Abstract
The lack of data hampers unconventional reservoir evaluation. Mudlogging is an underutilized formation evaluation tool which can help solve this problem. Typically, the only data available from horizontal wells are drilling parameters, gamma ray logs, and a mudlog. Although many vertical and horizontal unconventional reservoirs have been mudlogged, there are no established methods for interpreting the mud gas. Mudlog gas readings are not consistent, and their relationship to recoverable hydrocarbon volume is poorly understood. Pixler used gas ratios to determine reservoir fluid properties, but few published methods are available to related mud gas readings to recoverable hydrocarbon volume.
The objective of this presentation is to review methods which successfully evaluate unconventional reservoirs. The two evaluation methods presented are zone normalization and gas marker analysis. Mudlog gas evaluation methods range from rules of thumb, offset analogy, drilling parameter normalization, penetration rate versus mudlog gas Pickett type plots, zone normalization and gas marker analysis.
A mudlog gas model is used to determine which factors influence mudlog gas response. Also, presented is a sensitivity analysis to determine the magnitude of the each factor’s influence. The model includes the following factors; the gas volume in unconventional reservoirs, gas flushing in front of the bit, gas liberation from cuttings, gas transport from the bit to the surface, gas solubility in drilling fluids, temperature, and the gas trap. Gas trap factors include mud throughput, gas sample rate, design, and extraction efficiency. The model did not account for sensor response or chromatographic gas separation and condensation in sample lines. Sensor response data is available from mudlogging companies. Proper design mitigates sample line segregation and condensation effects. Gas in the formation and gas trap factors are the major contributors to mudlog gas response. The gas trap error is a zero shift error. Modeling results are presented. The model confirms zone normalizing, and gas markers analysis offer the best interpretation results.
The zone normalization method example is from the Marcellus formation. The sum of the normalized mud gas response along the completed horizontal interval is related to eighteen (18) months of production and the estimated ultimate recovery (EUR). The normalized mud gas response ranges from 1.0 to 5.0 million gas units, and cumulative production ranges from 0.4 to 2.0 Billion Cubic Feet of gas (BCF). The cumulative gamma ray response along the completed interval versus cumulative production is also presented.
The gas marker analysis example evaluates the Wyodak coals in the Powder River Basin. Gas marker analysis introduces a known volume of acetylene gas into the drilling mud to benchmark formation mudlog gas shows. The mudlog calculated gas content, and BCF per section is compared to thirty-six (36) months of actual production and EUR.
Both proposed evaluation methods are simple to implement and can estimate well performance. Digital mudlog data and computers use simple computations to calculate these evaluation parameters. The authors hope the industry adopts these mudlog evaluation methods.
Speaker Biography
Formation evaluation and petrophysics have been the focus of Bill Donovan’s career for nearly forty years. Bill is a registered Professional Engineer in New Mexico and Colorado
Bill is a graduate of the University of Wisconsin (Madison) with a BS in Geology and the Colorado School of Mines with an MS in Petroleum Engineering. While at the Colorado School of Mines Bill’s thesis advisor was Dr. Hilchie author of “Old Electrical Log Interpretation” published by AAPG and took graduate courses in petrophysics taught by Dr. Pickett the who created the Pickett Plot formation evaluation technique.
Bill has worked as a mudlogger, well site geologist, core analyst, a core laboratory manager, drilling and completions Engineer, Petrophysicist and Reserve Engineer. Bill is the President of Donovan Brothers Incorporated and Automated Mudlogging Systems. At Automated Mudlogging Systems Bill and his employees were mudloggers or wellsite geologists, working in the Canadian Arctic Islands, Makenzie Delta, Moldova, Romania and the Rocky Mountain Region. The techniques presented were first developed while evaluating coalbed methane resources in the San Juan, Raton and Powder River Basin.
Two US patents have been granted to Bill Donovan. The first patent was for a compensated mudlog Gamma Ray system which creates a gamma ray log from drill cuttings. The technique used two gamma sensors; one on the standpipe and the other on the flowline to measure the signal contribution from drilling mud and cuttings. A drilling rate sensor was used to lag and process the results into a typical Gamma Ray vs depth presentation. Second US patent was for a passive flowline gas sampling system. The now off patent gas sampling system is used by many mudlogging companies. All of Automated Mudlogging Systems equipment, software, and techniques were developed and field test by Bill and his staff of Geologists.
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When
Tuesday, March 20, 2018
11:20 am - 1:30 pm
Where
Wynkoop Brewing Company
(tell me how to get there)
Cost
$20 per person
$25 at the door (space permitting)
Next Month's Talk
Recognition of Capillary Seals in Hydrocarbon Accumulations Using SP Logs
Steve Cumella
Weatherford
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From the Editor
Dominic Holmes
The Workshop Deadline is Fast Approaching
Please note the registration deadline for the spring workshop is only two weeks away, March 20; the same day as the March luncheon. Make sure you don't miss this exciting workshop on Core Analysis. Register today!
If you were a member in good standing as of February 15, 2018, you should have received an email with the special members-only discounted rate. Make sure you dig up that email and use the link in there to get your discount.
But colleagues and associates that are not members are encouraged to attend as well! They can register from the web page link above.
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From the President
Sam Fluckiger
As always, I hope this message finds you all well and in good spirits. I would like to thank Dick Merkel for his luncheon talk last month and I look forward to the few remaining talks we have this spring. I am excited about the speaker lineup we have for the upcoming spring workshop focused on core analysis and I hope that many of you have the opportunity to attend. Registration details for this event can be found here, including a list of the Authors, their titles and a brief abstract.
I want to thanks all of those that participated in our membership survey sent out last month, your feedback is important and the DWLS Board of Directors have taken your input into consideration on our upcoming decision relating to the new SPWLA charter agreement. I plan to provide additional feedback on the Board’s decision in next month’s newsletter.
On another note, the Joint DWLS/RMAG Fall conference is coming together nicely and we will be sending out a request for abstracts in the near future. The theme of this year’s fall conference is “Conventional Evaluation Methods for Unconventional Reservoirs and Vice Versa” with the underlying question of what have we learned from unconventional reservoirs that could be applied in any petroleum system. I look forward to seeing what abstracts are put forward for this conference and I would ask that if any of you have a topic along these lines that you would like to present, please submit an abstract.
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From the Past President
Bob Lieber
Professional organizations like the DWLS run on the efforts of volunteers. We are so fortunate that so many members give their time and talents to keeping the DWLS running so well you never notice it. If you have served on the Board of Directors previously here is your chance to serve once again. If you have never served it might be your turn to volunteer. The time requirement is no a major one and the only prerequisite is you must be an SPWLA member. If you are interested please contact me at Past_President@dwls.spwla.org or give me a call at 720-966-9511.
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Calendar of Events
Click the calendar to the right to view events on the web.
Other Important Events
2018 SPWLA Annual Symposium, June 3-6, 2018 (London, England)
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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 * |
305 |
375 |
| # that are New members |
16 |
12 |
| # that are Students * |
3 |
11 |
| # that are Lifetime Members * |
259 |
311 |
| September luncheon meeting attendance |
53 |
60 |
| October luncheon meeting attendance |
33 |
71 |
| November luncheon meeting attendance |
53 |
60 |
| Holiday party attendance |
29 |
44 |
| January luncheon meeting attendance |
72 |
65 |
| February luncheon meeting attendance |
54 |
67 |
| March luncheon meeting attendance |
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53 |
| April luncheon meeting attendance |
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54 |
| May luncheon meeting attendance |
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49 |
| Summer social attendance |
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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.
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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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