Abstract
At reservoir conditions in a dry gas well, the fluid is outside of the pressure-temperature envelope and thus in a single phase. The reservoir temperature is above the cricondentherm (maximum temperature above which liquid cannot be formed regardless of pressure). Hence, the fluid can only be in a gaseous phase.
Estimation of reservoir pressure in tight gas formations, such as unconventional, has been elusive and highly uncertain. Industry common practices analyze buildups and drawdowns with Pressure Transient Analysis (PTA) (Tongyi, 2014). An example of PTA is well testing. In tight gas reservoirs, however, this method is neither reliable nor accurate since a virgin formation will not yield enough gas due to its low permeability, typically in the order of micro or nanodarcys. Other methods include Rate Transient Analysis (RTA) or Dynamic Data Analysis (DDA), which consists of applying the fundamental flow-pressure relationships on production data, matching the responses to preexisting reservoir models with the use of type curves. This method is more robust than PTA, but requires substantial time to collect enough data points in tight gas formations.
While drilling conventional formations, wellbore fluids (of density m) exert a hydrostatic pressure (Phyd) that is greater than the reservoir pressure (PRes) so mud filtrate (of density Rhomf) invades the formation up to a radius of invasion (ri). Mud additives quickly create a pseudoimpermeable layer (mudcake) that prevents the filtration process to continue. While the formation effective porosity (Phie) determines the extent of the ri for low- to highpermeable formations, it is the formation permeability (k) that controls the instantaneous or spurtinvasion process. Similar fluid dynamics occur while coring. The mud present in the borehole transmits the Phyd to the formation that is exposed by the core barrel while coring, which would tend to displace gas (of density g) deeper into the formation. However, in extremely low permeability, and with a coring process lasting only
minutes, the ri in the core is negligible so that the mud filtrates only cover (“paint”) the core, but do not penetrate it.
A tight gas formation is a system where the fluids do not flow or barely flow, and hence are static as opposed to dynamic. In addition, since in-situ water and rock compressibilities are easily calculated, the only change in volume is due to gas, which correlates with pressure and temperature downhole and in lab conditions. The current methods use dynamic measurements. This paper describes a static measurement of a static system.
The method presented in this paper uses data from pressurized cores obtained downhole. The fundamental gas laws, P1V1T2=P2V2T1 and PV=ZNRT, together with mixing laws for the density of fluids are used to calculate the original PRes in a dry gas-bearing tight formation. The method relies also on fluid and rock compressibilities and the estimation of porosity from wireline logs.
Speaker Biography
Luis Quintero is Chief Advisor - Production Management for Halliburton. He holds a BS in electrical engineering from Universidad Simón Bolívar, Venezuela; and Msc and PhD in petroleum engineering with a minor in geology from Louisiana State University, USA. His career
spans 30+ years in well logging, reservoir engineering, and production management in more than 40 countries. He was President of the Society of Petrophysicists and Well Log Analysts (SPWLA) during 2016-2017, and SPWLA’s VP of Technology (2015-2016). In 2014, Quintero was
awarded the Gold Medal of SPWLA for career services. He has authored or coauthored more than 30 technical papers and has 14 patents.
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When
Tuesday, February 16, 2021
11:00 am - 12:00 pm
Cost
At this time we are not going to charge anything for these webinars. We reserve the right to change this in the future.
Webinar reservation: 
Next Month's Talk
Pressure-Dependent Permeability of Shale Reservoirs and Implications for Estimated Ultimate Recovery
Greg Salter
Core Laboratories
Forward this newsletter to a friend to invite them to the webinar.
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From the President
Yulia Faulkner
Greetings DWLS members,
I hope your start of 2021 is strong, energetic, and prosperous!
Yes, we are hearing about more changes that are coming to Oil and Gas industry with the newly elected US President, US gas reserves remain at the second-highest level ever, but we all agree that the US is still very important in the oil market. Remember, a barrel of average crude oil has the energy equivalent of 5,800 cubic feet of dry natural gas, or 5,800,000 BTUs! And I leave this here.
Please do not forget to keep an eye for an upcoming announcement about the Spring Workshop and attend if you can. Personally, I always find workshops to be of great value.
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From the VP - Technology
Jenny LaGesse
Thank you to everyone who attended our first webinar of 2021. Our SPWLA Distinguished Speaker Nikita Seleznev started the year off with an engaging talk on dielectric dispersion methods. As always, your enthusiastic participation during the Q&A session makes these events feel more like we are back at the Wynkoop Brewery, and it’s greatly appreciated.
Registration is open for this month’s webinar featuring another SPWLA Distinguished Speaker, Luis Quintero of Halliburton. His talk, “Reservoir Pressure in Tight Gas Formations from a Pressurized Core System” will be held Tuesday, February 16, 2021. Please register at this link:
https://attendee.gotowebinar.com/register/4834879592798702096
A look ahead at the remainder of our 2020-2021 speaker season:
Registration for the DWLS 2021 Spring Workshop is open! We are excited to open registration for our spring workshop: “Horizontal Petrophysics: Applications and Interpretation Techniques in Reservoir Characterization” after the pandemic-induced cancellation of this annual DWLS event in 2020. The workshop will be held online on April 29, 2021, from 9 am – 4 pm. We have 9 expert speakers with original research, including 3 SPWLA Distinguished Speakers, Denver locals, as well as international guests. This is one to get on your calendar early!
After this past season of free monthly luncheons, we have decided to charge for this all-day event. Registration will include a workshop PDF with speaker abstracts, bios, and presentation slides. The agenda and speaker abstracts will be emailed to members and available online.
Register here: https://attendee.gotowebinar.com/register/3903816446859566349 Note DWLS members and students will get a discount code to use when registering. If you are a DWLS member in good standing, watch your inbox for a separate email with your code. Enter the discount code at the payment screen for your reduced cost. If you are not a member, today is a great day to join!
Workshop registration fees:
Non-members: $100
DWLS members: $75
Students: $20
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From the Past President
Patricia Rodrigues
We want to start 2021 by calling for volunteers to be part of the DWLS Board of Directors. Working with the DWLS helps your community and gives you an opportunity to learn and network. This year, in particular, we need candidates for VP of Technology and Social Events Director positions. If you are interested in one of these or any other position please reach out to us.
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Calendar of Events
Click the calendar to the right to view events on the web.
Other Important Events
2021 SPWLA Annual Symposium, May 15-19, 2021 (Boston,MA) - Note this will be held virtually
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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 * |
280 |
348 |
| # that are New members0 |
0 |
15 |
| # that are Students * |
7 |
7 |
| # that are Lifetime Members * |
261 |
263 |
| September luncheon meeting attendance |
49 |
48 |
| October luncheon meeting attendance |
31 |
37 |
| November luncheon meeting attendance |
42 |
32 |
| Holiday party attendance |
30 |
21 |
| January luncheon meeting attendance |
56 |
48 |
| February luncheon meeting attendance |
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60 |
| March luncheon meeting attendance |
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35** |
| April luncheon meeting attendance |
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29** |
| May luncheon meeting attendance |
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64 |
* 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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