Abstract
Introduction
The transition from conventional prospecting to unconventional plays in the late 2000s presented an opportunity to develop a new perspective on basinwide exploration. Information Theory, invented at Bell Labs in 1948 by Claude Shannon, offers an original approach to separating substantive (surprise) data from superfluous (redundant) data in the well-log signal. This distinction represents a key to recognizing anomalous reservoir parameters that are critical for effective hydrocarbon storage and deliverability in resource plays.
Information Theory
Information is present only in substantive data that say something you don’t already know or something you cannot predict. All other data are superfluous. Consider the binary example of results from a predictive search engine: once the correct prediction appears, any additional search criteria are unnecessary. In log evaluations we apply Information Theory to cross-plot data. A baseline trend is located in the low-response data of the scatter which represents the predicted relationship between the independent and dependent variables. Data that fall along or near the baseline carry no information. Anomalous data carry information (probabilistically) in relation to their distance from the baseline. The most substantive data lie farthest from the predicted baseline trend. Examples of this procedure will be shown.
Effective Porosity
Anomalous porosity is identified in a cross-plot of shale volume (VSH) versus total porosity. Here, the baseline represents the relationship where all log-measured porosity is derived from clay content only. Substantive data are identified based on their distance from the baseline and are quantified as effective porosity (PHIe) representing inter- and intra-particle pores, etc.
The basic porosity interpretation is enhanced by including a meta-data analysis for reservoir quality (RQ) which compares effective porosity (PHIe) with hydrocarbon saturation (HCSAT). A positive slope to this relationship within a target reservoir at irreducible water saturation suggests the presence of
larger pores with less surface area and implies better pore connectivity. RQ is applied as a scaled multiplier to PHIe producing a slope-adjusted effective porosity (PHIes).
When comparing the information-based interpretation of effective porosity (PHIes) with professional petrophysical calculations (PHIE), I find that higher ratios of PHIes/PHIE (typically < 1) correspond with increasing RQ. This suggests that the information-based effective porosity is accounting for pore connectivity in a way that conventional petrophysical calculations are not. I hypothesize that PHIes is computing a pore volume only for well-connected pores and does not include the pore volume associated with primary residual oil saturation. Evidence for this conclusion will be discussed.
Revised Volumetric Paradigm
By assuming that the hypothesis stated above is true, we can take a new look at traditional reservoir volumetrics which rely on recovery factor for reserve calculations. I view recovery factor (RF) as the product of efficiency in draining a reservoir based on three components: porosity (P), thickness (H) and area (A); that is: (RF = EFP*EFH*EFA). The efficiency factors EFP and EFH are reservoir properties whereas EFA is a function of completion design.
As described above, information-based effective porosity already incorporates EFP; that is: (PHIes = PHIE*EFP). The efficiency factor for thickness (EFH) is related to reservoir shale volume: total reservoir thickness (H) is reduced to a “fracable” thickness (Hf = H*EFH) in relation to increasing VSH. Finally, the areal efficiency factor (EFA) depends on common completion parameters and quantifies what fraction of the nominal drainage area (A) actually represents stimulated reservoir area (SRA); that is: (EFA = SRA/A).
The revised volumetric equation based on parameters derived from Information Theory looks like this: V = [C*(PHIes*HCSAT*Hf)*(A*EFA)]/Bf. You should note that the unpredictable and tyrannical recovery-factor parameter has been eliminated. This presentation will include a comparison of reserve calculations using revised and traditional volumetrics based on a Niobrara reservoir in the RedTail Field, Denver Basin.
Conclusion
Probabilistic log evaluation based on Information Theory gives us a new tool for basinwide assessment of established and emerging resource plays applicable to exploration and business development. Using a Big Data approach, all wells can be evaluated individually using computer algorithms that generate an appropriate reservoir model for volumetric reserve calculations at each location. The result is a fast, accurate, high-volume method to highlight anomalous data in select reservoir parameters which are one key to sweet-spot identification.
Speaker Biography
Paul Devine is Founder and Manager of Resource Analytics, LLC, a Denver-based startup. Paul began his petroleum industry career in Houston with Shell Oil in 1980. He moved to Denver in 1982 working in various roles as an exploration geoscientist for mid-sized and small independents. In 2015 Paul started Resource Analytics as a service company using Information Theory in well-log evaluations to provide a Big Data approach to basin-scale assessment of unconventional resource plays. He has a BS in Geology from Washington & Lee University (1975) and an MA in Geology from the University of Texas, Austin (1980).
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When
Tuesday, November 13, 2018
Note this is the 2nd Tuesday of the month instead of the 3rd due to Thanksgiving.
11:20 am - 1:30 pm
Where
Wynkoop Brewing Company
(tell me how to get there)
Cost
$25 per person
$30 at the door (space permitting)
Next Month's Talk
Annual Holiday Social Event (see details below)!
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From the Director of Social Events
Jesse Havens
Mark your calendars Dec. 4th for the annual DWLS holiday party held in the Strand Room at the Rialto Cafe from 4 pm - 6 pm. This year we'll be having three guest speakers: Michael Holmes, Dick Merkel, and Jack Bowler kick the night off by sharing some war stories about their trials and tribulations in the industry, don't miss it!
The cost is only $10/person and includes 2 drink tickets. Guests are welcome! You can register here.
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From the President
Shannon Borchardt
I hope everyone enjoyed October as we had a beautiful fall season here in Denver with mild temperatures and changing leaves. Thanks to Karthik Srinivasan for his excellent presentation about the industry pricing landscape and the impact to Rockies Basins. We are looking forward to the November presentation by Paul Devine on the 13th. A reminder, this month’s luncheon is a week earlier due to Thanksgiving. Also, please plan on joining us on Dec 4th from 4 to 6 pm for our winter holiday social event.
Feel free to contact me or the DWLS board at any time with any suggestions to continue to improve our society.
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From the VP - Technology
Patricia Rodrigues
The DWLS Spring Workshop is coming in 2019, it will be held on April 3rd at the American Mountaineering Center in Golden, CO. The theme for the workshop will be “Data Analytics in Reservoir Evaluation”, the topic includes data mining, predictive analytics, and different algorithms in artificial intelligence, like machine learning, neural networks, and genetic algorithms. Please submit your abstract or questions to Patricia Rodrigues at VP_Technology@dwls.spwla.org.
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From the Editor
Dominic Holmes
Do you find yourself attending the DWLS every month with regularity, but from time to time forget to actually make your reservation? If so, we're starting a new luncheon plan that might fit the bill for you. There are six luncheons remaining this year (November and January - May). You can pay now for just five luncheons and we'll give you the 6th for free. So pay $125 now and you won't need to register through the rest of the year.
If you join this program, you will be getting a separate email from me each month requesting you contact me if you find you cannot make the meeting that month, so we don't order an extra lunch for you.
Small Print
There is no refund should you not be able to attend any of the luncheons. Consider it a generous donation to your favorite local society.
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Calendar of Events
Click the calendar to the right to view events on the web.
Other Important Events
2019 SPWLA Annual Symposium, June 16-19, 2019 (The Woodlands, TX)
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DWLS Sponsors
Click here to view the sponsors on the website, or click on any image to contact a sponsor.
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Chapter Statistics
Statistic
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This Year
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3-Year Average
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| # of Active members * |
288 |
375 |
| # that are New members |
11 |
12 |
| # that are Students * |
3 |
11 |
| # that are Lifetime Members * |
251 |
311 |
| September luncheon meeting attendance |
44 |
57 |
| October luncheon meeting attendance |
29 |
62 |
| November luncheon meeting attendance |
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55 |
| Holiday party attendance |
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37 |
| January luncheon meeting attendance |
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67 |
| February luncheon meeting attendance |
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60 |
| March luncheon meeting attendance |
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45 |
| April luncheon meeting attendance |
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47 |
| May luncheon meeting attendance |
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51 |
* 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.
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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.
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