Denver Well Logging Society

April 2017 Newsletter

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Assessing Reservoir Quality in Tight Oil Plays with the Downhole Reservoir Producibility Index (RPI)

Erik Rylander


Methods for formation evaluation in unconventional reservoirs are evolving quickly as better optimized logging methodologies are being developed.  In gas-producing shale reservoirs, reservoir quality (RQ) is strongly correlated to the total organic carbon (TOC) content, because the kerogen, composed largely of organic carbon, hosts the pore system necessary for storing and transporting gas.  In tight-oil formations, however, TOC alone is not as strongly correlated to RQ because storage and transport through inorganic pores can also be significant.  Instead, the volume of oil—the only producible organic component in tight oil plays—is considered a dominant factor impacting RQ, while the immobile organic components (kerogen and bitumen) are typically neglected.  It has also been argued that immobile components are not inconsequential, but are actually negative RQ indicators in tight oil plays because they can adsorb oil, swell, and clog pore throats.  Indeed, methods to assess RQ in tight oil formations based on cuttings and core analysis, where the oil content is considered a positive RQ indicator and the immobile organic content is considered a negative RQ indicator, have been proven valuable in many formations such as the Bakken, where the organic-lean Middle Bakken and Three Forks are generally completed instead of the organic-rich Upper Bakken and Lower Bakken.  However, surface measurements alone are inherently limited because the oil content of cuttings and cores from tight-oil formations may be unrepresentative of reservoir conditions due to core alteration, evaporative losses, etc.  Here we present a new metric for evaluating RQ in tight-oil formations, the Reservoir Productivity Index (RPI).  The RPI accounts for the positive RQ properties of oil and the negative RQ properties of immobile organic carbon, and it avoids challenges regarding representativeness because the oil content and other measurements are based on in-situ logs (principally NMR and nuclear spectroscopy).  A term representing richness is included in the RPI, making this metric a single value that captures many of the factors describing tight oil RQ without requiring extensive log interpretation.  Several examples of the use of the RPI for evaluating RQ in tight oil plays are shown.

Speaker Biography

Erik Rylander is a Principal Log Analyst for the Production Technology Integration Center of Oilfield Services located in Dallas, TX.  Erik is part of a group responsible for the continual improvement of shale analysis workflows, and for its introduction and application to the domestic and international market.  Erik’s has been a petrophysicist focusing on organic shale reservoir characterization for 12 years.  Erik has been with Schlumberger for 21 years and began as a wireline field engineer in W. Africa and the Gulf of Mexico.  Erik has held an operations management position in the Gulf of Mexico and a marketing role at Schlumberger’s product center in Clamart, France where he focused on the application of dielectric logs.  Erik has been an author or co-author on 16 papers and hold five patents related to formation evaluation.  He received his BS degree from the Colorado School of Mines in engineering.
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Tuesday, April 18, 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


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 Past President

Katerina Yared (standing in for Suzanne Heskin)

Dear DWLS members, this our last call for volunteers to come forward and be part of our great community. If you would like to be part of our DWLS 2017/18 board please email me or come talk to me directly, I don’t bite.

Again I would like to thank all the volunteers of the DWLS BoD 2016/17 for their dedication and support of our society and for delivering value to our members. THANK YOU!
Thank you all and auf wiedersehen.

From the President

Bob Lieber

Standing on the Shoulders of Giants

On January 24th 2017 our industry lost another petrophysical giant.  Don Luffel passed away at the age of 89.  If you work on any mudstone reservoir from the Niobrara to the Marcellus to the Wolfcamp you owe Don more than you can imagine.  Don Luffel not a name you are familiar with?  Well that is not a surprise.  Don was an extremely gentle and humble man who had multiple careers within the petrophysical world.  It was Don who in 1992 published SPE Paper 20571 New Core Analysis Methods for Measuring Rock Properties of Devonian Shale.  What we now call GRI or crushed rock analysis was pioneered by Don and others under the sponsorship of the Gas Research Institute (GRI).  If you have never read that landmark paper you owe it to yourself to download a copy and read it.  Imagine a world without core analysis to use to calibrate your petrophysical model.  Not a pretty thought.  So much of what we do is based on fundamental work by giants of the industry who chose not to have their methods named after them.  Don certainly was within his rights to term his workflow the “Luffel Method”, but when I asked him about that once he just smiled and said that wasn’t his style.  We all learn from our mentors, I learned so much from all of my mentors, most of whom are no longer with us, that I wanted to pass on a reminder to say thanks.  I hope you will take the chance to follow my advice as soon as you can.  Even giants pass away.

From the VP - Technology

Jack Breig

The annual Spring Workshop, entitled “Petrophysical Workflows in Unconventional Reservoirs”, was held March 23rd, 2017 at the Student Center at Colorado School of Mines. Ten presenters, representing a true cross-section of the petrophysical profession, discussed field studies using modern well logs, vintage data sets, cased-hole logs, geological core descriptions, and nano-technology to explore pore geometries and pore filling fluids. The workflows tackled issues like shale gas resource evaluation, mineralogical and facies identification, confirmation of net pay criteria, geomechanical property assessments for well completion and stimulation derived from image logs and acoustics, and even a review of advances in unconventional EOR projects, with gas cycling.

The audience of 95 was the largest to attend at DWLS workshop in many years.

We wish to thank the generosity of each of the speakers for making this workshop a success, as well as the DWLS volunteers, and Colorado School of Mines for hosting us, again.

Finally, planning for a Fall Workshop is officially underway.

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)
2017 RMAG/DWLS Fall Symposium, Geology and Petrophysics of Unconventional Mudrocks, September 27-28, 2017

Digital Formation
Donovan Brothers Incorporated
Mount Sopris Instruments
The Discovery Group
MHA Petroleum Consultants
Stoner Engineering LLC
Standard Data Solutions
Graphic Controls

DWLS Sponsors

Click here to view the sponsors on the website, or click on any image to contact a sponsor.

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 70 76
March luncheon meeting attendance 48 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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