Hydrate control has always been essential to oil and
gas pipeline
flow assurance work. To study the decomposition process of the hydrate
deposition layer in the gas–water system, the decomposition
experiments of the hydrate layer on the gas-phase pipe wall under
different heating temperatures, different depressurization rates,
and the combined action of heating and depressurization were carried
out by using a high-pressure transparent rock-flow cell with a voltage
detection system. The dynamic decomposition process was observed,
and it was found that the decomposition rate was faster when decomposed
by the depressurization method compared to the heating method. The
decomposition process of the hydrate layer was quantitatively analyzed
based on the voltage signal, and an electrical signal-based method
for monitoring the decomposition of the hydrate layer on the pipe
wall was proposed. The decomposition mechanism of the hydrate layer
in different ways is summarized. During decomposition by heating,
the hydrate layer decomposes in the mode of shrinkage ablation. During
depressurization decomposition, it decomposes in the mode of differential
ablation with the shedding phenomenon. The impact force generated
by the gas release is the main reason for hydrate layer shedding.
Shedding of the mixture of ice and hydrate occurs at depressurization
rates ranging from 0.026 to 0.056 MPa/s, with the risk of ice blockage.
This work provides further insight into hydrate decomposition in gas–water
flow systems.