GB2472924A

GB2472924A - Wireless remote area sensor system

Info

Publication number: GB2472924A
Application number: GB1015263A
Authority: GB
Inventors: James Nicholas Wilson; Eric Atherton
Original assignee: Wireless Measurement Ltd
Current assignee: Wireless Measurement Ltd
Priority date: 2006-01-27
Filing date: 2006-01-27
Publication date: 2011-02-23
Anticipated expiration: 2026-01-27
Also published as: GB2472924B; GB201015263D0

Abstract

A system comprises primary and secondary wireless networks, at least one interconnection point 3 between the networks and at least one sensor 4 comprising means for sensing at least one of an oil or gas wellhead pressure, flowrate and temperature and a node of the secondary network, the primary network being a multipoint meshing radio network. The networks differ in at least one characteristic, which may be their range or frequency. The system may deliver information to a gathering point 6. Transmitters and receivers in either network may use a combination of battery and solar power and the sensor may switch off its network node when not in use. Nodes 2, 3 in the primary network may contain GPS receivers used to aid routing of information across the primary network and to provide timing information to synchronise sensors in the secondary network. The sensors may comprise a memory to store measured data before its transmission.

Description

Remote Area Sensor System

FIELD OF THE INVENTION

The current invention relates to a remote area sensor system for transmitting sensor data from oil and gas fields, which are remote and potentially harsh environments where there may be no mains power availability or telecommunications infrastructure.

BACKGROUND ART

The benefits of sensing parameters such as pressure, flowrate and temperature around a wellhead and associated flowlines and chokes are well known. Such sensors are routinely deployed in (for example) high value oil and gas wells, particularly offshore wells and land wells close to power and communications infrastructure.

However, a significant percentage of the world's oil and gas reserves are produced from wells completely remote from mains power or communications infrastructure. At present, such wells are largely unmonitored, or are only instrumented with mechanical gauges. They are visited occasionally by oil company personnel. The lack of real-time monitoring means that problems with the well can go unnoticed for some time, causing deferred or lost production.

The lack of a reasonable quality database on the well means that reservoir analysis is hampered, and the reservoir reserves are more uncertain.

The desirability of real-time sensing even where there is no power or communications infrastructure is thus a highly specialised requirement applicable to oil and gas fields. In contrast, sensors deployed for industrial process control measurements have power available relatively close to the sensor, as industrial processes requires power, in contrast to a free flowing oil or gas well.

Various solutions have been proposed to monitor wells in remote oil and gas fields. Battery powered data loggers have been deployed that record measurements from time to time. This data can then be manually collected later.

While providing a more regular electronic data record of the parameters associated with the well, the lack of real-time reporting is still a drawback along with the requirement to visit the wellsite at intervals for data collection.

Point to multi-point radio solutions have been implemented. In these systems the sensors around the wellsite are cabled to a welisite radio transmitter. This transmitter then communicates with a remote central receiving station where the data is gathered for the field. The drawbacks of these systems are the cost and vulnerability of the wellsite cabling, and the lack of resilience and range of a point to multi-point radio system. Repeater stations may be deployed to increase range, but the lack of resilience of the system, and the requirement for careful configuration during installation remain.

Radio systems have also been deployed where each sensor incorporates a transmitter, hence eliminating the wellsite cabling. As the sensors are located close to the ground by the wellhead, the radio range of such sensors is limited.

Typically such sensors communicate with a local wellsite receiver that then forwards the information on via satellite modem, GPRS modem, or a point to point radio system. Satellite and GPRS systems (when GPRS service is available) incur ongoing call charges that either substantially increase the running cost of the system, or force a very slow data collection rate to minimise call charges. Conventional radio systems incur the same problems of inflexibility, lack of resilience and requirement for field configuration that have already been mentioned.

SUMMARY OF THE INVENTION

The present invention seeks to provide a communications system, embodiments of which are capable of wide area operation, are self powered, and provide real time communication of sensor data, and that are convenient to install in remote oilfield environments where no power or communications infrastructures are available.

Accordingly, a first aspect of the present invention provides an integrated sensor and wireless data transmission system comprising a primary wireless network and at least one secondary wireless networks, the primary and secondary wireless networks differing in at least one characteristic, and at least one local data gathering point associated with the at least one secondary wireless network, incorporating a node of that secondary wireless network, a node of the primary network, and a gateway bridging the primary network to that secondary network, at least one sensor comprising a means for sensing at least one of an oil or gas wellhead pressure, flowrate and temperature, and a node of that secondary network adapted to transmit data relating to the parameter via that secondary network, the primary wireless network being a multipoint meshing radio network.

The primary wireless network is optimised for relatively long distance communications, of the order of at least 10km between nodes, and the secondary network or networks are optimised for relatively short distance communications of the order of lOOm, the radio power of each network being different and appropriate for each transmission distance required. This means that the secondary wireless network can have a restricted power output suitable for use proximate to wellheads, with the result that the useful range is less than that of the primary network and unlikely to be greater than 1 km. Typically, the useful range of the secondary network may be less than one tenth of that of the primary network.

The at least one sensor is preferably self powered such as by an internal battery or a solar cell. Ideally, it will switch off its secondary wireless network node when not in use, to conserve power.

The primary network can include other nodes that receive signals on the primary network and retransmit them to a further node of the primary network, but do not include a gateway or a node of the secondary network. These can in effect act as repeaters to extend the primary network or provide additional resilience.

The nodes of the primary network may contain a GPS receiver or other position sensing means such as the proposed Gallileo system (hereinafter collectively referred to as "GPS"). The information obtained will have a number of uses. For example, the GPS timing information can be used to synchronise the sensors with which the nodes communicate, and the GPS location information can be shared with other primary wireless network nodes to aid routing performance of the primary wireless meshing network.

At least some of the nodes of the primary network are preferably self powered, such as by a battery or a source of solar power. The latter will preferably include a battery back-up.

The primary network will generally be self-configuring and self-healing.

This can provide the resilience that has hitherto been lacking.

It is also preferred that the node of the secondary wireless network is within the housing of the sensor. The sensor can also contain an internal data store in which sensor data is retained, to help during malfunction of the primary or secondary networks. This will enable stored data to be retrieved once the network functionality is restored, further adding to the resilience of the system.

Older data may be deleted or overwritten to accommodate newer data, or after a period of time, for example if the storage capacity of the data store is limited.

Some primary network nodes may be located proximate to mains power and/or communications infrastructure. These points can therefore include a data storage means such as a computer, for retaining data prior to onward transmission or display. In general, there will be at least one such node that acts as an extraction point for the sensor data. This may be a control room from which the oilwells are monitored, or it may be an uplink to a satellite or other communication means.

The secondary networks can likewise be self-configuring and self-healing networks, often referred to as "meshing" networks. However, they can also be simpler star networks as they operate over a closer range.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described by way of example, with reference to the accompanying figures in which; Figure 1 is a diagrammatic representation of an oilfield and associated sensor and communication system; Figure 2 shows a modified communication path; Figure 3 shows a self powered sensor; and Figure 4 shows a gateway node.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring to figure 1, a plurality of oilwells Ba, 8b, Bc and 8d are fitted with self powered sensors 4a-4d'. A main data gathering point 6 is located remotely from the oilfield, in a location where mains power and telecommunications are available. The main data gathering point 6 is connected to a long range radio 5 via a cable 7. The long range radio 5 also receives power via cable 7. A plurality of self powered radios 2 operate on the same frequency and use the same network protocol and radio power level as long range radio 5.

Self powered radios 2 contain a rechargeable battery and solar panel charging system, so that they do not require mains power. Gateway nodes 3 also contain the same long range radio type as long range radio 5 and self powered radios 2.

Long range radio 5, self powered radios 2 and gateway nodes 3, together form a long distance communications mesh network that dynamically routes information for best performance using well known self-healing, self configuring mesh network principles.

The main data gathering point 6 is located in the oilfield control room. A display of real-time and historical data gathered from the remote area system is available in the control room for use by oilfield personnel. In addition, the data is made available over the oil company intranet so that offsite reservoir and production engineers can immediately monitor and use the information provided by the remote area system.

The long range radio 5, self powered radios 2 and gateway nodes 3 (long range nodes) each contain a GPS receiver, and hence each long range node can precisely determine its own location. It shares this information with the other long range nodes on the network. This self-acquired position information is used by the long range nodes to improve the routing of data within the long range network, as nodes closer to the data gathering point 6 are favoured for routing as compared to nodes that are further away.

The radios in the long range nodes are optimised for 10km hops between each node, and consume about 1W of transmitted power. This range dictates the maximum spacing between self powered radios 2 and gateway nodes 3 whereas the maximum distance from the oilwell to the main data gathering point 6 can be much further and is limited only by the number of such devices.

Self powered sensors 4a-4e' each contain a short range, very lower power radio with a transmit power of 1mW and a useful range of about lOOm line-of-sight -generally at least an order of magnitude difference in power and/or range as compared to those of the primary network. Each gateway node 3 also contains a short range radio operating on a frequency different to that of the long range radio, and can act as a local data gathering point that collects data from the cluster of sensors near to it via a (local) secondary network and passes this to the primary network that is formed by the long range radio 5, self powered radios 2 and other gateway nodes 3.

The self powered sensor 4 also contains a small amount of non-volatile memory, and readings are stored within this memory as well as being transmitted. This memory allows for 2 months of data to be recorded at typical recording intervals. Once the memory is used up, the oldest data is overwritten, so that at any moment in time, the previous 2 months data is available. This data store can be particularly valuable in the event of a major natural event (blizzard, hurricane, earthquake etc.) that temporarily disrupts the remote area system. The data is automatically recovered over the remote area system to the data gathering point 6 once functionality is regained.

The path 11 for data from one particular self powered sensor 4b to the main data gathering point 6 is shown. This chooses a particular pattern of gateway nodes 3 and self powered radios 2. Another route such as route 12 would also work; in practice the precise route will be chosen ad hoc.

Figure 2 illustrates the self-healing nature of the long range radio network. In this example, one particular self powered radio 2' has failed, for example. The path 13 for data from the self powered sensor to the main data gathering point 6 is shown.

Figure 3 shows one of the self powered sensors 4. A metal body 30 contains a pressure fitting 32 that allows the sensor to be screwed into a pressure fitting on the well 8 using a spanner on a hex formation 33. The metal body 30 contains a conventional strain gauge pressure transducer. A housing 31 is made in a material that is transparent to radio waves, so that the short range, low power radio contained inside is able to communicate through the housing 31. The housing 31 also contains a long life battery and conventional strain gauge signal conditioning electronics, together with power sequencing electronics. Typically, a pressure reading is taken every 30 seconds. Between readings, the strain gauge pressure transducer, signal conditioning electronics and short range radio are switched off to conserve battery life. The antenna for the short range radio is also contained within the housing 31. This provides a more rugged solution than an external antenna, and is less susceptible to wilful or accidental damage.

Figure 4 shows a gateway node 3 in which a weatherproof enclosure 45 is mounted on a pedestal 46 set in a concrete foundation. The enclosure 45 contains a rechargeable battery that is recharged by a solar panel 44 during daylight hours. The enclosure 45 also contains a short range radio that can communicate with any self powered sensors 4 that are in the immediate vicinity, via short range antenna 43. A mast 42 elevates the long range radio 40 that transmits via a long range antenna 41. The enclosure 45 also contains a GPS receiver.

The timing information from the GPS system is used to accurately synchronise any self powered sensors 4 with which gateway node 3 communicates. For example, if the sample interval for any self powered sensor 4 is set to 1 minute, the gateway node 3 will adjust the internal clocks within each self powered sensor 4 so that they power up precisely on the 1 minute boundary (e.g. 2:34:00, 2:35:00, 2:36:00, as opposed to 2:34:05, 2:35:05, 2:36:05). Synchronising to GPS time across the oil field enables flowrate calculations along pipelines and across choke manifolds.

It will of course be understood that many variations may be made to the above-described embodiment without departing from the scope of the present invention.

Claims

CLAIMS1. An integrated sensor and wireless data transmission system comprising; a primary wireless network and at least one secondary wireless networks, the primary and secondary wireless networks differing in at least one characteristic, and at least one local data gathering point associated with the at least one secondary wireless network, incorporating; a node of that secondary wireless network, a node of the primary network, and a gateway bridging the primary network to that secondary network; at least one sensor comprising a means for sensing at least one of an oil or gas wellhead pressure, flowrate and temperature, and a node of that secondary network adapted to transmit data relating to the parameter via that secondary network; the primary wireless network being a multipoint meshing radio network.
2. An integrated sensor and wireless data transmission system according to claim 1 in which the primary wireless network has a range of at least 10km.
3. An integrated sensor and wireless data transmission system according to claim 1 or claim 2 in which the at least one secondary network has a useful range of approximately lOOm.
4. An integrated sensor and wireless data transmission system according to any one of the preceding claims in which the primary wireless network has a range of at least ten times the range of the at least one secondary network.
5. An integrated sensor and wireless data transmission system according to any one of the preceding claims, in which the radio power of the at least one secondary network is limited to provide a maximum range of 1 km.
6. An integrated sensor and wireless data transmission system according to any one of the preceding claims, in which the at least one sensor is self powered.
7. An integrated sensor and wireless data transmission system according to claim 6, in which the at least one sensor is powered by an internal battery.
8. An integrated sensor and wireless data transmission system according to claim 6, in which the at least one sensor is powered by a solar cell.
9. An integrated sensor and wireless data transmission system according to claim 8 in which the at least one sensor has a battery back-up for the solar power source.
10. An integrated sensor and wireless data transmission system according to any one of the preceding claims, in which the at least one sensor is adapted to switch off its secondary wireless network node when not in use.
11. An integrated sensor and wireless data transmission system according to any one of the preceding claims, in which the nodes of the primary network contain GPS receivers.
12. An integrated sensor and wireless data transmission system according to claim 11 in which the at least one nodes of the primary network use GPS timing information to synchronise sensors with which they communicate.
13. An integrated sensor and wireless data transmission system according to claim 11 or claim 12 in which the nodes of the primary network retain location information and shares this information with other nodes of the primary network to aid routing performance of the primary wireless meshing network.
14. An integrated sensor and wireless data transmission system according to claim 13 in which the nodes of the primary network include a GPS receiver from which the location information is obtained.
15. An integrated sensor and wireless data transmission system according to any one of the preceding claims, in which one or more nodes of the primary network are self powered.
16. An integrated sensor and wireless data transmission system according to claim 15 in which the node(s) of the primary network are battery powered.
17. An integrated sensor and wireless data transmission system according to claim 15 in which the nodes of the primary network are solar powered.
18. An integrated sensor and wireless data transmission system according to claim 17 in which the nodes of the primary network have a battery back-up for the solar power source.
19. An integrated sensor and wireless data transmission system according to any one of the preceding claims, in which the primary network is self-configuring.
20. An integrated sensor and wireless data transmission system according to any one of the preceding claims, in which the node of the secondary wireless network is within the housing of the sensor.
21. An integrated sensor and wireless data transmission system according to claim 20 in which the housing of the sensor encloses an aerial of the node.
22. An integrated sensor and wireless data transmission system according to any one of the preceding claims, in which the sensor contains an internal data store in which sensor data is retained.
23. An integrated sensor and wireless data transmission system according to any one of the preceding claims, in which a main data gathering point is located proximate to one of mains power and communications infrastructure.
24. An integrated sensor and wireless data transmission system according to claim 23 in which the main data gathering point includes a data storage means for retaining data prior to onward transmission or display.
25. An integrated sensor and wireless data transmission system according to any one of the preceding claims in which the characteristic that differs as between the primary and secondary wireless networks is the signal frequency.