# Presentation: 949201

## 
Visualization of hydrate formation and dissociation in a core-size sediment sample

- Visualization of hydrate formation and dissociation in a core-size sediment sample

## Experiment Schematic

## Tests Performed

- Thermal test without hydrate
- Hydrate formation
- Thermal test with hydrate
- Thermal stimulation (dissociation)
- Second hydrate formation
- Depressurization and thermal stimulation (dissociation)

## Overview

**E**

**D**

**C**

**B**

**A**

**F**

## Experiment path

- B

- C

- E

- F

- D

- D

## Estimation of thermal conductivity by inverse modeling

- Sand/water/gas
- k=2.38 W/m/K
- Fa=0.00434

- Sand/hydrate/
- water/gas
- k=3.15 W/m/K
- Fa=0.00217

## Location of hydrate formation

- Difference

- Initial

- Hydrate conversion = 63%

## Attenuation differences

| Cause | Range | Density Change (g/cm3) |
| --- | --- | --- |
| Hydrate formation | 0 to 100% | 0 to ~0.03 |
| Saturation changes | 0 to 100% | 0 to ~0.36 |
| Mechanical deformation | 2% porosity change | 0.03 |
| Gas pressure | 0-6.1 MPa | 0.05 |

## Thermal Stimulation

## Second hydrate formation

## Depressurization/Thermal Stimulation

## Density changes (average over 51 images)

- Initial

- Hydrate
- Formation

- Thermal
- Stimulation

- Second Hydrate
- Formation

- Depressurization

## Sand/water system

**1 mm**

- Conceptual (l.) and imaged (r.) structure of partially water saturated sand.  In the microtomograph, gold is silica sand, purple is water, and black is gas.

## Hydrate-induced capillary pressure gradient

- Hydrate partially fills pore space reducing pore size and increasing capillarity.  This induces water flow towards the hydrate.

## Publications/Presentations

- Kneafsey, T.J., L. Tomutsa, G.J. Moridis, Y. Seol, B.M. Freifeld, C.E. Taylor, and A. Gupta, 2005, “Methane hydrate formation and dissociation in a core-scale partially saturated sand sample”, accepted, Journal of Petroleum Science and Engineering, December, 2005. LBNL-59087.
- Gupta, A., T.J. Kneafsey, G.J. Moridis, Y. Seol, M.B. Kowalsky, E.D. Sloan Jr., 2006. “Methane hydrate thermal conductivity in a large heterogeneous porous sample”, in preparation for submittal to Journal of Geophysical Research, January, 2006, LBNL-59088.
- Kneafsey, T.J., L. Tomutsa, G.J. Moridis, Y. Seol, B. Freifeld, C.E. Taylor, and A. Gupta, 2005. “Methane hydrate formation and dissociation in a partially saturated sand-measurements and observations”, Fifth International Conference on Gas Hydrates, Trondheim, Norway LBNL-57300.
- Moridis, G.J., Seol, Y. and Kneafsey, T.J., 2005. “Studies of reaction kinetics of methane hydrate dissocation in porous media”, Fifth International Conference on Gas Hydrates (ICGH 5), Trondheim, NorwayLBNL-57298.
- Kneafsey, T.J., L. Tomutsa, C.E. Taylor, A. Gupta, G. Moridis, B. Freifeld, and Y. Seol, 2005. “Methane hydrate formation and dissociation in a partially saturated sand”, 229th ACS National Meeting, San Diego, CA.
- Gupta, A., E.D. Sloan, T.J. Kneafsey, L. Tomutsa, G. Moridis, 2005, ”Modeling methane hydrate dissociation x-ray CT data using a heat transfer model”, Fifth International Conference on Gas Hydrates, Trondheim, Norway, June 2005.