Micro X‐Ray computed tomography imaging and ultrasonic velocity measurements in tetrahydrofuran‐hydrate‐bearing sediments

Abstract

Naturally occurring gas hydrates contain significant amounts of natural gas that might be produced as an energy resource in the foreseeable future. Thus, it is necessary to understand the pore‐space characteristics of hydrate reservoirs, particularly the pore‐scale distribution of the hydrate and its interaction with the sediment. Four end‐member models for hydrate distribution in the pore space are pore filling, sediment‐frame component, envelope cementing, and contact cementing. The goal of this study is to compare the models with pore‐scale hydrate distributions obtained in laboratory‐formed hydrates. Our results verify hydrate pore‐scale distributions by direct, visual observations that were previously implied by indirect, elastic property measurements. Laboratory measurements were conducted using tetrahydrofuran as a guest molecule since tetrahydrofuran hydrate can be used as a proxy for naturally occurring hydrates. We performed micro X‐ray computed tomography to obtain information about the distribution of hydrate in the pore space of synthetic sediment (glass beads). We also made ultrasonic velocity measurements on the same samples. Micro X‐ray computed tomography images and ultrasonic velocity measurements both indicate that the tetrahydrofuran hydrate forms in the pore space with a part of the hydrate bridging the grains without touching the grain surfaces. These hydrate‐bearing sediments appear to follow a pore‐filling model with a portion of the hydrate becoming a load‐bearing part of the sediment frame.

Hydrate morphology and mechanical behavior of hydrate-bearing sediments: a critical review

“…Different mechanisms contribute to different hydrate morphologies. Various researchers have explored the pore habit of the hydrate in the synthesized HBS using the X-ray computed tomography (CT) technique, which enables non-destructive 3-D visualization of porous media (Chaouachi et al 2015;Li et al 2019b;Mahabadi et al 2016b;Schindler et al 2016;Seol et al 2019;Takeya et al 2007;Wu et al 2020aWu et al , 2020bYang et al 2015). This technique provides an insight into hydrate nucleation, growth, and distribution in the HBS.…”

Hydrate Dissociation Using Microwaves, Radio Frequency, Ultrasonic Radiation, and Plasma Techniques

“…Experimental studies on characterization of tetrahydrofuran hydrates were carried out by Pohl et al [40]. On the other hand, pore space characteriza-tion using ultrasonic waves was performed by Schindler et al [41]. Recently, a more novel method of detecting natural gas hydrates using ultrasonic assisted technique was developed by Li et al [42].…”

“…3. As discussed earlier, the use of electromagnetic radiation for enhanced oil recovery is well known [35,41,42]. However, application of electromagnetic radiation for gas recovery from natural gas hydrate reservoirs is still largely unexplored territory.…”

“…On the other hand, pore space characterization using ultrasonic waves was performed by Schindler et al. . Recently, a more novel method of detecting natural gas hydrates using ultrasonic assisted technique was developed by Li et al.…”

Application of X‐Ray Computed Tomography Technology in Gas Hydrate

“…The micro X‐ray CT and ultrasonic velocity measurements were used to obtain the hydrate distribution information in the pore space of synthetic deposits (glass beads) by Schindler et al The results showed that tetrahydrofuran hydrate was formed in the pore space. To visually observe the occurrence mode of hydrate, the 40 wt% tetrahydrofuran and 25 wt% barium chloride were used in the artificial sand with a particle size of 500 μm.…”