14 Geomodeling: A Team Effort To Better Understand Our Reservoirs Part 6: Geophysicists And Geomodeling 21 Annual Young Geoscientists Networking ...
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14 Geomodeling: A Team Effort To Better
Understand Our Reservoirs
Part 6: Geophysicists And Geomodeling
21 Annual Young Geoscientists
Networking Reception
22 Gussow Conference 2015
Fine Grained Clastics: Resources
to Reserves Meeting Summary
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DECEMBER 2015
VOLUME 42, ISSUE 11
Canadian Publication Mail Contract – 40070050
DECEMBER 2015 – VOLUME 42, ISSUE 11
ARTICLES
Geomodeling: A Team Effort To Better Understand Our Reservoirs
Part 6: Geophysicists And Geomodeling ............................................................................ 14
CSPG OFFICE
Annual Young Geoscientists Networking Reception ........................................................... 21
#110, 333 – 5th Avenue SW
Calgary, Alberta, Canada T2P 3B6 Gussow Conference 2015
Tel: 403-264-5610 Fine Grained Clastics: Resources to Reserves Meeting Summary ................................ 22
Web: www.cspg.org
Please visit our website for all tickets sales and event/course registrations Honorary Member - Graeme Bloy ......................................................................................... 26
Office hours: Monday to Friday, 8:00am to 4:30pm
The CSPG Office is Closed the 1st and 3rd Friday of every month.
OFFICE CONTACTS
Membership Inquiries
Tel: 403-264-5610 Email: membership@cspg.org
Technical/Educational Events: Biljana Popovic
Tel: 403-513-1225 Email: biljana.popovic@cspg.org DEPARTMENTS
Advertising Inquiries: Kristy Casebeer
Tel: 403-513-1233 Email: kristy.casebeer@cspg.org Message from the Board ............................................................................................................. 5
Sponsorship Opportunities: Lis Bjeld
Tel: 403-513-1235 Email: lis.bjeld@cspg.org Technical Luncheons .................................................................................................................... 8
Conference Inquiries: Candace Jones
Tel: 403-513-1227 Email: candace.jones@cspg.org Division Talks .............................................................................................................................. 11
CSPG Foundation: Kasandra Amaro
Tel: 403-513-1234 Email: kasandra.amaro@cspg.org Rock Shop ................................................................................................................................... 25
Accounting Inquiries: Eric Tang
Tel: 403-513-1232 Email: eric.tang@cspg.org
Executive Director: Lis Bjeld
Tel: 403-513-1235, Email: lis.bjeld@cspg.org
EDITORS/AUTHORS
Please submit RESERVOIR articles to the CSPG office.
Submission deadline is the 23rd day of the month, two months prior
to issue date. (e.g., January 23 for the March issue).
To publish an article, the CSPG requires digital copies of the
document. Text should be in Microsoft Word format and illustrations
should be in TIFF format at 300 dpi., at final size.
CSPG COORDINATING EDITOR
Kristy Casebeer, Programs Coordinator,
Canadian Society of Petroleum Geologists
Tel: 403-513-1233,
kristy.casebeer@cspg.org
The RESERVOIR is published 11 times per year by the Canadian Society of Petroleum
Geologists. This includes a combined issue for the months of July and August. The
purpose of the RESERVOIR is to publicize the Society’s many activities and to promote
the geosciences. We look for both technical and non-technical material to publish.
The contents of this publication may not be reproduced either in part or in full
without the consent of the publisher. Additional copies of the RESERVOIR are available
at the CSPG office.
No official endorsement or sponsorship by the CSPG is implied for any advertisement,
insert, or article that appears in the Reservoir unless otherwise noted. All submitted
materials are reviewed by the editor. We reserve the right to edit all submissions,
including letters to the Editor. Submissions must include your name, address, and
membership number (if applicable).The material contained in this publication is
intended for informational use only.
While reasonable care has been taken, authors and the CSPG make no guarantees
that any of the equations, schematics, or devices discussed will perform as expected
or that they will give the desired results. Some information contained herein may be
inaccurate or may vary from standard measurements. The CSPG expressly disclaims
any and all liability for the acts, omissions, or conduct of any third-party user of
information contained in this publication. Under no circumstances shall the CSPG and FRONT COVER
its officers, directors, employees, and agents be liable for any injury, loss, damage, or
expense arising in any manner whatsoever from the acts, omissions, or conduct of Tavurvur is a stratovolcano within the Rabaul caldera, located at the eastern tip of
any third-party user. New Britain Island, Papua New Guinea.
Printed by McAra Printing, Calgary, Alberta. Explosive eruptions have occurred persistently since 1994, repeatedly covering the
town of Rabaul and surrounding area in fine, powdery ash.
Photo by: Nicholson, Paul G.
RESERVOIR ISSUE 11 • DECEMBER 2015 3
CSPG and geoLOGIC Systems Present our
Annual Holiday Social
&
Technical Luncheon
Talk:
Glacier Gas– Impact of Continental
Glaciation on Sedimentary Basins
Speaker:
Steve Grasby | Geological Survey of Canada
Tuesday December 8th , 2015
Wine & Appetizers 10:30-11:30am
Technical Luncheon 11:30-1:00pm
This is a sellout social event that you don’t want to miss!
Tickets are available at www.cspg.org
Sponsored by:
Message from the Board
A message from Astrid Arts, Finance Director
CSPG BOARD
PRESIDENT
Tony Cadrin
Financial Overview of
president@cspg.org Tel: 403.303.3493 the CSPG
PRESIDENT ELECT 2015 Fiscal Year
Greg Lynch • Shell Canada Ltd
presidentelect@cspg.org Tel: 403.384.7704
The CSPG 2015 fiscal year ran from org website by the end of December if
PAST PRESIDENT September 1, 2014 through to August 31, you are curious about all the details. For
Dale Leckie 2015. 2015 we posted a loss of ~$230 K, quite
pastpresident@cspg.org a swing from the ~$175 K profit we made
A lot can happen in a year.WTI went from
in fiscal year 2014. Most of that loss was
FINANCE DIRECTOR US $92.92 to US $49.20, the Canadian
the result of reduced sponsorship, lower
Astrid Arts • Cenovus Energy dollar went from $0.91 to $0.76 US and
directorfinance@cspg.org Tel: 403.766.5862 attendance at our events, donation to
over 35,000 people in Alberta lost their
CSPG Foundation and a reduced profit
jobs in the petroleum industry. Albertans
FINANCE DIRECTOR ELECT from the GeoConvention Partnership.
elected an NDP government in May
Scott Leroux • Long Run Exploration Nothing unexpected in a downturn.
who increased corporate and personal
directorfinanceelect@cspg.org Tel: 403.802.3775
income taxes and have left an air of As a Not-For-Profit society our metrics
DIRECTOR uncertainty over our industry. The CSPG for success are different than the E&P
Mark Caplan is registered federally under the Not- and Service companies many of our
conferences@cspg.org For-Profit Act and so as an organization members work for. The mission of the
we won’t feel an added tax burden but CSPG is to advance the professions of
DIRECTOR we recognize that many of our members, the energy geosciences – as it applies to
Milovan Fustic • Statoil Canada Ltd. corporate sponsors, advertisers and geology, foster the scientific, technical
publications@cspg.org Tel: 403.724.3307 exhibitors will. We are in a recession learning and professional development of
unlike any we have seen since the 1980’s. its members; and promote the awareness
DIRECTOR
Michael LaBerge • Channel Energy Inc.
Most companies are not projecting WTI of the profession to industry and the
memberservices@cspg.org Tel: 403.301.3739 prices to turn around until 2017 but public. As a society we accomplish this
even that may be bullish. How long this through the tireless work of volunteers
DIRECTOR will last is anybody’s guess. in 40+ committees, it is astounding what
Ryan Lemiski • Nexen Energy ULC our CSPG community accomplishes and
ypg@cspg.org Tel: 403.699.4413 The CSPG has felt the effects of the
it is something we should all be proud
downturn. On the whole though, we
of. Some highlights of our activities from
DIRECTOR are in good financial shape to weather
2015:
Robert Mummery • Almandine Resources Inc. the storm thanks to the solid work of
affiliates@cspg.org Tel: 403.651.4917 many past CSPG Finance Directors, • 16 Technical Luncheons, Fall &
CSPG Executives as well as Lis, Eric and Spring Education Weeks & a Gussow
DIRECTOR the rest of the CSPG office staff. Savings Conference on Geomodelling
Darren Roblin • Kelt Exploration during profitable years has positioned
corprelations@cspg.org Tel: 587.233.0784 • The GeoConvention Partnership
the CSPG with an Internally Restricted
ran its first geoConvention since its
Rainy Day fund of $1.1 MM and an
DIRECTOR formation as its own legal entity in
Jen Russel-Houston • Osum Oil Sands Corp. unrestricted fund of $720 K at year end.
which CSPG has a 45% ownership
Jrussel-houston@osumcorp.com Tel: 403.270.4768 Our portfolio is conservatively invested
(along with CSEG 45% and CWLS
where we hold an asset mix of 80% Fixed
10%)
DIRECTOR Income and 20% Equities on an Adjusted
Eric Street • Jupiter Resources Cost Base. Operationally, we brought • Three Joint Venture Conferences
street@jupiterresources.com Tel: 587.747.2631 in $1.9 MM in Revenue and had $2.2
• Oil Sands with AAPG, Playmakers
MM in Expenses. Fully audited Financial
EXECUTIVE DIRECTOR with AAPG & the inaugural Mountjoy
Statements will be available on the cspg.
Lis Bjeld • CSPG Carbonate Conference with SEPM
lis.bjeld@cspg.org Tel: 403.513.1235 (... Continued on page 7)
RESERVOIR ISSUE 11 • DECEMBER 2015 5
Submit your hike to be featured in the
“GO TAKE A HIKE” SERIES
Before writing an article please contact the series coordinator
via email at Philip.Benham@shell.com.
He can provide a template document and confirm that a
particular hike has not been submitted before.
Submission guidelines:
Preferred format is powerpoint, 2-3 pages in length, include map,
hike directions, annotated photos, Geological description and references.
While hikes focus on western Canada, hikes in other
parts of the world are welcome.
CSPG Regional Graduate Student Scholarships
4 x $2,500 awards available by region
(Atlantic/Quebec, Ontario, Western, Open)
Eligibility:
Graduate Students enrolled full-time at a Canadian University in their first year of an MSc
or PhD Geology or Earth Science Program
Disciplines include: Sedimentology, structural geology, stratigraphic studies involving
clastic or carbonate rocks, paleontology, geochemistry, hydrogeology, petrophysics and
reservoir geology
Active student members of CSPG (membership is free!)
Previous winners are not eligible
Application deadline is January 15, 2016
For application form and other requirements please see www.cspg.org/scholarships
(... Continued from page 5) our programs to best meet our member
needs in this new environment. We
• 4 sporting events recognize that our community is one of
• Road Race & Fun Run, Squash our biggest strengths and our society and
Tournament, Mixed Golf and Classic industry will be forever different when
Golf Tournaments (Classic moved prices rebound. Our demographics will
to a new 1 day format) have changed as many of our members
retire. New grads, young and seasoned
• Continued investment in our professionals who have struggled to find
Young Professional and Outreach work over the last year, may choose to
programs and we launched the leave industry and the profession. As a
CORPORATE CSPG Ambassador program which society we have money in the bank to
SPONSORS
is working on improving our pay for our activities for a few more
SAMARIUM relationships with universities and years at current spending levels but we
CSPG Foundation organizations across the country. have challenged our committees to see
geoLOGIC systems ltd. what they can do this year with 80% of
• $75 K donation to the CSPG
DIAMOND Foundation (from 2014 Audited their budgets. This is the 88th year of
AGAT Laboratories Profits) our society and if there is one thing we
can say with certainty, it is that every
Alberta Energy Regulators
Looking forward into the 2016 Fiscal time the price of oil goes down … it
TITANIUM Year we are looking at ways to adjust always goes back up.
Tourmaline Oil Corp.
APEGA
PLATINUM
Weatherford Canada Partnership
Cenovus Energy
Loring Tarcore Labs Ltd.
Imperial Oil Resources
SILVER
Devon Energy Corp
Enerplus Corporation
Nexen ULC
Seitel Canada Ltd.
MEG Energy Corp.
Husky Energy Inc.
BRONZE
Chinook Consulting
Talisman Energy
Long Run Exploration
Qatar Shell GTL Limited
Osum Oil Sands Corp.
Crescent Point Energy Trust
Pro Geo Consultants
Exxonmobil Exploration Co. Ltd.
Belloy Petroleum Consulting
GLJ Petroleum Consultants Ltd.
Gaffney, Cline & Associates
RIGSAT Communications
CSEG Foundation
MJ Systems
Paradigm Geosciences Ltd.
Core Laboratories
IHS Global Canada Limited
As of Ocotber 30, 2015
A Special Thanks to Geologic Systems Ltd.,
CSPG’s Top Sponsor of the Month.
RESERVOIR ISSUE 11 • DECEMBER 2015 7
TECHNICAL LUNCHEONS DECEMBER LUNCHEON Webcasts sponsored by
Glacier Gas
- Impact of
continental
glaciation on
sedimentary basins
SPEAKER
Steve Grasby
Geological Survey of Canada
11:30 am
Tuesday, December 8th, 2015
Calgary, TELUS Convention Centre
Macleod Hall ABC Calgary, Alberta
Please note: The cut-off date for ticket
sales is 1:00 pm, five business days before
event. [Tuesday, December 01, 2015].
CSPG Member Ticket Price: $45.00 + GST.
Non-Member Ticket Price: $47.50 + GST. salt beds now discharge as saline springs Canada on both source rock analyses as well as
along the basin margins. Highly overpressured groundwater issues across western and northern
Each CSPG Technical Luncheon is 1 APEGA conditions, developed in response to subglacial Canada. He has led and participated on
PDH credit. Tickets may be purchased online water pressures, also provide opportunities to several regional groundwater projects, including
at www.cspg.org examine the response of shales to extreme southern Manitoba, Alberta, the Okanagan
cases of fluid injection that may inform Valley, and currently the Nanaimo Lowlands. In
discussion on issues ranging from shale gas addition he has conducted extensive research
ABSTRACT
development to nuclear waste repositories. on the biogeochemistry of thermal and mineral
Northern hemisphere continents were
springs across Canada, including several of the
covered by ice sheets up to 4 km thick during
BIOGRAPHY northern most known springs in Canada’s High
the last glacial period. Until recently the impact
Steve Grasby - Since completion of his Arctic. He was awarded the Queen Elizabeth
this had on sedimentary basins has been largely
Ph.D at the University of Calgary in 1997, Dr. II Diamond Jubilee Medal in recognition of his
ignored. The underlying bedrock was exposed
Grasby has worked at the Geological Survey of research in 2012.
to both the lithostatic load of ice in addition to
tremendous sub-glacial water pressures. This
CRAINʼS LOG ANALYSIS COURSES
has a significant transitory effect on underlying
sedimentary basins. Where overlying more
porous and permeable units, subglacial waters
were injected into underlying sediments,
For Engineers, Geologists, Geophysicists, and Technologists
reversing continental-scale fluid flow systems.
Therefore relic pressure distribution patterns 35$&7,&$/48$17,7$7,9(/2*$1$/
TECHNICAL LUNCHEONS JANUARY LUNCHEON Webcasts sponsored by
Back for more? of the Barents Sea. The oil pool lies beneath
a sub-Early Triassic angular unconformity,
Permian pebble to cobble spiculitic chert
clasts. An angular relationship is observed on
The first Permian suggesting block faulting and tilting prior
to the onset of Triassic sedimentation. The
northern Ellesmere and Axel Heiberg islands.
From these observations we conclude the set
oil discovery in the reservoir rocks are Permian spiculitic cherts
and heterozoan carbonates of shallow
of conditions that led to Gohta is a genuine
play worth exploring some more in the
Barents Sea has origin that accumulated at a time of cool
oceanographic conditions. The porosity
Barents Sea and, when conditions are right, in
the Sverdrup Basin as well.
many analogues in may be the result of extensive sub-Triassic
the Sverdrup Basin, subaerial karsting. The seemingly unique set
of attributes of the the Gohta Discovery has
BIOGRAPHY
Benoit is a Professor of Geoscience at the University
Arctic Canada been observed at a number of localities in the
Canadian Arctic Archipelago. The Sverdrup
of Calgary. He obtained his undergraduate and
M.Sc. degrees in geology at the Université de
Basin was adjacent to the Barents Sea area Montréal studying Carboniferous carbonates
SPEAKER
Benoit Beauchamp throughout its Late Paleozoic-Mesozoic from Western Canada. Subsequently, he moved
Department of Geoscience, history prior to the break-up of Pangea. The to Calgary to pursue a Ph.D. in geology at the
University of Calgary, Calgary, Alberta succession is thicker than that of the Barents University of Calgary. For his dissertation, he
Sea, owing to greater subsidence rates, but its studied Carboniferous and Permian sedimentary
11:30 am stratigraphic sequences are identical. Permian rocks in the Canadian Arctic. After obtaining
Thursday, January 14, 2016 spiculitic chert is widespread, especially in the his Ph.D. in 1987, Benoit worked for 18 years
Calgary, TELUS Convention Centre Late Permian succession, when carbonates as a Research Scientist with the Geological
Calgary, Alberta were all but eradicated.The loss of carbonates Survey of Canada in Calgary, leading major
can be in part associated with cooler oceanic field expeditions to the High Arctic. In 2005,
Please note: The cut-off date for ticket conditions and possibly to upwelling-enhanced
sales is 1:00 pm, five business days before he became the Executive Director of the Arctic
ocean acidification along NW Pangea. Institute of North America at UofC. In 2011, he
event [Thursday, January 07, 2016]. Late Permian organic-rich shales locally
CSPG Member Ticket Price: $45.00 + GST. returned to the Department of Geoscience as
interfinger with the chert and may constitute a full-time professor. Much of Benoit’s research
Non-Member Ticket Price: $47.50 + GST. a source rock. Porosity is unusually high in interests revolve around understanding the Late
Late Permian chert. Large carbon isotopic Paleozoic-Early Triassic sequences and petroleum
Each CSPG Technical Luncheon is 1 APEGA
depletion in carbonate material beneath the systems, which takes him to exotic places such
PDH credit. Tickets may be purchased online at
sub-Triassic unconformity suggests extensive as Ellesmere Island, Svalbard and Oman. Benoit
https://www.cspg.org
meteoric leaching occurred. The sub-Triassic has been an active contributor to many CSPG
unconformity is widespread and one of the events and endeavours over the years, including
ABSTRACT basin’s most significant in terms of base level his leadership roles in the 1993 and 1997 CSPG
The 2013 Gohta oil discovery is the first drops.The unconformity is also locally angular Conventions and in the 2007 Gussow Conference.
significant discovery in the Permian succession and associated with basal conglomerates of
RESERVOIR ISSUE 11 • DECEMBER 2015 9
TECHNICAL LUNCHEONS JANUARY LUNCHEON Webcasts sponsored by
Antarctica’s Each CSPG Technical Luncheon is 1 APEGA
PDH credit. Tickets may be purchased online
CO2 conditions, like those predicted in
our future.
sedimentary at https://www.cspg.org
BIOGRAPHY
archives of ABSTRACT Julia Wellner - Wellner is a sedimentologist
past glacial During times of past extensive glaciations,
the Antarctic ice sheet extended from
and stratigrapher who works primarily in
the Gulf of Mexico and offshore Antarctica
history: Tools for its current position, reaching across the
continental shelf. As the ice sheet retreated
on questions related to sediment facies,
stratigraphic architecture, glacial history,
understanding to its modern extent, the shrinking ice sheet
left behind seawater, rather than ancient
and sea-level change. She earned her PhD
from Rice University in 2001 where she
climate change ice, leaving behind a sedimentary signature
of deglacial history. Marine geophysical
also completed a post-doctoral fellowship.
She has been at the University of Houston
SPEAKER survey data, including 3.5 kHz profiles and since 2006 where she teaches stratigraphy,
Julia Wellner multibeam swath bathymetry, combined sequence stratigraphy, marine geology, and
AAPG Distinguished Lecturer with sediment cores, are used to map the oceanography. Wellner has completed over a
extent of past ice, estimate the speed at dozen ocean-going cruises collecting seismic
11:30 am
which it was flowing, and understand the data and sediment cores, including eight in
Tuesday, January 26, 2016
style of retreat. Radiometric dating gives Antarctica.
Calgary, TELUS Convention Centre
ages of retreat and allows comparison to
Calgary, Alberta
other global archives. Past periods of glacial
Please note: The cut-off date for ticket retreat, which tend to be diachronous,
sales is 1:00 pm, five business days are compared to the modern day retreat,
before event [Tuesday, January 19, 2016]. which is happening across large areas in
CSPG Member Ticket Price: $45.00 + GST. a short period of time. Ongoing work is
Non-Member Ticket Price: $47.50 + GST. targeting records from times of past high
GeoConvention 2016
MARK YOUR CALENDAR
GeoConvention 2016 is March 7 – 11
In recognizing the business environment which we are
With low commodity prices and an ever -
changing economic and business operating in, GeoConvention is pleased to offer heavily
environment, it is imperative that the
industry optimize the way in which it
discounted delegate rates for the 2016 program.
operates. Whether enhancing recovery
methods, finding the optimal path for a
horizontal well or maximizing the return New for our 2016 program, in addition to the technical
of capital employed, Optimizing
Resources, the theme for GeoConvention
program and exhibit floor at the Convention Centre, we will be
2016, is key to success. hosting an offsite component at the Lake Louise Inn – check
Please join us and contribute as out geoconvention.com for details.
speaker, exhibitor or sponsor
EARLY BIRD REGISTRATION
NOW OPEN
www.geoconvention.com
10 RESERVOIR ISSUE 11 • DECEMBER 2015DIVISION TALKS INTERNATIONAL DIVISION Sponsored by
Husband and
Wife survive an
18-Month Trip
around Africa in a
Land Cruiser
SPEAKER
Tom Feuchtwanger
12:00 Noon
Wednesday December 9th 2015
Buzzards Restaurant & Bar
140-10 ave SW, Calgary, AB T2R 0A3
ABSTRACT
In an attempt to seek adventure, escape
the daily grind, and recharge their 30-
year marriage, exploration geologist Tom
Feuchtwanger and healthcare professional
Janet Wilson purchased a Land Cruiser in
South Africa, modified it for extended self-
supported travel, and spent 18 months
circumnavigating the African continent. He Tom Feuchtwanger P.Geol.
will present this once-in-a-lifetime adventure: themselves and the world along the way. Tom hydrocarbon resource opportunities and
its highs, its lows, and what they learned about will also include some comments about the challenges that Africa is facing currently.
CSPG Structural Geology Division Lunchtime Talk
12:00-1:00pm | Thursday December 3, 2015
Schlumberger, Conference Room, Second Floor, Close to Reception, 200 125-9 Ave SE
Random Rocks, Structures and Geo IQ– Christmas Social
Just us in December for something different.
Three things geologists love – rocks, structures and showing how brilliant they are!
We will be having a Christmas Quiz, with great photographs, brain teasers and cryptic clues.
Put together a team of 2-3 people, give yourselves a good name, then come along and test your Geology IQ.
See your friends, enjoy some snacks, have a bit of fun.
Contest starts at 12 noon – sharp!
All are welcome and no registration is required. Bragging rights for the winner!
For more information go to www.cspg.org
RESERVOIR ISSUE 11 • DECEMBER 2015 11DIVISION TALKS GEOMODELING DIVISION Sponsored by
Modeling three ABSTRACT
[This paper was previously presented at EAGE
continuous variables in 3D, ensuring they are
bounded and sum to 1, and a unique e-facies
ways from electro- Petroleum Geostatistics Biarritz, France, 7-11
September 2015]
code is assigned, by taking the e-facies with
the maximum probability at each location.
facies: categorical, Geomodeling for petroleum reservoirs is
e-facies conventionally done hierarchically by facies to
establish regions within which rock and fluid
BIOGRAPHY
David Garner is a chief scientist and technical
probabilities, and properties can be considered “stationary”.
Many reservoir models do not use depositional
advisor with the Landmark R&D Division of
Halliburton. His current focus is mainly on
petrophysics with facies description, but use “electro-facies”
from clustering of petrophysical log curves.
developing new technologies and filling gaps
in integrated subsurface earth modeling.
assignment This paper compares three approaches to David has previously worked in R&D at Statoil
and in various geomodeling/geostatistical
the development of e-facies geomodels, 3D
SPEAKER models of categorical codes that can be used roles at Chevron, ConocoPhillips and his old
David Garner as stationary domains within which rock and consulting company, TerraMod Consulting.
Halliburton/Landmark fluid properties can be simulated. The first Mr. Garner currently serves as a co-chair for
approach takes the e-facies codes developed the Geomodeling Technical Division of the
CO-AUTHORS through cluster analysis as conditioning CSPG. He previously served on the CSPG
R. Mohan Srivastava data and uses a method for simulating board of directors and was general chair
FSS Canada Consultants categorical variables, plurigaussian simulation, for the Gussow 2011 and 2014 conferences,
Jeffrey Yarus to directly build a 3D model of the e-facies. “Advances in Applied Geomodeling for
Halliburton/Landmark The second approach takes the petrophysical Hydrocarbon Reservoirs: Closing the Gap I
logs at the wells as conditioning data and and II”.
12:00 noon uses a standard method for co-simulating
Wednesday, December 9, 2015 continuous variables, to build 3D models of
Husky Conference Room A, 3rd Floor, the log responses; these are then converted INFORMATION
+30 level, South Tower, to e-facies using the rules developed through There is no charge for the division talk and we
v707 8th Ave SW, Calgary, Alberta cluster analysis. The third method works welcome non-members of the CSPG. Please
directly with the e-facies probabilities that bring your lunch. For details or to present a talk
most cluster analysis techniques can provide. in the future, please contact Weishan Ren at
These probabilities are co-simulated as renws2009@gmail.com
DIVISION TALKS BASS DIVISION Sponsored by
Data Integration formation, we need to be able to capture the
complex heterogeneity of the geology within
BIOGRAPHY
Pippa Murphy is a Geoscience Consultant and
Techniques for these models. We also need to gather a firm
understanding of the distribution of gas and
Petrel expert with Schlumberger Canada. She
started her career with Schlumberger in 2005
Geocellular Model water that may have an effect on the ability of
these steam chambers to grow.
as a technical consultant working on multiple
international plays out of the UK. Now based
Building, An The aim of the game is always to honor the
in Calgary, Pippa works closely with oil and
gas companies to leverage the full range of
Example from the information at the wells whilst achieving
sound results in terms of geostatistics. But
capabilities in Schlumberger software to solve
McMurray what other information could we use to
increase our confidence in the models that
their exploration and development challenges.
She is currently engaged in a number of heavy
oil related projects. Pippa is a Geologist by
SPEAKER we are building, and could we use some of
background and studied at Kingston University in
Pippa Murphy this data to impose a more geological flavor
London, England.
Schlumberger Canada to our models rather than relying on the fully
stochastic population techniques that we
12:00 noon commonly see today. INFORMATION
Tuesday December 15, 2015 | 12:00pm BASS Division talks are free. Please bring your
ConocoPhillips Auditorium, During this talk we’ll look at an example own lunch. For further information about the
Gulf Canada Square, model where geological analogues, as well division, joining our mailing list, a list of upcoming
401-9th ave SW Calgary AB as data derived from seismic have come talks, or if you wish to present a talk or lead a
together to build a realistic and confident field trip, please contact either Steve Donaldson
model of the McMurray which can then be at 403-808-8641, or Mark Caplan at 403-975-
ABSTRACT used for simulation and field development 7701, or visit our web page on the CSPG website
In order to accurately simulate the movement going forward. at http://www.cspg.org.
of a steam chamber through the McMurray
12 RESERVOIR ISSUE 11 • DECEMBER 2015DIVISION TALKS PALAEONTOLOGY DIVISION Sponsored by
Sue (the auction in which Sue sold for more than
8 million dollars to the Field Museum in
INFORMATION
This event is presented jointly by the Alberta
Tyrannosaurus Chicago with the bill footed by the Ronald
McDonald House and Disney. After years
Palaeontological Society, the Department of
Earth and Environmental Sciences at Mount
Rex) and the of preparation by staff and volunteers at
the Field Museum in Chicago, Sue is now
Royal University, and the Palaeontology
Division of the Canadian Society of Petroleum
Chicago Field proudly displayed at the Field Museum.
Mona will present an overview of Sue’s
Geologists. For details or to present a talk in
the future, please contact CSPG Palaeontology
Museum background and some of the things that Division Chair Jon Noad at jonnoad@hotmail.
Sue has taught us (scientific and otherwise). com or APS Coordinator Harold Whittaker
SPEAKER Mona will also illustrate some of the other at 403-286-0349 or contact programs1@
Mona Marsovsky treasures in the Chicago Field Museum. albertapaleo.org. Visit the APS website for
APS Executive Member and confirmation of event times and upcoming
Professional Engineer speakers: http://www.albertapaleo.org/.
BIOGRAPHY
7:30pm Mona Marsovsky is a life member of the APS
Friday, January 15, 2016 who has served as the APS treasurer since
Mount Royal University, Room B108 2002. She is also a member of the Society
of Vertebrate Paleontology. She is an amateur
whose paleo habit has been supported by
ABSTRACT her work as a professional engineer (Mona
In the 1990’s controversy erupted around Trick P. Eng.) programming gas and oil field
the Tyrannosaurus Rex (T-Rex) dinosaur optimization software for the oil industry.
named Sue. This included seizure of Sue’s As part of her work, she has taught training
skeleton by the FBI (Federal Bureau courses and given luncheon talks all over the
of Investigation), court hearings which world.
resulted in a jail sentence for the person
who excavated Sue’s skeleton, and an
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RESERVOIR ISSUE 11 • DECEMBER 2015 13GEOMODELING: A TEAM EFFORT TO BETTER
UNDERSTAND OUR RESERVOIRS
Part 6: Geophysicists and Geomodeling
| By Thomas Jerome, RPS, Sher Ali, Brion Energy and Nilanjan Ganguly, Canacol Energy
INTRODUCTION when it shows its potential. Geomodeling can be used for time-to-depth
conversion. This will be covered in the first
After discussing, in the last two papers, how A seismic cube does give us a 3D image of the
section. Secondly, seismic interpretation is
geologists and petrophysicists can get involved reservoir; however, the resolution is usual too
extremely useful to guide how the geomodel
in a geomodeling project, we now look at the low to capture the level of detail engineers
3D-grids shall be built. The second section
role of geophysicists.This paper is the last one need to truly understand the reservoir. Wells
focuses on the integration of stratigraphic
on the relationships between geoscientists data provides the level of detail we are looking
interpretation, while the third section looks
and geomodelers. The next three papers will for, but this data can be cumbersome to
at the integration of structural interpretation
talk about the role of engineers. interpolate in 3D. The solution is to integrate
in geomodeling. Lastly, considerable
well data and seismic data.
Geophysicists in oil and gas companies information about the rock characteristics
worked mostly on 2D seismic data before the We use trends extracted from seismic to can be extracted from the seismic cube,
technology to acquire 3D seismic data was guide the interpolation of wells data in such as seismic attributes or fracture density
developed and became popular. Companies 3D. Some uncertainty about the reservoir for example. This data can be used to guide
are now also using seismic data to monitor will remain, coming both from the seismic geostatistical algorithms. It will be the topic
the development of their fields thanks to the interpretation process, from the work on the of the last section. Each of these sections will
acquisition of 4D seismic data. Nowadays, wells and from the integration of the well data also cover the associated uncertainties.
geomodelers still have to integrate some 2D with the seismic. This uncertainty needs to be
To close the introduction, a second question is
seismic lines into their models and some are taken into account as well. Integrating different
in order: who should really be accomplishing
starting to work on the integration of 4D type of data together and understanding the
all these tasks that we will cover in this
time-lapse data. But for most of us, when impact of uncertainties in a model: these are
paper? The geomodeler with his geomodeling
we think about geophysical data, we have in two tasks that geomodels are designed for.
software or the geophysicist with his 3D
mind the integration of 3D seismic data into
As such, it’s advisable to build a geomodel geophysical package? Over the last few years,
our geomodels. This topic is the focus of this
whenever seismic data and seismic software companies specializing in geophysical
paper.
interpretation are available. In the meantime, packages have added more and more tools
First, one has to ask: Why do we need a building a geomodel only based on well data of grid construction, of geostatistics and
geomodel if we have acquired 3D seismic while seismic is readily available would be a of 3D-grid analysis (volume computation
data? After all, seismic cubes give us an shame. Good seismic information will always for example). In a similar way, geomodeling
image of our reservoirs between the wells. tell us more about the reservoir than the packages are now able to accomplish large
Don’t they solve all of our problems? Using results of pure mathematical interpolation parts of many geophysical workflows. So who
a technology as a stand-alone product techniques. If a geomodel is about to be built, should integrate seismic and well data and
has its use. When integrated with other a geomodeler should always ask if seismic study the remaining reservoir uncertainties?
technologies, such as geomodeling, that is data are available. The geomodeler or the geophysicist? As far
14 RESERVOIR ISSUE 11 • DECEMBER 2015as the authors of this paper are concerned, unit between the ground (for onshore the two first layers have more or less constant
it doesn’t matter who does the job. Our goal seismic) and the first key horizon HrzA, then interval velocity of 2,500m/s and 5,000m/s
is to highlight aspects of a reservoir study in for the unit A between HrzA and HrzB and respectively (Figure 2A) while the deepest
which we believe geophysics and geomodeling lastly for the unit B between HrzB and HrzC. layer has a sharp lateral change of interval
shall be combined. Each team will decide who In a given unit, sonic shows that the velocity velocity. The layer is a shale unit (3000m/s)
has the time, the tools and the experience varies vertically. The interval velocity is an truncated by a sand channel (4000m/s).
to do the agreed-upon workflow. Ultimately, integration of these local vertical variations. Facies is one of the key factors to control the
it’s all a team effort. It doesn’t matter who is Well tops are all we need to compute an distribution of velocity in a geological unit.
pushing the buttons on a computer, as long as interval velocity. The depth of top horizon This lateral change of facies has an impact on
the job gets done. and of the bottom horizon are known (by the geometry of the seismic horizon of HrzC
definition). As the well has been converted to (Figure 2B). Where we are in the sand, the
TIME-TO-DEPTH CONVERSION time, the time two way-time (TWT) is known layer appears thinner, in the time domain, than
Time-to-depth conversion means that each too. The interval velocity is the ratio between where we are in the shale; while in the depth
seismic data point in the time domain will be the delta-depth and the delta-TWT. If the domain, the thickness changes smoothly
given a depth coordinate. Each point keeps its interval velocity is more or less constant at between wells 2 and 3. In such a reservoir,
XY location. There is no lateral displacement, each well, an average constant interval velocity it is essential to properly capture the limit
only a vertical one. Such approach is might be assigned to the whole unit over the between the zone where the wells have an
insufficient in complex domains such as lease. This approach is also used when there interval velocity of more or less 3000m/s
structural plays or salt plays. There, depth- are too few wells to interpolate the interval and are in the shale, to the zone where the
migration and not time-to-depth conversion velocity on the map in any meaningful way. On wells are in the sand and show an interval
will likely be applied. This topic isn’t discussed the contrary, if we have enough wells and if velocity of 4000m/s. It means tracking the
hereafter. Only time-to-depth conversion is. the interval velocity varies from well to well, limit sand-shale between the wells and then
Readers interested in depth-migration can interpolation techniques are used to generate to interpolate the interval velocities within
refer for example to (Jones, 2010) for more an interval velocity map between the well each facies domain.
details. For more details about time-to-depth interval velocities. For every XY location,
conversion, the reader can refer to (Al- the interval velocity value from the map is
Chalabi, 2014). then assigned to every point of the seismic
cube at this coordinate. Having done this for
Well logs, such as sonic, are used to transfer
each geological unit, the seismic cube can
the wells to the time domain. A sonic log
be converted to the depth domain with all
quantifies the reverse of the instantaneous
the seismic interpretation. If only the seismic
wave velocity of the rocks in the vicinity of the
horizons need to be converted, it is done
borehole. Converting the wells to the time
directly from the interval velocity maps.
domain is also the time when the geophysicist
must decide which seismic event can be
associated with which well top. It guides the
seismic interpretation of the seismic cube;
that is to say the picking of the horizons Figure 2. Reservoir with a lateral change of facies and
velocity in the depth domain (A) and the time domain (B).
and faults from the seismic cube. Details on
how to integrate a seismic interpretation in All these approaches of computing velocities
geomodeling are covered in the two next at each well and then interpolating maps from
sections. Before doing so though, the seismic them can also be done in a geomodeling
interpretation must be converted to the package, if this is more convenient for the
depth domain. That’s where time-to-depth asset team to do so. Geostatistical algorithms,
conversion is being used. as introduced in the previous papers of
this series, are perfect for interpolating the
While sonic logs are being used to convert the
velocity maps. Not only to capture trends in
wells from depth to time in great details, sonic
Figure 1. Interval velocities (A) versus average the velocities, but also to generate multiple
is usually not used for converting the seismic
velocities (B). possible velocity maps, and so capture the
data to depth. It can be extremely challenging
velocity uncertainty between the wells.
to extrapolate sonic logs data between the
An average velocity is the mean velocity not
wells. It has the same level of uncertainty than No matter where these maps are generated,
between two horizons, as for the interval
extrapolating facies data or petrophysical data the geomodeler should make sure that these
velocity, but between the ground and a given
in 3D. Such an approach is sometimes needed maps do include all the wells needed for the
horizon (example, Figure 1B). Once the
though and the topic will be discussed in geomodeling workflow, and not only those
average velocity for a given horizon is known
more detail later in this section. used by geophysicist. In many projects, some
at each well, a map of average velocity is
wells might have facies and petrophysical logs,
Instead of defining the time-to-depth defined, either as a constant everywhere, or
but they might not have a sonic log. Such wells
conversion from the sonic log, interval using interpolation techniques. The average
would not be converted to the time domain
velocities or average velocity are used. velocity maps are then used to convert the
by the geophysicist. It might be perfectly
seismic cube and/or interpretation to the
An interval velocity is the mean velocity fine for seismic interpretation: once the
depth domain.
between two horizons at a given XY location. time-converted wells have confirmed which
Interval velocities are computed along each Interval velocities are preferred to average seismic event shall be picked, the interpreter
well. Figure 1A illustrates the concept with velocities for units with lateral changes of can follow these events in the whole cube,
interval velocities computed for the shallow interval velocity (Figure 2). In this example, even around wells without a sonic log. The
(... Continued on page 16)
RESERVOIR ISSUE 11 • DECEMBER 2015 15(... Continued from page 15) depth-conversion. But in many projects, the needs to decide if that was the intention or
geophysicist might have the reflex, or be team might not have the time for that. The if a different approach is needed. Creating
forced by his software, to create the velocity geophysicist might have been already assigned a map showing the difference between the
maps only from the time-converted wells. to some other tasks (or projects)...or the final original and the corrected geometry is a nice
As a result, the depth-converted horizons, deadline for the whole project might be too way to understand how the geomodeling
while fitting nicely to the wells with sonic, close to provide an opportunity to redo the process modified the map exactly.
may not match to the wells without sonic. depth-conversion.
Instead of interpolating the depth values
Such mismatches can be cleaned in the If the mismatches are large, it is still directly, we suggest another approach which
geomodeling workflow, as discussed in the recommended to adjust the velocity model better respects the geometry of the seismic
next section, but it might be more elegant to and redo the depth-conversion. But if interpretation: create a map of the adjustment
create the velocity maps from all the wells mismatches are reasonable, then they can be you need to apply to the seismic horizon map
in the first place, as well tops are all that is fixed directly in the geomodeling package.The (Figure 3A, blue line) to get it to fit to the
required to compute interval and average technique, described hereafter, can probably markers. Then move the seismic horizon map
velocities. Sonic is not needed. be applied in many geophysical packages. with this adjustment map.
While illustrating the concept of lateral The first step of this workflow is to compute
change of velocity, Figure 2 was also the mismatch between the original seismic
overly simplistic. In many reservoirs, the map and each well marker. In our example
heterogeneity is such that facies do change (Figure 3A), the mismatch at well 1 is
both laterally and vertically, in very complex +1.2m, the mismatch at well 2 is +0.9m and
ways, and difficult to predict from wells. the mismatch at well 3 is -0.6m. A negative
The velocities in such geological units might number means that the marker is deeper than
be better defined by creating geomodeling the surface at this location.We now know that
3D-grid in the time-domain. A 3D facies the adjustment map must have the value +1.2,
model can then be built with geostatistical Figure 3. A) Original (blue) vs marker-adjusted (red) +0.9 and 0.6 at the respective XY locations
algorithms, and then the velocity can be seismic interpretation. B) Adjustment map needed to of wells 1, 2 and 3 (Figure 3B). We also
modeled by facies. In such reservoirs, it might correct the mismatch observed in (A).
decide that the adjustment must be null past
be necessary to interpolate sonic logs by In Figure 3A, a seismic interpretation (blue a certain distance from each well location. It
facies instead of interval velocities, to really line) has been depth-converted using the means that outside of areas centered at each
capture the heterogeneity. This geomodel will three wells 1, 2 and 3. The interpreted well, we don’t want to modify the original
create multiple cubes of velocity for this unit, horizon is close to the well markers but a seismic map.
each one representing a possible distribution mismatch remains. Should it be corrected? A
of the facies and the velocity in 3D. Overall, The second step of this workflow is to
general rule in geomodeling is that if well data
geomodeling packages are better equipped define the radius of these areas. More details
and seismic data are partly in contradiction,
than geophysical packages to do such complex will be given in a later paragraph. Once the
the well data shall be respected in priority
time-to-depth conversions. radius defined, we know the displacement
because well data are more precise than
at each well and we know the displacement
SEISMIC INTERPRETATION AND seismic data. In the process of adjusting to
is 0m beyond the radius. All that remains to
STRATIGRAPHIC MODELING the well, we try to respect the seismic data
do is to use some interpolation technique
as much as possible. Naturally, if well and
When depth-converted seismic horizon data to extrapolate a decreasing displacement
seismic data are in complete contradiction,
are available, the geomodeler must consider from each well toward the limit of its
it is wiser to understand ‘why’ instead of
how to integrate the data into the model. associated area. On Figure 3B, it is illustrated
enforcing this rule blindly. Once the source
He must create horizon surfaces which by a bell shape around each well. Lastly, the
of the inconsistency is identified, the team
respect both the seismic interpretation and displacement map is added to the original
might agree that the data can be corrected to
the well markers. Even when all the wells, seismic horizon. The resulting, corrected
make them coherent one with the other, or
with or without sonic, are used for time-to- horizon is equal to the original map far from
the team might decide that the inconsistency
depth conversion, it is rare that the seismic the wells (= outside of the pre-defined radial
is the result of different interpretations (for
interpretation matches precisely to the well zones around each wells) while the horizon
example). In that case, several geomodels
markers. The reasons are many. The velocity has now changed around each well. Each
might be needed, one for each interpretation.
maps might not have respected exactly the marker is now respected while keeping the
For the purposes of this section, we assume
velocity value at each well. The time-depth overall geometry of the seismic interpretation.
that it makes sense for our dataset to modify
conversion itself, once the velocity is modeled, the seismic horizon to fit to the well markers.
might not have been exact either. This is not
as rare as one might think. The reason might One might be tempted to simply create a
be also a question of timing in the team. Some surface from the seismic interpretation and
well locations or some well KB elevation then adjust this map directly to the markers.
might have been adjusted after the depth- By doing this, we mean using the depth of
conversion was done. Similarly, the geologist each marker to adjust the depth of the map.
might have modified slightly the markers Such an approach might be risky. While the
interpretation after the velocity maps were markers will be respected, it is also very likely
completed. At last, some wells might have that the whole surface will be completely
been drilled after the seismic data got depth- smoothed out even far from the wells. The Figure 4. Effect of using different radius to compute the
adjusted map might look very similar to the adjustment map. A) map resulting to three different radii
converted. Or it might be a combination (small, medium or large). B) map resulting from using at
of all these events. In a perfect world, the map we could generate from the markers each well a radius function of the local mismatch.
geophysicist would systematically redo the alone. If it happens, at the least the team
16 RESERVOIR ISSUE 11 • DECEMBER 2015As illustrated in Figure 4, the challenge is to wells. When this happens, it is recommended only from the well markers. The mismatch
decide what radius to use around each well. In to treat such horizon as we did here with between the two maps tells us how incorrect
this example, the mismatch at well A is half of Horizon A, and then create horizons for the – that is to say how uncertain – our map of
the mismatch at well B. If we use a very small real stratigraphic tops (= the horizons we do Horizon A from the markers alone is. On
radius for both wells (Figure 4A, black thin need for the 3D-grid) following the approach Figure 5, the error is reasonable between the
line), the adjustment zone is really narrow proposed here for Horizon B. wells (yellow color), while it is very large to
and the corrected horizon surfaces might the east beyond well 3. One might assume
Other horizons known only from well
show an obvious bullseye around each well. that a similar range of uncertainty would have
markers are simply not conformable to any
Using a medium-size radius (Figure 4A, red been found around Horizon C if it would
horizon picked on seismic. Such horizons can
dashed line), the bullseye effect might be less have been possible to pick it on seismic. If we
only be modeled from the well markers. No
noticeable, and so acceptable, around well A, accept this assumption, we can simply assign
seismic horizon, such as Horizon A, can be
while it might still be too visible around well the uncertainty map from Horizon A onto
used as a reference. In Figure 5, this is the case
B. At last, using a large radius (Figure 4A, green Horizon C (Figure 5, vertical thick arrows).
of Horizon C.
thick line), the bullseye effect might now be
Many geomodeling packages have tools to
minimal on both wells, but the question might
create multiple versions of a given horizon,
become that we are altering a too large
each version being a variation around a
portion of the seismic maps around each well.
base case geometry. The tool is fed with
Ultimately, this is all a trade-off that the an initial geometry of the horizon (Figure
team must agree upon. If some mismatches 5, the interpolated Horizon C map from
are really too large or the bullseyes are too the well markers) as well as an estimate of
visible, then, as mentioned earlier, it might the range of uncertainty (Figure 5, the map
be wiser to redo the depth-conversion. An of mismatches computed on Horizon A).
alternate approach might be to use different Each variation is slightly different from the
radii for each well (Figure 4B). The idea is to reference surface, but all surfaces fall within
select a radius proportional to the absolute the range of uncertainty pre-defined by the
value of the mismatch: the more important uncertainty map. In Figure 5, a few possible
Figure 5. Modeling horizons from seismic interpretations
the mismatch, the larger the radius. In Figure and/or well markers and managing the uncertainty variations of Horizon C are represented in
4B, we could use a medium radius around well associated to the model. thin dark lines.
A and a large one around well B.
Another use of seismic interpretations is for
Once surfaces are created for each horizon on quantifying the uncertainty on the geometry
the well markers and a seismic interpretation of the horizons. Horizons A, B and C illustrate
exists, the geomodeler can continue taking different type of uncertainty geomodelers
advantage of the seismic interpretation in two have to consider.
ways, both illustrated in Figure 5.
Horizon A is the best defined horizon as it
Figure 5 is an extension of the example was visible on seismic. There are still two
presented in Figure 4. Horizon A is the one sources of uncertainty though: uncertainty
for which a seismic interpretation existed, and in the picking itself in the time domain and
got adjusted to the well markers at wells 1, uncertainty in the depth-conversion (or
2 and 3. For the horizons B and C though, depth migration as discussed at the beginning
there is no seismic interpretation, only well of the previous section).
markers.
Horizon B was created from Horizon A. As
In many reservoirs the horizons, or a subset such, it inherits all Horizon A’s sources of
of them, might be conformable, one with the uncertainty. An additional uncertainty must
other. If one of these conformable horizons be considered too: the uncertainty on the
has been picked on seismic, then it can thickness of the unit between Horizon A and
be used as a reference to model the other Horizon B.
horizons. In Figure 5, Horizon B is interpreted
Horizon C, at last, is only known from well
as conformable with Horizon A. We can use
markers. As such, we have no real idea of
the geometry of the Horizon A to model the
how uncertain the interpolated surface is. Of
geometry of Horizon B. A thickness map of
course, mathematically, we can run different Figure 6. Reservoir in which the horizons are defined
the unit between Horizon A and Horizon B
scenarios for this horizon, but which scenario from seismic and from well tops. A) traditional approach
is interpolated from the thickness at each
bound to the uncertainty shall we use? +/- to build the mesh of the 3D-grid (horizontal mesh).
well (using geostatistical algorithms). Then, B) modern approach integrating local seismic events
5m? +/- 50m? More maybe? A solution is to
the geometry of Horizon B is calculated by interpreted in the reservoir.
define the range of uncertainty on Horizon C
subtracting the thickness map to the depth
from Horizon A with the following approach. Up to this point, this section focused on
map of Horizon A.This is a first additional way
to take advantage of a seismic interpretation. Firstly, we create a new surface for Horizon integrating “traditional” seismic horizon
Sometimes, none of the seismic events they A only from well markers. Such geometry is interpretations. By “traditional”, we mean
can interpret correspond to any of the illustrated in a dashed blue line on Figure 5. surfaces that can be picked across the whole
stratigraphic markers interpreted by the We now have two geometries for Horizon seismic cube such as Horizon A on Figure 5.
geologists on the wells.These events are linked A: the surface made from the seismic and In the last few paragraphs of this section, we
to other change of log signatures along the the well markers and the geometry made are considering the integration of the smaller
(... Continued on page 18)
RESERVOIR ISSUE 11 • DECEMBER 2015 17You can also read
