, in use, a first fraction of the light emitted by the light source (<NUM>) is reflected by the reflection surface (<NUM>) before illuminating a periphery of the field of view of said lens (<NUM>) and a second fraction of the light emitted by the light source (<NUM>) travels to the field of view of said lens (<NUM>) without being reflected by the reflection surface (<NUM>), and
characterised in that the inspection assembly comprises a cap (<NUM>) including an optically transparent dome-shaped window portion (<NUM>) and an attachment portion (<NUM>), said window portion extending beyond a distal end face of the main body (<NUM>) and extending over the lens (<NUM>) and the attachment portion (<NUM>) being engaged with the main body (<NUM>) to secure the cap (<NUM>) at the distal end (<NUM>) of the main body (<NUM>) and clamp the flange (<NUM>) of the collar (<NUM>) between an abutment surface (<NUM>) of the main body (<NUM>) and an end (<NUM>) of the cap (<NUM>) such that a part of the metal collar (<NUM>) is located around the attachment portion (<NUM>) of the cap (<NUM>) and the flange (<NUM>) extends over and covers the end (<NUM>) of the cap (<NUM>) to block light emitted by the light source (<NUM>) that would otherwise be incident on the end (<NUM>) of the cap (<NUM>).