Small Angle Scattering using neutrons and X-rays for the analysis of microporous materials

Sponsors
Through generous allocation of beam time by Jülich Centre for Neutron Sciences, GER; Paul-Scherrer Institute, CH; Oak Ridge National Laboratory, USA

Investigators
Andreas Busch, Amirsaman Rezaeyan, Jingsheng Ma

Collaborators
RWTH Aachen University,  Jülich Centre for Neutron Sciences, Germany; Paul-Scherrer Institute, Switzerland; Oak Ridge National Laboratory, USA; Shell Global Solutions International B.V., NL; SCK CEN, BE; Stanford University, USA

Research

Mudrocks form about 2/3 of all sedimentary rocks. Given that mudrocks hold the potential to produce oil and gas, it has been of much interest for the petroleum industry even though they are heterogeneous and anisotropic in nature and the general geomechanical, geochemical and hydrodynamical understanding is still limited. From a geological perspective, due to its low permeability, they are barriers for oil and gas but also CO2 storage reservoirs and are currently studied as a host rock for radioactive waste storage. Therefore, the detailed characterisation of the pore network needs to be taken into consideration. Mudrock is naturally defined by a broad range of pore size distribution, from macropores through mesopores and micropores. A large fraction of the porosity is associated with pores smaller than 2 nm which is partly inaccessible or non-resolvable to several invasion or microscopy methods . Contrary to such standard techniques, Small Angle Scattering (SAS) using neutrons (SANS) and X-rays (SAXS) has shown to provide a detailed resolution of the shale pore space, providing connected and non-connected porosity, as well as pore size distribution, specific surface area, pore alignment, pore relation to mineral phases and fractal dimensions. SAS results are expected to add valuable information to the pore network of mudrocks which is lacking in imaging methods due to insufficient resolution. Image-based modelling associated with SAS can accordingly make a contribution to a better understanding of fluid flow in mudrocks.

a) We use small angle scattering (neutrons and x-rays) to characterise pore structure of microporous earth and engineered materials, such as mudrocks, coal and cements
b) We aim for a better understanding of pore connectivity and gas-rock interactions by injecting deuterated methane and CO2
c) We analyse the impact of different humidity on pore connectivity and porosity distribution
d) We combine with low pressure sorption using N2 and CO2 to deliver a better understanding of pore size distributions
e) We use fractal dimensions obtained from SAS data to predict transport properties, such as effective diffusion coefficients
f) We study the relationship between pore space and mineralogy as well as pore orientation