Denver Well Logging Society Chapter of the SPWLA

Meeting Information

"Application of NMR for Evaluation of Tight Oil Reservoirs"

Richard E. Lewis
Petrophysics Technical Manager, Unconventional Resources

The reservoir quality (RQ) of gas shale reservoirs can be equated to the amount of kerogen or Total Organic Carbon (TOC) because the majority of the producible pore volume is hosted in the organic matter (OM pores). Determining the RQ for a tight oil is more difficult due to 1) the presence of two hydrocarbon types at reservoir conditions--high-viscosity, low-maturity bitumen and light oil; plus 2) the presence of pore systems hosted within the inorganic matrix (IP pores).

Comparison of paired core and log NMR measurements from the Eagle Ford and other shales indicates that a portion of the pore fluids that are measured with the log are not present in the core sample. This pore volume has been expelled during core extraction and storage. The remaining pore volume is generally not producible, and this hydrocarbon fraction represents either bitumen or oil sorbed to the OM pore walls. The difference between the two pore volumes has proven to be an acceptable proxy for the determination of producible pore volume, and a primary challenge is to differentiate between the water and hydrocarbon fractions. This is currently performed through core NMR using fluid reinjection.

Jarvie (2012) introduced an index (Oil Saturation Index) to highlight producible zones within a tight oil reservoir. It is based on RockEval analysis, and it is the ratio of producible oil (S1) divided by all hydrocarbons as measured by this technique (S1, S2, and S4). This total includes the carbon in light oil, bitumen, and kerogen. The higher the ratio the higher the RQ. Higher RQ can be caused by 1) conversion of bitumen to light oil, or 2) migration of light oil from OM to IP pores—a hybrid reservoir. We have adapted this index for in-situ log measurements and have adjusted it to award intervals with higher weight % light oil. In contrast to a gas shale, the intervals with a lower kerogen content are generally more prospective. Examples from the Bakken, Eagle Ford, Woodford and several  international shales will be presented.

The exclusive use of a T2 distribution limits ones ability to differentiate between pore hydrocarbon phases, pore type (OM vs. IP), and pore fluid (water vs. oil). The addition of T1 distribution permits one to quantify bitumen (above a lower T1/T2 bound) and differentiate between OM and IP pores up to intermediate T2 relaxations. An enhanced logging service that measures both T1 and T2, and which is also optimized to provided better accuracy at lower T2 relaxations, is currently undergoing field tests.

About the Speaker

Richard (Rick) Lewis is the developer of the gas shale evaluation workflow that was initially fielded thirteen years ago and has been applied to more than 4000 wells in North America and abroad. In his current position, located in Denver, Rick manages a small group responsible for the continual improvement for this workflow, for its introduction and application to the international market, and for the development of workflows for the evaluation of liquids-producing shales.

Rick is also the interface to the Schlumberger research and engineering groups for the development of evaluation technologies for unconventional reservoirs. Prior to this assignment, he was responsible for wireline interpretation development for the central and eastern United States. Rick has also worked for Shell Oil and the U.S. Geological Survey.

Rick received a BS degree from UCLA and MS and PhD degrees from Cal Tech, all in geology.

From the President

Suzanne Heskin

I hope you all had a fantastic summer filled with hiking, biking, camping, or your favorite Colorado activity!  It went quickly for me, and my daughter is already an old pro at being in the first grade!  DWLS Season is upon us, time to focus on sharing knowledge and improving ourselves professionally again.  Hopefully some or many of you were able to attend the SPWLA symposium in CA, or URTeC in TX.  These conferences continue to be vital to the health of the industry, especially in downturns such as this.  I invite any of you who attended to share with those who didn't.  Share ideas, thoughts, papers, CDs, suggestions for speakers as well.

Bob Cluff worked over the summer to line up some high quality speakers for the fall, and I hope attendance remains as high as it was last year, if not higher.  Bring coworkers or friends to our meetings who haven't attended before and perhaps our membership can grow a bit this year.

Moving forward into the 2015-2016 year, please feel free to approach any board member if you have concerns, suggestions, or compliments!

Thanks, welcome back, and I look forward to seeing everyone soon!


From the Vice President - Technology

Bob Cluff (The Discovery Group)

We're off to another exciting year for DWLS.   My plan for 2015/16 will be to combine selected technology/tool talks from the major service providers with interpretation and case history talks on the 5 or 6 major tight reservoir plays.  In these economically challenging times most operators are focused on just a small number of key play opportunities with the best economics, and I'll follow the crowd and try to focus our attention on those key plays.  Nonetheless, new technology is our lifeblood and it's important we stay on top of new developments as they occur.

I have lined up for us two talks this Fall from the 2015 SPWLA conference in Long Beach on NMR applications to tight reservoirs (Rick Lewis in September, and Margaret Lessenger in November), and a third on advanced logging measurements and core data from the Bakken play (Gary Simpson in October).   I'll also be drawing from recent papers presented at URTeC and AAPG to fill out the Spring 2016 program.  If you attended any of these summer conferences and saw something you think is particularly appropriate for the chapter, please contact me right away and let me know – I can't see every paper!

Plans for the DWLS Fall and Spring workshops will be forthcoming shortly.   There might be some changes in the planning.


From a Vice President - Membership

Aaron Fisher (Tracker Resources)

Hello everyone!

Fall is shortly around the corner which means that the yearly renewal process is upon us.  Those of you who have not renewed your yearly dues will be receiving a friendly reminder from me with renewal instructions soon.  If you would like to be proactive, please follow the link: (  All active members are given a three month grace period to renew their membership.  November marks the end of the grace period.  On a positive note, the low commodity prices have not hampered membership as we are up to 370 active members, of which 307 are lifetime members.

There has been a lot of turnover in the industry in the past six months.  Please be sure to send you updated contact information ( so we can keep everyone current.  Don't miss out on hearing about the holiday party, spring workshop, and all the monthly talks.


From a Director (Monthly Beverage Sponsorship, and Social Events)

Bryan Page (Weatherford)

The drinks during our monthly lunch meeting are traditionally sponsored by a company or organization. This practice serves several worthy objectives. First, it encourages people to arrive on time, because after 11:30 no free drink coupons are issued, second it creates a good social atmosphere prior to the talk, and third it gives the sponsor the opportunity to promote their organization in the DWLS monthly newsletter and at the monthly meeting. Therefore we encourage our members to sponsor these drinks or contact their marketing department to do the same.

For more information or to save your spot, please contact Bryan Page


SPWLA Events

2016 Annual Symposium, June 25-29, 2016 (Reykjavik, Iceland)

Meeting Details

Beverage Sponsor
Please thank Schlumberger for sponsoring the free beverage tickets this month (beer, wine or soda)!

11:20 am - 1:30 pm
Wynkoop Brewing Company
(tell me how to get there)
$20 per person
$25 at the door (space permitting)
Must be made on-line at before 5 PM on Thursday, . Or click below to go directly to PayPal.

Please note that the room has a maximum capacity of about 100 people. We have generally allowed walk-ins in the past. However, if we approach this limit with paid reservations, walk-ins will be turned away!
Cancellations must be made no later than 5 PM the Friday prior to the talk, or you will be responsible for the full cost of the luncheon!  or contact Kim Mosberger at 303-770-4235.  Our full cancellation/wait list policy is available on the website.
Luncheon Talk
"Using advanced logging measurements to develop a robust petrophysical model for the Bakken "

Gary Simpson

Calendar of Events

Click to view the calendar on the web.

Chapter Statistics


This Year


# of Active
370 345
# that are
New members
3 27
# that are
11 9
# that are
Lifetime Members
307 275
September luncheon
meeting attendance
October luncheon
meeting attendance
November luncheon
meeting attendance
December holiday party attendance   59
January luncheon
meeting attendance
February luncheon
meeting attendance
March luncheon
meeting attendance
April luncheon
meeting attendance
May luncheon
meeting attendance
June summer social attendance   31



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