Polymer-Assisted Chemical Inhibitor Flooding: A Novel Approach for Energy Recovery from Hydrate-Bearing Sediments

Abstract

Recent production technologies to extract methane from mysterious hydrate reservoirs are not effective and need additional efforts to develop novel technologies to improve methane production. Chemical inhibitor injection is appraised as an effective method due to ease in operation, improved energy efficiency, and reduced threat of hydrate reformation. In the current study, several experiments on methane recovery have been performed in a simulated laboratory-based hydrate reservoir by injecting chemical inhibitors and combinations of aqueous chemical inhibitor/polymer systems. Different combinations of inhibitors and polymers, viz., chemical inhibitors such as methanol, ethylene glycol, methanol + polyacrylamide, and so forth, with varying concentrations, have been explored. Polyacrylamide has been used as in our previous study, it was shown that it can act as a better kinetic hydrate inhibitor, and also, the same polymer is often used for the enhanced oil recovery process in the upstream oil industry. In total, seven different simultaneous hydrate formation and dissociation experiments were performed. The inhibitor + polymer aqueous solution was injected to produce methane by dissociating the hydrate. The gas production ratio and the effectiveness of inhibitor aqueous solution and pure inhibitor in terms of methane recovery from hydrate-bearing sediments have been discussed and analyzed. This study provides a good insight into the use of some of the conventional hydrate inhibitors along with the oilfield polymer for methane recovery from hydrate-bearing sediments.

Review and Perspectives of Energy-Efficient Methane Production from Natural Gas Hydrate Reservoirs Using Carbon Dioxide Exchange Technology

“…KHIs, such as amino acids, inhibit the formation of hydrates by delaying nucleation . Chemical inhibitors injected inside the hydrate formation interfere with the in situ stable hydrate formation’s inherent stability and prevent the hydrate from continuing in its solid state . Some nanoparticles such as nanosilica (SiO 2 ), zinc oxide (ZnO) aluminum oxide (Al 2 O 3 ), and fluorinated graphenes improve sediment conductivity and alter pH values that eventually improve CH 4 displacement either by extending the induction time or by improving adsorption promoting exchange .…”

Review of Gas Hydrate Research in India: Status and Future Directions

“…Chemical inhibitor injection is one of the methods for methane recovery from hydrates, Advantages include the avoidance of re-formation of hydrates along with improved energy efficiency and ease of operation. Gupta et al 85 performed experiments to study the effect of a polymer, polyacrylamide, at a low concentration of 200 ppm alongside methanol of two different mole fractions, 0.07 and 0.2. In both cases, a significant improvement in recovery was noticed.…”

A Comprehensive Review on Well Completion Operations and Artificial Lift Techniques for Methane Gas Production from Natural Gas Hydrate Reservoirs

“…However, because of certain associated problems with depressurization (mostly slow production rate due to endothermic nature of hydrate dissociation) it is advised to used depressurization alternated with thermal stimulation . In addition to the standard methods, inhibitors combined with polymer aqueous systems were also observed to enhance methane production from hydrate bearing sediments in some recent literatures. , Thus, low temperature and high pressure environment accompanied by change in physical properties of the hydrate bearing sediments due to hydrate dissociation requires a tailor-made production strategy that would be different from conventional resources …”

“…13 In addition to the standard methods, inhibitors combined with polymer aqueous systems were also observed to enhance methane production from hydrate bearing sediments in some recent literatures. 21,22 Thus, low temperature and high pressure environment accompanied by change in physical properties of the hydrate bearing sediments due to hydrate dissociation requires a tailormade production strategy that would be different from conventional resources. 23 Some of the immediate challenges associated with gas hydrate reservoirs includes, narrow margin between pore pressure and fracture gradient, surface hole instability, subsidence caused by hydrate production, pressure and temperature management, which alters hydrate dissociation in wellbore, ice and hydrate reformation, etc.…”