Hydrate bearing clayey sediments: Formation and gas production concepts

Abstract

Hydro-thermo-chemo and mechanically coupled processes determine hydrate morphology and control gas production from hydrate-bearing sediments. Force balance, together with mass and energy conservation analyses anchored in published data provide robust asymptotic solutions that reflect governing processes in hydrate systems. Results demonstrate that hydrate segregation in clayey sediments results in a two-material system whereby hydrate lenses are surrounded by hydrate-free water-saturated clay. Hydrate saturation can reach 2% by concentrating the excess dissolved gas in the pore water and 20% from metabolizable carbon. Higher hydrate saturations are often found in natural sediments and imply methane transport by advection or diffusion processes. Hydrate dissociation is a strongly endothermic event; the available latent heat in a reservoir can sustain significant hydrate dissociation without triggering ice formation during depressurization. The volume of hydrate expands 2-to-4 times upon dissociation or CO 2-CH 4 replacement. Volume expansion can be controlled to maintain lenses open and to create new open mode discontinuities that favor gas recovery. Pore size is the most critical sediment parameter for hydrate formation and gas recovery and is controlled by the smallest grains in a sediment. Therefore any characterization must carefully consider the amount of fines and their associated mineralogy.

Introduction to Special Issue on Gas Hydrate in Porous Media: Linking Laboratory and Field‐Scale Phenomena

“…Writing in the Special Section, Sánchez et al () apply THMC to both laboratory experiments and simulations of field production testing. One of their key findings is that mechanical perturbation (shearing) can destabilize shallowly buried gas hydrate that has accumulated to high saturations, confirming an earlier laboratory result (Jang & Santamarina, ). Sánchez et al () also derive an analytical solution for the production of gas from a depressurized cylindrical hydrate reservoir and show that the solution closely matches that produced by the THMC code.…”

Mechanisms of Methane Hydrate Formation in Geological Systems

“…An alternative interpretation is that methane hydrate sourced from the local microbial process developed enough crystallization pressure to generate tensile fractures (Daigle & Dugan, ). This will occur when hydrate forms in pores of radius less than 4 σ hl /( P lith − P hydr ) ( P lith : lithostatic pressure [M · L · T 2 ], P hydro : hydrostatic pore pressure [M · L · T 2 ]; Clennell et al, ; Henry et al, ; Jang & Santamarina, ).…”

“…(P lith − P hydr ) (P lith : lithostatic pressure [M · L · T 2 ], P hydro : hydrostatic pore pressure [M · L · T 2 ]; Clennell et al, 1999;Henry et al, 1999;Jang & Santamarina, 2016).…”

Interfacial tension and contact angle in CO2‐water/nanofluid‐quartz system

“…) Moreover, at the same nanoparticle weight concentration, the IFT between air and water containing smaller nanoparticles is lower than that of the nanofluid containing a bigger size of nanoparticles . Because of the ability of nanoparticles to modify the properties of fluids and sediments, nanoparticles have a potential to be used in high‐pressure CO 2 applications such as geological CO 2 sequestration, CO 2 ‐enhanced oil recovery, CO 2 ‐enhanced coalbed methane recovery, CH 4 ‐CO 2 replacement in hydrate‐bearing sediments, and CO 2 ‐water foam generation …”

“…31 Because of the ability of nanoparticles to modify the properties of fluids and sediments, nanoparticles have a potential to be used in high-pressure CO 2 applications such as geological CO 2 sequestration, CO 2 -enhanced oil recovery, CO 2 -enhanced coalbed methane recovery, CH 4 -CO 2 replacement in hydrate-bearing sediments, and CO 2 -water foam generation. 16,17,[36][37][38][39][40] There are several explanations for the mechanism of IFT reduction due to nanoparticle inclusion. One of probable reasons for IFT reduction is (1) the alignment of nanoparticles at the interface between two liquids.…”