NERC's investment in long-term geomagnetic monitoring, combined with BGS expertise in core, crustal and external magnetic field modelling, has allowed the geomagnetism team to build commercially successful continual sub-surface navigation services for the oil and gas sector, and space weather hazard monitoring, analysis and modelling services for the electricity industry.
The BGS global geomagnetic model (BGGM), in-field referencing (IFR) and interpolation in-field referencing (IIFR) services have improved directional drilling performance, bringing economic benefit, and helped mitigate environmental and safety risks.
The oil industry requirement in extended reach directional drilling is to hit small (about 100 m) targets at large distances (about 10 km) for economic benefit. Well plans need a reliable ellipse of uncertainty along their entire path to show that hitting the target is feasible, and that collisions with other wells (potential blowouts) will be avoided.
IFR is the provision of magnetic field estimates at a series of locations and times along a planned well path, which includes estimates of the crustal field from local observations. The IIFR service, for determining the geomagnetic field in real-time with uncertainty estimates, was developed during the early 1990s by the BGS with the support of Halliburton (Sperry Drilling Services) and BP. At the core of the IIFR/IFR services is the annually updated BGGM (1990–present) which is based on worldwide magnetic measurements made on land (e.g. at the nine BGS observatories), sea, air and by satellites.
The key breakthrough was demonstrating, through both theory and testing in the field, how a global core field model (now the BGGM) could be combined with aeromagnetic survey data, via the application of novel analysis methods to generate vector field estimates from scalar measurements, and real-time magnetic observatory data (including from the BGS magnetic observatory network) to reduce well-path uncertainties. The concept was to operate a 'virtual' magnetic observatory at the drill bit. The potential time, and hence cost, savings motivated the industry to fund the research.
The BGS-led development of IFR and IIFR has resulted in cost-effective services for the oil industry able to compete with gyro-based surveys. This has allowed the exploitation of small hydrocarbon targets, e.g. in the North Sea, that may otherwise have been left untapped.
An offshore rig may (conservatively) cost £250 000 per day to operate. Gyro surveys require the drill string to be removed before the survey, whereas wellbore surveys using magnetic tools, supported by BGS services, can be carried out with the drill string in place (measurement while drilling or MWD). Where downhole magnetic surveys displace gyro surveys, many hours of rig time are saved on every hole drilled: up to around 50 wells may be drilled from any one offshore rig.
Drilling safety has been improved through reduced risk of blowouts from intersecting wellbores, which have damaging consequences for the environment and operator reputation.
IIFR and IFR services have had impact in terms of the environment, public policy and services, and the economy in new and improved business (e.g. expansion from the North Sea to worldwide). The demand for services has been steadily growing around the world; IIFR/IFR is used in the North Sea, Norwegian Sea, Barents Sea, Alaska, the Gulf of Mexico, Canada, the Far East, Australia and Africa. IIFR has now been applied in drilling several thousand wells worldwide.
Space weather is an ever-present natural hazard with an approximate 11-year cycle of activity, but extreme and damaging events may occur at any time. It can cause large and rapid geomagnetic variations, which are a growing concern for the power industry. Geomagnetically induced currents (GICs) are a manifestation of space weather at ground level: GICs flowing in grids can trip or burn out transformers and result in blackouts, with severe economic consequences. A nine-hour space weather blackout in Quebec in 1989 cost the Canadian economy an estimated C$2 billion. The risk is increasing as space- and ground-based technologies evolve (e.g. global navigation satellite system services (GNSS), satellite operations and electricity grids), increasing vulnerability and exposure.
The BGS recognised the potential to connect geophysical measurements, models of ionospheric source magnetic fields, and crustal and ocean conductivity models with engineering models of grid systems to simulate the flow of GICs in the UK's transmission system. This led to the following developments:
This work was funded by NERC National Capability, with additional support from Scottish Power, National Grid and the European Space Agency.
The BGS currently provides the primary UK capability in modelling and analysis of geomagnetically induced currents in electrical transmission systems caused by space weather. This expertise has been drawn on in developing extreme event scenarios and their impacts to support the Cabinet Office (for the National Risk Assessment) and other Government departments (e.g. Government Office for Science, DECC, DfT). Real-time services have been developed for National Grid (aiding operational management) and for the UK Met Office (the Natural Hazards Partnership daily hazards assessment).
Russell, J P, Shiells, G, and Kerridge, D J. 1995. Reduction of well-bore positional uncertainty through application of a new geomagnetic in-field referencing technique. Paper SPE 30452.
Williamson, H S, Gurden, P A, Kerridge, D J, and Shiells, G. 1998. Application of Interpolation In-Field Referencing to Remote Offshore Locations. Paper SPE 49061.
Macmillan, S, and Grindrod, S. 2010. Confidence Limits Associated With Values of the Earth's Magnetic Field Used for Directional Drilling. SPE Drill & Compl 25 (2): 230-238. SPE-119851-PA.
Hapgood, M, and Thomson, A W P. 2011. Space Weather: Its Impact on Earth and Implications for Business. Lloyds 360 Risk Insight Report. www.lloyds.com/News-and-Insight/Risk-Insight