Project Goal
The project serves to provide thermal property data of pure, non-porous hydrate and non-porous hydrate-bearing sediments with varying hydrate composition that will provide data to help predict gas hydrate stability in sediments for the purposes of production or estimating release into the environment due to gradual warming.

Project Performers
Eilis Rosenbaum, NETL, Office of Research and Development
Robert P. Warzinski, NETL, Office of Research and Development
Ronald Lynn, NETL, RDS/Parsons
Dr. David Shaw, Geneva College

Project Location
National Energy Technology Laboratory, Pittsburgh, PA

Project Description
In Fiscal Year 2008 a greatly improved experiment design was completed for simultaneously determining the thermal conductivity and thermal diffusivity of hydrate and hydrate-containing sediments using a one-sided measurement approach. The process has been tested and research to repeat past experiments in which pure hydrate was measured need to be completed in the new system. An approach for accurately determining the thermal diffusivity will also be implemented into the data analysis. A numerical approach has been developed and will be tested for this purpose.

Research will also be performed to form hydrate in consolidated sediments that were once hydrate-bearing. Incorporation of the new, one-sided, thermal properties device in reactors designed for CT scanning will be pursued. X-ray CT scans will be obtained that provide information on the porosity and composition of the sample being measured. The best approach for determining the thermal properties of samples in the field is also being pursued for both portable devices and well-bore tools. The one-sided approach will be used with modifications such as a larger sensor having a larger signal and less noise and incorporating a durable design. Coordination with related researchers working in the field and with natural samples will continue.

Background

Measurement Technique
NETL utilizes a modified transient plane source (TPS) shown in Fig. 1 in a technique originally developed by Gustafsson [1, 2], in a single-sided configuration (Fig. 2). The TPS technique provides simultaneous determination of the thermal conductivity and thermal diffusivity. During the measurements, the TPS serves as a heat source and temperature sensing element. This technique is suitable for small sample sizes utilizing Vishay Micro-Measurement, Inc.’s commercially available ETG-50B temperature sensor (Figure 1). The sensor is adhered to PVC which provides support for the sensor, especially during compaction experiments and also allows for development to progress to an in-situ probe. This single-sided approach does not require large samples and it enables measurements to be made by surface contact with any sample.

	Figure 1: Vishay Micro-Measuremetns, Inc.'s temperature sensor, used in NETL's single-sided technique.		Figure 2: Single-sided (1 sided) TPS technique with the sensor adhered to PVC, as in NETL's arrangement, and the double-sided arrangement (2 sided).

Facilities and Equipment
The experimental equipment is shown in Figure 3. The TPS is part of an integrated container called the High-Pressure Thermal Properties Measurement Device (HTMD) that allows sample formation to occur directly on the sensor and subsequent sample consolidation, all in the same container under pressure. The HTMD consists of a sample cup containing the TPS sensor, an internal piston for controlling gas volume and for performing sample compaction, and pressure (digital Heise gauge, ± 0.02 %) and temperature (platinum RTD, ± 0.3°C) sensors. The HTMD is housed in an explosion resistant, programmable environmental chamber to provide temperature control (243 K to 343 K within 0.1 K) during experiments. Measurements are made on the sample during formation and throughout the experiment. Since the sample is formed in the container where measurements are made, sample integrity is better preserved. A picture of compacted methane hydrate formed in the HTMD and recovered in liquid nitrogen is shown at the bottom of Fig. 3.

Figure 3. The NETL high-pressure thermal property measurement system. A sample of compacted methane hydrate formed in the HTMD is also shown.

Current Status
Thermal property measurements have been made on pure methane hydrate and methane hydrate in sediments that have been formed in the laboratory. Validation of an improved experimental design is in progress. This new design will improve accuracy and facilitate field deployment. We are in pursuit of collaborations with other groups to incorporate our technique into existing devices for measurements in the field on preserved hydrate-bearing sediments and development of a mobile device for in situ measurements.

DOE Fiscal Year 2008 Contribution: $150,900.

Additional Information:
In addition to the information provided here, a full listing of project related publications and presentations as well as a listing of funded students can be found in the Methane Hydrate Program Bibliography [PDF].

2008 Hydrate Peer Review [PDF-2.08MB]

Publications
In addition to the information provided here, a full listing of project related publications and presentations as well as a listing of funded students can be found in the Methane Hydrate Program Bibliography [PDF].

Warzinski, R.P., I.K. Gamwo, E.J. Rosenbaum, E.M. Myshakin, H. Jiang, K.D. Jordan, N.J. English, D.W. Shaw; “Thermal Properties of Methane Hydrate by Experiment and Modeling and Impacts upon Technology,” [PDF] Proceedings: 6th International Conference on Gas Hydrates, Vancouver, Canada; July, 2008.

Rosenbaum, E.J, N.J. English, J.K. Johnson, R.P. Warzinski; “Thermal Conductivity of Methane Hydrate from Experiment and Molecular Simulation,” J. Phys. Chem. B, 112, 2007, 10207-10216.

Warzinski, R. P., R. J. Lynn, D. W. Shaw and E. J. Rosenbaum, “Thermal Property Measurements of Methane Hydrate Using a Transient Plane Source Technique,” in press, AAPG Hedberg Conference book on Gas Hydrates.

References
1. Gustafsson SE, Transient plane source techniques for thermal conductivity and thermal diffusivity measurements of solid materials. Review of Scientific Instruments, 1991; 62(3): 797 - 804.

2. Gustafsson SE, Device for measuring thermal properties of a test substance-the transient plane source (TPS) method. 1991, U.S. Patent 5,044,767 Thermetrol AB (SE): U.S. p.