A Multi‐Scale Experimental Investigation of Flow Properties in Coarse‐ Grained Hydrate Reservoirs During Production Last Reviewed December 2017


The objective of this project is to gain insight into the relative permeability behavior and depressurization response of coarse‐grained methane hydrate deposits subjected to perturbation through observation of behaviors at the macro- (core) scale and examination of the underlying processes controlling the behaviors at the micro- (pore) scale.

University of Texas at Austin, Austin, TX 78712

Depressurization of coarse‐grained gas‐bearing reservoirs involves multiple processes that interact at multiple length and time scales. These include, but are not limited to, relative permeability, capillary, compaction, kinetic, and thermodynamic behaviors. Two properties that are poorly understood are 1) the relative permeability behavior of these systems as the hydrate and gas saturation change, and 2) the effect of local changes in pore water chemistry as hydrate dissociation occurs. These are macro scale behaviors that can be measured at the core scale, and they have a large impact on the production rate of methane from hydrate reservoirs. Accurate predictions of gas production from hydrates await a better understanding of these behaviors. This understanding will result from both a macro‐scale description of the behavior and a micro‐scale analysis of the underlying processes driving these macro‐scale behaviors.

This project will explore the relative permeability of coarse‐grained reservoirs and the response of these reservoirs to depressurization at the macro‐ (1 m) and micro‐ (1x10‐6 m) scale. At the macro‐scale (e.g., 0.1 to 1 m sand‐pack cores), researchers will determine relative permeability and perform production tests (pressure dissipation). Simultaneously, they will perform micro‐CT and micro‐Raman analysis to understand the habit and phase distribution at the micro- (pore) scale and will examine the evolution of these properties during dissipation. The project will develop constitutive relationships to describe these processes and inform reservoir simulation efforts.

Methane hydrates within sand‐rich marine reservoirs represent a potentially enormous reservoir for methane. Previous drilling/logging in marine sand reservoirs within the Gulf of Mexico has verified that methane hydrate filled sand reservoirs are present and that sand reservoirs can be identified from seismic analysis. DOE is now focusing on acquiring intact samples through its project "Genesis of Methane Hydrate in Coarse‐Grained Systems: Northern Gulf of Mexico Slope," DOE Award No.: DEFE0023919. It is anticipated that the first conventional and pressurized cores of these reservoirs will be collected under that project in spring 2017.

Laboratory studies to determine the effect of solid phases (hydrate) on relative permeability are of the highest importance because this behavior has a large impact on gas recovery in hydrate bearing systems. Current modeling approaches are limited to relying on theoretical extensions of conventional multi‐phase flow models. It is vital now to go beyond these limitations and pursue an experimental program that will illuminate, at the core and the pore scale, the effect of methane hydrate on gas flow behavior and the process of hydrate dissociation due to perturbation. A successful testing program leading to analysis of intact cores (as is planned under this project) provides a pathway to this understanding. The learnings that result will provide a significant step forward in our ability to simulate hydrate production and make realistic estimates of the ability of the methane hydrate resource to be a viable energy source.

Accomplishments (most recent listed first) 

  • Completed initial macro-scale lab experiments in sand packs demonstrating capability to form methane hydrates at targeted saturations, and conducted dissociation tests of the samples while under CT monitoring.
  • Initiated hydrate dissociation experiments monitored by x-ray CT in the Micro-CT device.
  • Demonstrated capability to synthesize and dissociate methane hydrate with deionized water and glass beads in the static Micro-Raman cell.
  • Developed a process to reliably transfer sand pack samples into Experimental pressure vessel with varying water saturations.Conducted initial Micro-CT measurements of sand pack samples using xenon hydrate to optimize system resolution.
  • Completed the initial build and testing of a micro-consolidation device for use in lab experiments using Micro-CT.
  • Completed the design and build of a static hydrate pressure vessel for use in Micro-Raman spectroscopy experiments and demonstrated formation of pure methane hydrate (without porous media), and measurement of Raman spectra of the hydrate.

Current Status (December 2017)
Efforts at UT have shifted from experimental set up and shakedown to performance of actual experimental runs at both the micro and macro scales. Going forward, macro-scale efforts will include continued depressurization experiments on synthetic hydrate in sand packs with a focus on varying the magnitude of gas release at various stages of depressurization to test pressure rebound in system with salt diffusion (varying volumes of fresh water release). Experiments will also target achieving synthetic hydrate sample saturations greater than that achieved to date (27%), with a target of up to 50% hydrate saturation. These depressurization experiments will be conducted with CT monitoring. Micro-scale efforts will continue both the Micro-CT and Micro-Raman efforts. Micro- CT hydrate growth, monitoring, and dissociation experiments will continue and incorporate a mini-gas collection chamber to assess mass balance calculations during dissociation. Micro-Raman efforts will continue depressurization efforts at varying P-T conditions, with attempts to form hydrate in the presence of saline fluids (at higher temperature and pressure conditions). This work will also include a shift to use a flow-through Micro-Raman cell, in which researchers can create advection flow and pressure gradients to simulate natural production environments.

Project Start: October 1, 2016
Project End: September 30, 2019

DOE Contribution: $1,199,991
Performer Contribution: $300,000

Contact Information:
NETL – Richard Baker (
UTA – Dr. Peter Flemings (

Additional Information:

Quarterly Research Performance Progress Report [PDF] July - September, 2017

Quarterly Research Performance Progress Report [PDF] April - June, 2017

Quarterly Research Performance Progress Report [PDF] January - March, 2017

Quarterly Research Performance Progress Report [PDF] October - December, 2016