Denver Well Logging Society

February 2017 Newsletter

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A New Rock Type Based Evaluation Method for Unconventional Reservoirs

Robert Lieber
Corsair Petrophysics 


The use of measured capillary pressure curves to determine saturation based on height above free water level has long been used as the best in class analysis methodology for understanding hydrocarbons in place as well as reservoir deliverability in conventional reservoirs.  The use of rock types, each with a unique capillary pressure relationship, is the preferred method of capturing reservoir heterogeneity and for computing irreducible water saturation for the creation of static and dynamic reservoir models.  In unconventional reservoir this approach has proven more challenging as fluid saturation is not controlled by the current rock based measured capillary pressure relationships.  This has led to the industry, for the most part, to use more electrically based analysis (such as embodied in the Archie relationship) even though the rocks being analyzed do not fit the characteristics in a classic Archie rock type.  In addition these conventional work flows ignore fine scale variations in rock properties that are well documented in unconventional reservoirs which are well below log resolution.  This paper proposes a methodology where unconventional rock types are defined by clay volume, porosity, and water saturation based on core measurements that more accurately represent the storage capacity of these reservoirs.  While the rock type approach is very core dependent, the industry has gathered tremendous volumes of core data which for the most part is highly underutilized once an initial reservoir evaluation has taken place.  This method does require that we gather more core data, but rather that we use our existing data more rigorously.  The issue of matrix deliverability is discussed, but until the physics of fluid flow in nano-pore systems is better understood prediction of matrix efficiency will remain an enigma.  The use of a rock type based method for unconventional reservoirs allows a better predictive ability for field wide hydrocarbon pore volumes since rock types are based on depositional and digenetic processes which are at least partially understood rather than simple trend maps based on calculated porosities and fluid saturations which depend on assumptions which are not based on any relevant physical understanding.  Adoption of this new approach will lead to improvement of our understanding field wide productivity and allow for the delineation of sweet spots essential for the economic viability of unconventional reservoirs. 


Speaker Biography

Robert Lieber is a petrophysicist with over thirty-five years of varied petrophysical experience in domestic and international offshore and onshore basins with a focus on challenging reservoirs.  Bob has split his career between operating companies and consulting activities from supermajors to one off consulting projects.  Bob is currently with Corsair Petrophysics as a consulting petrophysicist where he splits his time between technical activities and mentoring the next generation of petrophysicists and integrators.  Bob has a long track record in integrated reservoir studies with emphasis on seismic reservoir characterization.  He also has extensive experience with workstations and computers relating to log analysis, geological mapping, and stratigraphic modeling using seismic attributes and geostatistics.  Bob is a former SPWLA Distinguished Lecturer, an AAPG Certified Petroleum Geologist, past president of the SPE GCS Reservoir Study Group and a member of the SPWLA and SPE.  He has published numerous papers in the SPWLA, AAPG, GCAGS and GSA on a variety of topics dealing with reservoirs of both conventional and unconventional natures.  He has given talk to SPE, SPWLA, GSA, and SEG sections all over the world.
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Forward this newsletter to a friend to invite them to the luncheon.


Tuesday, February 21, 2017
11:20 am - 1:30 pm


Wynkoop Brewing Company
(tell me how to get there)


$20 per person
$25 at the door (space permitting)

Next Month's Talk

Techniques to compute Total Hydrocarbon in Place in the Bakken using low and high field NMR
Ravinath Kausik
Schlumberger-Doll Research

Reservations and Cancellations

Reservations must be made using the PayPal link above or on the DWLS website; reservations must be made by 5 PM the Thursday prior to the talk. Cancellations may be made until 5 PM the Friday prior. Email your cancellation or contact Dominic Holmes at 303-770-4235. Our full cancellation/wait list policy is available on the website.

From the President

Bob Lieber

As a petrophysicist who has worked both conventional and unconventional reservoirs on of the most common questions I get is “What do you do differently to analyze unconventional reservoirs?”  In this year’s Spring Workshop we have assembled an impressive array of experts to address that very question.  Each expert will address the workflow they use for different types of data.  It should be an instructive day of talks, new ideas and time for Q&A.  In appreciation of the state of the industry we have kept the price at last year’s level of $225 for non-members; $175 for DWLS members.  It also gives you a full day to network with colleagues and find out what other folks are doing with unconventional reservoirs.  I hope to see you there on March 23rd at 7:30 for registration and a continental breakfast!

From the Past President

Katerina Yared (standing in for Suzanne Heskin)

It is that time of year again where we start recruiting for the next generation of DWLS Board members 2017/2018. We invite everyone that would like to contribute to our ever growing society as a board member to email me or approach anybody on the board.

The DWLS provides workshops, lunch and learn seminars and networking opportunities for everyone, and it has been doing it successfully for years thanks to volunteers that keep "the engines" going. You can help the DWLS continue its mission to provide expertise and support for our local oil and gas community and beyond by offering your time as well.

If you have any questions in regards to any position on the board please let me or any other board member know. Don’t miss this opportunity to contribute to a great society!

Thank you very much!

From the Editor

Dominic Holmes

Robert M. Cluff Scholarship

The RMAG Foundation has established the Robert M. Cluff Scholarship for Petrophysics and/or Reservoir Characterization in honor of Bob for his vital participation in RMAG and the broader community, his technical expertise, the generosity with which he shared that expertise, and his dedication to his friends and colleagues.  Contributions can be made online from the RMAG Foundation website ( or with a check to:

RMAG Foundation
Independence Plaza B-180
Box 165
1001 17th Street
Denver, CO. 80265

Please note 'Cluff Scholarship ' in the memo section of the Check.  Donations and company matches are tax-deductible.

Thank you for your generosity.

From the Webmaster

Tony Holmes

It is that time of year again to remind our members where to find various items we have available for sale; please visit:

Our stock of workshop books is dwindling, so do not delay, get yours now if you were unable to attend the event. As you are probably aware, the cost to produce the workbooks is significant, and at these prices do not really provide income to the DWLS. We provide them at these costs to get the information out, and to be honest to clean out our closets. Come give us a hand and buy some stuff!

Calendar of Events

Click the calendar to the right to view events on the web.

Other Important Events

2017 SPWLA Annual Symposium, June 18-21, 2017 (Oklahoma City, OK)

DWLS Sponsors

Click here to view the sponsors on the website, or click on any image to contact a sponsor.
Standard Data Solutions
Graphic Controls
Digital Formation
Donovan Brothers Incorporated
Mount Sopris Instruments
The Discovery Group
MHA Petroleum Consultants
Stoner Engineering LLC

Chapter Statistics


This Year

3-Year Average

# of Active members 375 362
# that are New members 18 16
# that are Students 12 11
# that are Lifetime Members 316 299
September luncheon meeting attendance 38 75
October luncheon meeting attendance 69 66
November luncheon meeting attendance 38 76
Holiday party attendance 46 48
January luncheon meeting attendance 71 79
February luncheon meeting attendance   76
March luncheon meeting attendance   70
April luncheon meeting attendance   59
May luncheon meeting attendance   59
Summer social attendance   31
The DWLS Newsletter is published monthly September through June by the Denver Well Logging Society.  For information on membership or advertising, contact the editor.  For other inquiries, contact a member of the Board of Directors.
Copyright © 2017 Denver Well Logging Society, All rights reserved.

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