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Coupled Hydrologic, Thermodynamic, and Geomechanical Processes of Natural Gas Hydrate Production
Project Number
FWP 72688
Last Reviewed Dated
Goal

This project seeks to bring new understanding of the coupled hydrologic, thermodynamic, and geomechanical processes that control the outcome of applying production technologies to natural gas hydrate bearing reservoirs for the purpose of recovering methane economically and at commercial scales.

Performer(s)

Pacific Northwest National Laboratory (PNNL), Richland, WA

Background

Hydrate systems in geologic media are multiple phase systems, in which the potential for both mobile and immobile phases occupy the same pore space, with the potential mobile phases being aqueous, gas, and nonaqueous liquid, and the potential immobile phases being ice and hydrate. Gas hydrates form at high pressures and low temperatures, and the stability envelope for natural gas hydrates span the triple-point of water, complicating the thermodynamics of hydrate systems via phase transitions, appearances, and disappearances. For example, a hydrate bearing formation, stable at temperatures above freezing, could yield ice formations with strong depressurization, resulting in hydrate dissociation and cooling. Hydrate structures vary across their host geologic settings, from large concretions in suboceanic muds to connected, pore-filling bodies in subarctic sandstones. The geomechanical reaction of a hydrate-bearing formation to the dissociation process depends on the contribution of the hydrate structure to the mechanical properties of the formation. Production of natural gas hydrates from geologic reservoirs is controlled by coupled processes, each with inherent complexities. 


This project will investigate the numerically and experimentally coupled hydrologic, thermodynamic, and geomechanical processes that dominate the production of natural gas hydrates from geologic accumulations. Production technologies will include both conventional (such as depressurization, thermal stimulation, and inhibitor injection) and unconventional (such as nitrogen injection, air injection, and former swapping). Production of natural gas hydrates from geologic reservoirs is controlled by coupled processes, each with inherent complexities.

Impact

This project will bring new understanding of the coupled hydrologic, thermodynamic, and geomechanical processes that control the outcome of applying production technologies to natural gas hydrate bearing reservoirs for the purpose of recovering methane economically and at commercial scales. Numerical simulation provides scientists and engineers with analytical tools for investigating the behavior of hydrate systems, incorporating coupled processes in the governing and constitutive equations.

Accomplishments (most recent listed first)

Budget Period (BP) 3

  • Completed initial simulations of production from Unit B via depressurization for the proposed Alaska Hydrate Production Test site using core and NMR based permeabilities. 
  • Initiated efforts to enable the the execution of the STOMP-HYDT-KE simulator with injection and production wells

BP 2

  • Led the conclusion of the 2nd International Gas Hydrate Code Comparison Study (IGHCCS2) with the submission of a manuscript to the Journal of Marine and Petroleum Geology (White et al., 2020). This study focused on the modeling of coupling thermal-hydrological-thermodynamic processes with geomechanical processes.
  • Continued collaborative research with KIGAM in support of its objectives of developing gas hydrate production technologies for reservoirs in the Ulleung Basin of the Korea East Sea

BP 1 

  • Continued development of CH4-O2-N2 gas hydrate modeling capabilities.
  • Lead the 2nd International Gas Hydrate Code Comparison Study (IGHCCS2) participants through a series of benchmark problems involving coupled flow, transport, thermodynamics, and geomechanics and contributed PNNL solutions to four of the five problems.
  • Initiated development of a publication to capture results of the IGHCCS2.


Please see the project page for FWP 65213 to view accomplishments from previous related efforts.

Current Status

IGHCCS2 logoEfforts under BP4 continue and are expected to be completed by end of September 2021.  Remaining activities focus on continued simulations related to potential Alaska hydrate production testing, full demonstration of the execution of the STOMP-HYDT-KE simulator with injection and production wells and the demonstration of the parallelization of the STOMP-HYDT-KE code through its simultaneous execution on a minimum of 8 core processors.  Discussions regarding activity for BP5 of the FWP will be ongoing in the early summer of 2021. 

Project Start
Project End
DOE Contribution

All DOE Funding
Total Funding to Date: $300,000 

Contact Information

NETL – Richard Baker (richard.baker@netl.doe.gov)
PNNL – Mark White (mark.white@pnnl.gov)