Abstract
The total gas in place (TGIP) in gas shale resource is a direct measure of the reservoir quality of the play. Knowledge of TGIP as a function of depth enables the identification of gas-bearing zones and aids in the determination of sweet spots for landing horizontal drain-holes. We describe a new method to determine TGIP directly from Nuclear Magnetic Resonance (NMR) logs, and demonstrate how this can be further improved with multi-sensor analysis.
Gas shale resources are more difficult to evaluate than more traditional gas reservoirs. Evaluation of gas reserves in conventional reservoirs requires an estimate of gas volume, i.e. porosity and saturation, and the direct application of natural gas tables. In gas shales, the hydrocarbon exists not only as pore-filling free gas but also as adsorbed gas on high- surface-area kerogen. Because the pore-filling free gas and the surface-adsorbed gas have different densities and exhibit fast exchange on magnetic resonance time scales, their downhole NMR signals cannot be separated and the effective hydrogen index of the hydrocarbon phase cannot be determined. The current method of evaluating TGIP, based on the use of the Langmuir isotherm to estimate adsorbed gas, requires laboratory investigations on core which are rarely performed in a time-frame appropriate for production decisions. Moreover the limited number of measured isotherms are often insufficient to characterize the heterogeneity of the resource The current method of computing gas in place also requires accurate estimates of effective porosity, effective water saturation, total organic carbon, Langmuir isotherm, pore pressure, formation temperature, and gas composition. In contrast, the TGIP-NMR method requires only the measured NMR porosity, the gas composition, and the bulk volume of water and does not depend on natural gas tables which require knowledge of the in-situ gas density
We show that the TGIP-NMR is uniquely able to assess gas shale resources on the basis of measurements available to the operator immediately after a vertical pilot is drilled. The evaluation makes use of the principle that magnetic resonance logs are intrinsically sensitive not to volumes and porosities but rather to the number of hydrogen atoms in the sensitive region of the NMR tool. It follows that TGIP, reported as standard cubic feet of gas per ton of rock, can be directly determined from NMR logs, without estimating quantities such as effective gas porosity and gas hydrogen index, which have no physical basis as free and adsorbed gas are rapidly exchanging. In summary, the proposed method converts NMR measurements into TGIP by counting hydrogen nuclei directly. The method circumvents of the requirement to know the hydrogen index, pore sizes, pore pressures, formation temperature in order to use natural gas tables. We show examples comparing gas in place estimates using the current model (free and adsorbed gas) with TGIP-NMR. In these examples the TGIP-NMR technique shows around 20% more gas than the free and adsorbed method, most likely because organic shales have very small pore sizes and the free gas may not conform to the natural gas tables.
Speaker Biography
Dr. Ravinath Kausik K.V is a Senior Research scientist at Schlumberger-Doll Research in Cambridge, USA where he has focused on the development of novel NMR and petrophysical techniques, especially of unconventional shale gas and tight oil formations. His work has led to the development of new interpretation techniques such as TGIP-NMR and RPI for unconventional shale gas and tight oil plays, respectively. He has also worked on the development of next generation NMR diffusion and relaxation measurements for both laboratory and downhole applications. His work has been recognized with the Conrad Schlumberger prize for technical depth and the Henry-Doll prize for innovation at Schlumberger, and has been serving as the distinguished speaker for SPWLA in 2015-16 and 2016-17. He was also elected to the international advisory committee of the Magnetic Resonance in Porous Media (MRPM). He obtained a M.Sc. from IIT Madras, India and Ph.D. degree in physics from the Universität Ulm, Germany. He worked as a postdoctoral fellow at the University of California, Santa Barbara before joining Schlumberger-Doll Research in 2009. He has co-authored more than 20 peer-reviewed publications and several patent applications and is a scientific reviewer for more than 10 international journals.
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From the President
Bob Lieber
Have you ever said the phrase "that is good enough" to get the job done. I wonder if you understand the moment you say something is "good enough" it probably is not. I know I have been in many meetings where the conversation goes like this: "Sure this is an 80% solution but, it will get the job done. We know we can do better, but why do more, this will be good enough!" When this would happen in a meeting I was in I always have and always will challenge this sort of attitude and I hope you feel the same. If you go into a restaurant do you expect your meal to be prepared "just good enough" or do you expect the chef to do the best job they can? My father was a chef and I can promise you that every plate that went out of his kitchen (and the restaurants he worked in were not always the "best in class") was the best he and his staff could do. Why do I bring this up? Well in these tough times it is really easy to say I’ll do just what is required of me that will be "good enough". When working with log data and performing petrophysical analysis there are times you do have to do a less than perfect job to meet deadlines or control expenditures, but there are times when we all take unnecessary shortcuts just to get something done. Remember this is your career. No one else will take the same interest in your future that you will. Go the extra mile, do just a little more than what folks expect. Why? Because when you leave the job you currently have all you take with you is your reputation. Hope to see you at both this month’s luncheon and at the Spring Seminar at Colorado School of Mines!
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From the Past President
Katerina Yared (standing in for Suzanne Heskin)
Dear DWLS members, as acting Past-President it is part of my duty to recruit the next generation of the DWLS board. There is no better time than now to volunteer for the DWLS board and keep connected with the oil and gas industry. Become actively involved and experience a very rewarding and educational organization. We are a strong community and we hope you can help us keep our members up-to-date and informed. You can help do your part for all good reasons.
If you are interested in joining the DWLS board please come talk to me at our meetings or email me: Past_President@dwls.spwla.org!
The current board has done a great job in keeping us informed and connected all through the year despite the hardships in their lives. I want to thank them all again for their time and for a job well done! Thank you!
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From the Editor
Dominic Holmes
Fall Symposium / Hot Plays
The Rocky Mountain Association of Geologists and the Denver Well Logging Society are teaming up to present "Geology and Petrophysics of Unconventional Mudrocks, 2017", September 27-28, 2017. This first-time combination of the two societies will combine the two Fall Technical Symposia on the first day at the American Mountaineering Center in Golden and RMAG’s ‘Hot Plays’ Core Workshop at the USGS in Lakewood on day 2.
The proposed technical program will be organized topically and will attempt to provide cross-disciplinary collaboration with DWLS. We welcome abstracts in the following categories:
- Unconventional mudrock plays in the Rockies
- Stratigraphic analysis of mudrock reservoirs
- Petrophysical analysis of carbonate, siliciclastic, and mixed mudrock reservoirs
- Applied reservoir modeling in mudrock reservoirs
- Fractures vs matrix: are both critical for hydrocarbon storage and flow?
- Resource assessments
- Case studies
- Analysis of abnormally pressured mudrock reservoirs
- Techniques for investigating reservoir quality of mudrock reservoirs
We are especially interested in recent multidisciplinary reservoir studies, new interpretations of outcrop to subsurface stratigraphy, new play concepts and prospects based on application of stratigraphy and petrophysics, and new insights into unconventional petroleum systems of Rocky Mountain basins. We welcome abstracts for the technical talks at the symposium with or without an associated core for the core workshop. Send your abstract in today and join us for Unconventional Mudrocks, 2017! Deadline for abstract submission is May 1, 2017. Decisions will be returned by June 1.
Speakers of accepted abstracts will be encouraged to submit a short (4-10 pages) technical paper by Aug. 1. We intend to publish separate booklets for the symposium and the workshop with abstracts and/or technical papers for participants.
For more information, or to submit an abstract, please contact: David Katz (david.katz@whiting.com) for the core workshop or Katerina Yared (katerina.yared@qepres.com) for the technical symposium.
Sponsorship opportunities exist.
- Permian Basin level $2500
- Western Gulf-Eagle Ford $1500
- Williston Basin $1000
- Powder River Basin $500
- Greater Green River Basin $250
Potential sponsors should contact Barbara Kuzmic (bkuzmic@rmag.org) for more information.
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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
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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 |
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 |
|
70 |
| April luncheon meeting attendance |
|
59 |
| May luncheon meeting attendance |
|
59 |
| Summer social attendance |
|
31 |
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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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