Skip Links

USGS - science for a changing world

Scientific Investigations Report 2009–5141

Anisotropic Velocities of Gas Hydrate-Bearing Sediments in Fractured Reservoirs

By Myung W. Lee

Thumbnail of and link to report PDF (1.85 MB)

Abstract

During the Indian National Gas Hydrate Program Expedition 01 (NGHP–01), one of the richest marine gas hydrate accumulations was discovered at drill site NGHP–01–10 in the Krishna-Godavari Basin, offshore of southeast India. The occurrence of concentrated gas hydrate at this site is primarily controlled by the presence of fractures. Gas hydrate saturations estimated from P- and S-wave velocities, assuming that gas hydrate-bearing sediments (GHBS) are isotropic, are much higher than those estimated from the pressure cores. To reconcile this difference, an anisotropic GHBS model is developed and applied to estimate gas hydrate saturations. Gas hydrate saturations estimated from the P-wave velocities, assuming high-angle fractures, agree well with saturations estimated from the cores. An anisotropic GHBS model assuming two-component laminated media—one component is fracture filled with 100-percent gas hydrate, and the other component is the isotropic water-saturated sediment—adequately predicts anisotropic velocities at the research site.

First posted August 6, 2009

For additional information contact:

Team Chief Scientist,
USGS Central Energy Resources
Box 25046, Mail Stop 939
Denver, CO 80225

World Wide Web: Central Energy Resources Team

Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.


Suggested citation:

Lee, M.W., 2009, Anisotropic velocities of gas hydrate-bearing sediments in fractured reservoirs: U.S. Geological Survey Scientific Investigations Report 2009–5141, 13 p.



Contents

Abstract

Introduction

Theory

Isotropic Velocities

Anisotropic Velocities

Modeling

Fractures in High-Porosity Shale

Fractures in Sandstone

Gas Hydrate Saturations

Discussion

Conclusions

Acknowledgments

References Cited

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: http://pubsdata.usgs.gov/pubs/sir/2009/5141/index.html
Page Contact Information: GS Pubs Web Contact
Page Last Modified: Thursday, 10-Jan-2013 19:27:30 EST