Similarity Solution for Gas Production From Dissociating Hydrates in Geologic Media

Authors: Moridis, George (speaker), and Reagan, Matthew, Lawrence Berkeley National Laboratory

Venue: American Geophysical Union fall meeting, San Francisco, CA, December 10-14, 2007 (http://www.agu.org/meetings/fm07/ [external site]).

Abstract: By using the Boltzman transformation, the nonlinear partial differential equations governing multicomponent mass flow, energy transport, and phase changes in a geologic system involving methane hydrate dissociation can be reduced to simpler ordinary differential equations, without resorting to simplifications or approximations that require removal of any of the nonlinearities. This capability indicates that the problem admits a similarity solution, which results in invariance of any of the parameters (e.g., pressure, temperature, phase saturations) with respect to the similarity variable r/t^1/2. The similarity solution is confirmed in test problems involving gas production from hydrate deposits undergoing dissociation by depressurization and thermal stimulation. The existence of the similarity solution provides a robust estimator of the gas production potential of natural hydrate accumulations, in addition serving as a reliable tool for evaluating the validity of numerical simulators of gas hydrate behavior in porous media.

Related NETL Project
The proposed research of the related NETL project FWP-G308, “Numerical Studies for the Characterization of Recoverable Resources from Methane Hydrate Deposits,” is to develop and maintain 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).

NETL Project Contacts
NETL – Kelly Rose (Kelly.Rose@netl.doe.gov or 304-285-4157)
LBNL – George Moridis (gjmoridis@lbl.gov or 510-486-4746)