advances in geophysics - iploca · advances in geophysics prof. george tuckwell ... geophysical...
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Advances in Geophysics
Prof. George Tuckwell
Divisional Director, Geosciences and Engineering
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Outline
▪ Geophysics in context
▪ Advances in acquisition and processing
▪ New instruments
▪ New physics
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Risk and information maps
•Conceptualisation of risk/need for information
3
top
side
3D view
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Risk and information maps (cont.)
•Tools at our disposal to gather information
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x-section geophysicse.g. resistivity, seismic
boreholes
surface geophysicse.g. EM conductivity,
magnetics, GPR
trial pits
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Risk and information maps (cont.)
•Following a detailed intrusive SI
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Risk and information maps (cont.)
•Following a detailed intrusive SI – where do you have information?
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Risk and information maps (cont.)
•Following a detailed intrusive SI – where does risk remain?
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Risk and information maps (cont.)
•Using geophysics as a site investigation tool
•Find out something about everything in the near-surface
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Surface geophysics
indicates some
buried structures
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Mine shafts (and archaeology, and UXO)
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Advances in acquisition and processing
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Project Example
Brownfield Site
Carrington Power CCGT
860MW gas fired combined cycle power plant on location
of former Carrington Power Station.
3km pipeline corridor from adjacent National Grid Site to CCGT.
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Case Study - Location
NG Site
Proposed
power
station
Pipeline
route
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Case Study - Project Details
▪Geophysical Surveying to establish constraints
along pipeline route -
▪ Buried Services
▪ Underground obstructions
▪ Geophysics to compliment boreholes
Power cables (lots!) Gas pipe tracing Radar EM mapping
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Case Study - Final Interpreted Results Plan
CAD Plan
▪ Pipeline Route
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Case Study - Final Interpreted Results Plan
CAD Plan
▪ Pipeline Route
▪ Topographic
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Case Study - Final Interpreted Results Plan
CAD Plan
▪ Pipeline Route
▪ Topographic
▪ Statutory service records
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Case Study - Final Interpreted Results Plan
CAD Plan
▪ Pipeline Route
▪ Topographic
▪ Statutory service records
▪ Drainage tracing
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Case Study - Final Interpreted Results Plan
CAD Plan
▪ Pipeline Route
▪ Topographic
▪ Statutory service records
▪ Drainage tracing
▪ Power & radio electrolocation
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Case Study - Final Interpreted Results Plan
CAD Plan
▪ Pipeline Route
▪ Topographic
▪ Statutory service records
▪ Drainage tracing
▪ Power & radio electrolocation
▪ Radar data
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Case Study - Final Interpreted Results Plan
CAD Plan
▪ Pipeline Route
▪ Topographic
▪ Statutory service records
▪ Drainage tracing
▪ Power & radio electrolocation
▪ Radar data
▪ EM data
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Case Study - Final Interpreted Results Plan
CAD Plan
▪ Pipeline Route
▪ Topographic
▪ Statutory service records
▪ Drainage tracing
▪ Power & radio electrolocation
▪ Radar data
▪ EM data
▪ Combined Drawing
Multiple techniques
= More information
= Less risk
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Case Study - Intrusive Investigation
Pipes found at location and depth
shown by geophysics;
subsequently exposed;
found to be cut at end; proven to be disused
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Case Study – Depth to bedrock & Faults
Borehole data
?
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Case Study – Depth to bedrock & Faults
P-wave refraction seismics
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Electrical resistivity and seismic data with targeted boreholes to develop a detailed ground model
Case Study – Depth to bedrock & Landfill
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Case Study – Depth to bedrock & Landfill
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New instruments
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Research into new capabilities
Finding Infrastructure with Non-
Destructive Imaging Technologies
(FINDIT)
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Evaluate the full potential of new instruments
BT’s business challenge is
to deliver fibre connections
inc allowing access to
competitors
•Locating existing
infrastructure and ducting
•Detecting non-metallic
connections
•Detecting blockages and
voids
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Evaluate the full potential of new instruments
Benefits of new
instruments:
•Much greater data density
•Fully 3D imaging
•Ability to look at the
characteristics of reflections
in the data, not just their
presence
•New processing
approaches possible similar
to exploration seismic work
flows
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BT infrastructure – detection and condition tests
•Locating existing infrastructure and ducting
•Detecting non-metallic connections
•Detecting blockages and voids
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New physics
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Next generation of gravity meters
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Isolating the signal of interest
instrument reading
+drift
correction+
Free Air anomaly
+Bouguer anomaly
=Simple Bouguer
Anomaly
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What we might measure with what limitations
Forward modelling for the Scintrex, the QT gravity sensor and the QT gravity
gradiometer
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QT Gravity Sensor potential
e.g. Detection of buried mine shafts
which currently are not detectable
from the surface
Density o
f m
ine e
ntr
ies in
an u
rban s
ett
ing,
West M
idla
nds.
(To
pogra
phy b
ased o
n O
rdnance S
urv
ey
mappin
g ©
Cro
wn C
opyrig
ht
and D
ata
base R
ight
2011).
Ref:
Geoscie
ntist
April 2016.
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Market interest
Engagement with the industry
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Direct feed into current commercial work
Increased ability to model out the effects of strong
topography to isolate the gravity signal of interest
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Modelling out the terrain effect
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UoB test site – Laser scanning
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UoB test site
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Visibility
“Clocks are not the only means to get a handle on gravity. At the microscopic scales where quantum mechanics rules, streams of matter particles can behave like waves. Like those on a pond’s surface, those waves can interfere, adding to and subtracting from one another—in the quantum description, altering the probability of finding a particle here or there. In a device called an atom interferometer, two particle streams are sent at differing heights and then brought back together to interfere with each other. The degree to which the two paths are different, indicating the relative strength of the gravitational tug from below, measurably alters the degree of addition and subtraction.
Such devices have a multitude of uses. In Britain, for example, 4m holes are dug every year in the course of roadworks and construction, but two-thirds of the time the diggers have no idea what they will find beneath the surface. Test boreholes cover only a small area, and ground-penetrating radar does not reach deep enough. A gravity sensor that could tell pipework from pebbles would save a lot of trouble.
RSK, an environmental consultancy involved in cleaning up brownfield sites and the like, reckons that a third of construction projects overrun by up to a month, and another third by two months or more, and that half of these delays arise because of underground surprises. The company is collaborating with the University of Birmingham in Britain on fieldworthy quantum gravity sensors, in the hope of deploying them in big infrastructure projects. Other efforts to develop cheap sensors have drawn interest from companies such as Schlumberger, an oilfield-services giant, and Bridgeporth, a surveying firm.”
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Summary
✓ Geophysics in context
✓ Advances in acquisition and processing
✓ New instruments
✓ New physics
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