Feasibility of Monitoring Gas Hydrate Production with Geophysical Methods

Authors: M.B. Kowalsky (speaker), S. Nakagawa, and G. Moridis

Venue: 2008 Offshore Technology Conference, Houston, Texas, May 5-8, 2008 ( http://www.spe.org and http://www.smenet.org [external sites] )

Abstract: Many studies involving the application of geophysical methods in the field of gas hydrates have focused on determining rock physics relationships for hydrate-bearing sediment. The goal is to delineate the boundaries of gas hydrate accumulations and to estimate the quantities of gas hydrate such accumulations contain using remote sensing techniques. However, the potential for using time-lapse geophysical methods to monitor the evolution of hydrate accumulations during production, and thus to manage production has not been investigated. This work begins to examine the feasibility of using time-lapse geophysical methods for monitoring changes in hydrate accumulations that are predicted to occur during production of natural gas. This is made possible through the coupled simulation of (1) large-scale production in hydrate accumulations, and (2) time-lapse geophysical surveys. A geological system is considered, based on a hydrate accumulation in the Gulf of Mexico, which represents a promising target for production. While the current study focuses on seismic measurements, the approach can easily be extended to consider additional geophysical methods, such as electromagnetic methods. In addition to examining the sensitivity of geophysical attributes and parameters to the changing conditions in hydrate accumulations; the aim is to determine optimal sampling strategies (e.g., source frequency, time interval for data acquisition), and measurement configurations (e.g., surface seismic reflection, and vertical seismic profiling), while taking into account uncertainties in rock physics relationships. The numerical simulation tool being developed in this work provides a means for designing cost-effective geophysical surveys to track the evolution of hydrate properties. This work also serves as a basis for developing a comprehensive method for monitoring production that integrates multiple types of geophysical and hydrological data. The modeling procedure is described and some preliminary results are presented.

Related NETL Project:
This presentation is related to the NETL project G308-01, “Numerical Studies for the Characterization of Recoverable Resources from Methane Hydrate Deposits.” The objective of this project is to develop a reservoir model that simulates the behavior of hydrate-bearing geologic systems and evaluates appropriate hydrate production strategies for both permafrost and marine environments, including thermal stimulation, depressurization and dissociation induced and/or enhanced by inhibitors (such as brines and alcohols). This research will enhance natural gas hydrate research and development activities by bringing new numerical simulation capabilities and laboratory measurements to bear on the difficult problems of characterization and gas recovery of methane hydrate deposits.

Project Contacts
NETL – Richard Baker (Richard.Baker@netl.doe.gov or 304-285-4714)
LBNL – George Moridia (GJMoridis@lbl.gov or 510-486-4414)