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Behavior of Sediments Containing Methane Hydrate, Water and Gas…

DOE-FE-Office of Fossil Energy

Behavior of Sediments Containing Methane Hydrate, Water, and Gas Subjected to Gradients and Changing Conditions

 

OBJECTIVES
The objective of this work is to measure physical, chemical, mechanical, and hydrologic property changes in sediments containing methane hydrate, water, and gas subjected to varying stimuli and conditions such as injection of non-methane gases, effects of sediment layering, and the effects of relevant gradients (thermal, chemical (salinity or gas chemistry), and capillary pressure) on hydrate behavior. In this set of tests, we plan to evaluate the mechanical properties of hydrate-bearing sediments under controlled conditions to provide data sets for comparisons to numerical models. Measurements performed in this project are designed to supplement and support field and numerical simulation investigations to provide benchmark measurements and reality checks. We will share our results with those analyzing the test data, and the scientific community, and communicate with those analyzing the field test to ensure our tests are on target to answer their questions. The investigated hydrate-bearing sediments that are intended to model potential energy targets.

Hydrate systems are by nature complex, and simplification is required in laboratory studies to generate conceptual models that can be expressed numerically to aid in predicting gas production and mechanical changes of the sediments. A number of recent potentially relevant studies have been performed regarding measuring and interpreting mechanical properties in hydrate-bearing sediments. These studies and their results will be considered in test designs for this study.

SCOPE OF PROJECT
The purpose of this project is to gain a better understanding of the effects of the behavior of hydrate-bearing systems under a variety of conditions that could be expected in the field particularly under gas production conditions. During gas production, hydrate systems will be subject to thermal (from the endothermal dissociation), capillary (from the multiple phases) chemical (from water freshening and varying gas chemistries) and mechanical (from stress redistribution) influences, and each of these are likely to affect gas production.

  • How this will help meet program goals for hydrates?

This will help meet the program goals for hydrates by improving the understanding of the processes associated with 1. quantifying relevant processes and influences 2. aiding in understanding gas production from sediments having a variety of properties (e.g. layers, varying materials), and 3. providing a better understanding of hydrate behavior in systems having a natural or imposed gradient, and 4. aiding in understanding mechanical property changes.

  • What is the expected final product for the project (Model, Best Practices Manual, etc.)?

The final product will be reports submitted to NETL with interpreted results of laboratory tests. We will also provide informal intermediate reports and data sharing with interested parties prior to the preparation of the final report.

  • What value does this project provide to the hydrate scientific community?

This project will provide important information for interpreting other laboratory and field tests quantifying the importance of natural and imposed thermal, chemical, or capillary pressure gradients, and impacts on hydrological and mechanical behavior of hydrate-bearing sediments. Questions asked and answered on this project will be from a reservoir perspective understanding that many nonideal conditions can exist.

 
LBNL Tasks
Task 1.0 Project Management Plan
Task 2. Laboratory benchmark geomechanical tests for code validation

  • Subtask 2a. Design task with feedback from geomechanical modelers
  • Subtask 2b. Test design and construction in existing or off-the-shelf pressure equipment
  • Subtask 2c Perform a series of tests (cementing hydrate)
  • Subtask 2d. Devise transfer method/sample composition for pore-filling hydrate
  • Subtask 2e. Perform tests on pore-filling hydrate