Denver Well Logging Society

November 2017 Newsletter

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Mixed Reservoir Wetting in Unconventional Reservoirs and Interpretation of Porosity/Resistivity Cross Plots, Derived from Triple-Combo Log Data

Michael Holmes
Digital Formation


In a prior publication (Holmes 2016) methodology was presented to define porosity components that are water wet and those that are oil wet. Data were included showing the effective porosity in clean formation is water wet and that porosity associated with organic material is oil wet. It is postulated that organic porosity is of a secondary nature, created during the maturation process as oil is generated from the organic component. Glorioso (2012) gives SEM examples of secondary porosity associated with total organic carbon.

Included in the Holmes publication are examples of porosity/resistivity cross plots (Pickett Plots) for effective porosity and organic porosity.

As wettability to oil increases, the Archie saturation exponent (n) also increases (Keller 1953, Sweeney and Jennings 1960, Ransom 1995). Interpretation of Pickett Plots involves recognition of linear alignment of data. The slope of the data is a direct measure of the difference between cementation exponent (m) and saturation exponent (n). This interpretation is a consequence of the Buckles (1965) relationship:

          Porosity x Irreducible Water Saturation = Constant

For a number of different unconventional reservoirs it was shown that the effective porosity is consistently water wet and the organic porosity is oil wet. In addition, the data indicate the organic porosity has consistently low to very low values of the Archie cementation exponent (m) suggesting linear flow paths.
This publication extends the interpretation to include porosity/water saturation relationships for the two wetting porosity categories. Data are presented on a log/log plot. Levels at irreducible saturation will fall on a straight line. For the Buckles relation to hold, the slope of the line is 1.0.

Data are presented for wells from the Bakken, Niobrara, and Permian Basin. In all cases, the effective porosity is interpreted using the Buckles relation with of the constant in the range of 1 to 3 percent. Also, many intervals show water saturation larger than irreducible water saturation, indicating mobile water. For the organic porosity, the data align on very consistent slopes suggesting little or no mobile water. Additionally, the values of the Buckles constant are very low, always less than 1 percent and frequently less than one-tenth of one percent. This result is consistent with the interpretation of oil-wet systems in the organic porosity fraction.


Speaker Biography

Michael Holmes has been involved in oil and gas exploration activities for 57 years. He started his career with British Petroleum working in England, Libya, East Africa, and the North Sea.  He then joined Shell Canada, working the west coast offshore Canadian Basin.  Subsequently he was with Marathon Oil Company, research division, and Berry Wiggins, UK.  For the past 30 years he has been in all aspects of exploration and exploitation activities worldwide, with particular emphasis in petrophysics.  In 1994 he formed Digital Formation, Inc., a consulting and software development company, with his two sons as partners.  Dr. Holmes has a BSc and PhD degrees in geology from the University of London, and an MSc in Petroleum Engineering from the Colorado School of Mines.
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Forward this newsletter to a friend to invite them to the luncheon.


Tuesday, November 14, 2017
Note this is a week earlier than usual to avoid the week of Thanksgiving!
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 Talk (January)

Alan Byrnes

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 Director of Social Events

Jesse Havens

Remember our holiday social is just around the corner! We will be holding this year's holiday party at the Rialto Cafe on Tuesday, November 28th from 4:30 - 6:30 pm. For a $10 door charge, food and beverages will be provided and the Rialto Cafe is offering $4 discounted parking passes to the Independence Plaza underground Structure located between the 16th street mall and 17th street.

Please register by November 22nd to reserve your spot at this once a year opportunity. Note that spouses and colleagues are welcome to register too!

See you there!

From the VP - Membership

Stefani Brackenoff

If you are not a LIFETIME MEMBER or a NEW MEMBER, please go pay your yearly dues on the website!

If you are an annual member and have not paid by December you will no longer be getting the monthly newsletter. If you don’t know what kind of member you are please email me and I will let you know your current status!!!!!

Also, if you haven’t updated your contact info, you have till the Holiday party to do so to get the FREE copy of the Historical Logging Charts CD. Please email the following information EVEN IF you think that your information hasn’t changed as it probably has since you updated your DWLS details! :)

Mailing Address:
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Happy Fall!

From the President

Sam Fluckiger

Fall is in the air and we’re back into the swing of things with our monthly talks.  Thanks again to Lauri Burke and Patrick Hayes for presenting during our September and October luncheons.  In particular I enjoyed the talk on unconventional moon rocks which was a unique experience for all that attended. Not only did we get to take a look at some extremely rare rocks but we also gained a bit of street cred when several of the regular Wynkoop patrons took notice of the number of police officers heading in to the back room for the presentation.  The reality was that the officers were there to provide security for the moon rocks but I figured we’d let those out front think it was because we’re a pretty rough crowd.  Last month we announced the date and time for our holiday season social at the Rialto Café so be prepared to get together and help keep our reputation going.

I would also like to take this opportunity to remind all about the Robert M. Cluff memorial scholarship announced in September which supports graduate students specializing in Petrophysics and/or Reservoir Characterization.  This provides a great opportunity to support the younger generation interested in developing skills sets in our field of expertise.   I look forward to interacting with all of you during our various technical and social events this fall and with that I’ll leave you with a parting thought and a quote.  As we transition from summer to fall and then in to winter we recognize and accept the inevitability of change.  Our industry has seen significant change in recent years and continues to evolve today.  How we adapt to these changing times will be key to our success going forward.  I won’t claim to have the answers but I do like the following quote:
“Without change there is no innovation, creativity, or incentive for improvement.  Those who initiate change will have a better opportunity to manage the change that is inevitable” – William Pollard

Calendar of Events

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

Other Important Events

2017 SPWLA Fall Topical Conference, November 1-2, 2017 (Houston, TX) - Quest for Quality Data in High Angle/Horizontal (HAHZ) Wells
2018 SPWLA Annual Symposium, June 3-6, 2018 (London, England)

The Discovery Group
MHA Petroleum Consultants
Digital Formation
Donovan Brothers Incorporated
Mount Sopris Instruments

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 * 278 375
# that are New members 3 12
# that are Students * 7 11
# that are Lifetime Members * 257 311
September luncheon meeting attendance 53 60
October luncheon meeting attendance 33 71
November luncheon meeting attendance   60
Holiday party attendance   44
January luncheon meeting attendance   65
February luncheon meeting attendance   67
March luncheon meeting attendance   53
April luncheon meeting attendance   54
May luncheon meeting attendance   49
Summer social attendance   22
* Note that we did a thorough cleanup of bad email addresses that resulted in some of our members being removed until they can be tracked down again.  So this year's membership numbers are going to be a bit lower.
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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