NO20150394A1 - Method for monitoring position and movements of a riser - Google Patents

Abstract

The invention is a method of monitoring a riser for detecting the position and movement of the riser. The method is characterized by placing at least a first reference mark on the riser and filming said reference mark with a camera connected to a video processor. The recorded pictures are interpreted in the video processor for detecting position and movement of the riser.

Description

Introduction

The invention relates to monitoring of a riser. More specifically the invention comprises a method for detecting position and movement of a riser.

Background

A riser is generally a vertically section of piping or cable used for connecting topside equipment to seabed equipment. There are different types of risers serving different purposes. One purpose is to convey fluids like oil and gas. Another purpose is to carry signals and power. Such risers are called umbilicals. There are also risers carrying signals, power and fluids. A riser can also be used as a conduit for transporting tools to and from equipment located at each end of a riser.

Depending on the purpose, risers can be rigid or flexible. There are also risers combining these properties making a hybrid flexible riser.

A marine drilling riser is an example of a rigid type of riser used for providing an extension from a floating drilling vessel to a subsea well.

Upper and lower fl ex joints (UFJ, LFJ) are typically used for connecting an upper end and a lower end of a riser to topside and subsea equipment. Flex joints are flexible joints that are used for reducing the bending moment of force in a marine riser and a subsea well.

Large flex joint angles may damage equipment going through the flex joints, in addition to putting excessive stress on the subsea well. It is desirable to monitor movements of a riser for avoiding overstressing these components.

There are some prior art describing methods for monitoring a riser. These do however use other methods and means for performing monitoring.

US 7,328,741 B2 describes a system for sensing riser motion. A riser measurement instrument module is connected to a riser. The instruments module is relatively complex and comprises sensors for detecting acceleration and orientation. The module is provided with a data communication line and is electrically connected to equipment for processing data. These are all exposed to being physical damaged due to riser movements.

There is a need for a method and system for monitoring a riser without connecting sensors and measuring instruments to the riser and exposing them to damage.

The present invention is a cost efficient solution with a very low physical footprint that is not exposed to damage.

Short description

The present invention is defined by a method for monitoring a riser for detecting position and movement of the riser. The method comprises placing at least a first reference mark on the riser, filming said reference mark with a camera, and interpreting recorded pictures in a video processor for detecting position and movement of the riser.

Further features of the invention are defined in the claims.

Detailed description of the invention

The invention will now be described in detail with reference to the drawings illustration different embodiments: Figure 1 shows a configuration for detecting movements in an upper flex joint; Figure 2 shows a configuration for detecting movements in a lower flex joint;

Figure 3 shows a configuration for detecting movements of a telescopic joint.

The present invention is defined by a method and system for monitoring a riser for detecting its position and movement. This is performed without physically connecting sensors or measuring equipment to the riser as is known from prior art.

The method according to the invention is placing at least a first reference mark on a riser and filming said reference mark with a camera.

The camera used can be a generic video camera. Depending on the application other types of cameras may be used for monitoring tracking marks, e.g. high speed cameras.

If monitoring is to be performed at night or in dim lit surroundings, an IR camera can be used. This type of camera may also act as a backup camera for a conventional video camera. The different types of cameras may record one or more reference marks from the same place, or they may record reference marks from different places.

The reference marks are flat shaped tags with an imprinted pattern that easily can be detected and recognized in the video processor. A reference mark can be fixed to the riser with glue, or the reference mark may be a magnetic sticker. The reference mark may also be painted directly onto the riser. Each reference mark leaves a minimal footprint and will not disturb different riser operations.

Using only one reference mark will enable the invention and make it possible to monitor and detect position and rotation of a riser in all 6 degree of freedom. In one embodiment two or three reference marks may be placed on a riser. They can then be spaced apart to a certain degree as long as they all are in the focal view of the camera. Using more that one reference mark on the riser may improve the sensitivity when detecting small movements.

The camera filming the reference mark(s) is connected to a part of a construction, e.g. a platform, such that free view to the reference mark on the riser is obtained, and such that the riser and the camera move independently of each other. This will ensure that riser movements will be detected. If it is difficult to obtain free view in a specific setup and installation, more than one reference mark should be used for increasing the chances for detecting riser movements. The reference marks may then be placed on different sides of the riser and at different locations along the riser. More than one camera may then be uses for monitoring different reference marks. As mentioned more that one camera can be uses for filming reference marks. These may be placed at different locations and be of different types.

Recorded pictures are interpreted in a video processor and position and rotation of the riser is detected. A camera can be directly connected to the video processor, or video form a camera can be transmitted and being processed in a video processor placed elsewhere. The video processor recognises the marker in the video frame, and calculates its orientation and position. Signal processing is used to ensure stable performance and to remove high frequency vibrations and false readings.

Augmented reality may be used for presenting an image of the riser integrated with motion and angle data. This will provide an optimal visualization of riser position and movements for an operator.

In one embodiment of the invention at least a second reference mark is placed in the proximity of the riser, i.e. not placed on the riser itself. This is preferably a device connected to the riser. This configuration will make it possible to determine movements between the riser and said device as well as the angle between the riser and the device.

The video processor comprises tracking software for monitoring and tracking the angle between the first and the second reference marks.

Figure 1 shows one example of an embodiment of the present invention with a configuration made for detecting movements between a riser and a device which is an Upper Flex Joint connected to the upper end of the riser. The first reference mark is placed on the riser close to the upper flex joint, and the second reference mark is placed on the upper flex joint itself. A camera recording the reference marks will provide a connected video processor with image data. The size of a marker is an input value for the software in the video processor. This value is used for scaling the measurements and the angle between the different reference marks will be calculated.

Based on said measured angle, the degree of bending of the upper joint can be determined. Ideally the angle is as small as possible. If the degree of bending exceeds a limit, a notification or warning may be given to an operator indicating that equipment and tools going through the flex joint may be damaged.

Figure 2 shows another example of an embodiment of the invention. The configuration and the placing of the reference marks are similar as in the first example shown in Figure 1, but this time the riser is connected to a lower flex joint above a blow out preventer (BOP). The first reference mark is placed above the rotation point of the lower flex joint, and the second reference mark is placed below the rotation point of the lower flex joint. The camera used is water proof and placed such that free view to the reference marks is obtained, and it is connected independently of the riser for enabling detection of riser movements.

In one embodiment the camera is comprised in a ROV operating below sea level. When a riser operation is to be performed and monitored, a ROV with camera takes position and focuses on the reference marks below and above the rotation point of the lower flex joint. Monitoring and measuring performed will be similar as described above with reference to Figure 1. The ROV may transmit video to a control room comprising the video processor for detecting position and movement of the riser. The video processor may also be comprised in the ROV and detected position and movement data can be transmitted from the ROV to an operator.

Figure 3 shows yet another embodiment of the invention. This time the method is used on a riser configuration with telescopic joint, monitoring the magnitude of the stroke of the joint. The outer barrel of the joint is suspended with constant tension wires and the inner barrel of the joint is moving with the vessel. At least one reference mark is placed on the outer barrel and the stroke is monitored by filming the reference mark. The camera is connected to a part of a construction, e.g. a platform, such that free view to the reference mark on the riser is obtained, and such that the riser and the camera move independently of each other. Riser motion will be extracted in the video processor connected to the video camera.

The present invention provides a novel and efficient method for monitoring a riser for detecting position and movement of the riser and doing so without connecting cables to the riser and exposing sensors or electronic equipment to damage. Each reference mark provides a minimal footprint and will not disturb different riser operations.

Claims (10)

1. A method for monitoring a riser for detecting position and movement of the riser characherized in: - placing at least a first reference mark on the riser; - filming said reference mark with a camera, and - interpreting recorded pictures in a video processor for detecting position and movement of the riser.

2. The method according to claim 1,characherized in further placing at least a second reference mark on or in the proximity of the riser.

3. The method according to claim 2, characherized in that the first reference mark placed on the riser is placed close to an upper flex joint of the riser, and the second reference mark is placed on the upper flex joint of the riser.

4. The method according to claim 2, characherized in that the first reference mark placed on the riser is placed close to a lower flex joint of the riser, and the second reference mark is placed on the lower flex joint of the riser.

5. The method according to claim 1,characherized in that the first reference mark is placed on an outer barrel of a suspended riser.

6. The method according to claim 1,characherized in that the video processor comprises tracking software for monitoring and tracking the angle between the first and the second reference marks.

7. The method according to claim 1,characherized in that the reference mark is a magnetic sti eker.

8. The method according to claim 1,characherized in that the reference mark is painted directly onto the riser.

9. The method according to claim 1,characherized in that detected position and movement data are presented to an operator controlling riser operations.

10. The method according to claim 9, characherized in that the position and movements data are presented as augmented reality.