The overall objective of this project is to conduct numerically-based studies to characterize and analyze recoverable resources from gas hydrate deposits, evaluate appropriate production strategies for both permafrost and marine environments, and analyze the geomechanical behavior of hydrate-bearing sediments, as well as provide support for DOE’s hydrate-related activities and collaborative projects.

Lawrence Berkeley National Lab (LBNL), Berkeley, CA 94720: model modifications and runs; project management

TOUGH+/HYDRATE (pT+H) is a code developed by LBNL that simulates the behavior of hydrate-bearing geologic systems. By solving coupled equations of mass and heat balance, pT+H can model the non-isothermal gas release, phase behavior, and flow of fluids and heat under conditions typical of common natural methane (CH₄) hydrate-bearing deposits in complex formations. pT+H includes both an equilibrium and kinetic model of hydrate formation and dissociation. The model accounts for heat and up to four mass components, i.e., water, CH₄, hydrate, and water-soluble inhibitors, such as salts or alcohols, portioned among four possible phases (gas phase, liquid phase, ice phase, and hydrate phase) and up to five components (heat, hydrate, water, CH₄, and water-soluble inhibitors). Hydrate dissociation or formation, phase changes, and the corresponding thermal effects are fully described, as are the effects of inhibitors. The model can describe all possible hydrate dissociation mechanisms, i.e., depressurization, thermal stimulation, salting-out effects, and inhibitor-induced effects. Under this project, LBNL is developing and maintaining pT+H as well as actively using the program to predict the behavior of hydrates and hydrate-bearing geologic systems in the laboratory or field, and from pore to regional scale.

These numerical modeling efforts will enable hydrate scientists to better assess, identify, and predict the behavior of hydrate-bearing sediments under natural- and hydrate-production conditions for various hydrate occurrences in both Arctic and deepwater marine environments. The efforts will contribute to the planning and assessment of hydrate program field tests and continue to define the feasibility of hydrates as an energy resource.

Overall Project

• Developed the knowledge base and quantitative predictive capability to describe and simulate gas production from hydrate deposits.
• Expanded capabilities of the TOUGH+HYDRATE (T+H) serial and parallel codes, which are used by over 40 research institutions in 18 countries and have been part of nearly every international hydrate program.
• Developed new coupled geomechanical capabilities and increased understanding of the geomechanics of hydrate reservoirs.
• Contributed to the design and evaluation of DOE and international field tests, including the Prudhoe Base Unit (PBU)-L106, Ignik Sikumi, Korea’s Second Ulleung Basin Gas Hydrate Drilling Expedition (UBGH2) site 6, and Indian National Gas Hydrate Program (NGHP) site 2.
• Published or submitted more than 10 peer-reviewed papers since 2012 (50+ overall).

Budget Period 6 (April 2017–July 2018)

• Completed simulations of the production behavior of horizontal wells in sloping systems including geomechanical effects. Results reflect little to no chance of slope failure during a phydrate production cycle.
• Completed testing of the new integrated T+H/Millstone geomechanical code through use in real world simulations of Offshore India site 9.
• Completed simulations of six India NGHP Site 9 production scenarios with and without coupled geomechanics and examined the fate of hydrate reservoirs after the cessation of production, which resulted in two conference papers. Results presented to NGHP in a meeting in April 2018.
• Generated new meshes for continuing simulations of NGHP Site 9 using new geologic models developed in consultation with NETL, the United States Geological Survey , and Indian scientists.
• LBNL team continues  participation in the new International Code Comparison study of gas hydrate simulators with a focus on the study of coupled flow, thermal, and geomechanical processes.

Budget Period 5 (May 2016–June 2017)

• Completed initial simulations of long term production test at Indian Hydrates site 9.
• Completed initial model development and simulations of offshore Indian Hydrates site 9 including base cases, parametric sensitivity studies, heterogeneous systems, and varying layer configurations. Results were presented to DOE and Indian NGHP representatives at a meeting in December 2016.
• Developed and tested non-Darcian flow capabilities combining the capabilities of TOUGH+ Real Gas Brine code with T+H.
• Completed simulations of long term fate of hydrate reservoirs following cessation of hydrate production. Results are being processed.

Budget Period 4 (August 2015–July 2016)

• Concluded simulations describing gas production using slanted wells in homogeneous/heterogeneous hydrate deposits with emphasis on alternating sand-clay lenses.
• Completed preliminary investigation into production potential and geomechanical behavior of recently discovered offshore gas hydrate deposits in the Bay of Bengal, India.
• Incorporated improvements to the T+M coupled flow-thermal-geomechanical code to include parallelization of ROCHMEC component, new matrix solver, and new grid creation capabilities.
• Completed a new series of 10 highly heterogeneous realizations of system properties as part of coupled flow geomechanical simulations describing the short term gas hydrate production field test planned by the Korean hydrate program in the Ulleung Basin, offshore Korea (using the new V1.5 T+H and T+M codes).

Budget Period 3 (June 2014–July 2015)

• Completed a design package on the revised evaluation of production from Korean hydrates, accounting for both flow and geomechanical issues, and delivered the assessment to the Korea Institute of Geosciences and Minerals (KIGAM).
• Completed incorporation of parallel solvers into the pT+H code, with a new version (V 1.5) released in September 2014.
• Completed simulations of coupled flow and geomechanics describing a short-term field test of gas production from hydrate for the Ulleung basin, Korea.

 
Budget Period 2 (June 2013–June 2014)

• Completed initial analysis and history matching efforts of the depressurization phase of the 2012 ConocoPhillips Ignik Sikumi gas hydrate production test.
• Completion of simulations on the effectiveness of slanted wells in production of gas from highly stratified hydrate deposits and analysis of results.
• Completed a study of production from a large-scale, extremely heterogeneous reservoir in contact with large aquifers in the Gulf of Mexico (GoM) using both horizontal and vertical wells (paper currently in press in Transport in Porous Media).
• Completed the simulation analysis of coupled flow, thermal, and geomechanical system response during gas production for sites in the GoM (GC955 and WR313) expanding on a prior Offshore Technology Conference (OTC) paper.
• Addition of capabilities to TOUGH + HYDRATE code that enable tracking of properties, conditions, and flows throughout the simulation.
• Completed incorporating a new package of parallel solvers (PETC Package) into the Unicode version of TOUGH + HYDRATE (uT+H).
• Completed the simulation analysis of coupled flow, thermal, and geomechanical system response during gas production from a well representative of PBU L106 well (Alaska North Slope) using both horizontal and vertical wells (submitted for publication to SPE Journal).
• In cooperation with the KIGAM, completed simulations in support of planning for a 2014 short-term production field test in the Ulleung Basin of the Korean East Sea including a base case, three different depressurization rates, sensitivity analyses on multiple parameters, and a fully coupled flow and geomechanics study. Results were presented in a paper at OTC 2014.

Budget Period 1 (June 2012–May 2013)

• Developed a working prototype of uT+H.
• Publicly released new versions of both the serial and parallel T+H codes (with improved thermodynamics and thermophysical properties and new control and output capabilities).
• Completed two collaborative studies (with KIGAM, Korea) on the production potential and corresponding geomechanical system behavior of Korean marine hydrates in the Ulleung Basin.
• Developed and tested a two-way, fully-coupled flow-thermal-geomechanical simulator (involving T+H and ROCMECH).
• Published two papers on coupled flow-thermal-geomechanical processes in producing hydrate systems.
• Completed the largest numerical study ever conducted on evaluating the behavior of marine hydrate deposits.
• Completed studies on gas recoverability from the PBU-L106 site in Alaska.
• Published a chapter in Advanced Biofuels and Bioproducts on the status of gas production from hydrates.

For accomplishments from past, related efforts, please see the project page for FWP G308.

pT+H is available to commercial and non-commercial users from LBNL [external site]. Non-commercial licenses are available to academic and research institutions at reduced cost and are free of charge for users working on U.S. government-sponsored research projects. Details on licensing and associated licensing costs can be found on the TOUGH+ licensing site [external].

Activities under the project are now complete and a summary of activities, accomplishments and key findings can be found in the project Final Report accessible from the additional information section below.  Numerical simulation activities with LBNL will be ongoing but will be conducted under new project number FP00008138, which initiated in October 2018.

Key findings resulting from activities under this project include:

• The careful characterization of reservoir boundaries (top, bottom, lateral) is essential to assessing production potential, as effective -depressurization is needed to ensure sufficient production
• Coupled geomechanics is key to realistic simulation of reservoir evolution, beyond just the assessment of geohazards
• Both large- and small-scale simulations are required to understand hydrate behavior — subtle thermodynamic behavior and fine structure is important for description large-scale reservoir performance

$1,250,000

$0

NETL – Richard Baker (Richard.Baker@netl.doe.gov)
LBNL – George Moridis (gjmoridis@lbl.gov)

Final Project Report [PDF] December, 2018