Robotic Mining and Optic Fibre in Petroleum Engineering
Robotic Mining
With advance in technology in the mining industry, most modern mines are becoming more mechanised.
In 1996, Mining Automation Program (MAP), a joint venture research project between Inco Limited, Tamrock OY, Dyno Explosives Group and CANMET was formed. The idea behind this program was to mechanise the mining equipment and systems to see whether the mining of an orebody can be accomplished without human interaction. In particular, the area of interest consists of:
Underground telecommunications, Positioning & Navigation, Process engineering, monitoring & control systems Mining equipment.
Underground Telecommunication
Advance in communication technology is what made robotic mining program possible. Creation of this communication system came from some straightforward concepts, as follows: • • • Entire radio spectrum is available to underground mining because the rock in the mine shields surface radio communication systems from any interference. Manufacturing concepts can apply to mining if a high capacity radio-based network existed. The needs of future underground mining would be to provide control systems that allow remote operation of mining equipment and systems. Remote operation requires operators to have their senses available. These senses are (hearing, smelling, touching, and tasting.)
Conceptually, the communication system is simple. The main part of the system is a CATV (Computer Aided TV) cable system for the transmission of high-speed voice, data and video. Linked to this are “microDAT” (Distributed Antenna Translators). MicroDat allow the radio transmission of voice, data and video.
Position and Navigation
Unlike the automotive industry, which is investigating global positioning systems (GPS) as a navigational aid in new vehicles, the mining industry cannot use GPS because it is not practical to use satellite signals below earth‟s surface.
Investigation is underway for the potential use of gyroscopes and magnetic electronic compasses to locate the position of underground vehicles. By developing the process control systems with the new positioning software, a central computer will be able to control many functions in the automated mining operation. Some of the issues to be resolved in this field are: Can a positioning system to do the job be obtained or developed that will work in an underground mine? Is the positioning system able to work in the mine environment? What accuracy is required of this type of positioning system for use in underground mining? When a positioning system is found/developed how will we need to use it to enable robotic mining One product that has a high potential for the future use is a system under development by Honeywell and the former United States Bureau of Mines. Although expensive, this system may prove to be reliable and accurate for underground mining purposes.
Process Engineering, Monitoring & Control Systems
Process engineering, monitoring and control systems are what keep the robotic mine together. The interweaving of engineering, monitoring and control information is commonplace in manufacturing. Although the function of each is distinctly separate, yet they need to be highly interactive. Tamrock, Inco and Dyno have been working independently on the software. Establishment had been made for the technical directions of the project. The core systems interactively communicate with strategic tools and strategic systems. The mine specific systems will interact with business systems. The core system that all mining software needs to interact with includes; data repository, mapping and 3D modelling systems, machine control systems and mine network managment. The core systems will communicate with strategic systems and strategic tools via configuration management. Strategic systems and tools include; surveying & robotic sensing, ore estimation and blasting design. In turn the strategic tools and systems will interact through translators to business systems such as financial accounting and inventory managment.
Mining equipment
LHD Automation LHD (Load Haul Dump) automation application provides Remote Teleoperation. Remote teleoperation is a branch in Telemining. Telemining is the use of current state-of-the-art technology, including underground communications, positioning, process engineering, monitoring and control systems, to operate mining equipment and system. It greatly increases safety of underground mining and improves productivity and working conditions. In Remote teleoperation, a remote operator runs multiple machines-LHDs or trucks, in a safe, confined and comfortable space of a cabin that could be located on the surface of an underground mine. From the control station, the operator can control the load, haul and dump action of an LHD or truck. In the control station the operator is provided with hand and foot controls, to operate the LHD. They are also provided with real-time TV screen and audio, to see and hear what is going on down the mine. A specially designed control system for the LHD is the Autonomous Guidance. This system allows the autonomous operation of the LHD or truck, by executing the operator‟s tramming instructions. The machine then trams to and from the dump/load sites automatically, allowing the operator to control the loading or dumping of another LHD or truck.
The benefits which remote teleoperation offers are: One operator can operate multiple LHDs or trucks. Decreased personnal travel time to/from excavation levels Improved quality of work for miners. Increases safety since the control station can be located above ground. Reduces operating errors.
Remote Drilling Remote drill provides live video of one or more existing drills with pan/tilt/zoom/focus of the picture through camera controls provided for the remote operator. From the control station at or near the surface, an operator can observe the drilling actions of one or more existing, electrically controlled drills. The Camera control pod on Remote drill application can be operated by the operator to pan/tilt/zoom and focus with a flick of a switch. Once drilling of one drill is completed, the operator can turn his/her attention to another drill. A specially designed control system allows for remote control and operation of multiple cameras, which enable the operation of the drills by a remote operator. Using the combined speed and bandwidth of broadband cabling and the Multiple Access Video (MAV) control system, the operator can operate the drill at maximum safety and efficiency.
Conclusion
Robotic mining technology and techniques offer many positive benefits and some unique engineering challenges. Current mining techniques are typically determined by the nature of the rock mass and the ability to remove ore at rates that allow a mine to be profitable.
Introducing robotic mining techniques that speed up this process puts new emphasis on the
need to have more sophisticated tools to measure the impact of faster removal rates both in terms of risk and reward. When considering deep mining, robotic mining techniques offer the potential to reduce opening size, facilitate the move to more selective techniques and
continue to reduce costs so the operations can remain profitable.
The technique being developed over the next five years in MAP will change the way mining is done. Mining”. In essence the mining industry is moving to the verge of “Virtual
References
Automated Mining Systems, 1999 [Online, accessed 9/4/02]. URL: http://www.robominer.com Baiden G.R, Strom R & Preston C, 2000 Mining Automation Program, 2000 [Online, accessed 5/4/02]. URL: http://www.incoltd.com/about/telemining/baiden.html.
Optical Fibre in Petroleum Engineering
With the growth in telecommunications, cable TV and the Internet, optical fibre has become a part of everyday life. „However, the use of optical fibre in the petroleum industry has been restricted to applications supporting technology that cannot operate with “standard” electrical communication‟ (Wright 2000, p. 1)
A recent study (Wright 2000) has shown that, presently, the offshore industry uses subsea fibre optic systems to provide communication where high levels of electrical noise disturbance prevents the use of copper-based communication. It is also use for access to optical sensors for both subsea and downhole, for communication with sensor systems providing continuous real-time data.
Communication
In the past, electrical for subsea control and data acquisition has been limited to about 1,200 bit/sec. Today, optical fibre is a proven technology for transoceanic communication; it can provide the offshore oil industry with gigabit communication bandwidth. 2.5 Gigabyte/second is an equivalent of 32,000 telephone at one time (George 1999, p.1). Optical fibres will provide offshore oil production platforms with the infrastructure for high volume, high-speed voice data, and video capabilities. It will offer offshore platforms services such as video conferencing, high speed internet access and virtual private networks. When optical fibre replaces copper umbilical the building and installation cost is reduced significantly. This is due to a large reduction in umbilical cross-section. Construction saving arises from the reduction in cross section in the umbilical core that comes from removal of multiple copper communication wires and their replacement by one or two fibre elements. This saving is further reduced due to the reduction of armouring needed for the smaller core. Reduced installation costs come from the decreased cross section and weight per unit length of the umbilical, and therefore the maximum length that can be installed in one piece.
Subsea production
Development of subsea production technologies such as multiphase pumping, have for the first time made possible to take high power machinery subsea. The electrical noise disturbance around these machineries creates conditions that are not practical for conventional electrical communication to operate. However, with the fibre optics this problem is solved.
The next step for fibre optic technology is to move downhole (Wright 2000). In this environment, it could be use to measure effects such as: Position and movements (Fibre gyroscopes) Acoustics (Fibre hydrophones) Chemicals and reactions Electrical supply characteristics Fibre optics will be used to provide high bandwidth, electrical noise immune, environmentally stable communication with multiplexed sophisticated subsea and downhole equipment. „The fibre will be connected to a range of optical sensor heads, enabling them to measure temperature, pressure, flow, and vibration‟ (Wright 2000, p.4). Fibre optics is already in use to measure temperature gradient in land-based wells. This technology can be use to monitor continuous pipeline temperature from the well to the platform and hence it can provide early warning of waxing or hydrate formation or monitoring of pipeline temperature change during a shut-in.
Environmental applications
Optic fibres offer greater advantages over electrical conductors for durability in the subsea and downhole environments. In case of water leakage through a copper conductor, there would be an immediately failure in communication. However, an optical fibre system would not experience any immediate changes in performance but failure may occur over a very long period of time. Due to its very high temperature resistance characteristics, an optic fibre has no problems being in downhole environment. The glass fibre will survive temperatures above 1,000C and when protected by polymide coating it will survive temperatures up to and around
1,600C. For permanent downhole installation, the fibre is placed inside a specially welded
tube fill with buffer gel. According to (Wright 2000), the offshore oil industry has the perception that optical fibre is
costly and fragile. „The current price of a single mode fibre is 5 cents/feet, compared with
30 cents/ft for 18AWG twisted shielded pair copper cable‟ (Wright 2000, p.5). With continuous expansion of fibre optics being manufacture for this industry worldwide, in future it will be the cheaper option on a line-for-line basis.
At first optical fibre would appear to be fragile, however, under tension, it is as strong as steel. Laboratory aging studies have shown that long term exposure of optical fibre to water does not alter its optical characteristics. One effect that can result in a decrease of optical fibre performance is the leak of hydrogen into the optical fibre. Hydrogen ions are present at low partial pressure in subsea environment and around corrosion sources (Wright 2000). The fibre will readily absorb the hydrogen and this result in an attenuation of 0.2dB/km. When hermetically welded steel or copper tube, filled with a buffer gel are used there is usually no risk of hydrogen ingress. Carbon coated fibre has been proven to be very effective against hydrogen ingress. The coating process involves direct application of 500angstrom carbon onto the glass fibre. Although affective against hydrogen ingression, it has worse fracture characteristics and fatigue properties, especially so under strain. In almost all applications, hermetically welded steel or copper tube, filled with a buffer gel is adequate to provide 25-years lifetimes for installed fibres systems.
Conclusion
In future, optical fibre will be a vital technology in many aspects of advanced subsea installation. This will initially be evident anywhere high-power machinery is placed subsea, as these installations will continue to be dependent upon the noise immune
communication properties of optical fibre. As subsea system complexity continues to
increase, the need to provide real-time control and data acquisition will drive the communications bandwidth up to the point where copper is no longer a suitable
communication medium. Optical fibre already offers a step change in bandwidth capacity
for the communication within this industry. This performance increase means that the cable design no longer has any impact what so ever, on the performance of the communication link. Once knowledge of the availability of high bandwidth communication becomes widely distributed, many controls and sensor improvements will appear, to make use of the available bandwidth.
Reference
Dev George, Sonet Ring Links Offshore Oil Installations, 7/1/1999 [Online accessed 11 Apr. 2002]. URL: http://www.fiberiopticsonline…d={c9055cca-3156-11d3-b648-00c04f481017/ Michael A. Marcus, Process Monitoring with Optical Fibers and Harsh Environment Sensors, 1999 [Online, accessed 12 Apr. 2002]. URL: http://www.spie.org/web/abstracts/3500/3538.html Perry Joseph Wright, Optical fiber’s gigabit bandwidth, 200 km range attractive for subsea work, 2000 [Online, accessed 10 Apr. 2002]. URL: http://www.findarticle.com/cf_1/m3037/2000_May/62793624/print.html