The EM network October 2010 Newsletter

The EM Network Newsletter October’2010

1

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It’s been a while since I last put out an EM Network newsletter, 4 months in
fact. Since May there have seen very encouraging business news for the use of
the EM technology in the oil & gas market. Large contracts have been awarded,
and many oil companies are now back wanting to use EM data in their
exploration. Fingers crossed that the trek in the desert finally is over! ☺

Our network now counts more than 410 members, verifying the need and the
interest in sharing information and news on the EM technology. As usual, I have
a breakdown of the members into the following categories:

Oil companies 16%
Data acquisition companies (CSEM, MT, GravMag, etc.) 35%
Software & services 13%
Recruiting 5%
Others (universities, gov, etc) 31%

Our old logo... A good mix of people with an interest in developing and using the EM
technology!

Our new logo!
After some feedback from a few of you on our old logo, we ran a competition to
find a new one. From about 5 entries, the winner is here:

The new logo was submitted by Mr. Andrew Pethick. He is undertaking a PhD in
marine CSEM at the Curtin University of technology, Department of Exploration
Geophysics.

Page 1 The EM Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com


Comment from Andrew: “I have a feeling that quite a few people have only
pictured marine EM as the ray diagram as seen in quite a few places. It is my
hope that people understand the behaviour of EM waves as being diffusive (in
the case of marine EM) rather than reflective.”

Andrew Pethick wins the
Blueback iPod for designing the
new EM Network logo!

Flux lines of electromagnetic fields interacting with a hydrocarbon body. Image
courtesy of Andrew Pethick.

Call for articles for the next newsletter
The next newsletter is scheduled for January’11 and I would like to encourage
you to submit articles, reviews, questions, opinions, technology news etc.

Your feedback and input is important to make this Newsletter an interesting
read!

Please also participate in the various discussions on the network web site. We all
can learn from reading each other’s views on the EM technology. I appreciate
we are all busy but please take a few minutes to do this if you can.

Paul Hovdenak (Sponsor and group administrator)
paul.hovdenak@blueback-reservoir.com



Table of Contents

1. Member Articles, Reviews, Questions, etc

1.1 Articles Page 4

1.2 Company news Page 7

1.3 Players in the EM market - update Page 9

1.4 Discussion from the web site Page 12

2. Events and technology updates Page 16

3. Career Networking Page 17

4. Request for input to newsletter No6 Page 18



1. Member Articles, Reviews & Questions

1.1 Articles

There are several articles that were candidates for inclusion in this newsletter,
but because of copyright laws, and size I decided to instead provide you with
some links.

The Geophysics magazine from SEG has for the September’10 issue a couple of
excellent articles. One by Michael Zhdanov and another one by Steven
Constable. Also worth mentioning, is a case study off the coast of Brazil by
WesternGeco. See below for the abstracts and where you can find the full
articles.

Geophysics, Volume 75

Electromagnetic Geophysics: Notes from the past and the road ahead

Author: Michael Zhdanov, University of Utah and TechnoImaging Salt Lake City.

Abstract:

During the last century, electrical geophysics has been transformed from a
simple resistivity method to a modern technology that uses complex data-
acquisition systems and high-performance computers for enhanced data
modeling and interpretation. Not only the methods and equipment have
changed but also our ideas about the geo-electrical models used for
interpretation have been modified tremendously. This paper describes the
evolution of the conceptual and technical foundations of EM methods. It
outlines a framework for further development, which should focus on multi-
transmitter and multi-receiver surveys, analogous to seismic data-acquisition
systems. Important potential topics of future research efforts are in the areas of
multidimensional modeling and inversion, including a new approach to the
formulation and understanding of EM fields based on flux and voltage
representation, which corresponds well to geophysical experiments involving
the measurement of voltage and flux of electric and magnetic fields. ©2010
Society of Exploration Geophysicists



Geophysics, Volume 75

Ten years of marine CSEM for hydrocarbon exploration

Author: Steven Constable , Scripps Institution of Oceanography, La Jolla
California.

Abstract:

Marine controlled-source electromagnetic (CSEM) surveying has been in
commercial use for pre-drill reservoir appraisal and hydrocarbon exploration for
10 years. Although a recent decrease has occurred in the number of surveys and
publications associated with this technique, the method has become firmly
established as an important geophysical tool in the offshore environment. This is
a consequence of two important aspects associated with the physics of the
method: First, it is sensitive to high electrical resistivity, which, although not an
unambiguous indicator of hydrocarbons, is an important property of
economically viable reservoirs. Second, although the method lacks the resolution
of seismic wave propagation, it has a much better intrinsic resolution than
potential-field methods such as gravity and magnetic surveying, which until now
have been the primary non-seismic data sets used in offshore exploration.
Although by many measures marine CSEM is still in its infancy, the reliability and
noise floors of the instrument systems have improved significantly over the last
decade, and interpretation methodology has progressed from simple anomaly
detection to 3D anisotropic inversion of multi-component data using some of the
world's fastest supercomputers. Research directions presently include tackling
the airwave problem in shallow water by applying time-domain methodology,
continuous profiling tools, and the use of CSEM for reservoir monitoring during
production. ©2010 Society of Exploration Geophysicists

The Leading Edge, July’10 issue

The Potiguar integrated exploration project: CSEM prospectivity
assessment offshore Brazil

Authors: Andrea Lovatini, K.Myers, P.Watterson, T.Campbell, WesternGeco

Abstract:

Newly acquired CSEM data were integrated with several different types of
complementary measurements and techniques in an exploration prospect
evaluation study—which included petroleum systems modeling (PSM)—of the
deepwater offshore area of the Potiguar Basin, northeast Brazil.



Potiguar is the second most productive basin in Brazil, but to date, all production
is from its onshore and nearshore areas. A 2D seismic data set was reprocessed
then interpreted to provide regional scale horizons, which were used as input,
along with other geological and geochemical information, for the study. The
CSEM data clearly defined resistive anomalies over five features interpreted as
potential traps on the seismic data. The CSEM resistivity volumes have provided
added value to the PSM and prospectivity study of this basin.

Resistivity modeling with an EM survey layout. Image courtesy of EMGS.



1.2 Company news

EMGS updates (from EMGS web site)
• July’10
o Contract with Pemex for a multi-year contract worth a minimum
of $150 million for 30 deep-water 3D EM surveys. The work
programme is in the Mexican sector of the Gulf of Mexico.
• September’10
o Contract worth a minimum of $ 3 million in Asia. This contract is
a continuation of the previously announced global 3D EM
campaign for a major oil company, the first part of which was a
survey performed in the Caribbean in the first quarter of 2010.
o Woodside has awarded Fugro a controlled-source
electromagnetic survey contract on Australia’s North West Shelf
in 4Q 2010. Fugro has subcontracted the acquisition portion to
EMGS. This $2-million contract will be the first executed under
the Fugro/EMGS alliance which was organized in 2009. The
agreement gives Fugro full access to EMGS’ marine
electromagnetic services.
• October’10
“It is only when they o Electromagnetic Geoservices ASA (EMGS) announced
go wrong that today that it has secured late-sales worth approximately
USD 4 million for its multi-client 3D EM data in the Barents
machines remind you Sea, ahead of Norway's 21st exploration licensing round.
how powerful they These revenues will be recognised in the third quarter of
are” 2010. Industry pre-funding and late-sales year-to-date
Clive James totals approximately USD 10 million, of which USD 6
million were recognised in the second quarter of 2010.
• Edda consortium
o EMGS is pleased to announce that it has received industry
funding for a joint project to accelerate the use of 3D EM data in
exploration and production. The EDDA project involves acquiring
state-of-the-art 3D EM data over known fields on the Norwegian
Continental Shelf. Data acquisition over the Linerle and Valkyrie
fields has already started using EMGS's mobile acquisition set
deployed on the vessel Siem Mollie. The vessel will subsequently
acquire data over the Snøhvit field, and it is expected that this
survey will be completed by the end of September’10.

OHM updates (from OHM web site)
• June’10



o Contract with Bridge Energy UK in the North Sea. The project,
under OHM's WISE (Well Integration with Seismic and
Electromagnetics) product includes providing the client with
a fully integrated dataset, comprising seismic, CSEM and well
information. The OHM Express, a state-of-the-art vessel for
conducting safe and reliable CSEM operations, will acquire
the CSEM survey.
• July’10
o Several projects in the Asia-Pacific region performed during the
summer, with contract extensions expected.

Petromarker updates (from Petromarker web site)

• August’10
o PetroMarker AS and Concedo ASA, a Norwegian exploration
oil company, have signed a contract for the acquisition of EM
data on the Norwegian Continental Shelf (NCS). TEMP-VEL, the
proprietary marine vertical EM technology of PetroMarker,
will be used to provide Concedo with valuable assessment
data.

Blueback Reservoir updates

Blueback has released another version of the Bridge CSEM visualization and
interpretation Petrel plug-in software. The new version includes upgrades to the
Bridge interpretation loop for combining EM forward modelling with
interpretation of recorded data and EM inversion analysis.

Blueback Reservoir and TechnoImaging have entered into a development
agreement for adding TechnoImaging technology within EM forward modeling,
EM inversion and imaging to the Bridge interpretation workflow.
For more information contact Blueback on www.blueback-reservoir.com.



1.3 The players in the EM market

This overview of the players in the EM market will be included in future
Newsletters – and will be updated based on your feedback and input.

I expect this list of companies to grow based your feedback, so please take
a moment to look through it and send me your comments.

Companies offering survey planning and design, data acquisition,
processing and interpretation

• OHM
o www.Ohmsurveys.com
• EMGS
o www.emgs.com
• Schlumberger WesternGeco.
o http://www.westerngeco.com/services/electromagnetics.aspx
• Petromarker
o www.petromarker.com
• PGS
o www.pgs.com/Geophysical-services/Electromagnetic-services
• EMTEK
o www.emtek.as
• Multifield Geophysics
o www.multifield-geophysics.com
• KMS Technologies (owned by EMGS).
o www.kmstechnologies.com
• Fugro
o www.fugro.com
• Quantec Geoscience
o www.quantecgeoscience.com

Companies offering data processing and/or interpretation

• Comsol
o Software solutions for multiphysics modeling
o www.comsol.com
• Blueback Reservoir
o Software development and consulting services
o www.blueback-reservoir.com
• OHM-RSI (owned by OHM)



o www.ohmrsi.com
• Geosystem (owned by SLB WesternGeco)
o www.geosystem.net
• TechnoImaging
o www.technoimaging.com

Industry consortia

• SEMC consortium at SCRIPPS
o http://marineemlab.ucsd.edu
• Marine Control Source ElectroMagnetic Consortium (CSEM)
o http://geophysics.mines.edu/cgem/consortia/csem.html
• Wise
o www.rocksolidimages.com/wise.htm
• CEMI at University of Utah
o http://cemi-dt-13.gg.utah.edu/~wmcemi/

Academia, research institutes, etc

• National Oceanography Centre, UK
o www.noc.soton.ac.uk/gg/research/geophysics/em.php
• NGI, Norway
o www.ngi.no/en/Areas-of-research-and-
development/Geophysics
• Colorado School of Mines, USA
o http://geophysics.mines.edu/cgem/hot_topics/csem_full.ht
ml
• SCRIPPS Institution of Oceanography, USA
o http://marineemlab.ucsd.edu
• SINTEF research, Norway
o www.sintef.no/Home/Petroleum-and-Energy/SINTEF-
Petroleum-Research/Seismic-and-Reservoir-
Technology/Seismic/Electromagnetic-modeling
• Open EM – a community resource for electromagnetic geophysics
o www.openEM.org
• EarthScope
o www.EMScope.org – the MT component of a large US
project managed by Oregon State University
• The Electromagnetics Academy
o http://emacademy.mit.edu/
Page The EM Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com
10


• MTNet
o A resource for scientists engaged in the study of the Earth
using electromagnetic methods, principally the
magnetotelluric technique (magnetotellurics).
o http://mtnet.dias.ie/main/

As you can see from this temporary list, it only covers the companies
involved with the CSEM technology. This is not a limitation so please
forward to me links to companies working on the electromagnetic
technology for the oil and gas business.

Companies providing hardware and EM equipment

• Phoenix Geophysics Limited
o Land Instruments (receivers and transmitters) for MT -
AMT - CSEM - TDEM (Fixed loop, LOTEM) , FDEM, IP, SIP.
o Instruments engineered for deep exploration. Sensors
adapted for Marine CSEM. Transmitters from 3 to 200 kW
(FD and TD)
o http://www.phoenix-geophysics.com
• Geometrics
Scientists have discovered a o Stratagem system (AMT-CSAMT) and their shallow FDEM
noise made just prior to the o http://www.geometrics.com
Big Bang, which sounds • Metronix
o MT receiver equipment
something like "Oops" o http://88.198.212.158/mtxweb/index.php
Cully Abrell • Zonge
o Receivers and Transmitters fro AMT MT (16 bit) CSAMT TEM
and SIP
o http://www.zonge.com.au
• Alpha Geoscience
o light TDEM system called Terratem
o http://www.alpha-geo.com

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1.4 Discussion from the web site

Our web site has a Discussions page with several interesting discussions lately.
Here is an example:

Vertical vs Horizontally Oriented Sensor Arrays

Chris Walker, RXT

Can anyone in the group share with me their experiences of CSEM using the
vertical array (Petromarker) method, and compare it to the traditional
horizontal array (EMGS/OHM) approach?

Kerry Key, Scripps

I took a theoretical look at this in a Geophysics paper published last year:
E-H streamlines. Image courtesy
http://marineemlab.ucsd.edu/~kkey/Pubs/2009b.pdf
of Andrew Pethick.
In brief, the horizontal transmitter has superior resolution to a vertical
transmitter. This was also suggested, but not proven, in the original paper on
marine CSEM:

Chave, A. and C. Cox, 1982, Controlled electromagnetic sources for measuring
electrical-conductivity beneath the oceans. 1. Forward problem and model
study: Journal of Geophys- ical Research, 87, no. NB7, 5327–5338

“It was with unalloyed
Mårten Blixt, Blueback
pleasure that I became
aware that a vigorous To add some nuance, PetroMarker has made a comment to your article Kerry:
earthquake was in http://petromarker.com/comment-article-geophysics
progress”
G.K.Gilbert on the 1906 San To be fair, both methods have their pros and cons, but without doubt is the
Fransisco earthquake traditional approach more mature and robust.

Kerry Key, Scripps

Thanks Mårten for pointing that out, hadn't seen that yet. My paper doesn't
consider Petromarker's specific Jz-Ez system, rather it was intended to be an
apples-to-apples comparison of horizontal versus vertical transmitters, with all
other parameters and noise levels being equal.

12


Terje Holten's comments about my paper are interesting and I would love to see
them elaborated in a peer-reviewed paper. Certainly both horizontal and
vertical transmitter methods benefit in measurement precision (but perhaps not
survey cost) when the transmitter is parked on the seafloor for each
transmission location. So Petromarker's method does have a precision
advantage, but i'm not sure that the increased cost of slowing down the survey
acquisition is a fair trade off in the value proposition. And obviously you could
park a horizontal transmitter on the seabed and also achieve a higher precision
measurement. So apples-to-apples, I still say the resolution is better for a
horizontal transmitter.

I'd also like to respond to his concern about the 1% relative noise floor I used,
which he stated is much larger than what Petromarker's system can achieve. An
absolute noise floor of about 0.1 - 1 nV or so is fairly standard for good electric
field sensors. Normalize that by a dipole moment of about 100,000 Am and you
get around 10^-15 V/Am^2 as the absolute system-noise floor. This is what
Holten states in his response, which I agree with as a representative absolute
noise floor and hence why I used that in my paper. So what about the relative
noise floor? That depends on the uncertainty in parameters such as the sensor
orientation, sensor calibrations and most importantly the absolute positions of
the source and receivers. For the sake of argument, lets suppose we'd like to
have 0.1% relative error, rather than the 1% I used. The relative orientation
Image courtesy of Westerngeco angle between transmitter and receiver needs to be known to with 3 degrees to
get 0.1% relative error, which could easily be obtained with present day tilt
meters, so that isn't much of a practical issue unless the tilts aren't measured.
Sensor calibrations can be done accurately in the lab to levels of no worse than
0.1%. Finally lets consider position uncertainty. Suppose the receiver is at 500 m
offset, as Holten mentions. At this short an offset, the electric field peaks at
around 10^-11 and has a spatial gradient in the radial direction that is about
10^-14 V/Am^2 / m. If the source-receiver position uncertainty was 1 m, the
relative error would be 0.1%. If the uncertainty in position offset was 10 m, then
the relative error would be about 1%. I don't know any contractors getting 1 m
position accuracy between two deep water seafloor instruments with standard
USBL systems; 10 m is probably more realistic. So i'd say that at best a 0.1%
relative error might be possible for some very very carefully collected data. I
could re-run my synthetic inversions with this lower noise floor...okay, just did,
here are the results:

http://marineemlab.ucsd.edu/kkey/RelativeErrorComp.jpg

So bumping down the relative error to 0.1% did improve the resolution of the
Jz-Ez inversion, but it is still vastly inferior to the horizontal transmitter and
receiver (Jy-Ey) with a 1% relative error.

I agree with Holten's statement that time-domain and frequency domain
methods have different sensitivities. However, since time-domain responses can

13


be obtained by Fourier transformation of the frequency domain responses, the
better resolution of horizontal transmitters and receivers will hold for time
domain data as well.

Stefan Helwig, Emtek

Very interesting discussion.
Kerry, in your last reply you pointed out that: "since time-domain responses can
be obtained by Fourier transformation of the frequency domain responses, the
better resolution of horizontal transmitters and receivers will hold for time
domain data as well."

There is of course no doubt that time domain fields can be calculated using
Fourier transform. In order for your argument to work all the time the sensitivity
of the response generated by a horizontal transmitter would need to be better
than the one generated by a vertical one for all frequencies. Is that actually
true?
The situation becomes even more complicated if we look at this in 3D. While the
above described condition might be true in 1D there actually might be
differences in the sensitivities of both approaches depending on reservoir size
Intelligence is the ability to and survey objective.
adapt to change For a vertical downhole transmitter part of this is discussed in Sholl & Edwards
Stephen Hawking 2007 (Geophysics). They point out that the sensitivity towards the lateral
boundary is superior with the vertical borehole transmitter. At the same time
they point out that the vertical resolution is poorer which is in agreement with
your observations. While the situation with the Petromarker system is not 100%
the same I still think that the argument should hold for their system too.

Terje Holten, Petromarker

Hi, I’d like to join this interesting discussion. This discussion is a good reminder
for us to publish more results. My college Eirik Flekkøy will have a poster talk at
EAGE in Barcelona where we elaborate more on measurement of noise.
For the Petromarker technology to work it is necessary to turn off the
transmitter during measurement and therefore work in time domain since the
offsets are small. Apart this point, it is possible to do a transformation between
the two domains, so the difference in theory is small.
I agree with Kerry’s comment about positioning. The main contribution comes
from the constant uncertainty from the positioning of lower electrode, which is
usually larger than the random noise that originates from the movement of the
vessel from the fixed point above the measured position of the lower electrode.
Some kind of uncertainties have a large magnitude, for instance errors in
measured seawater resistivity, but have minor or no impact in the inversion
since it only affects the early times. While tilt effects modifies the slope at late
times and have a major impact on the inversion. The noise frequencies of 0.1-1
Hz is the most problematic since stacking is not effective here.

14


So how does this compare to the relative noise in Kerry’s paper? The relative
noise originates from the transmitter, as I understand. In our case, most of the
uncertainties are systematic and repeatable between each pulse , and a smaller
part is random. The horizontal method has errors with more random than
systematic contributions. The error in offset has low impact on our inversion
since it only affects early times, so basically the tilt of transmitter dominates our
‘relative noise’. All in all, adding realistic noise to the vertical dipole is somewhat
complicated.
I also pointed about that the averaging produced a bias since only short offsets
have a value for our method and offsets up to 20 km are used for averaging in
Key’s paper. I would prefer a fixed offset of 1000m for Petromarker method,
while the horizontal dipole method can use its best offset (7km?). It is possible
to do a rerun with a fixed offset, Kerry? Also, what is spectrum of your relative
noise?

David Alumbaugh, Schlumberger

So just to add my two cents here....
We are presenting papers both in Barcelona as well as the SEG looking at the
resolving capabilities of the two acquisition scenarios in 1D and 2D (or 3D) from
a theoretical perspective; we will also be publishing a paper in Geophysics(
when we get around to finishing it). What we have found from both a pure
theoretical perspective (approximate analytic solutions) as well as empirical 1D
inversion results is that the close offset vertical-vertical system does not have
the resolving capability of the standard CSEM configuration. The theoretical
analysis has shown that at close offsets such as used by Petromarker, the layer
response is dominated by an 'image like' term. This is similar to DC resistivity
and central loop TEM. However, in standard CSEM you make measurements at
large offsets where you pick up a 'guided mode'. As it turns out this guided
mode has much more sensitivity to the properties of the resistive layer than
does the image term. So if you run a 1D inversion for the Petromarker
configuration and compare it to results for the standard CSEM configuration,
what you find is you get much better resolution of the layer resistivity and
thickness for the latter, even if you set the noise level for the Petromarker
configuration at 10 times less than the horizontal-horizontal data.

However the better resolution scenario breaks down in two cases. The first is if
for the horizontal-horizontal when you go to a low enough frequency such that
you are approaching DC. In this case the guided mode is not generated and all
you are left with is an image like layer response (note that this does away with
the concept of going to low frequency as a method for mitigating the air-wave
effect). Thus the low frequency CSEM inversion results look similar to those that
you get by inverting the close offset transient Jz-Ez data. The second case that
was alluded to by Stefan above is when you get into 2D and 3D scenarios. To
generate the guided mode requires the target to be of sufficient lateral extent.
So if the target is smaller than offset that is required to really detect the guided
mode, you again only detect an image-like layer response. And in this case
because the standard CSEM method is using larger offsets where as the
15


Petromarker example is at fairly short offsets, the Petromarker anomaly is
actually larger for the same target. Plus it appears to have better lateral
resolution as you go over the edge of the target. However to make use of this
lateral resolving capability would require dense, nearly continuous
measurements like you get with the towed horizontal source. As I understand it,
this continuous profiling acquisition mode is rather difficult with the current
Petromarker configuration due to fact that the source boat has to stop and
position each new source position rather than continuously towing.

I think what it comes down to is both methods have some advantages and
disadvantages, with the 'best' measurement system changing depending on
geologic situation that is being investigated.....

This discussions continues on the web sites with input from Aramco and
Fugro/EMGS.

2. Events and technology updates

• SEG 2010 in Denver
o http://www.seg.org
o EM sessions all 3 days. Check out the program on the web site
• SCRIPPS
o Will host Marelec 2011 – the world’s foremost conference on
marine electromagnetics
o http://www.marelec.co.uk
• Links to various technical papers on EM (please forward additional links for
inclusion on this list):
o http://www.westerngeco.com/media/resources/articles/200809_a
ogr_mmt_improves_subsalt.pdf
o www.emgs.com/research_publications/technical_papers.php
o www.ohmsurveys.com/case.php
o http://www.westerngeco.com/~/media/Files/WesternGeco/resourc
es/papers/2009/2009seg30.ashx

16


Find a job you love and
you’ll never work a day
in your life”
Confucius

3. Career Networking
Another of the reasons for instigating The EM Network was to advertise career
positions that may be of interest to our members. This will never be the major
part of our newsletter as the intention is to keep it as technically focused as
much as possible. However I intend to carry on with this section until someone
convinces me otherwise.

The source for these positions is mainly from
1. Our group’s JOBS section on the web site
2. the company web sites
3. recruiters contacting our group

17


• OHM Surveys - http://www.ohmsurveys.com/careers.php

• EMGS - http://www.emgs.com/careers/

• Oil Careers recruiting
http://careers.infooil.com/fx/jobs/listings/1.343276/sr.geophysicist.in
terpretation.of.gravity.magnetics.electromagnetics.aspx

• Working Smart recruiting
o http://www.earthworks-jobs.com/oil/ws754.html

• Misco jobs recruiting
o http://www.miscojobs.com/jobs/L_2/job_451282.htm

• Piper Morgan recruiting
o http://jobview.monster.com/Sr-Geophysicist-Interpretation-
of-Gravity-Magnetics-Electromagnetics-Job-Houston-TX-US-
90231607.aspx

18


4. Requests for input for newsletter #6
After receiving this few EM Network newsletters you should now realize the kind
of newsletter we are trying to achieve. If you would like to add an article, or
some input for the Technology section, for the next newsletter (scheduled for
January 2011), then simply email me the proposed article and I will do my best
to include it.

Regards,
Paul.hovdenak@blueback-reservoir.com

Autumn is here!
- at least on the northern hemisphere :-)
19

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