--> Abstract: Thermal Maturity of the Upper Mississippian Barnett Shale in Southeastern Wise County, Texas, by Geoffrey S. Bayliss, Karl W. Schwab, Michael A. Smith, Gordon D. Wood, and Nelson B. Yoder; #90078 (2008)

Datapages, Inc.Print this page

Thermal Maturity of the Upper Mississippian Barnett Shale in Southeastern Wise County, Texas

Geoffrey S. Bayliss2, Karl W. Schwab3, Michael A. Smith1, Gordon D. Wood4, and Nelson B. Yoder5
1The G2 Group, Grand Prairie, TX
2Geochem Laboratories, Inc., Houston, TX
3Emenu Inc., Houston, TX
4IRF Group, Inc., Katy, TX
5Integrated Exploration Services, LaPorte, TX

Forty-six core samples from the Upper Barnett Shale, Forestburg Limestone and Lower Barnett Shale of the Mitchell T.P. Sims No. 2 and the Texas United Blakely No.1 wells, Wise County, Texas, were analyzed for organic matter type and state of thermal maturity. For the past two decades, some geologists and geochemical service companies have placed these stratigraphic units in the thermally mature gas/gas-condensate phase of hydrocarbon generation. Although conflicting visual kerogen (TAI) and vitrinite reflectance (%Ro) data were available, only Tmax data generated from Rock-Eval analyses were used for this thermal maturity interpretation.

More than 5,000 spectral photometer color measurements were made on organic constituents extracted from core samples. The ICA-SPD technique, visual kerogen, vitrinite reflectance and organic geochemical extraction data indicate that organic matter in the Barnett Shale is only at a moderately mature to mature stage of hydrocarbon generation near, or slightly above, peak oil generation (i.e., vitrinite reflectance of ±0.95%Ro).

Gas that is currently being produced from the Barnett Shale is a “low-temperature” generated hydrocarbon that is linked to the high percentages of degraded herbaceous and algal-amorphous organic constituents that make up the bulk of the organic matter extracted from the core samples. Our geochemical analyses show that production of gas, wet gas and/or condensate from the Barnett Shale in the Fort Worth basin is not necessarily restricted to areas where sediments have been reported to have average vitrinite values of 1.20%Ro or greater, as suggested by other authors. Based on this new information, explorationists should be aware that the Lower Barnett Shale is capable of producing vast amounts of “low-temperature” gas over an even wider area of the Fort Worth basin than previously thought possible.

 

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