Experimental Study of Brine Injection and Depressurization Methods for Dissociation of Gas Hydrates

Abstract

The two most promising techniques for producing natural gas from hydrate reservoirs are depressurization and brine injection. This paper examines the dissociation characteristics of methane hydrates during these processes. A correlation for the rate of hydrate dissociation during brine injection as a function of salinity, brine temperature, brine injection rate, pressure, and hydratelbrine surface area is presented. Depressurization experiments show that hydrate dissociation results in a decrease in the rate of pressure decline and contributes significantly (15% to 70%) to the cumulative gas production.

Mechanical behaviors of permafrost-associated methane hydrate-bearing sediments under different mining methods

“…In recent decades, several methods have been proposed to produce methane gas from methane hydrate-bearing sediments, including depressurization, heating, chemical injection, and CH 4 -CO 2 replacement (a potential CO 2 storage method) [8][9][10][11][12][13][14]. However, there are many uncertainties in the production process, especially related to the deformation of the ground caused by hydrate dissociation [7].…”

Methane Hydrate Production From Alaskan Permafrost

“…Kamath, Mutalik et al 1991;Yousif, Abass et al 1991;Goel, Wiggins et al 2001) • A single well, cyclic thermal injection model where hot brine or steam is injected into the hydrate formation, hydrates are allowed to dissociate during a "soak" period and then gas and water are produced from the well ).…”

“…Most of the research conducted to date consists of lab scale experiment to evaluate stimulation techniques (Sira, Patil et al 1990;Kamath, Mutalik et al 1991;Ershov and Yakushev 1992) and the development of numerical models to simulate thermal stimulation and…”

“…In addition, the dissociation of hydrates will add pure water to the formation diluting the brine concentration. (Kamath, Mutalik et al 1991) conducted laboratory experiments on hydrate dissociation using the brine injection methods. Salinity of the brine used to dissociate the hydrates was reduced by approximately 3 to 5% as the hydrates dissociated.…”

Modelling and economic analysis of gas production from hydrates by depressurization method

“…In terms of energy content, they are more similar to heavy oil and tar sand bitumen than to other unconventional gas resources. While hydrates contain 40-50 SCM of hydrated gas (42-53 MI) per cubic metre reservoir based on 30% porosity, coalbed methane contains 8-1 2, tight sands contain 5-1 0, Devonian Shale and geo-pressured aquifers contain only 1-2 SCM of gas per cubic metre of reservoir (Mutalik, 1989).Gas hydrates exist in reservoirs as relatively immobile and impermeable solids. The first step in production is to decompose gas hydrates into gas and water by various means.…”