Effect of thermal formation/dissociation cycles on the kinetics of formation and pore-scale distribution of methane hydrates in porous media: a magnetic resonance imaging study

Abstract

A magnetic resonance imaging study was conducted to explore the kinetics and spatial characteristics of the thermally induced methane hydrates formation in both synthetic and natural sediment samples. Low-resolution images...

Advances in Characterizing Gas Hydrate Formation in Sediments with NMR Transverse Relaxation Time

“…Given the advances in modern technology, many non-destructive detection techniques (e.g., X-ray computed tomography (CT), magnetic resonance imaging (MRI), Cryogenic scanning electron microscopy (Cryo-SEM), 13 C solid-state NMR, and NMR T 2 ) are used to acquire in situ quantitative and real-time characterization of gas hydrate formation process [47,50,51,[68][69][70][107][108][109][110][111][112][113][114][115][116]. This study compares their application characteristics in the fields of resolution, phase recognition, scanning time, advantages, and drawbacks.…”

“…NMR T 2 test provides a fast, easy, and non-destructive way of detecting hydrogenbearing fluids, which is widely used to monitor the dynamic behavior of gas hydrate formation and pore structure in sediments [30,[45][46][47][48][49][50][51][52][53]56,66,[68][69][70]. Figure 4 shows the schematic diagram of the NMR T 2 method applied to quantitative characterization of gas hydrate formation in sediments.…”

“…The gas hydrate showing a short T 2 cannot be identified because complete relaxation occurs before the first echo is detected [73]. Therefore, it is assumed that the NMR signals of hydrate and gas can be ignored by the LF-NMR [49,52,[54][55][56]66,69,70,74]. That is, the effective signals in the NMR T 2 measurement of gas hydrates are all from the water.…”

“…where I o is the T 2 spectral area of the water in the saturated sample before the hydrate formation, M c is the relative molecular mass of gas, M w is the relative molecular mass of water, and n is the hydration number. The chemical formula of methane hydrate is CH 4 •nH 2 O [1] in which n is taken as 5.78-6.1 in the process of saturation calculation [47,52,66,69,74]. The volume of gas hydrate (v h ) can be calculated by:…”

Insights into the climate-driven evolution of gas hydrate-bearing permafrost sediments: implications for prediction of environmental impacts and security of energy in cold regions

“…5,6 Tremendous research effort has been conducted so far to tackle technical and economic hurdles in order to develop commercially viable and environmentally friendly exploitation techniques. [7][8][9] Furthermore, injection of CO 2 or CO 2 -contained mixtures into gas hydrate-bearing sediments is a promising and efficient technique for simultaneous methane recovery and direct capture and storage of CO 2 . [10][11][12][13][14] From a different perspective, however, gas hydrate-bearing sediments play an important role in the global carbon cycle inuencing the Earth's climate, 15 as methane is 20-30 times more potent as a greenhouse gas than CO 2 .…”