Deep Oligocene Regional Study (S. LA.)


Geological and petrophysical evaluations were conducted on conventional cores from thirty-one (31) wells, extending from Jefferson County, Texas, to St. Martin Parish, Louisiana. The entire Oligocene database is evaluated to provide facies relationships, petrographic data, and petrophysical properties characteristic of Oligocene sandstones – irrespective of biostratigraphic units.

The study is based on the detailed examination of 2,595 feet of conventional core, representing over 3,000 feet of Oligocene section. Cores were provided from both the Frio and Anahuac Formations, with the major emphasis being on middle to upper Frio Strata. Conventional cores from each of the project wells were analyzed and evaluated to determine:

  • Core to log correlations, lithologies, sedimentary structures, vertical sequences, and depositional environments
  • Foraminifera and nannofossil content, age, and Paleozoic water depth
  • Sandstone reservoir quality in terms of texture, mineralogy, diagenesis, and pore system characteristics
  • Sandstone petrophysical properties based on log evaluations and conventional core analysis data.

Individual well reports contain detailed core descriptions, core photographs, well logs through the zones of interest, and conventional core analysis data, as well as the results of micropaleontological evaluations, petrographic analyses, and log evaluations. The final report evaluates the compiled Oligocene database first with respect to individual biostratigraphic units and then in terms of the entire Oligocene section in southwestern Louisiana. Sections of the final report deal with a separate biostratigraphic unit, providing a concise summary of depositional environment, petrography, diagenesis, and petrophysical properties for eight (8) different target horizons. Each discussion incorporates a series of summary tables, figures (including a type-log, type-section, and depositional model), and photographic plates. One chapter of the report is devoted to special core analysis and engineering recommendations. A total of fourteen (14) sandstones were selected to cover the spectrum of reservoir rock type throughout the examined Oligocene section. For each of these samples, a variety of petrophysical parameters were measured in the laboratory. A complete suite of petrographic, advanced rock properties, and fluid compatibility test results for each sample is provided in a rock catalog format. The last chapter is essentially an overview or regional synthesis.

  • Thirty-one (31) wells
  • 2,595 feet of conventional core
  • Jefferson County, Texas to St. Martin Parish, Lousiana