DOE/NETL METHANE HYDRATE PROJECTS
 
A Multi‐Scale Experimental Investigation of Flow Properties in Coarse‐ Grained Hydrate Reservoirs During Production Last Reviewed June 2017

DE-FE0028967

Goal
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.

Performer
University of Texas at Austin, Austin, TX 78712

Background
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.

Impact
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) 

  • 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 (June 2017)
Efforts will continue on finalization and shakedown of experimental equipment. Moving forward emphasis will be on transitioning experimental work on relative permeability and CT scanning to incorporate the use of methane hydrate in sand packs, developing and demonstrating techniques for efficiently and effectively generating synthetic hydrate samples in those sand packs with controllable hydrate saturations, and the ability to CT scan samples with sufficient resolution to distinguish hydrate from porous media. Micro-Raman work will continue to transition experimental processes to incorporate porous media with methane hydrate and demonstrate the ability to measure Raman spectra of those samples.

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

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

Contact Information:
NETL – Richard Baker (richard.baker@netl.doe.gov)
UTA – Dr. Peter Flemings (pflemings@jsg.utexas.edu)

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