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OGEASIA APRIL 30 – MAY 30, 2015
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T
he first 50 years of Earth
observations from space
imparted the fundamental
lessons that everything
connected with the land, ocean, and
atmosphere is intricately intertwined
and that the Earth is a complex and
dynamic system. In addition, “each
(satellite) mission taught scientists
not only something new about the
Earth’s system, but also something
new about how to create, operate,
and improve the technology for
observing the Earth from space.
In the 1970s, laser technology
was first employed in combination
with satellites (Laser Geodynamics
Satellites [LAGEOS] 1 and 2) that
were designed for maximum
reflectivity to allow for the study of
the Earth’s geoid and the movements
of tectonic plates. Interestingly, this
type of satellite does not contain any
instrumentation, and for that reason
the first such satellite launched in
1976 is still operational today.
Plate tectonics, topography,
seismology, and volcanology
The theory of plate tectonics was
driven largely by observations in the
1950s from ocean vessels mapping the
magnetic field and the seafloor shape,
some of which can now be obtained
more easily from satellite observations.
Several decades later, satellite
observations enabled a scientific
revolution in advancing the theory
of plate tectonics by providing highly
OPINION
Satellite derived data for
conclusive results
detailed, quantifiable measurements
of the Earth’s surface. GPS has enabled
measurement of plate positioning and
velocities, thus resolving the geologic
Earth Reference Frame.
Few scientific accomplishments
are as “transformative” as the
advances in space geodesy over
the past five decades, particularly
with the ubiquitous introduction
of GPS devices. This breakthrough
has not only transformed the field
of geodesy but has also provided
vital information for studying global
sea-level change, earthquakes, and
volcanoes, as well as providing
precise position/location information
for all Earth science research.
At the time of the International
Geophysical Year (IGY July 1957 -
December 1958), the geolocation of
most points at the surface of the Earth
entailed errors that reached hundreds
of meters in remote areas. Today,
scientists rely on an International
Earth Reference Frame from which
geographical positions can be accurately
described relative to the geocenter
in three-dimensional Cartesian
coordinates to centimeter accuracy
or better, which is a 2 to 3 order of
magnitude improvement compared to
50 years ago. On an active planet, where
every piece of real estate moves relative
to every other piece, the exact location
of these is extremely important.
Geodesy observations from space
have enabled accurate measurements
of the Earth’s rotation. The change in
position of the rotation axis (the poles)
is determined daily to centimeter
accuracy, and changes in the length of
a day are determined to millisecond
accuracy within a few hours.
Improvements in GPS measurements
over the past few decades have enabled
instantaneous geodetic positioning.
Real-time GPS
GPS receivers are now available
inexpensively to consumers, who are
rapidly becoming accustomed to GPS
navigation on the road, on the water,
and in the air without realizing the
enormous body of science behind
this technological achievement:
accurate ephemerides of the
satellites, very stable clocks, well-
calibrated atmospheric corrections,
and even relativistic corrections.
and contemporary velocities. For
example, Iaffaldano et al. (2006)
found that the Nazca Plate moves
at a velocity of 6.9 cm per year,
compared to its geologic velocity of
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10.1 cm per year 10 million years
ago. Geologic timescale velocities
typically disagree with present
rates, with implications for crust-
mantle interaction. Factors such as
friction or time dependent processes
can be modeled if we understand
how the rates vary with time.
Known phenomena and processes
Satellite observations often reveal
known phenomena and processes
to be more complex than previously
understood. This brings to the fore
the indisputable benefits of multiple
synergistic observations, including
orbital, suborbital, and in situ
measurements, linked with the best
models available. The greatest benefit
of Earth observations from space is
gained when data is integrated into
state-of-the-art models, combined with
ground-based observation network
and process studies, and analyzed
with sophisticated methods. Model
development has aided in developing
an interdisciplinary thinking in the
Earth sciences. Building sophisticated
models and data analysis tools often
involves long lead times and requires
training of a skilled workforce.
Consequently, a major scientific
breakthrough might be years after the
satellite data has first become available.
To capitalize fully on the investment,
satellite data also requires careful
calibration. In addition, building long-
term data records for climate research
requires cross and inter calibration
between various sensors and follow-on
missions, data processing and archiving,
and maintenance of the metadata.
To develop the aforementioned an
understanding of the complex, changing
planet on which we live is important,
how it supports life, and how human
activities affect its ability to do so in the
future is one of the greatest intellectual
challenges facing humanity. It is also
one of the most important challenges
for society as it seeks to achieve
prosperity, health, and sustainability.
Open data policy
NASA’s open and free data policy
has created a worldwide linked
community of budding and professional
Earth scientists. This open-access policy
encourages use of the data for scientific
purposes and maximizes the potential
societal benefits of the observations.
The long list of accomplishments is
unlikely to have materialized without
this open data policy.
Gravity and altimetry
measurements from space have also
led to discoveries in topography. The
Shuttle Radar Topography Mission
(SRTM) employed InSAR topography
to produce the first (and only)
fine-resolution, worldwide, consistent
model of elevation. This discovery
has mapped the world at a 30-meter
posting; with 10-meter elevation
accuracy; a worldwide elevation
model of 3 arc-seconds (approx. 90
meters) is openly available. New data
is being released at 1 arc-second
(approx. 30 meters) pixel size, which
now reveals the full resolution of the
original measurements.
Down-looking radar altimeters
measuring ocean heights, which follow
the geoid and captures the sea-surface
topography over the entire ocean at a
data density unobtainable on a global
scale from shipboard measurements.
Applications of detailed gravity
information include oil exploration and
the location of undersea volcanoes.
Measuring the earths process
Measuring surface displacement is
now an important ingredient in seismic
risk analysis.
For example, the 1999 Hector Mine
earthquake in southern California
(magnitude 7.1) occurred only 20 km
from, and 7 years after the 1992
Landers earthquake (magnitude 7.3).
This suggests that the Hector Mine
earthquake was triggered in some
fashion by the earlier event. Stress
changes in the crust due to an
earthquake can hasten the failure
of neighbouring faults and induce
earthquake sequences in some cases.
Other processes are occurring
every day in the solid Earth, many of
which escape our knowledge because
they occur at a rate slow enough
not to radiate seismic energy that
can be detected with our present
seismographs. Yet these mechanisms
for the transfer of energy through
the upper crust need to be observed
and measured if we are to be able to
explain many natural hazards. For
example, GPS has enabled the discovery
of aseismic (“slow”) earthquakes
occurring in many subduction zones
around the Earth and adding stress
to subduction faults (The GPS time
series for the Cascadia subduction
zone shows the result of continual
aseismic earthquakes (Melbourne and
Webb 2003). Aseismic earthquakes
may either dissipate or increase
stress, affecting risk probabilities.
Unknown until 12 years ago, aseismic
earthquakes are a recent discovery that
is dependent on satellite observations.
Article meaning
So, what is this article about? To
put it simply, it is trying to state that
George Barber
Marketing Partner Terra Energy & Resource Technologies Plc.
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OPINION
Geologists produced this map, which is based on the expensive data
that was collected and then made available to them.
Figure 1
Figure 2
The below map was produced with no data being made available by the client.
what happens on the earths surface
can be detected by satellites, and
by integrating and processing this
information by highly sophisticated
programs which have been developed
by leading scientists and people of
immense knowledge, we are able to
observe and discover far more than
we can ever hope to if we are located
on the earth. We can now locate and
position (with a depth) that hard to
find resource, be it onshore, in the
desert, in the jungle or be it offshore.
Data interpretation
Traditional methods of exploration
which mainly uses seismic has
limitations, some geology is so difficult
that seismic can be blind to it, many
areas have difficult conditions where
you have steep beddings, basalt, salt
or pre-salt deposits. The geologist
will try to interpolate (Figure 1) this
information, although many times they
have to guess what is there.
When a geologist cannot explain
something, they utilise the technic of
faulting, they will say, there must be
a fault here, and try to and explain
why there is a difference in the
stratigraphy, and also in the depth of
certain horizons. The faulting is used
to cover up the lack of information or
knowledge of the area.
Let us erase the geological map
(Figure 1), instead we do a paleo
reconstruction without the data that
the geologists had available to them,
we then superimpose the results with
the geologists results, we can clearly
see that the structure has identified
all of the production and dry wells,
with even better results in some areas
(Figure 2).
This is a powerful picture, this
shape; these fingers; represent
structural highs, which are
determined by connection points
of zero curvature, which might not
be apparent through conventional
analytical tools such as seismic.
The below Picture (Figure 333)
is from an actual project in South
America, the picture clearly shows
the number of dry holes that had
been drilled by using traditional
methods of exploration.
What is being stated is that
traditional methods cannot compete
with modern methods. Why is the
average success rate in the world for
drilling approximately 10%? Why
are so many dry holes drilled? Do oil
companies like drilling dry holes? It
appears as if they do.
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Figure 333
Figure 333: Final map of Base Level 1 HC prospectivity zones on Southern AOI (1:100,000).
1. Zones of HC prospectivity; 2. Prospective zones within basalt covers and tops of highly
dissected elevations; 3. Areas of priority leads; 4. Wells drilled in the past; 5. Productive well.
All seismic data is subject to
interpretation, and no two experts will
interpret data identically. Geology is
still a subjective science. Although dry
holes have been greatly reduced by 3D
seismic technology, they have not been
eliminated. The correct interpretation of
3D data is a critical step in the process.
Is satellite exploration technics
full proof? Of course not, nothing is
full proof or guaranteed in life, but if
something can give you a 60/70% plus
or even better (at times) probability of
drilling a successful hole, it has to be
better than a 10 or 20% success rate
which is normal today.
Conclusions
The above information is not
threatening to seismic, it’s not
threatening to conventional methods,
it enhances what the explorer is doing.
Satellite derived information and
independent processing methods are
reliable, they add value; it does not
replace, but refines what you do.
If we are humble, we would admit
that we need all the help that we can
get in figuring out the field model
to reduce the risk. After all, if the
technology that is available was being
used, we would not be saying, we
need to do more exploration.
The modern day explorer needs to
elevate the early exploration result;
they need to drill valid targets as
apposed to low value targets.
If the modern day explorer
continues to utilise traditional methods
and does not incorporate technology
that has been developed for the specific
purpose of enhancing the modern day
explorers capabilities, the development
of new resources will not progress at
the rate it should or is required to, and,
the resources that are discovered will
cost far more money than they should.
To arrive at the results as indicated,
the wheel has not been reinvented;
some of the ideas have been on the
table for a long, long time, “Paleo
Reconstruction” for 100’s of years,
“Geodynamic Analysis”, (Leonardo da
Vinci 1452-1519) introduced this idea.
With the advent of satellites which has
allowed acoustic images, geothermal
information, topographic data and other
details to be observed, and also with
the advent of powerful computers to
process all of the information that is
available, we are in a position to save
time, save cost and most importantly
carry out exploration in a more
environmentally and non-evasive
manner from what we do today.
A new version of operating
software or new models of a smart
phone is enhancing what was
previously used. This is exactly what
early exploration utlising satellite
derived data is all about: it enhances
what the explorer is trying to do.
“In exploration, there’s always risk
associated, We need to decrease the
risk and always be optimistic.”
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