Technical Support for Geopressured Geothermal Well Activities in Louisiana Annual Report

The rationale previously developed and utilized in interpreting various databases were outlined in the DOE final report titled "Technical Support for Geopressured-Geothermal Well Activities in Louisiana" (August 31, 1981), authored by Fred M. Wrighton, Don G. Bebout, Dale R. Carver, Charles G. Groat, and Adrain E. Johnson, Jr., under Contract No. DE-AS05-78ET27160. Due to the importance of the concepts presented in the previous report for developing an assessment evaluation program, much of the text and illustrations have been repeated for the convenience of the reader. However, the assessment techniques and calculations presented in this report are new.

Estimates of the in-place methane resource in the geopressured zone of the U.S. Gulf Coast have varied widely, ranging from less than 1000 trillion cubic feet (TCF) to 49,000 TCF. The most recent assessment for onshore Texas, conducted by Gregory, Dodge, Posey, and Morton in 1981, estimated a total of 690 TCF. Well logs from deep oil and gas wells served as the primary data source for all assessment studies, although the interpretation of these logs varied significantly. In this study focusing on Louisiana, the methods and results were found to compare favorably with those of Gregory and others for Texas. The assessment included the Wilcox, Frio, and Miocene formations.

Constructing regional cross-sections across the south Louisiana Gulf Coast was a prime objective to aid in assessing the total solution-methane resource in place. These cross-sections provided point sources of information from key wells and offered insights into the significance of each well through logical correlations with others on the section. Additionally, detailed studies of smaller areas conducted at LSU and other institutions throughout the Gulf Coast were considered, with data from these studies also contributing to the assessment.

The total area under consideration in south Louisiana exceeds 18,000 square miles, with geopressured formations including the Wilcox (1692 square miles), Frio (5200 square miles), and Miocene. Parameters considered in this assessment included pressure, sandstone volume, porosity, temperature, and salinity.