My students and I are searching for new, more precise methods for reservoir characterization in carbonate and siliciclastic reservoirs. We have been using mercury injection capillary pressure (MICP), nuclear magnetic resonance (NMR), and petrographic image analysis (PIA) methods to find rock properties (pore and pore-throat characteristics) that can be linked to such reservoir properties as saturation and capillary pressure behavior to identify flow units, baffles, and barriers in reservoirs and aquifers.

The focal point of this research is our new, genetic classification of carbonate porosity (see Ahr et al., 2005 in publications listed below). We are exploring ways to find indirect measurements such as NMR borehole logs that can identify genetic pore types and enable workers to link different pore types to distinctive and mappable stratigraphic attributes. In essence, we are looking for rock properties that serve as proxies for pore types. Rock properties that can be mapped at stratigraphic scale can enable workers to make predictive maps of pore systems at field scale — a critical problem in so-called ‘compartmentalized’ reservoirs or aquifers. The thumbnail photos below show the end-member pore types in our new genetic classification of carbonate porosity — namely, depositional, diagenetic, and fracture pores. Mixed-origin pore types are classified as hybrids in our new system. A simplified illustration of the classification is included later in this webpage.

We have recently completed projects on Smackover (Jurassic) grainstone and microbialite reef reservoirs at Womack Hill, Vocation, and Appleton fields in Alabama, Happy field (Permian) in Texas, Diamond M field (Pennsylvanian) in Texas, and we are currently working on Grayson field (Jurassic) in Arkansas and Sunflower field (Permian) in Texas.

For more information, please see some of our publication titles and abstracts below. My work in this area was featured in the 2008 issue of the College of Geosciences' annual magazine Geoconnections, and my textbook Geology of Carbonate Reservoirs was published in August 2008 by John Wiley & Sons.

Graduate Student Research

M.S. student Christina Dicus is completing her study of Grayson field pore types, their origin, and their relationships to depositional rock properties. Her main objective is to determine the cause-effect relationships between genetic pore types and the spatial distribution of flow units, baffles, and barriers in the field. Christina is finishing her studies in Paris at the IFP (French Institute of Petroleum) to obtain her IFP diploma in reservoir geosciences in addition to her soon-to-be-completed M.S. degree at Texas A&M.

M.S. student Stephanie Lafage is one of our IFP students who has completed her IFP degree and is presently working toward her M.S. at A&M on an evaluation of the Winland R 35 criterion as a measure of flow unit quality in carbonate reservoirs. She is using data from our previous MICP studies on Permian and Jurassic reservoirs.

M.S. student Aubrey Schellhorn is working on spatial distribution of genetic pore types, how their distribution fits (or does not fit) in sequence stratigraphic architecture, and which pore types have greatest influence reservoir performance in Sunflower (Permian) field, Texas.

M.S. student Riene Vera is working on a study on Upscaling from Pore-to-Core-to Reservoir.

Experience

Joint Appointment as Professor of Petroleum Engineering (1998) and Professor of Geology & Geophysics (2002–present)
Mollie B. and Richard A. Williford Professor of Petroleum Geology and Geophysics (1995–2002).
Associate Professor, Texas A&M, (1976–83); Professor (1983)
Assistant Professor, Texas A&M, (1970–76)

Recent Publications

Recent abstracts in PDF format.
Ahr, W.M. 2008. Geology of Carbonate Reservoirs. John Wiley & Sons, New York.
Ahr, W.M. 2004. Comparison of mounds and level-bottom beds in the Sacramento Mountains with analogues in Europe. SEPM Field Guide to the Carboniferous geology of the Sacramento Mountains, New Mexico. R.J. Stanton, Ed. 5 pages
Ahr, W.M. 2004. The Carboniferous geology of the Sacramento Mountains, New Mexico. Introductory chapter to SEPM Field Guide, p. 1-20.
Ahr, W.M., Allen, D., Boyd, A., Bachman, H.N., Smithson, T., Clerke, E.A., Gzara, K.B.M., Hassall, J.K., Murty, C.R.K., Zubari, H., and Ramamoorthy, R. 2005. Confronting the carbonate conundrum. Schlumberger Oilfield Review. Spring, 2005, 18-29. (Available in Russian and Spanish)
Fornos, J.J., and Ahr, W.M. 2006. Present-day temperate carbonate sedimentation on the Balearic Platform, Western Mediterranean: compositional variation along a low-energy isolated ramp. In: Pedley, H.M. and Carannante, G., Eds. Cool-Water Carbonates: Depositional Systems and Palaeoenvoironmental Controls. Geol. Soc., London, Special Publication 255, pp. 71-84.
Ahr, W.M., 2006. Introduction to Getting started with carbonate reservoirs. Amer Assn Petrol Geologists Reprint Publication on CD, p. 1-10.
Mancini, E.A., Parcell, W.C., and Ahr, W.M. 2006. Upper Jurassic Smackover Thrombolite and Associated Nearshore Facies, Southwest Alabama. Transactions Gulf Coast Assoc. Geol. Socs. Sept. 2006.
Genty, C., Jensen, J.L., and Ahr, W.M. 2007. Distinguishing carbonate reservoir pore facies with nuclear magnetic resonance measurements. Natural Resources Research. v. 15, no. 4.

Awards

2008 Outstanding Educator Award from the Gulf Coast Association of Geological Societies for outstanding contributions in the education and training of geologists through teaching, research, and publications.
Texas A&M Former Student Association Distingushed Achievement Award in Teaching (College level) 2005
Best Paper Award (coauthor with John Layman), West Texas Geological Society, 2003.
Best Paper Award, 2nd Prize (coauthor with Tiffany Hopkins) AAPG, 2002

Additional Info

Certified Petroleum Geologist. American Association of Petroleum Geologists. Certification # 3790.
Emeritus Member – Society of Economic Paleontologists and Mineralogists (SEPM) Past Member Publications Policy Committee; Past Member Nominating Committee
American Association of Petroleum Geologists (AAPG) Member,Past membershiops: Membership Committee; Vice Chairman, Academic Liason Committee
Life Member of The Fulbright Association. Member of Advisory Committee on Science and Technology and Member, Board of Directors, Brazos Valley Chapter, Fulbright Organization.
USA Board Member, Editorial Board of The Geological Journal, John Wiley & Sons Publication, (UK)
Associate Editor – Bulletin, American Association of Petroleum Geologists (2004 - present)