Previous Talks

Wednesday, November 14th, 2007

Exploration & Production in the Deepwater Gulf of Mexico: Geomechanics Challenges in the Sub-Salt Environment

Joanne Fredrich - BP America

Abstract

Over the next decade a significant amount of exploration and new field developments will take place in salt provinces around the world – in the deepwater Gulf of Mexico, and offshore Angola, Brazil, and North and West Africa. Salt formations provide both opportunities and challenges to the design and construction of the often complex wells to be drilled in these locations. Presently, the Gulf of Mexico (GoM) is the most active deepwater region in the world, and here, salt formations with thicknesses in excess of 10,000 feet have been penetrated, with total well depths approaching 35,000 feet. Besides being a dominant structural element of the deepwater GoM petroleum system, salt affects drilling risks and long-term well integrity. The origin of the effects in both cases relates to the constitutive behavior of salt; that is, its inability to sustain a deviatoric state of stress. This presentation addresses three specific challenges resulting from the unique constitutive properties of salt: Locating wells that will penetrate salt canopies including salt exit strategy; Drilling fluid weights required for borehole stability; and Long-term well integrity. We constrain the constitutive response of deepwater GoM diapirs with analyses of salt cuttings from a large number of deepwater wells and laboratory creep tests on rotary sidewall cores recovered from deepwater GoM diapirs, in combination with previous knowledge gained from well-studied onshore Gulf Coast diapirs. This elemental understanding is combined with numerical geomechanical simulations to understand the interaction between salt and the surrounding sediments, as well as both the short-term and long-term behavior of through-salt boreholes. We also show the influence of overlying salt on the reservoir recovery factor. Specific field cases are discussed. Application of this science-based engineering analysis framework have led to cost-savings in excess of $30 million at a single deepwater oil field development alone.

Speaker Biography

Joanne Fredrich is currently Geomechanics & Petrophysics Advisor with BP's Exploration and Production Technology Group based in Houston. She joined BP in 2006 following a 13-year career at Sandia National Laboratories in Albuquerque, New Mexico, where she was Distinguished Member of the Technical Staff. Prior to SNL, she worked for 2½ years at TerraTek in Salt Lake City, Utah. She holds a Ph.D degree in geophysics from MIT, and a BS (Honors) degree in geology from the State University of New York at Stony Brook. She is a past member of the National Academy of Sciences' National Research Council Committee on Geological and Geotechnical Engineering, and the U.S. National Committee on Rock Mechanics, a past Associate Editor for the Journal of Geophysical Research, a current member of the SPE Editorial Board, and a current as well as past member of the Physical Properties of Earth Materials Committee of the AGU. She has authored over 60 technical reports, including 25 in the peer-reviewed scientific literature. At BP, she leads a strategic R&D project in rock physics, and in her spare time, performs geomechanics consultancy for various business units.