A Petrophysical Study from Floyd Shale

Mriganko Sarkar, Chandra S. Rai, and Carl H. Sondergeld
Mewbourne School of Petroleum & Geological Engineering, The University of Oklahoma, Norman, OK

With shale plays becoming increasingly important source of natural gas, it has become all the more important to characterize shales. This paper attempts to improve the overall understanding of gas shales using laboratory based petrophysical measurements. A systematic petrophysical study on Floyd Shale samples from Black Warrior Basin, Alabama was done on 27 suites of plugs, obtained from 100 feet of core from one well, using measurements of total organic carbon TOC, quantitative mineralogy, native bulk and grain densities, effective porosity, velocity as a function of effective pressure, NMR spectroscopy, magnetic susceptibility and SEM imaging. Except for the TOC measurements all other measurements were done on samples from oriented plugs taken in 0, 90 & 45 degrees respectively to the symmetry axis. The TOC was less than 6% by weight and shows a weak trend of increasing with depth. The effective porosity ranges from 4 to 10%. The grain densities vary between 2.5 & 2.8 gm/cc, showing a general decreasing trend with depth. All samples have clay content more than 50 weight percent and illite is the dominant clay mineral. Based of velocity measurements transverse isotropic symmetry is seen in only 6 samples. NMR T2 distribution shows that the majority of the water was bound water.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas