Development of enabling scientific tools to characterize the geologic subsurface at Hanford

Petrophysical models that relate borehole neutron and gamma ray data to reservoir properties including clay content, porosity, permeability, and water saturation have been successfully employed in the petroleum industry, but remain relatively undeveloped in the area of subsurface remediation.

The objectives of this research are to:

1) Analyze core and outcrop samples from representative facies for a variety of mineralogical, chemical and physical properties

2) Predict the response of a variety of neutron and gamma logging tools based on these measurements

3) Develop algorithms to translate log responses into reservoir properties useful for input in flow and reactive transport models

Initial work performed on eleven samples from Hanford well 399-3-18 (C4999), located near the Hanford 300 Area Integrated Field Research Challenge (IFRC) site, indicates a significant correlation between core gamma ray data and total clay as determined by Dual Range Fourier Transform Infrared spectroscopy. The core gamma ray data permit calibration of the existing gamma ray logs, hundreds which already exist at Hanford, into standard API units and then into total clay as a function of depth.

The algorithms being developed are applicable to archived borehole logs as well as to more complete suites of logs collected more recently and will therefore lead to improved interpretations. It is anticipated that this research will provide guidance in selecting the most appropriate logs to run in future logging programs depending on the desired properties and the uncertainty of the estimate. In addition it will improve our ability to remotely define subsurface petrophysical and flow properties, a pre-requisite for understanding subsurface processes and deigning effective remedial strategies. Although the focus of this study is on a single site, the approach may serve as a template for application at other sites where DOE has remediation responsibilities and stewardship challenges.