!! ATTENTION GEOLOGY DEPARTMENTS !!

EDITOR’S NOTE: A few months back, Bob Cowdery asked each of the state universities to write an update on the activities and programs in their respective Departments of Geology.  The only university to respond to this request was the University of Kansas.  I hope that after seeing this article, the other departments will respond in kind.  Please forward by mail to the KGS to my attention or e-mail to whansen@southwind.net

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   LOG ANALYSIS of the LANSING-KANSAS CITY LIMESTONES

By Willard J. (Bill) Guy
Kansas Geological Survey

Abstract for January 8, 2003 Technical Program

 The analysis of pay in Lansing-Kansas City limestone reservoirs, particularly the oomoldic zones by wireline logs has been a subject of great interest for over 60 years.  This discussion has usually been fueled by operators, using “normal” Archie log analyses to determine only the water saturation and the porosity, recovered only saltwater from zones having what has been considered pay.  The value of Sw alone is usually quite meaningless since reservoirs can have an Sw of 20-30% and be water productive or can have an Sw of 70-80% in a zone with water free production.  The BULK VOLUME WATER (Sw X Porosity) is the most critical parameter for analyzing all oil and gas reservoirs.  The BVW is the quantity of formation water present in a reservoirs while Sw is the percentage of the pore volume occupied by water.

     There are two primary types of reservoirs in the Lansing-Kansas City limestones.  The bioclastic limestone with interparticle and intercrystalline porosity has approximate economic cutoffs of Sw 50%, BVW 8-10% (0.08-0.1), and porosity 10%.  In comparison, the oolitic limestone with oomoldic porosity has approximate economic cutoffs of Sw 22%, BVW of 5% (0.05), and porosity of 15%.  As an example, an oolitic reservoir with excellent oomoldic porosity of 30% and an Sw of 30% might sound good to many operators, but with a BVW of 9% (0.09), this reservoir will always be water productive.

     An added practical tool for log analysis of the Lansing-Kansas City limestone reservoirs is pattern recognition when analyzing how the resistivity and porosity curves behave with depth.  The best way to view this relationship is with a resistivity-porosity cross plot where points are connected by depth and where contouring of BVW accompanies those of Sw.  For instance, if the resistivity and BVW curves are constant, the reservoir is at or near irreducible water saturation, while if the porosity is nearly constant, the resistivity is decreasing with depth, and the BVW is increasing, the reservoir is in transition.  With careful analysis of the patterns, analysis of the changes in pore geometry is possible.

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Fort Hays State University Offering Workshop for Licensing CEU’s

      FHSU is now providing university credit (1-credit = 45 CEU’s) one-day workshop opportunities for working geologists who are seeking CEU’s towards Licensing under the Kansas State Board of Technical Professions.  The next opportunity is on Friday, May 3, 2003 on the campus of Fort Hays State University.  Meet in Tomanek Hall, Room 225 at 8:00 AM—4:30 PM.  Refreshments provided in the morning and there will be a 1-hour lunch break. 

     This workshop will introduce you to a hands-on field survey utilizing a state-of-the-art cesium magnetometer (Geometrics), GPS, computer modeling using MagMapper 2000 and Surfer 7.0, as well as the integration of this data with soil data bases, topo maps and digital orthophoto quad (DOQ) imagery using ArcView GIS. 

     Contact Dr. Kenneth R. Neuhauser at 785-628-5349 or kneuhaus@fhsu.edu.  You can enroll on-line at www.fhsu.edu (click link to the Virtual College for the enrollment procedure.  Don’t wait, the class is limited to 10 students/workshop.  Course specifics:  GSCI 475 CA  Applied Geophysics workshop.  Line # C017.