Mechanisms Leading to Co-Existence of Gas and Hydrate in Ocean Sediments

Steven L. Bryant, Ruben Juanes

Overview

Sponsor: National Energy Technology Laboratory, U.S. Department of Energy  
Award Number: DE-FC26-06NT42958
Duration: October 2006 - September 2010

This project seeks to quantify how methane is distributed and transported within a hydrate resource area. In concept, methane is transported when gas pressure builds up until it fractures the sediment; water and gas then move into the fracture, the gas drains into the sediment, and hydrate forms at the gas/water interfaces. Researchers will model fracture initiation and propagation as well as the geometry of gas/water interfaces, coupling the two models to help simulate a mechanism for how gas and hydrate coexist. The resulting model would be an important step toward characterizing and predicting the behavior of active vs. stable hydrate deposits, and it will help us better understand the complex systems containing hydrate, water, free gas, and sediment. (DOE award: $1.074 million; cost share: $268,746; project duration: 4 years)

Data

We will periodically post data related to this research project in this space.

Model Sediment Data Files

We created a set of model sediments (dense random packings of spheres with several size distributions) at MIT using PFC2D/3D and at UT-Austin using the Thane codes. Only the UT-Austin results are included here.

The sediment models developed at UT were generated using a cooperative rearrangement algorithm, and they have periodic boundaries to eliminate edge effects. For all packings the spatial locations of spheres and the packing porosity were recorded. Pore throats were identified in these models with Delaunay tessellation. A network structure that preserves the topology of the throats was extracted. The topology and geometry of the network representation of pore space were recorded for each packing. On the other hand, the PFC models were generated with boundary and initial conditions, including gravity, that simulate relevant depositional environments.

The packings will serve as the foundation for studying at the grain scale the competition between capillarity-controlled displacements (of brine by gas, and of gas by brine), formation of hydrate (at the brine/gas interface), and fracturing (induced by pore pressure in the gas phase).

Available downloads:

Principal Investigators

Contact Info:

Dr. Steven L. Bryant
CPGE, U. of Texas at Austin
CPE 2.502
Austin, Texas 78712

Phone: (512) 471-3250
Fax: (512) 471-9605
E-mail: Steven_Bryant@mail.utexas.edu