Energy analysis and determination of controlling mechanisms of dissociation for hydrate reservoirs via tracking of dissociation front

Abstract

A number of dissociation techniques like depressurization, thermal stimulation, CO2 exchange, etc. have been reported and investigated for natural gas hydrates in literature. However, dissociation of hydrate reservoirs is a complex process that is actually governed by several parameters. Hence, when inspected closely, the dissociation characteristics are a reflection of how these parameters are interlinked with each other. The present study is designed to numerically simulate a matrix of 21 different cases, which comprises an in-depth analysis for thermal stimulation, drawdown pressure, permeability, intrinsic rate constant, and thermal conductivity. The focus of the current study is motivated by practical interest, which aims at deciphering the associated mechanisms with hydrate dissociation. Over the years, different researchers have outlined the role of mechanisms such as heat transfer (HT), fluid flow (FF), and dissociation (D). The governing mechanisms are deduced through mathematical fitting and plotting of thermodynamic parameters for deciphering associated mechanisms. A “characteristic exponent” is determined for each of the cases to identify and delineate the different mechanisms for each of the 21 cases. Further, energy conversion from hydrate and energy quantification has been described in detail. As such, this information pool about hydrate dissociation is vital and necessary for efficient energy harvesting from hydrate reservoirs from varied geological settings and composition.