# Experimental Investigation into Dissociation Characteristics of Methane Hydrate in Sediments with Different Contents of Montmorillonite Clay

## TL;DR

This study examines how different amounts of montmorillonite clay affect methane hydrate dissociation in sediments, showing that higher clay content significantly slows down the process.

## Contribution

The novel contribution is the experimental investigation of methane hydrate dissociation in sediments with varying montmorillonite content, revealing its inhibitory effect.

## Key findings

- Montmorillonite content increases from 10 to 20 wt% cause a 47%–78% decrease in methane hydrate dissociation rate.
- Higher montmorillonite content leads to uneven dissociation due to low thermal conductivity and high water absorption.
- Resistivity changes are more pronounced in sandy sediments compared to clayey ones due to bound water effects.

## Abstract

The characteristics of gas production
in sediments are crucial
to the safe and efficient exploitation of gas hydrate resources. However,
research on methane hydrate dissociation in these sediments, particularly
in silty-clayey sediments, which are commonly found in nature, remains
limited and contains significant gaps. To address this, a series of
depressurization experiments were conducted to investigate the dissociation
behavior of methane hydrate in silty-clayey sediments with montmorillonite
contents ranging from 0 to 20 wt %. The results indicate that montmorillonite
significantly inhibits methane hydrate dissociation. When the montmorillonite
content increases from 10 to 20 wt %, the average dissociation rate
of methane hydrate decreases by approximately 47%–78% compared
to sandy sediments. An excess temperature drop of around 0.13 to
0.40 K was observed in the depressurization process as the montmorillonite
content increased from 10 to 20 wt %. Methane hydrate dissociates
unevenly in montmorillonite clay-bearing sediments due to the nonuniform
distribution of the methane hydrate, coupled with the low thermal
conductivity and high-water absorption capacity of montmorillonite,
which restrict the supply of extra heat. The electrical resistance
changes further reveal that the increased bound water content in clayey
sediments reduces the impact of water fluctuation on the resistivity
changes. Consequently, the resistivity changes in sandy sediments
are more pronounced compared to silty-clayey sediments. These findings
provide valuable insights for optimizing methane hydrate production
technology via depressurization.