Technical Field

The present invention relates to an assembly and a method for measuring properties of an elongate member, and more specifically to wireless monitoring of properties along a hydrocarbon transporting tubular.

Background

The production or exploration of hydrocarbons usually involves the use of tubulars. Hydrocarbons are organic compounds consisting of hydrogen and carbon. Examples of hydrocarbons, which are used as an energy source, are methane, ethane, butane, pentane and hexane, but many other hydrocarbons are used as an energy source or for other industrial purposes. Crude oil includes hydrocarbons and crude oil is commonly produced from reservoirs in geological formations, typically below the seabed. Hydrocarbons are transported to the surface or to a vessel through tubulars such as a riser, a pipeline, a flexible pipe, a coated pipe or an insulated pipe. Insulated pipes are also used onshore, for example at refineries. It is desirable to monitor conditions of the tubular and indirectly conditions of the contents of the tubular. A tubular can extend through water, formations, or complex production systems, and monitoring conditions of the tubular may be challenging at remote locations which are difficult to reach. Pipes can also be used for water injection, chemical lines, umbilicals and other tubulars which do not carry hydrocarbons.

Summary

According to a first aspect of the invention, there is provided an assembly for wireless data transfer along a tubular, wherein the tubular is suitable for transporting hydrocarbons; the assembly comprising a plurality of sensor devices distributed along the longitudinal direction of the tubular, the sensor devices comprising a sensor and a wireless transducer; wherein the distance between adjacent sensor devices is within the communication range of the wireless transducers.

The plurality of sensor devices may be arranged adjacent to an outer surface of a main body of the tubular and underneath a coating, such as a polymer coating The sensor device further comprises a battery and an induction power receiver, wherein the induction power receiver is electrically coupled to the battery and is operable to re-charge the battery. Additionally, an induction power source may be provided external to the tubular and the plurality of sensors.

The assembly may further comprise a sensor interrogator provided external to the tubular and the plurality of sensors.

The wireless transducer can be one of: a Bluetooth, a Bluetooth Low Energy device, Wireless HART mesh, Zigbee or an RFID device. Examples of the tubular are: a riser, a pipeline, a flexible pipe, a coated pipe or an insulated pipe. The sensor may be one or more of: a strain gauge, a moisture sensor, a pressure sensor, a temperature sensor, a corrosive gas sensor, a pH sensor or a hydrocarbon sensor.

A reading unit may further be attached to the tubular adjacent to one of the sensor devices and comprising a wireless communication module for reading said one of the sensor devices and for communicating to a receiver provided at a vessel or platform.

According to a second aspect of the invention there is provided a method of sending and receiving sensor data along a tubular, wherein a plurality of sensor devices are distributed along the longitudinal direction of the tubular, the sensor devices comprising a sensor and a wireless transducer; the method comprising: collecting sensor data, sending the sensor data from a first wireless transducer of a first sensor device of the plurality of sensor devices to an adjacent second wireless transducer of a second sensor device, and forwarding the sensor data from the second wireless transducer to a third wireless transducer, wherein the third wireless transducer is adjacent the second wireless transducer.

The method may further comprise communicating with one of the wireless transducers with a reading device provided external to the tubular. The sensor may further comprise an induction power receiver and a battery, and wherein the method further comprises charging the battery with an external induction power source.

The method may further comprise sending the sensor data from one of the wireless transducers to an external transducer attached to the tubular, and forwarding the sensor data to a receiver provided on a vessel or a platform. Brief Description of the Drawings

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

Figure 1 is a cross section through a tubular illustrating a sensor device and external reader device;

Figure 2 is a schematic drawing showing a vessel, a riser and wireless sensor devices;

Figure 3 is a longitudinal cross section through a tubular illustrating a plurality of sensor devices; and

Figure 4 is a flow diagram of a method.

Detailed Description

The inventors have realised that conditions of a tubular or the contents thereof can be monitored using a series of wireless sensing devices. The wireless devices are not directly connected to each other, but adjacent devices are sufficiently close to be able to communicate via wireless signal transmission. Devices that are not adjacent may or may not be close enough to communicate directly with each other, but will be able to communicate with each other via intermediate devices. The wireless devices therefore form a wireless communication chain without requiring wired connections, which are vulnerable to damage. The wireless devices may also comprise computing devices for processing the sensing data. Each wireless device may have a unique identifier such that once a signal has travelled up a chain of devices the source can still be identified.

Sensor data can travel along the chain of wireless devices and can be picked up with a reading device provided external to the tubular. A subsea reading device may be provided on a remotely operated vehicle, but a reading device can also be provided as a clamped on reader above the water surface near one of the last wireless devices in the chain. The reading device can in turn store the data for further processing later on, or may transmit the data to a receiver at a vessel or platform. The reading device may therefore communicate directly with one of the sensing devices, or may communicate indirectly via other sensing devices in the chain.

The sensor devices can be attached on the outside of the main body of the tubular, but underneath a coating such as a polymer coating. The coating protects the device against environmental conditions and contact with water but can also be used to secure the devices to the tubular.

The wireless devices have a sensor, a wireless transceiver, and may also have a battery and an induction power transmitter for charging the battery. As such, the devices can be encapsulated under the coating without a need to access the device directly, instead providing remote access both for power transfer and data transfer.

More generally, the inventors have appreciated the opportunities provided by instrumentation inside a watertight, or pressure tight, or insulated part of a cable, tubular or other elongate member, and have the reading of the instrumentation and battery available external to the insulated cable.

Examples of wireless communication are Bluetooth, Bluetooth Low Energy device, or RFID. Other wireless standards which may be used are Wireless HART mesh or Zigbee. Each of these wireless technologies are well known as such and the skilled person will be able to implement the technology without a detailed description herein. The communication range of the devices will depend on the wireless technology which is used, and the distance between the wireless sensor devices is selected accordingly. A so-called class 1 Bluetooth device has a typical range of 100 metres and at 100mW power, class 2 has a range of 10 metres at 2.5 mW, while class 3 has a range of less than 10 metres at 1mW. Bluetooth Low Energy requires less power, while maintaining a similar communication range of up to 100m. RFID (Radio-frequency identification) can operate in a similar range of 1 to 100m.

Some examples of sensors to read characteristics of the tubular are now provided. Strain gauges may be used on flexible steel risers, pipelines, or armour wires to measure strain. When strain at one of the gauges exceeds a threshold, this can be communicated through the chain of devices to alert an operator. Moisture sensors may be provided in low points for coated or insulated pipelines. Pressure or temperature sensors may be provided, for example for a flexible riser provided inside an annulus. The pressure or temperature sensors can also be used to infer conditions of the hydrocarbon flow within the riser. A corrosive gas detector may be provided, for example for detecting hydrogen sulphide, which is corrosive and poisonous. A combination of any or all of these sensors may be provided along the pipeline, with possibly multiple sensors at one sensing device and coupled to one wireless transducer via a processing device, or different sensors can be used at different locations.

Figure 1 illustrates a cross section through a tubular in radial direction. The main body 1 of the tubular is surrounded by a polymer coating 2. The interface 3 between the two layers is the instrumentation layer which can be used to house any combination of the sensors mentioned before. The sensors may be distributed around the entire circumference of the tubular. A transducer and induction power receiver 4 is provided which can communicate with external communication device 5, which also includes a power source to charge the sensor device inductively via the induction power receiver.

Figure 2 illustrates a flexible riser 21 as an example of a tubular, whereby the riser extends from the seabed to a vessel 22. A plurality of sensor devices 23 is provided along the longitudinal direction of the flexible riser. At the final sensor device, a reader and transmitter 24 is clamped around the riser at the outside of the polymer layer. The reader is arranged to communicate with the final sensor device, and to all other sensor devices through the chain of devices which can communicate with each other. A transceiver 25 is provided on the vessel to communicate with the transmitter 24.

Figure 3 illustrates a plurality of sensing devices 31 , which are located at an interface of a main body 32 of a tubular and a polymer coating 33. Arrows 34 indicate how sensor data are passed on through the chain of devices.

Figure 4 illustrates the method described above in a flow diagram, including the steps of collecting sensor data (S1) at a first transceiver, sending the data to an adjacent second transceiver (S2) and forwarding the data to a third transceiver (S3).

Although the invention has been described in terms of preferred embodiments as set forth above, it should be understood that these embodiments are illustrative only and that the claims are not limited to those embodiments. Those skilled in the art will be able to make modifications and alternatives in view of the disclosure which are contemplated as falling within the scope of the appended claims. Each feature disclosed or illustrated in the present specification may be incorporated in the invention, whether alone or in any appropriate combination with any other feature disclosed or illustrated herein.