Meeting Information

"Why doesn't my cap pressure model match my core data?"

Mike Miller
BP

Basin modeling including reservoir quality risk modeling helps to explain apparent inconsistencies in water saturation calculations in tight gas sandstones. 

The late Cretaceous Almond formation produces in the Wamsutter Field, Wyoming.  The average porosity is less than 12 percent and the average permeability is less than 0.1md.  These rocks have a complex chemical and mechanical compaction history making a simple water saturation model tied to capillary pressure data elusive.  Over small areas of the field simple models seem to fit, but often the complex history of these reservoirs needs to be understood before a regional model makes sense.

It is difficult to explain the apparently inconsistent relationship between capillary height and water saturation in this reservoir.  Water saturation models in the same reservoir interval suggest gas columns ranging from 100’s to 1000’s of meters.  Often, these inconsistencies are written off as problems with gathering the “correct” data and applying them in the “correct” saturation model. 

It is indeed difficult to obtain reliable core data in these low permeability and pore volume rocks.  Water resistivity, capillary effects and clay effects on electrical properties can wreak havoc on core analysis results unless one is diligent.

Basin modeling suggests that although initially in primary drainage, after gas charge, this reservoir was uplifted, regionally tilted, and the reservoir is no longer likely to be in a state of primary drainage equilibrium.  Any saturation height modeling will need to take in to account some higher order of drainage or imbibition equilibrium. 

Reservoir quality modeling tied to fluid inclusion data suggests that these rocks had much higher porosity and permeability when they charged with hydrocarbons.  This degradation of reservoir parameters after hydrocarbon emplacement is a nice modeled example of how rocks can potentially end up in permeability jail (Cluff, 2009).

Incorporating the basin history modeling, including the timing of diagenesis as well has hydrocarbon generation and trapping, helps to make sense of this system.  Application of these techniques may provide a means of high grading areas during initial field development.

From the President

Stefani Whittaker (The Discovery Group)

Are you an SPWLA member?

Have you heard about our parent society?

A Little History…

In the 1940’s the oil industry recognized a need to share and trade logging lessons, practices, and knowledge. As a result a study group was formed consisting of a dozen major oil companies of that era. Each year these big players shared log studies and new technological findings in a closed meeting. Two employees from each member company were allowed to attend, and each company had to make a presentation each year as a membership requirement. However, in 1958 the study group dissolved when the host of a yearly meeting failed to organize the event.

Although the original study group no longer existed, the field of well logging was rapidly advancing and becoming increasingly accepted as a true science. The ever growing need to share ideas and findings inspired a few individuals to create a professional society. In January  of 1959 the Society had its first official meeting in Tulsa, Oklahoma. Ever since the Society’s establishment in the late fifties, chapters like the DWLS have been forming and joining. Currently SPWLA has grown to include19 international chapters and 9 U.S chapters. Are you ready to become a part of SPWLA History?

Why should you join SPWLA?

• Discounts: The Denver Chapter has just been awarded the honor of hosting the 2011 SPWLA Convention. When you are a member of SPWLA you will receive discounts on the annual symposium as well as regional symposia, and topical conferences you wish to attend.
• Professional Network: Becoming a member allows you to professionally network on an international level. By building these relationships you can share knowledge, experiences and advice with each other around the world.
• Petrophysics Journal: You are automatically subscribed to the Petrophysics Journal which contains articles, technical notes, case studies, reviews, and tutorials that are relevant to our ever advancing industry. The journal also publishes news about events happening in other International and U.S. chapters.
• Online Resources (www.spwla.org): The members of SPWLA receive free electronic downloads of the Petrophysics Journal, papers and symposium transactions, as well as access to a Job Posting/ Job Seeking page.
• SIG’s: Special Interest Groups have been formed to focus on the different aspects of well logging that require more intense studies. The four groups that currently exist for SPWLA members focus on: High Angle and Horizontal Wells, Nuclear Technology, Resistivity Technology, and Unconventional Resources.

How do you join SPWLA? It’s Easy as 1-2-3

1. Go to www.spwla.org. Click the “About SPWLA” link on the left menu bar and then click on the “Join SPWLA Now” link.
2. Get an SPWLA member reference (If you need assistance in finding a reference, please contact a DWLS board member and we will be happy to help out as many of us are already members and are willing to be references!)
3. Submit your application (downloadable from the site) and your first year’s dues.

After you join, you can stay informed and up to date with SPWLA news by reading the new column in the Denver Chapter newsletter that will be written by Sue Cluff, our SPWLA North American Representative. Look for it in this months newsletter.

I encourage all of you to join SPWLA and become involved in the Annual Symposiums (in Perth Australia June 2010 and in Colorado for 2011), topical conferences, and special interest groups. Our parent society is such an exceptional resource for DWLS members. It gives us the opportunity to further our personal knowledge, form international relationships, and increase the productivity within each of our companies.

I hope to see you all at the upcoming workshop and October luncheon. Please take a moment to visit the website (www.spwla.org) and consider becoming a member of SPWLA!

From the Vice President - Technology

Terri Olson (EOG Resources)

The DWLS Fall Technology workshop on capillary pressure, to be held Oct. 19, has attracted significant interest. There are over 100 people signed up. One change from previous years is the large number (~25) of student registrations received, from the University of Wyoming and Colorado School of Mines. This may be because two of the speakers are professors from those schools, and the location is at CSM. I expect the workshop to provide new insight on the utility of capillary pressure data as well as a great opportunity to network.

From the Vice President - Membership

Dan Krygowski (The Discovery Group)

First, the bugling… Please pay your dues!! Less than 10 percent of our active membership has put their $10 down for another year of good times and timely information. PayPal makes it easier than ever. When you sign up for the luncheon, please pay your dues at the same time. And for those still not connected to the digital world, the alternative is to seek me out at the luncheon with greenbacks or check in hand. I’ll trade either of those for a receipt.

And second… If you’d like your nickname on your luncheon nametag instead of your given name, please let me know at the luncheon, or by email. We’re adding a “nickname” field to our membership list and I’ll be happy to add yours. The request must come from you, and not one of your “friends” in case someone is out to get you.

From the SPWLA Regional Director

Sue Cluff (The Discovery Group)

OnePetro is a new multi-society library hosted by SPE where you can search for and purchase documents from multiple societies in a single transaction. Current participants include American Rock Mechanics Association (ARMA), NACE International, Society of Petroleum Engineers (SPE), Society of Petrophysicists and Well Log Analysts (SPWLA), and World Petroleum Council (WPC). OnePetro is the first online availability of individual ARMA and WPC documents. OnePetro is expected to continue to grow as new organizations join. Please note that SPWLA members cannot download any of their 10 free papers from OnePetro.

SPWLA Statistics             

SPWLA conducted a member survey several years ago. Members were asked to describe their job. 56% described themselves as petrophysicists or log analysts, 11% geologists, 8%, engineers, 3% as geophysicists, and the rest are R &D, Sales and marketing, and other. Who do our members work for? 44% work for oil and gas companies, 23% for logging companies, 22% are consultants or self-employed,  5% academics, 3% software vendor and the rest are something else.

From the Webmaster

Tony Holmes (Digital Formation)

It's great to see that the Digital Age hasn't left us behind – the PayPal system for making luncheon reservations and registrations for the Fall Workshop appears to be working well.  Although we did still have a line to get into the lunch, it dissipated much more quickly than in the past.  This was our first try with pre-printed nametags, too, so we'll work to get the process more streamlined for this month.

One reminder – if you are paying for multiple people, please be sure to fill in the Additional Information field during checkout, to let us know who's coming.  Do it then, or you'll feel Noga's wrath (or more likely receive an extremely polite reminder email from her)!

Comments, suggestions, spare cash, whatever, please send them along to me.

SPWLA Events

Meeting Details

Sponsors