Abstract
When evaluating unconventional (tight) oil reservoirs one of the ultimate objectives is the development of a core-calibrated petrophysical log model and associated oil-in-place (OIP) estimates. However, in these reservoir systems, obtaining OIP data that hold utility for reservoir engineering calculations or estimates of ultimate recovery (EUR) requires that we clarify what we are actually talking about when using the term OIP. It also requires that we understand what is really being measured when employing the various analytical methods available to us in the laboratory.
When discussing OIP estimates in unconventional plays it is necessary to speak in terms of total, versus mobile, versus producible OIP. This stems from the fact that these reservoirs systems are frequently composed of parasequences containing source rocks and/or closely associated carrier beds. Being the parent substrate from which hydrocarbons are sourced, kerogen is oleophilic by nature and possesses a very high affinity to absorb and adsorb oil. As such, at the onset of thermogenic oil generation, the saturation capacity of the kerogen must first be accommodated before any expulsion and subsequent migration can occur, even into the inorganic matrix of the source rock itself. This kerogen-bound oil is effectively immobile. Therefore, any mobile oil present in the reservoir system resides predominately within the organically lean beds, whether they exist on a micro or macro scale. Furthermore, due to the fine-grained nature of these reservoir systems, the mobile oil fraction can in turn be affected by the presence of pore throats with sufficiently small diameters as to create mole sieve effects, resulting in the impedance and/or fractionation of the mobile oil during production.
In addition to the complexities introduced by the physical attributes of unconventional reservoir systems, the fundamental measurement of OIP can itself vary significantly, depending upon which analytical method is employed in the laboratory. Solvent extraction techniques remove all soluble hydrocarbons, to include the fraction entrained in the kerogen and any other immobile, heavy molecular weight components. Conversely, “dry” thermal extraction techniques like retort or pyrolysis measure the mass of hydrocarbons that volatilize at some predetermined isothermal temperature (typically 300°C). In general terms, this results in the liberation of hydrocarbons ranging from C5 to C17 (b.p. of heptadecane is 302°C) with all heavier molecular weight components being retained upon the rock matrix. Lastly, low temperature hydrous pyrolysis (LTHP) methods result in OIP volumes that are generated neither by dissolution nor phase change, but rather by expansion and buoyancy effects. Individually, each of these analytical techniques will provide an “accurate” measure of OIP, but only relative to their specific methodology. When compared collectively they produce very different values.
We propose that through the application of a comprehensive rock and fluid analytical workflow, which includes a range of both petrophysical and geochemical analyses, a better interpretation and delineation between the total, mobile, and producible OIP fractions can be developed. This in turn would enable us to improve our appraisal of unconventional oil plays and make better estimates of producible reserves.
Speaker Biography
Chad Hartman received his Bachelor of Science in Chemistry (1999) from Fort Lewis College in Durango, Colorado. Mr. Hartman is an expert in unconventional reservoir assessment with over 19 years of experience, specializing in rock and fluid data interpretation, core-calibration of petrophysical log models, and formation evaluation. He currently serves Stratum Reservoir’s clientele by helping them with the interpretation of rock, fluid, and log data for the appraisal of unconventional reservoir economic prospectivity, the evaluation of legacy data, and the development of fit-to-purpose rock and fluid analytical programs.
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From the President
Yulia Faulkner
Time flies by when we are having great Luncheons and good chats with members who keep supporting DWLS and keep attending talks, thank you! Hard to believe Thanksgiving is around the corner and DWLS has the last luncheon for 2021. We are also hoping to have Holiday Gathering!
As winter slowly approaches, we are lately spending a dollar more for a gallon of gasoline than what we used to a year ago, natural gas prices have shot up more than 150 percent over the same time, we are seeing some threats of rising prices of food, chemicals, plastic goods and heat this winter. The cost of oil, natural gas and coal has climbed rapidly in recent months. The memories of the negative barrel oil prices are still fresh, even if happened 16-17 months ago, making producers to worry about pandemic and climate, and not increasing production. It seems like the energy system is suddenly in crisis around the world, I recently started to notice lines to get gasoline, which I am not used to at all. Let’s hope that we are not going to see blackouts and gasoline shortages as some other countries are seeing already.
As always, if you have ideas about how to improve DWLS, please reach out
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From the VP - Technology
Jenny LaGesse
Thank you to all our attendees and to Patrick Hayes of Tracerco for his engaging talk last month. It was great to see you all in person! We’re moving right along into November with our featured speaker “Chad” Robert Hartman (Stratum Reservoir) and his talk “Unconventional (Tight) Oil Reservoir Characterization and the Difficulties Associated with Quantification of Producible Oil-in-place”. Tickets can be purchased online.
Please remember that in accordance with CDC guidelines for large groups, we ask that unvaccinated attendees wear a mask when not enjoying their lunch during our meetings and that if you feel unwell you do not attend. As the CDC suggests, we encourage but will not require all members regardless of vaccination status to wear masks to slow transmission, particularly during these upcoming winter months. (Considerations for Events and Gatherings | CDC)
We are looking for speakers! If you would like to be a speaker or have suggestions for luncheon topics, please send them along to: VP_Technology@dwls.spwla.org.
In the months to come our luncheons will feature:
- January 2022: Patricia Rodrigues, SeisPetro and Strategic Decisions Group
- February 2022: Gama Firdaus, CSM
Stay tuned for more details regarding scheduling.
We are calling for suggestions for the Spring 2022 workshop topic. If you have any requests, please send your thoughts to: VP_Technology@dwls.spwla.org.
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From the Treasurer
Rich Whittington
Happy Fall everyone. I would like to bring you up to speed on the financial health of DWLS. In short, we are on solid footing with a cash balance of greater than $35,000 across our multiple accounts.
Looking back on the 20-21 fiscal year, as one would expect with the decrease in luncheons and conferences, revenue was down sharply but so too were expenses with only one large expenditure for the Go To Meeting service. We purchased this service to support our monthly luncheons and agreed it was a cost that should be borne by the organization and not passed on to you, the members, during those trying times.
Looking ahead at the 21-22 fiscal year, luncheons are back, conferences are being planned and we are financially secure to support our members and the broader Denver petrophysical community.
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Calendar of Events
Click the calendar to the right to view events on the web.
Other Important Events
2022 SPWLA Annual Symposium, June 13-15, 2022 (Stavanger, Norway)
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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 * |
233 |
314 |
| # that are New members |
1 |
15 |
| # that are Students * |
7 |
7 |
| # that are Lifetime Members * |
258 |
261 |
| September luncheon meeting attendance |
25 |
46 |
| October luncheon meeting attendance |
17 |
37 |
| November luncheon meeting attendance |
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28 |
| Holiday party attendance |
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38 |
| January luncheon meeting attendance |
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43 |
| February luncheon meeting attendance |
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54 |
| March luncheon meeting attendance |
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38** |
| April luncheon meeting attendance |
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43** |
| May luncheon meeting attendance |
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48 |
* 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.
** These numbers are skewed due to COVID-19 luncheon cancellations.
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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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