Time-of-flight neutron diffraction studies of clay-fluid interactions under basin conditions

Neutron diffraction experiments can provide an extremely high-resolution st ructural picture of clay-fluid systems. Here we describe the application of time-of-flight neutron scattering to hydrated clays, including discussion of issues such as isotopic labelling, sample containment, and data analysis . Recent studies of hydrated vermiculites under ambient conditions are used as an example. We then describe a new high-pressure/high-temperature sampl e environment that is being used to study clay-fluid interactions, in situ under hydrostatic sedimentary basin conditions. This environment enables us to approximate conditions encountered during burial, at depths of up to 10 km.