Denver Well Logging Society Chapter of the SPWLA

Meeting Information

"Using Advanced Logging Measurements to Develop a Robust Petrophysical Model for the Bakken Petroleum System"

Gary Simpson
Hess Corporation

The Bakken petroleum system (BPS) can be considered a hybrid play because it is composed of both conventional and unconventional elements.  The conventional aspects include the presence of separate reservoir intervals (Scallion, Middle Bakken, Sanish and three Forks) and source rock intervals (Lower Bakken and Upper Bakken shales) along with more problematic intervals (Basal Bakken).  This is in direct contrast to most unconventional shale plays, in which a single lithology or stratigraphic interval comprises both the source rock and reservoir.  The unconventional aspects of the BPS include very low permeability conventional reservoir sections, as well as combined shale-rich source and reservoir intervals.  Additional complexity results from stacked depositional environments with significant variations in lithofacies, mineralogy, total organic carbon (TOC), and rock textures ranging from highly bioturbated to finely laminated.

Historically, development programs and petrophysical analyses in the Bakken were centered on a volume of shale calculated via deterministic models using triple combo log data that were focused primarily on the Middle Bakken reservoir.  Production type-curves generated from such analyses showed reservoir recovery factors that were inconsistent with actual production data as well as knowledge of the reservoir.  Additionally, rock mechanical properties used to model hydraulic fracturing performance and real-time measurements of microseismic events recorded during hydraulic fracturing indicated fracture height growth that extended into surrounding formations.

Based on these results, a series of science wells were drilled, cored over the entire BPS and logged extensively using advanced logging devices to better understand the overall system.  Results from these wells provide a basis to refine production type curves and to re-calculate stock-tank oil originally in place (STOOIP).  The formation evaluation program consisted of conventional triple combo logs supplemented with advanced downhole measurements including: (1) tiraxial resistivity for thin-bed analysis; (2) nuclear magnetic resonance for porosity, free fluid and kerogen identification; (3) dielectric dispersion for water saturation; (4) geochemical spectroscopy for mineralogy and total organic carbon (TOC); and (5) dipole sonic for dynamic rock properties.  Petrophysical models were developed using both deterministic and probabilistic methods to integrate the measurements acquired for analysis of porosity, saturation, and mineralogy, and describing the hydrocarbon production potential of the BPS more accurately.  The advanced evaluation results will enable the development of computation models in areas of the basin where only minimal logging suites such as triple combo logs exist as data.  Petrophysical models that encompass the entire BPS will be the basis for updated STOOIP calculations that can be used to revise production type curves and improve confidence in estimated recovery factors that have better agreement with measured production results.

About the Speaker

Gary Simpson is a Senior Petrophysical Advisor working for Hess Corporations in Houston since 2012.  He is a member of the Unconventional Resource Technology team advising business unit asset teams on research and development projects for unconventional reservoirs.  He has more than 36 years combined industry experience working in service sector positions with Halliburton, Computalog Inc. (now part of Weatherford), and Perf-O-Log (now part of Schlumberger) and operating company positions with Shell, ConocoPhillips and Forest Oil Corporation.  He is a member of the SPWLA and SPE.  Gary is a 1978 graduate from Texas A&M University.

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

Bryan Page (Weatherford)


From the President

Suzanne Heskin

Here comes fall!  The kids are back in school and the temperatures are cooling.  Time for DWLS to get back in gear.  I hope everyone who attended the luncheon in September enjoyed it, I heard great things about it.  Our VP-Technology has lined up more great speakers for this fall, so let's keep meeting and learning.  In October we will host Gary Simpson from Hess, who spoke to us at one of the workshops last year and was fantastic.  He will be discussing petrophysical models of the Bakken, something sure to be of interest to many.

On a less serious note, be sure to enter our Fall Social (it's not at Christmas this year) into your palm pilot, black berry, smartphone, laptop, tablet, planner, or your mental calendar.  It'll be on Nov 3 at Marlowes.  I think it'll be a great time to gather socially, and it's coming up soon!


From the Vice President - Technology

Bob Cluff (The Discovery Group)

The board has decided to implement a significant change with respect to how we plan and run our Fall and Spring workshops.  Traditionally, the board handoff is made in May and the incoming VP Technology has to immediately scramble to find a topic and speakers for the Fall workshop.  Unless the prior board made significant progress on this before the handoff, this tends to not work well considering the difficulty in contacting people over the summer months and lining up all the talks.

For 2015/16, we've decided to rotate the responsibility by one workshop so the new VP Technology is responsible for the Spring workshop and the following year's Fall workshop.  In my case, that means I will be doing the Spring and Fall 2016 workshops.  The 2015/16 board will have better input on the topics for both workshops and we'll have the Fall topic decided along with most if not all the speakers ready to go by May.  The next VP Technology will then execute the Fall workshop and start planning the following Spring workshop with the new board, and so forth.  This means we have to skip a workshop to get on the new schedule, so we will NOT be having a Fall 2015 workshop.  If there ever has been a time where it is appropriate to skip one, this is probably the year!

The topic for our Spring 2016 workshop will be "Petrophysics of Midland Basin plays", with an emphasis on the Spraberry-Dean-Wolfcamp plays in that basin.  If you have seen great talks you think would be appropriate, please send me the speakers name and a link.  I'll be lining up the program starting in October.


From the Treasurer

Iain Pirie (Schlumberger)

As of September 29, 2015

  • Checking = $43,538.75
  • Savings = $2,551.15
  • Petty Cash = Closed Out


  • Salvation Army = $335.00

The annual donation to the Salvation Army is a result of donations collected from our members at the Christmas social and matched by the DWLS. This year's contribution was down slightly from that of the previous year's donation of $570.00.

DWLS continues to enjoy a strong fiscal disposition thanks to our strong membership support and well attended short courses.


SPWLA Events

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

Meeting Details

Beverage Sponsor
Please thank The Discovery Group 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 Lisa Gregor at 303-770-4235.  Our full cancellation/wait list policy is available on the website.
Luncheon Talk
"Subsurface fluid characterization using downhole and core NMR T1T2 maps combined with pore scale imaging techniques (2015 SPWLA UUU)"

Margaret Lessenger

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
80 81
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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