Vicksburg Regional Study and Rock Catalog

This study was initiated to provide a detailed geological, petrophysical, and engineering characterization and evaluation of Vicksburg sandstones from conventional cores. This project is base on approximately 5,000 feet of core from thirty-nine (39) project wells with cores that span subsurface depths ranging from 6,100 feet to 16,200 feet. Thirty-eight (38) of the wells are located in the South Texas counties of Nueces, Kleberg, Jim Wells, Kennedy, Brooks, Starr and Hidalgo. One well is located in Chambers County in the Houston Embayment.

The objectives of the study were to provide participating companies with detailed geological, petrophysical, and engineering characterizations and evaluations of productive and potentially productive Vicksburg reservoir sandstones. More specifically, the study provides participants with data and interpretations regarding:

• Sedimentary characteristics, depositional environments, vertical sequences, and lateral relationships of Vicksburg reservoir sandstones
• The textural, mineralogical, diagenetic, and pore space properties of reservoir sandstones and the factors controlling reservoir quality and producibility
• Integration of rock matrix and pore space properties with special core analysis test results and log properties to more accurately interpret and evaluate hydrocarbon-bearing sandstones from wireline logs in the Vicksburg
• Rock-fluid compatibilities to better determine the most compatible completion and/or frac fluid to be used in stimulating the reservoirs
• Regional geological data to aid in further exploration or production endeavors for the Vicksburg sandstones within the study area
• Measurement, documentation, and interpretation in a catalog format, an extensive array of geological and petrophysical properties commonly used to evaluate the producibility of potential Vicksburg gas-bearing sandstones

The data and interpretations for the individual project wells are provided as well as a final report volume that contains a regional summary derived from the evaluation and integration of data obtained from project wells. Results from special core analysis tests and rock-fluid compatibility tests are also included in the final reports with specific recommendations regarding drilling and completion practices.

The Vicksburg Rock Catalog analytical program was designed to characterize the geological, petrophysical, and rock-fluid compatibility properties of the various Vicksburg reservoir types observed in the regional study wells. The rock catalog entries will serve as reference analogs for more accurate estimates of formation parameters and producibility of non-cored zones of interest. The catalog data can be applied to many areas of Vicksburg exploration and exploitation, some of which include:

• Selection of the least damaging fluids necessary for the various phases of well operations
• The causes of formation damage in previously completed wells and suggested remedial action
• Identification of damaged versus non-productive intervals
• The assessment of post-completion/stimulation well performance
• Evaluation of well test data (i.e., DST and pressure build-up)
• Characterization of Vicksburg sandstone reservoir quality and expected producibility

Each Vicksburg rock type in the catalog is presented in a format which characterizes, as completely as possible, the rock types’ various geological and petrophysical properties. Other support data, such as open-hole logs, drilling and completion procedures, and production test data, will be provided for each rock-type entry.

• Thirty-nine (39) wells
• 5,000 feet conventional core
• Regional rock catalog